Yolume 42rr. 1-212003

rssN 0375 7633

Bollettinodella

Societn Paleontologic aItalianaPubblicato sotto gli auspicidel Consiglio Nazionale delle Ricerche

MUCCHI - MODENA

Bollenino della Societh Paleontohgica ltaliana 42 (r-2),2003rssN 0375-7633 1-29 Modena, Giugn o 2003

KEY II(/ORDS - Algoe, Systematics, Palaeobiogeography, Late Ordouician, Sardinia, Italy

ABSTRACT - From the siliciclastic Portixeddu Formation, LAte Caradoc-Early Ashgill, ofand Cyclocrinites (Dasyckdales) aw d.escribed. Thrt are fepresented by Cyclocrinite s- afi viCyclocrinites. g., Ischadites g. a ayd Ischadite! ?. b in thi hight, pait of'theformation"."Cy,structure at thi base of bryo7oan colonies. Secordory growth of ,bq thZllus i|CyLtocrinites hiplrosettes. As this groryth mbchqnism I drfferent fom' Ftttptatit;t;dot but found in certain DaiytVariation in abundance and spatial distribution of the algae correlate with water depth indiiatities of the substrate. In Sardiiia Cyclocrinites zi ionfinetr n siltstone beds deposited below norm,Fauna in the lower. part and the Nicolella Community in the upper pirt of the PortixedtAssociations 3-4 indiTating water depth of 20-60 m, Wlhln this siope th, abindance decreAs,in intercalated mudstone beds as *eil at i uery shallow neAr shore sindstone facies with CalynIschadites has b:tryfoynd only.a! orye locality uthere it rarely occurs in storm dominated mudstonwater elements Ischadites and.Cyclocrinites supports the concept of southequatorial curcents th,aia Baltica to the North Gondwana margin duing Late Caraioc io Middle Ashgilt times. It alsSardinia in a marginal position within ihe outerltnstable shelf region of North"Gondwana dui

KURZFASSU /G - Aus der siliziklastischen Portixeddu Formatiory des spciten Caradoc biIschadit 9s (Rgceptaculitidae) qnd Cyclocrin ires (Dasycladales) beschrieben, uon denen CyclocrTbil und_Cyclocrinites s2., Ischadites sp.a und Ischadite! ?. b im hiiheren Tbil der Formationmorphe_Stuhtur an der Basis uon Bryozoenkolonien erhaltin. Das sekundiire Thalluswachstumneuen Laterals im Zentrum uon Rosetten. Dass dieser W'achstumsmechanismus sich uon dem der .gen Dasyckdales wiederfndet, deutet.auf eine Zugeharigkeit zu den Letzteren ltin. (Jnterschieddieser Alge sind aon der tWassertiefe abhangig, die wiede/um ilber das Energieniueau, die BenthrDie Vorkommen uon Cyclocrinit es in Sardinien beschriinken sich auf Silisteine, die unterhalbAufneten zusAmmen mit der Svobod aina-Fauna im tieferen Tbil und der l\icolella-Gemeinscerkubt eine Korrelation mit den Benthos-Assoziationeh 3-4, was einer Wassertiefe uon etwaBereiches nimmt die Haufigheit mit abryeQmgnder Ti:ft qb. Cyclocrinites fthl, in zwischenge,Flachwassqrfaziu mit Dreyfussina exophthalma und Calymenella boisseli. Ischadit es dagege'gen Lokalittit in Sturm-dominierten Tbnschiefern gefunden. Das Aufreten der zirkr*liq,Cyglo-grinites unterstiltzt die Hypothese der Existenz uon siidiiquatorialen Meeresstiimungin,Ashgill temperierte

'W'assermAssen und Laraen uia BalticA zum.Ngrdgondwana-Rand trarupor

tonische Annahme, dass SVf Sardinien zu dieser Zeit eine randliche fage innerhalb des instabi,

RASSUNTO - [ generi Ischadites Murchison, 1839 e Cyclocrinites Eichwald, 1840 dPortixeddu (Sardegla q\ft)l - Wngono seg?qkti e descrini in alcuni liuelli della formazione(kceptaculitidae) q9yrlpcrinites (Dasyqkdales). Essi sono rappresentati da Cyclociinites aff ,Cyclocrinites sp., Ischadites sp. ? r Ischadites g. b nelk parte piil alta della formazioni. Cailomorfca alk base di colonie di briozoi. L'acciescimento irtorlorio del tallo 2l Cyrlocrinirr"lateral" al centro d.elle "rosette". Poichi questo meccanismo di crescita i diuerso'da quelloDasyckdalu, i ciclocrinitidi uengono inclusl i7 quesq' ultimo gruppo. La uariazione della fequecon la profrnditQ dell'acqua inrtcata anche dal'liuello di eneigii,' dalle comunitd bentonichi , ,si noua tolo i, liuelli siltitici che si sono depositati al di soio del liuello normale della base aSvobodaina" nelln parte bassa e con la *Comunith

a Nicolglt? " nella parte aba della Formaziola "Benthic Association 3-4" che indica una profondith dell'acqua Tompresa trA i 20-60 mediminuisce parallekmente al diminuire delk profondith. Cyclociitriter *onto negli strati piil nnarie d!..acQua bassa con Calymenella boissef e breyfussina exophthalma. Ischaiit es i stato tr,rnro all'interno di yemp.estiti marnose. La 2resenza di Ischadites c di Cyclocrinites, normaln,falrgrisce l'ipotesi che, durante un interualJo co.mpreso tra la parte aha del Caradoc e la parteabbiano^trasportato masse di acqu4 temperatq, krue comprese,-da Balticafno al margine sinennua del fooo- che k Sarfugna tud-octiilentale aarebbe ottupato, duranti quetl'inteiuallo di teiporzioie instabih pin estirna del Nord Gondwana.

The rlg.l genera Ischadites Murchison, 1839 and Qtfrom the Upper Ordovician Portixeddu Formation

t \fofgang HauueNN'Wasserlosen

Enrico SnnpncllUniversit) di Modena

L E G E N D

I ITI HAMMANN, E. SERPAGLI

Autochthonous unitpre-Sardicsequence

Arburese nappe

l-ll l

1;F1| + + + ll + + + ' lH ffi ffiiJffJt? ;:1f.ffi#$,.t.n ru overthrusr1-Por 13; 2-Por7a; 3-Por 10; 4 -Por 12; 5 -Flu 4; 6'Text-fig. I - Generalized geological map of the Iglesiente region with study areas and outcr

* localities L.Ord.-Dev.rockspost-Hercynian

igneous rocks

DASYCIADALES AND RECEPTACULITIDAE FROM L, ORDOVICIAN OF SARDINII

INTRODUCTION

"Lower Silurian" or Upper Ordovician rocks and

fossils from the Iglesiente region of southwesternSardinia have been known for almost 150 years(Della Marmora, 1857) and have been subject ofmany earlier publications (Meneghini in DellaMarmora, 1860; Meneghini, 1880; Thricco, 1922;Vinassa, 1927, l94l). Systematic mapping and col-lecting carried out during the last rwo decadesrevealEd a wealth of new dita and led to a modernlitho-and biostratigraphical subdivision and correla-tion of the post-Sardic late Ordovician succession(Leone et Al., l99l; Bechstiidt & Boni, 1994; Leoneet Al. , 1998).

In the present article the senera IschaditesMurchison, islg for the first time"and CyclocrinitesEichwald, I840, whose presence was alreadyannounced (Leone et Al., 1993, p. 412) as

"a very

common, small, net-like problematic probably refer-able to receptaculitids", or preliminary reported(Serpagli & H"--ann, 2000i from the'PortixedduFormaiion (late Caradoc-early Ashgill). V/hile Ischa-dites is very rare and has so far been observed at onlyone localiry Cyclocrinites is more widespread andlocallv abundant.

Iichadites and Cyclocrinites belong to thePalaeo zoic fossil g.olpr of recept".,tlitidt and

ryclocrinitids, respectively, whose systematic place--.trt has been disputed since their first descripiions.As the skeleton oI both these groups show lertainmorphological similarities, e.g. a central caviry sur-ro,ttrded b"y a calcareous wall Jf itrdividual lateral ele-ments which consist of a radial shaft and a polygonalhead, they were often compared and placed, amongothers, with foraminifera, bryozoa, sponges, mol-luscs, echinoderms or algae.

\7hile a relationship of cyclocrinitids with dasy-clads, which was first proposed by Stolley ( 1896,I 898), is generally accepted today, the systematicplacement

-of receptaculitids is stili being discussed

(Nit..kr et al., l9r9). Apart from a possib-le relation-ships with either sponges (Foster, 1973; Bassoullet etal.: 1979, p. $9; Dz-ik, 1994) or archaeocyarhids,with which they may constitute the kingdomArchaeata Zhuravlaeva 6( Myagkova, 1970 (seeNitecki Sc Debrenne, 1979; Rietschel & Nitecki,1982), placement among algae (Kesling & Graham,1962; Byrnes , 1968; Rietschel, 1959, 1977; Elliott,1972; Campbell et al., I974; Brummer, 1979) and inparticular ri'ith cyclocrinitids (Nitecki, 1968, 1970,1972; Nitecki 6{ Toomey, 1979; Spjeldnaes 6(Nitecki, 1990a, 1992; Nitecki 6{ Spjeldnaes, 1992)have been reconsidered. In fact, the algal hypothesis,which is supported by the majoriry of authors, andthe usage of botanical nomen.i"t,ti. is also preferredby us.

From the palaeobiogeographical point of view theoccurrence of Ischadites and Cyclocrinites in Sardinia is

a surprise. Both genera, and in _particular Cyclo .crinitis, are conside"red indicators of

^warln, eeuatorial

shelf seas. Hence, their existence at high latitudes ofabout 50"S, where Sardinia is generally placed in LateOrdovician palaeogeographic reconstructions, requi-res explication.

GEOLOGICAL AND STRATIGRAPHICAL BACKGROLJND

The Palaeo zoic basement of Sardinia represents asegment of the European Variscan fold belt exhibiting" ["rt of the highly *.t"-orphic internides in centra-irtrd northerri Sardinia ind low-metamorphicexternides in the southwestern part of the island(Text-fig. I ).

In ihe autochthonous structural unit of south-western Sardinia a several-thousand-metre thick,almost complete sedimentary succession of LowerCambrian to Devonian strata is exposed. Due to tec-tonical uplift, the

"sardic Phas€", I major sedimenta-

ry break -took

place during the Middle Ordovician.The post-Sardic Upper Ordovician to Devonian suc-cession (Text-fig. 2)- unconformably overlies rocks ofCambrian to Tiemadoc ase.

The post-Sardic Ordo"vician succession consists ofabout 1000m thick, prevailinely siliciclastic rocks.The basal, largely ,-,tfottiliferoiri conglomeratic redbeds (Monte" Argentu-Formation)

" of probably

Caradoc (? Soudleyin) age grade upwards into fossil-iferous marine sandstones and shales of the MonteOrri, Portixeddu, and Domusnovas formations ofLonryillan (?) to Rawth:y"," *q.. The. O.rdoviciansuccesslon terminates with the clastic, glacio-marineRio San Marco Formation of Hirnantian age.

The facies development of the post-SardicOrdovician succession passes from alluvial, tidal,shallow to finally deeper marine conditions. It reflectserosion and subsequent marine transgression andsubmergence of an iiland, the so-called

'5"rdic Land"(Hammann & Leone, 1 997, p.18) which hademersed durine the late Lower to Middle Ordo-viciari. The inflilence of the

"sardic Land" as a source

areavanished during the deposition of the PortixedduFormation. The gJner"l deepening upwards trendwas interrupted by two short-term sea level drops,indicated by coarse clastic facies of the MaciurruMember and basal member of the Rio San MarcoFormation. These are interpreted to be related toearly Ashgill and early Hirnantian, respectively, gla-cial regressive events, known from other North Gon-dwana areas (Loi, 1993; Leon e et Al., 1998, p. 53).

DISTRIBUTION OF FACIES AND AGEOF THE PORTIXEDDU FORMATION

The Portixeddu Formation consists of 70-90 mthick, greft fossiliferous, siltstones and fine sand-stones prevailing at the lower part, and claystoneswith irregul arly?istributed siliceous and phosphatic

--\-r_

--

t W. HAMMANN, E. SERPAGLI

nodules, becomi.g more abundant in the middle toupper part. Intercalations of storm. lay.ers with con-centration of bioclasts are frequent in all levels.

The general aspect of the formation is relativelyunifor- f,.tt ,o-.^ local variation of lithofacies andfaunal associations indicates differences of deposi-tional environments along irregular shorelines of theSardic Land.

In the eastern and northern areas of the Iglesienteregion near the vi l lages of Domusnovas andFluminimaggiore the marine transgression took placealready at the base of the Monte Orri Formation. Inthe south-western area near Gonnesa the transgres-sion occurred later and probable equivalents of theMonte Orr i Formation and the base of thePortixeddu Formation are represented by about l5 mof cross-bedded coastal sandstones (Text-fig. 2).

The Portixeddu Formation is most fossi-liferous inthe lower and middle part where fossils are often con-centrated in storm-layers with pavements and chan-nels. The highly diverse fauna is generally dominatedby bryozoans, brachiopods and echinoderms (ryr-toids, crinoids). It also comprizes solitary corals,siliceous sponges, conularids, hyolithids, bivalves, gas-tropods, cephalopods, cornulitids, ostracods, trilo-bites, macheiridians and rare graptolites. These faunasare locally associated with Cyclocrinites or Ischadites,

The Portixeddu Formation can be subdividedinto three brachiopod (BH2, BH3, BH4) and rwotrilobite horizons (TH2, TH3), respectivell (Text-fig.2) (Leone et al., 1991 , pp. 214,216). The lower part(BH2 , TH2) is characterised by the brachiopod asso-ciation with Suobodaina haulicehiYillas, 1985, whichhas a wide distribution within North Gondwana andis known from the Iberian Peninsula, France and fromSE Turkey. The Suobodaina hauliceki Thxon RangeBiozone has a probable Actonian to Pusgillian age inBritish and Zahorany-Bohdalec age in Bohemianterms, respectively (Villas, 1995; Villas et Al., 1995)and includes also the Suobodaina Fauna of BH3.

In the Iglesiente region rwo trilobite biofacies(TH2a, THzb) occur within the Suobodaina haulice-ki Biozone (Hammann 6{ Leone , 1997, text-fig. 4).In the Fluminimaggiore and Domusnovas areas thislevel is entirely represented by siltstones (TH 2b) withDeanaspis goldfussi fluminenis Hammann & Leone,1997. In the Gonnesa area a near shore, sandstonefacies with Drffissina exophthalma and Calymenellasp. (.f. boisseli) (TH2a) occurs below siltstones withDeanaspis goldfussi fluminenis (TH2b). The Drffis-sina exophthalma-Calymenella boisseli association isalso kno*n from theilaucy Formation of southernFrance (Dreyfuss, 1948), the upper part of the"Bancos

Mixtos", Spain, (Hammann, 1976), the baseof the Upper Shale Member of the BedinanFormation of SE Turkey (Dean , 198il and from thePunta Serpeddi Formation of SE Sardinia (Ham-mann 6{ Leone , 1997). In the

"Bancos Mixtos" it is

associated with Orthograptus amplexicaulis (Hall,

1847), suggesting an Onnian-Pusgillian age (Gutier-rez Marco-& Rabano, 1987). The presence of

" Ortho-

graptu.r sp. (ex gr. amplexicaulis)" ln the siltstones ofthe cyclocrinitid localiry Flu 4 (Leone et al., 1991)suggests a correlation. The localiry Por 12 with amore arenaceous lithofacies has yielded brachiopodsof BH2 but no trilobites have been recovered so^far.

BH3 is characterized by the brachiopod associa-tion with AegiromenA meneghiniana (Vinassa, 1927),Suobodaina ip. (".f. ellipsoTdes Barrande, 1848) andRafinesquina- cf . pseudoloricata (Barrande, 1848) ofprobabfe Bohdal6c age (Leone et al., 1 99 I ). As thisfauna lacks trilobites in the Fluminimaggiore area,where it was first defined, its correlation with trilobitehorizons is problematic. The cyclocrinitid localiryGon I has yielded a trilobite association ofTH2b anda Suobod,aina fauna which may possibly be correlatedwith BH3.

B}J4 and TH3a respectively, comprize the mid-dle and upper part of the Portixeddu Formation. Thislevel, which contains the cyclocrinitid localities Por7b, Por l0 and Por 13 and localiry Can I c withIschadites, is represented by a lithofacies of silt- andclaystones yielding a brachiopod association withNicolella actoniae (Sowerby, 1 839). According toVillas (1985) the appearance of the NicolelkFauna inNorthern Gondwana approximately coincides withthe Bohemian lGalodvorian and therefore has anearly to mid-Ashgillian age.The highly diverse trilo-bite fauna of TH3a comprizes elements of theCystoid Limestone of NE Spain but also MiddleAsian species. The striking similarities with the faunaof the Obikalon Member of the ShakriomonFormation, Uzbekhistan, in particular suggest a cor-relation in age and close biogeographical relationship(Hammann & Leone, 1997).

p RES E RVAr r o N, tTifffi3 "IJrc

H N r QUES

The specimens of Ischadites and Cyclorinites fromthe Portixeddu Formation are preserved as internaland external moulds in a clayey to silry matrix. Oftenthe original, calcareous skeletal matter is replaced byfinely granular silicx, or, more rarely, by iron-oxide.

AII specimens of Cyclorinites from BH.}|BH3show deformation by compaction and tectonicalstrain. As they display only plastic deformation, dis-solution of the calcareous skeletal matter and replace-ment by silica is early diagenetic. The two specimensof Ischadites are undeformed and preserved insiliceous nodules, either as a hollow mould or an ironoxide pseudomorph.

Preparation was carried out with mechanical tools(needles, vibrotool, chisels). In some instances ironoxide was removed with concentrated hydrochloricacid. Latex casts were taken from external and inter-nal moulds. Thin sections did not reveal additionalinformation on internal structures. The specimens

\

DASYCIADALES AND RECEPTACULITIDAE FROM L, ORDOVICIAN OF SARDINI/I

lglesiente region Gonnesa area Fluminimaggiore area

S I L U R I A N

U. CAMBRIAN --1. ORDOVICIAN

canlc ',9#i::lB: 3Cydrctinites sp.

Ffu 4 CydrcrinitesPor 12 afr. vantreffeni

7a1 01 3

Lithology

Text-fig. 2 - Stratigraphical colums of the post-sardicGonnesa and Fluminimaggiore areas wirhchiopod horizons.

were photographed after blackening with graphiteopaque paste and coating with magnesium-oxide.

Repository: the material is deposited in theMuseum of ih. Palaeontological Institute of theUniversiry of Modena, Italy,- under the numbersIPUM 25601-25689.

ECOLOGY

Receptaculitids and cyclocrinitids are known roinhabit shallow marine environments. Their ecologi-cal behavior, however, is quite different (BeadTe,1988). As a general rule receptaculitids seem ro bemore tolerant, -e.g. to water enerry, substrate andtemperature. \7hile many species lived in high ener-gy rief environmentr, oth.risettled calm, r.t,rldy car-bonate and non-carbonate substrares. Nitecki (1970,

PorPorPor

Wsandstones,parttycrossbodded E=n clbaroorr3mudstonos

ffil sltstones f#l hncrroncs

r-:.-iz-=r -

E=:d conglom-sandslones ffi fl*nd mudstoncs

td ---o oI congtor:rerates : (with nodules)

tffilP----Y---4Wl volcanicrodts@

Ordovician of the Ielesiente resion and of the Portixeddu Formation of rhelocalities of Ischaditei and Cyclolrinites. Correlation based on trilobite and bra-

pp. 29-30) reports specific adaptation of NorthAmerican Silurian species of Ischa,d,ites to one or theother of these environments. Most recepraculitidsinhabit warm equatorial seas (Nitecki & Forney,1978) but occurrences at hieh palaeolatitudes havealso been reporred (Beadle, tIgS).

In contrast, ryclocrinitids are ecologically morerestricted thus having a high palaeoecologi"."l potentid(Nitecki, 1970, pp. 5l-56; Mork 6{ tWorsley, 1980;Beadle & Johnson; 1986; Beadle 1988, 1991; Bret t etdl., 1993). The palaeogeographical distribution of

ryclocrinitids indicates that thgf pr.e&pbly.settled incircumequatorial shallow, marine shelf environmentshardly exceededing 35" palaeolatitudes. Like in recentdasyilads the .n"Lt factors conrrolling disribudon,abundance and growth are depth relate-d such as lightintensiry, water energy, and the qualiry of the substrite.

t VI HAMMANN, E. SERPAGLI

Accorditg to the above authors cyclocrinitids areusually foun{ in fine-grained rocks iuch as micriticlimestones or siltstott.f that formed a relatively firmsubstrate on which the alea were either attached tosolid objects or settled looJely on the surface. Typi.llreef environments, mobile sandy or very soft, muddybottoms were avoided. The shape of the thallus seemsto be related to the substrate and water enerry: pyri-form thalli indicate a fixed position in a calm envi-ronment, while globular forms compr rzing cushion-shaped to sphaeii.cal yper y.t:^1q;pted -* :I.ghtlystronger water action (Nitecki, 1970, PP. 52-53).

Biing fragile and easily transported, -cyclocrinitids

seem to tr"rrJ avoided very shallow, agiiated bathy-metric zones and preferably settled below normalwave base. On the other hand, they were dependenton light supply and therefore restricted to the photic,onr"^t " d.pfh of less than 100 m. The occurrenceand abundance of Lower Silurian ryclocrinitids cor-relates with depth-related brachiopod communities(Mork 6{

'Worsiey, 1980; Beadle & Johnson, 1986;

Brett et dl., 1993, fig. 2). Several Lower Silurianspecies of Cyclocriniles from Scandinavia, NorthAmerica and ihe British Isles have been found to bemost commonly associated with Pentamerus, andnotably with Stricklandia communities, but less fre-quendy with the Chlorinda and Cryptothyrella com-munities. In general these occurrences agree with thelife zone of iyclorinites, but transports" into deeperfacies have been observed (Mork 6r Vorsley, 1980).According to Beadle 6c Johnson (1986) thalli and

glo,bella ;f Cyclocriylte1 gl?* larger. with increatitgIight intensity, which allows estimating relativepilaeodepth.^

Similar, detailed ecological studies of Ordoviciancyclocrinit ids have not

- been carried out. The

Portixeddu Formation, which was deposited on amorp.hologically structured shelf with changitg localconditions represents an interesdng test case. I heirregular, p",Lhy distribution of eycQrinites andkch"ad.ites suggest a strong environmeirtal control.

Dr,scruPTIoN oF LocALITIES

Leuel TH2\-BH2/8H3, lower Part of PortixedduFormation (Text-fig. 2)

Flu 4 Via Pinna s'ombra': located at the southernshore of the Riu Bau Porcus east of Fluminimaggiore,IGMI 546 2, N6543 0-E57210 Grey argillaceoussiltstones with rare intercalations of thin storm layers.Thin sections show a homogeneous, bioturbatedsiltitic matrix of mica and qt"tl with relics of lami-nation. Isomorphic cubes lnd aggregates of pyriteoften attached io bioclasts, are frequent. The sParce,randomly dispersed fossils in the siltstones do notshow siehifi."h, indications of transport. Disarticula-tion of"skeletons may largely result from bioturba-tion. The association is Jo-it ated by Cyclocrinites

and, second in numbers, graptolites (dendroids andbiserial graptoloids) (LeonE ei al., 1993). The sPaI99:ly assoc--iat-ed .shelly fauna comprises hexactinellidsponges, rnarticulaie and articulale brachiopods, bi-.r"lrr.i, gastropods, cephalopods, bryozoans ind trilo-bites. fh"lli of Cvclocrinit1s belong to the slobularrype. Six out of iet specimens haie been fbund inphysical closeness with other solid objects (IPUM25634: bryo zoan; IPUM 25635: bivalve; IPUM25636: lingulid, IPUM 25657: cephalopod; IPUM25672' deridroid; IPUM 25624: sificeous sponge) towhich the alga could have been attached. The lownumber and diversiry of fossil groups involved rathersuggests an accidential juxta[osition. The thallusdii'iretres of 161 specimens measured vary from 5-5mm to 17.5 InIrI, with a maximum abundance at 13-l4 mm (Tbxt-fig. 9). As the intercalated storm layerscontain pavements of brachiopod_s, bryozoans andechinoderms but lack cyclocrinitids and graptolites,this taphocoenosis may'be allochthonous.-Tlie faciesindicaies a calm, probably relatively deep environ-ment which was lrery rarely disturbed by storm-gen-erated currents. Preservation and pyritisation of grap-tolites and low abundance and dfu'ersiry of the tlt.flyfauna suggest some oxigen deficiency. The Ortho-

Kraptus d6l'tti"ated gt"pt"'olite assemblage indicate aB"iny-etric situatio.'n *ithitt the highe"r part of the*"r., column, about 50-200 m depih *1i... Ortho-

traptus amplexicaulis predominates-(Cisne & Chan-11.., 1982). Attribution of the few trilobites (D eAnA-spis, Nobiliasapltus, Dalmqn!1inq) and brachiopods to; definite association is difficult but may belong tothe mid-shelf.

Gon I "Sa

Siliqua"; located at small valley west ofhill

"Sa Siliqua' nbrth-east of Gonnesa, IGMI 555 3,

I\47320-E 4720 Grey homogeneous, bioturbatedsiltstones with relatively abund"ant intercalations ofstorm layers. Fossils are relatively sparce and random-lv distributed in the siltstone beds but are concen-trated in the storm layers. As both taphocoenoses arewidely idendcal, erosigtt, stirring gp ind more or lessin-situ redeposition of bottom sEaiittent and benthosduring short-te rm storm events can be inferred.Cycloirinites is relatively rare in both, the siltstoneb6ds and storm layers. In the latter the thalli are oftenfractured and sometimes swept together into smallclusters. The probably cushion-shiped thalli oftencontain cribell". Th. ih"ll,tt diameties (l specimensmeasured) varies from 8- 16 mm. The highty diverseassociated fauna is dominated by articulate bra-chiopods (Sz obodaina Fauna), echinoderms (grinoids,cystoids) and bryozoans. It also comprisgs bivalves,gastropods, ostracods, trilobites, hyolithids, inarticu-I"t. brachiopods, cornulitids, machaeridians and veryrare graptolites. Lithol oW, abundance of storm layersand High faunal diversiti'ttggest an oxigenated uppfroffshoie clastic depositional environment, not farbelow normal wave base.

DASYCLADALES AND RECEPTACULITIDAE FROM L. ORDOVICIAN OF SARDINII

Por 12 - "B,tggeru old road N of Piscina Suigas", cre;g

between elevaiions 125 and 136 m at Buggeru oldroad, 200 m north of small pond called PiscinaSuigas; IGMI 546 3, N65760-E5 1880 Several ex-porlt.r of grey, fossiliferous silt- to fine sandstones*itn storm"l.y.r, scatterd in bushland. The tapho-coenoses of storm layers and interbeds are widelyidentical, al l showing indicat ions of transport.Crinoids, articulate brichiopods of the SuoborJainaFauna (Leone et Al., 1991 , p. 214), bryozoans andcystoids are abundant. Subordinate are gastropg4t,bivalves and cornulitids. Only one incomplete, glob-ular thallus of Cycl.ocrinites was found. Most,frequentare a camerate crtnotd with a coiled, flexible stemclosely related to Bakcrinus Ramsbottom, 196l andthe knob-shaped bryozoa CeramoPora discoidalis(Vinassa, 194), which both are adapted to agitatedenvironments. The facies indicates a shallow, fre-quently perturbated depositional environment withtiigh .["rti. supply, just belo* normal wave base.

Leuel TH3a-8H4, middle Part of the PortixedduFormation (Text-fi g. 2)

Por 7a - "Punta

Pedrona", eastern peak 153 m of hill"Punta

Pedrona", about 3 km north-east of Porti-xeddu, IGMI 546 3, N67800-E5l9l0 - Large exPo-sure of very fossiliferous greenish-grey, bioturbatedsiltstones and fine sandstones, which contain numer-ous storm layers with pavements. The fauna of stormlayers and interbeds ft identical and dominated bybryozoans, articulate brachiopods (^A/i colella Commu-niry) Trd pelmatozoans .

(cystoids, crinoids). It alsocompnses gastropods, bivaives, ostracods, trilobites,conul"riansl hyolithids, cornulitids and very raregraptolites (a single diplograptid from intercalatedmudstones) . Cyclicrinites is-rare and preserved alwayswith bryozoan overgrowth. The diametres of theglobular'th_alli vary llo- 17 to 22 mm. The faciesiuggests a freque.^rly, aqitated, clastic upper offshoreenvlronment not tar below normal wave base.

Por 13 Localiry "C^bu

de Figus", small outcrop atwestern slope of elevation 62 m, about 1-5 km north-east of Portixeddu, west of hill Cabu de Fieus, IGMI546 3, N67100-E50500 Litholopy anJ biofaciesincludirg rare Cyclocrinites sp. are idintical with thatof Por 7"^, in particular with levels containing pave-ments of Longuillia mediterrnnet Havlicek, 1981 .

Por 10 Localiry at "Btggerru

old road", southernembankment of road at sharp curve, IGMI 546 3N660 50-851 820 Greenish-grey siltstones withabundant thin storm layers containing a rich bra-chiopods fauna (Nicolelk Communiry), bryozoans,echinoderms, xs well as gastropods, bivalves, cornuli-tids, ostracods, and tlilobites (Deanaspis, Thu-ringaspis). Only one specimen of Cyclocrinites sp. isfoind. The facies corresponds to thit of Por 7 a.

-

Can lc - Localiry "Otile

Cannamenda", pasture withfrasments of bedrock 100-200 m south-east of theshe"ep farm, about 2.5 km south-east of Bacu Abis.IGMI 555 3, N43450 856750 Grey, argillaceousshales with nodules and frequently intercalated, part-ly amalgamated, vev fossiliferous storm layers. Thef"tr." i'r dominated by bryozoans, brachiopods(Nicolelk Communiry) and pelmatozoans. Associa-ted are trilobites (Deanaspis, Thuringaspis, illaenids,asaphids, proetids, odontopleurids,-liihids), ostra-.odt, hyolithids, cornulitids, conularians and veryrare Ischad.ites. The facies indicates an upper offshoresituation with low clastic supply, immediately belownormal wave base.

CoNcLUSIoNS

Distribution - Ischadites occurs only in Can 1c ofBH4 where Cyclocrinites seems to be absent . Cyclocri-nites is most abundant in BH21BH3. In BH4 it israre and only preserved as an allomorphic structure atbryozoan colonies, which excludes iny conclusionsabout the original abundance of the alga.

Substrat;- Cyclocrinites is confined"to beds of silt-and fine sandstones. As taphocoenoses are autochtho-nous and parautochthonous, respectively, these sedi-ments constituted the original substrate.'The absenceof Cyclocrinites in mudstJtt. beds of a similar bathy-metnc srtuation suggests an unsuitable substrate. Itsabsence in lithoral li'ndstones with Calymenella bois-seli-Dreyfussina exophthalma seems to 5e primary aswell, but second "iy destruction in this high enirgyfacies cannot be excluded.

Depositional enaironment Both the siltstoneswith Cyclocrinites and mudstones with kchadites con-tain more or less abundant storm layers. Theinterbeds represent periods of relative calmness indi-cating a depositional environment below normal*"rr.-base. Th.t. conditions were interrupted fromtime to time by short-term storm events with erosion,transport and redeposition of bottom sediment andbenthos.

'Within thls scope of environments attribut-

able to the upper offshore to lower onshore three

rypes can be distinguished:r L Typ. 1 (Cycloiinites-localiry Flu 4) is character-

ized bt occurrence of graptolites, low diversiry ofshelly fauna, argillaceous siftstones, rare storm layers.This environment was deepest and calmest, rarelyreached by currents and slightly oxigen deficient.

r

Type 2 (Cyclocrinites-loJalities G6tt 1 of BH3 andPor 7'a, Por 10 and Por 13 of BH 4; Ischadites-localiryCan 1c) is characterized by almost complete absence ofgraptolites, high diversiry of shelly fauna, many stormI"y.rr. The fafies was well oxigenated, more agitated""d slightly shallower than in Type l. V/hile in-locali-ties wiih Cyclocrinites the sedimettt"ry influx was rela-tively high, it was low in the localiry with kchadites.

-Apr'- 3 (Cyclocrinites-localiry Por 12) is character-

ized 6y abseti. of graptolites, ielatively low diversiry

T TJ(I HAAIMANN, E. SERPAGLI

of shelly fauna dominated by crinoids (aff.Bakcrinus), silt- to fine sandstones, many storm l^y-ers. Showing indications of permanent reworkitrg, itwas located very close below normal wave base andslightly shallower than Typ. 2.lt is transitional to thenear-shore sandstone facies with Calymenelk boisseli-D reyfuss ina exop hth almA.-Abundanci

- The decrease of abundance of Cych-crinites from facies Type I to Typ. 3 in level BH}|BH3indicates a preference of cdm environments, whileagitated, very shallow zones were avoided. OxigendEficiency does not seem to be a limiti.g factor. L-"owabund"ti. in localides of BH4, how.rr.i, is preserva-tional.

Shape and size - A depth related variation of theshape aird size of the thalli and elobella is difficult todemonstrate on the basis of smlll numbers of speci-mens on hand from most localities. VithinBH}|BH3 the sizes of thalli and globella of Cyclo-crinites aff. uanhoeffeni from shallovier facies (Typ es 2and 3) are within-the range observed from the-sup-posedly deepest facies (Type I ). As far as can be esii-mated from the deformed material variation in thal-lus shape did not exist. All specimens belong to theelobular rype, and were eithefspherical or doried and[robably i6sted freely on the r.^di-.ttt.

Benthic associations In Gon I and Por 12 ofBH2-BH3 Cyclocrinites is associated with a brachio-pod assemblage of Bohemian genera such asSuobodainA, DiabouiA, Aegiroment,"Rofintquina andRo s tri ce I lu k, p rovisio ndlylalled " S uo 6o da i na Fauna"(Leone et Al., 1991, p. 216). In Por 7a,Por 10, Por 13and Can I c of BH4 Cyclocrinites and Ischadites occurwith the Nicolelk Community. Both the SuobodainaFauna and the Nicolella Communiry have beenassigned to Boucot's ( 1975) Benthic fusemblages 3-4(Leone et Al., 1991 , p. 216). This corresponds to thebathymetric position of Lower Silurian Pentamerusand Strickkndia Communities which contain theprincipal occurrences of cyclocrinitids and receptac-ulitids (Eckert & Brett, 1989; Brem et al., 199r. It ispossible, though, that facies Typ. I (localiry Flu 4)may reach into BA-5. Based on Brerr et al. (1993) andtfing in account a fairly turbid environment, theestimated absolute depth of our facies Typ.r l-3 mayhave ranged berween 20-60 m.

PALAEOGEO G RAPH I CAL CO NS I DERATI ON S

Both, ryclocrinitids, as well as Ordovician occur-rences of Ischad,ites (including the genus Tbttragonis)are found in circumequatorial ronei (Text-fi g. U andconsidered indicators of warm shelf seas.

Cyclocrinitids, which existed from MiddleOrdovician to Late Llandovery are known fromBaltoscandia (Norway, Saint Petersburg area ofRussia, Estonia, Baltoscandian elacial erratics ofnorthern Germany and Poland)," the British Isles(Scotland, \7ales), North America (USA, Canada),

eastern Kazakhstan, India (central Himalayas) andSouth China (Sichuan). Thus their main palaeogeo-graphical distribution lies within gf tropics and sub-tropics and hardly exceeded 35" palaeolatitudes.Poncet 6( Roux ( 1990) who discussed the distribu-tion and migration of Ordovician cdcareous algaeexplained thiir absence from Gondwana (excEptAustralia) due to cold climatic conditions. The onlyrecord of qclocrinitids from northern Gondwana is"

Coelosphaeridium aff . sphaericum" from theBohdallc Formation of Bohimia (Havlfcek & Vanek,1966, p. 59). According to Havl(cek (1999) faunaland palaeomagnetic data suggest an ave rageOrdovician position of only 30"S for Bohemia.Though this may be too low for the Late Ordovician(Villas et al., 1999), it would explain this occurrence.

Most current late Ordovician palaeogeographicalreconstructions show Sardinia, foi whicl tri Ordo-vician palaeomagnetic dat a are available, as a part ofthe North Gondwana shelf located at palaeolaiitudesof about 50-65" S (Scotese 6( McKerrow 1990;Cocks & Fortey, 1990; Young, 1990; Paris & Robar-det, 1990; Poncet 6c Roux, 1990; Roux, l99l; Ven-nin et Al., 1998; Villas et dl., 1999). In some of thesereconstructions the central and south EuropeanPalaeo zoic areas are arranged in an actualistic way,which is not in accordance with the observed faciesrelationships. A better understanding may beachieved on the basis of plate tectonic mo?els, whichconsider this area an accretion of various terranes.

Because of a concurring tectono-sedimentarydevelopment the Eastern Pyrenees, Catalonia,Montagne Noire, the Carnic Alpr and Sardina can beconsidered to belong to a common palaeogeographicunit, the

"Ebro-Aquitanian Domain" (Paris & Robar-

det, 1990), "Catalan

Region of the European Plat-

&r-" (Young, 1990) or t-h. "Lfnstable

Sheif Region"forming the-North Gonwana margin (Hammann,1992). Palaeomagnetic data suggest a position ofabout 50"S for the Carnic Alpt (Schonlaub, 1992,1998), which may be taken as an orientation for theabove mentioned terranes. Close similarities of theCambrian and Ordovician trilobite faunas of theIglesiente region with eastern Turkey also agree withthis suggestion. The estimated distance berween thesouthern margin of Baltica at about 35" and theNorth Gondwina margin may have ranged about 15"in late Caradoc-early Ashgill times.

After a period 6f tovi faunal similariry berweenAvalonia/Baltica and North Gondwana durine theLlanvirn and early Caradoc an immigration of Ealticelements took place with increasing intensity.Spieldnaes (1967), who first describ.d the faunalchange of this time interval ("T"filaltiatr"), men-tioned among others the sudden occurrence of bry-ozoa, a group almost completely lacking during theMiddle Ordovician in northern Gondwana.

This faunal change, however, happened succes-sively in time and space. Vhile Baltic elements

DASYCIADALES AND RECEPTACULITIDAE FROM L, ORDOVICIAN OF SARDINA

Text-fig . 3 - Global distribution of Clclocyinites (black dot), other cyclocrinitids (circle) arduring late Caradoc-early nshgill dmes. ( I ) Sardinia (this paper) ; (2) Bohemia (Havlfcek E(Eichi,ald, 1860; Stolley, 189"6, 1898; Roomusoks, 1970); (4) Scandinavia (Mork & \7or1986; (5) Scotland (Nicholson 6{ Etheridge, 1878; Elliom, 1972; Beadle &Johnson, 1986)(Nitecki , 1970, 1972; Nitecki et al., 1999); (7) Califonia (Nitecki, 1970, 1972; Foster, 19'& Caldwell, 1977); (9) Eastern Kazakhstan (Gnilovskaya, 1972); (10) Tibet (Mu Xi-nan, Ial., 1987); (12) Batang, Sichuan (Mu Xi-nan, 1982a, b).The North Gondwani Region includes Perunica (Per), the unstable, outer shelf area of(EAD) with Northeastern Spain, Southern France, Alps, Sardinia and Carpates as well asfumoric" (Ar) and Central Iberia (CI).Mrp adopted from Stouge & Rasmussen (1996) with modifications in the south-west Eurolstable Gondwana from instable peri-Gondwana regions.

occurred still relatively rare in the late CaradocMediterranean Suobodaina Fauna, they became pre-dominant in the early to mid Ashgill Nicolelk Fauna.On the other hand Baltic elements seem to appearearlier and more abundantly at the shelf margins ofnorthern Gondwana (Bohemia, S'W Sardinia) than inthe more interiorly located shelf regions, e.g. the theMaroccan Anti-Atlas which was never reached by theNicolella Fauna, but where the MediterraneanMucronaspis cold water fauna persisted throughoutthe fuheill.

It his been suggested that these processes maypossibly b. related to the Middle Ordovician Sardictectonic movements, which reorganized the palaeo-geography of the North Gondw"ana margin iH"--mann, 1992). Duritg a compressive phase (Latefuenig-Llanvirn) this region was lifted up and partlybecame a land barriet the so-called

"Sardinian-Thu-

rian Rise", which may have inhibited free exchange oftemperate waters and faunas with cold inner shelfseas- Subsequent riftine and breakdown of this riseduring the earado. -"i have allowed gradual mixingwith temperate waters and arrival of larvae transport-ed by south-equatorial currents via Baltica. Oceano-

graphic models based on Vilde (1991) have repeat-;dli been proposed to explain biogeographic

-rela-

tionships benveen Kazakhstania, Baltica and theEuropean to Asian Gondwana margins (Cocks &Fortey, 1990; Bergstrom, 1990; Poncet 6( Roux,1990; Roux, l99l; Schonlaub, 1992; \7ebby, 1992;Popov et al., 1997; Stouge & Rasmussen, 1996). Thearrival of the warm *atEr elements Cyclocrinites andIschad,ites at the European North Goridwana margincorroborates these concepts.

SYSTEMATIC PAIAEONTOLOGY

Order RTcEpTACULITIDAE James, I 885

Remarks - The systematic placement of receptac-ulitids is still discussed (Nitecki et dl., 1999).Nevertheless, arguments in favour of an attributionto calcareous algae are most convincing and in agree-ments with Rietschel (1969) receptaculidids are con-sidered an independent algal group not included inDasycladales as was proposed by Kesling & Graham(1962), Byrnes (1968) and Nitecki (1968, 1970,t97t, t972).

1 0 T VI HAMMANN, E. SERPAGLI

Terminoloy employed (Text-fig. 4) largely fol-lows Rietschel

"(i 969) "ttd Fisher & lrlitecki (tggZ).

Family IscHIDITIDAE Miiller, 1968

Remarks - Mtiller (1968, p. 12) who consideredreceptaculitids an order of unknown affiniry withposibl. relationship to sponges or archaeocylthiit,^otooosed

a subdirrision i-ttto Receptaculitidaeii i.h*ald, 1860 and Ischaditidae n. fam. TheReceptaculitidae were defined as possessing an innnerwall formed by the expanded feit of the

-shafts, and

the Ischaditidae, which have simple, needle-likeshafts not forming an inner wall.

Rietschel ( 1969, p. 506) who placed the recepta-culitids with algae did not discusJ this proposal butintroduced a Jassification comprizing-the familiesReceptaculitaceae Eichwald, 1860 (includitg also theg.r,ri Ischadites Murchison, 1839) and the new fam-i"li.r Tettragonaceae and SphaerosPongiaceae. Accor-ding to thiiauthor the meromt o.i.tr In whorls in the

Receptaculitaceae while thel are arranged.in spirals inthe Tettrasonaceae. The Sphaerospongiaceae weredistingishel by havitg reduied shaftt "id hexagonalplates.^

Although still accepted_ by Nitecki 6( Toomey(1979, p.728), Rietschel's classification subsequentlyseems to h"rre lost its validiry as more recently Niteckiet al. (1999, p. 30) included Ischadites and TbttragonisEichwald, 1842 (non Tbtragonis Lonsdale, 1845,nom. van.) in the Tettragonaceae. Similarly, Recepta-culites orbit Eichwald, iS+0, Lower Ordovician ofSweden, which was attributed to Tbttragonis byRietschel (1969, 1970), was attributed to the genusFisherites Finney & Nitecki, 1979 and included in theReceptaculitaceae. However, amendments of Riet-schelts original concept have not been discussed andnew family diagnoses were not giYg.. Accorditg toNitecki ei Al.

-(1999, p. 30) ilifferences between

Receptaculitaceae and Tettragonaceae lie "in

the,r",,ri. and extent of calcificatiJn, in the morpholoryof meroms, in particular in the thickness and internal

A - ISCHADITES

A1 A2

B - CYCLOCRINITES

osh

B1 B2

Text-fig . 4 - Comparative terminolggy.of (A) \ch.aditgs"l^{(B) Cyclocrinites. (Al) Partly sclrp. b, .ros-r..rion.J, tlft i"g apical pole. (A2) ReJonstruction of meroms of Ischaditg sp

iirg[ll ri.* Cni) p"rdy scherilati. r..onstruction of a tlrirll.u: 9f Cyclocrinites aff. ua.nhoefeni,i.ti.r;'elobella are eith.t.-pry or filled by cribellum. (B2) Morphology of an isolated-laterAUUtliiarions for Ischadittti nb = nuclear'pole; p = plate; ss = stailate structure consisting o"J. "t-, i* = latitudin"l ar.nr; sh = shaft;'r* = iadi^al wrinkling; ti = trianBulum-interpolitcc = centrd cavify; me = merom.Abbreviations foi Cyclocrinites:g = globellum; cr = cribellum; sh = shaft; cc-= ce-ntral caviry;bellum filled with &ib.ll,rm; ro = rosette with six petals; osh = oPening. of shaft.Althoueh there are sufficienr criteria to determine th. t.r.leus "nd apex-in each recePtaculiti;t-;;;r;Ai- J.u",. "Uo", the orientation of these poles. \fhile Rietsihel ( I 969) ptoposes th:""rn"rrJBfr.s, 1968; Nitecki , 1971, 1972; Campbell et al., 1974; Brumm.t i 979) basinlit the upper pole of the living organism.

DASYCIADALES AND RECEPTACULITIDAE FROM L, ORDOWCUN OF SARDINI/

complexities of shafts and feet". This seems to implythat both are distinguished mainly by the Presence orabsence of feet anil an inner wall. As this concePtlargely coincides with Mtiller's ( 1968) ProPosal, wecoisider the Tettragonaceae Rietschel (1969) a syn-onym of Ischaditidie Miiller, 1968.'

A further problem concerns the possi_ble q{n-onymy of Tethgonis Eichwald , 1842 *ith IschaditesMurchison, l{39 . Gtimbel (187 6) consideredTbttragonis a synonym of Ischad,ites, arguing that thisgenus *": baied oh an incomplete lFtp.yq. of therype specres Tbnragonis murchisoni Eichwild, 1842d'hi.n

^lacks plates.-this view was accepted by many

subsequent authors (Hinde,- 1884; Rauff, 1892;Byrnei , 1968). Rrytr (1 892), fbt gxapple, stated thatTbttragonis murchisoni was identical with Ischaditeswhiletther species, e.B. Tbttragonis sulcata Eichwald,1855 and Titragonis laruipori Eichwald, 1855 weredifferent. A sim-ilar view was reached by Brummer(1979) who showed that T ettragonis sulcata differsfrom ischadites in havine spirally irranged meroms aswell as smaller, strongtli i-Uriiating pT"t.t. He con-cluded that this would justify placing this speciestogether with the closely related genus LepidglitesUl'rich, I 879 (ryp. species LepiTolites f,ickhautiUlrich, I 879) info the family

- Tettragonaceae as

defined by Rietschel ( 1969). Brummer .(1979? P. 36)emphasizes, however, that there are substancial sPe-cifii differences berween Tbttragonis sulcata andTbnragonis murchisoni so that "it may be necgs91ry^lobase Jne* genus on T sulcatt" . Nitecki et Al. (1999,p. 28) did ,t"ot discuss this problem but stated that alliborr. mentioned Ordoviciln Baltic species belong toTbttrasonis. The holorype of Tbttragonis murchisoni,whicliis refigured by Niiecki et al. (7999, fig. 2.5),isan internal riould showing the impression oF the stel-late structures and shalts, which are obviouslyarranged in whorls and different from Tbttragonis suLcatn. Calcification of shafts, stellate structures and,possibly, of the non-preserved plates was not veryh."ry,

'which agrees with the delicate calcification

observed in sJctions of Tbttragonis sulcata (seeBrummer, 1979; Nitecki et dl., 1199, figt 2,6, 4.Il).In contrast, species usually placed in

- Ischadites as

exemplified bi the rype speiies Ischad,ites koenigii,sho*'a much heaviet tl.inlation of the meroms.

fu long as these problems remain unsolved, wetentatively"separate Tbtt agonis from Ischadites on thebasis of the ciiteria menti6ned. Beside s Ischadites andTbttragonis, the Ischaditidae Miiller, 1968 mayinclude Lepidolites Ulrich , 1879, Selenoides Owen,185 2 and possibly Sphaeros!?"gi(,Gt1y, 1857 .

In some cases, e.g. Selenoides iowensis Owen,1852, Ischadites mA*iillarit (tValcott, 1884) , Isclta-dites burntensis (Shrock S( Twenhofel, 1939), ? Tbttra-gonis cf . murchisoni Eichwald, 1842, shafts may Prox-Imally be thickened and partly fused in the nucleadepart of the thallus. ThiJ structure, however, differsho.n the rype of feet characterizing the Receptaculi-

taceae which include the genera ReceptaculitesBlainville, I 830, HexabactronC-ampbell, Holloway ASmith,1974 and FisheritesFinney & Nitecki, 1979.

Genus IscHeDITES Murchison, 1839

Tvpe species - Ischadites koenigii Murchison, 1839,from-ih. Sil,.ttian of the British Isles.

Remarks-The senera Acantochonia Hinde, 1884,rype species Acaniochonia barrandei Hinde, 1884,Silurian of Bohemia; Ehlersospongia Fagerstrom'1961, rype species Ehlersospongia stellata Fagers-troq,1961, Miaaf. Devonian, Ontario, Goldsonla Shrock& Twenhofel , 1939, ryPe species Goldsonia burntensisShrock & Twenhofel ,'l^93i, Silurian, Newfoundland,Dictyorinus Hall, 1859, ryPe species Dictyocrinussquimifer Hall, 1859, Devonian, New York, are con-rid.r.d synonyms of Ischadites (Byrne_s, 1969; Gould6c Katz,'1975'; Nitecki, l97tb; Nitecki et Al., 1987).

Byrnes (1968, p. 368)_als_o synonymized .LEido-lites Ulrich , 1879, Selenoid,es Owen , 1952 and Tbttra-qonis Eichwald, 1842 with Ischad,ites. Lepidolites was?ttributed to cyclocrinitids (Nitecki, 1970) but place-ment in the Ischaditidae may be more justified. The

rype species of Selenoides, Selenoides iowensis Owen,ig5Z,^Th.ntonian, USA, was redescribed and attrib-uted to Ischadites by Foster (1973) but constructionof shafts and arrangement of plates may justifr reten-tion of a separate genus (Nitecki et Al., 1999).

The g.tttt kchadiles shorys ? great v.aliety of thal.-lus shapis ranging from globulai ovoid to conical.The mbrpholoiy

"of the ilt.to-t is very variable as

well and in. n.I-b.r of arms (4 or 3) and length andshape of the shafts in particular may consi-derablyvary even within a given species_. In some sPecies theshahs may, especialfy in thi nucleade Pa{t oF the thal-lus, develop pto"imil expansions. Th; plates are gen-erallv rhombic in outline but may apically becomep.ni"- or hexagonal which is reminiscint o'f Sphaero-ioonsia. The eiternal ornamentation of the plates isi^rrfy described but seems to be rather varied andmay consist of tubercles, radial ridges or concentricgrowth lines.v

In Ischadites growth of the thallus happens by "complex combinltion of intercalation of new apicalwhoils with bifurcation of parastichies as well as con-centric growth of the plates. Bifurcation of parastichiestakes pf".. at an interpositum-triangulum unit andmay occur at irregular intervals in different directionsof p"rastichies (Rletschel, 1969; Foster, 1973; Gould& Katz, 1975; Fisher 6c Nitecki, 1982, fig. 15).

Ischadites is known from Lower Ordovician toUpper Devonian and comprizes a large number ofp"r',ly poorly known species listed byNitecki et al.itggg,^pp. iez-rc, *hi.h may comprize numeroussynonyms.

t2 t V HAMMAAIN, E, SERPAGLI

IscHnotrES sp. aText-fig. 6

Material - From "Ovile

Cannamenda", Can I c,level BH4 of the Portixeddu Formation, I incompletespecimen, IPUM 25603.

Description - The specimen, which is preserved ina nodule as internal and external mould, is incom-plete and par t ly d is integrated in to indiv idualmeroms. The shape and size of the thallus cannot bereconstructed. The meroms which are in originalposition indicate an arrangem.ell along a system ofrwo lntersecting regular parastichies around a centre.Interposita-triangulum units are not observed.

The plates are mostly rhomboidal in outl ine butbecome sub-hexagonal and smaller apically. The platediametres range from 3-5 mm. The external surfacesof large plates are almost plan, while they are marked-ly concry. in smaller plates. These surfaces bear 10-12coarse, lrregular, concentric, sharply edged growth-

ridges, which are separated by deep grooves. Thethickness of the plates is 0 .3-0.4 mm. The plate mar-gins do not imbricate but meet and are surrounded bya concave flange. The internal side of the plates,which is about parallel to the external side, shows arelatively inconspicuous radial wrinklirg (describedby Rietschel, 1969, p. 478, pl . 3, f ig. 15, as

"radiale'Wellung"

or "Querrunzelung"

or by Niteckr et al.,1999, f ig. | .3 as

"head endasters").The stellate struc-

ture lies immediately below and is partly incorporat-ed into the plate. The four arms which are directedtowards the corners of the plate do not emerge fromthe shaft at the same level. The nucleade arm lies moredistally than the three remaini.g arms and is widelyfused with the plate. Its distal, pointed end is free andslightly flattened. The opposing apicade arm is freefrom its base and slightly inclined internally. The lat-itudinal arms are fused with the plate for more thanhalf of the plate diametre. The tips of the arms ofneighbouring meroms interlock in the usual recepta-culitid way. The shafts hardly vary in length and

Ischadites sp. b. IPUM 25604, from Can 1c.(Al) Overall view of thallus enclosed in a nodule; internd mould composed of rwo broken p:thallus along upper surface of lower part of specimen Al, showing shafts, * 4.(N) Obliqueof Al, x 3.5. (AQ Baclaide of A3, tangential section with traces of several shafts; x3.5. (Bl) lclose up showing in situ position and crossing of stellate structures; x 10. (B2) As B I , close tlate structures; x 10. (C) Latex cast of external mould, showing ornamentation of outer surfa

Text-fig. 5

DASYCIADALES AND RECEPTACULITIDAE FROM L. ORDOWCIAN OF SARDINIZ

thickness. They are simple, smooth, straight and nee-dle-like, weakly tapering proximally. Their lengthmay exceed the plate diametre three times. Internalstructures of the meroms are not preserved.

Discussion - The presence of simpl., proximallypointed shafts and the heavily calcified plates suggestan attribution to the genus Ischadites.Incompletenessof the thallus makes specific comparison difficult.The gendy convex apicade region may suggest a glob-ular to perhaps pear-shaped or discoid shape makinga specific identiry with the turnip-shaped formIschadites sp. b from the same localiry unlikely.

The meroms of Ischad.ites sp. a are characterizedby a concave external plate surface, veA stronglyexpressed growth lines, weak transverse wrinkling onthe internal plate side and thin, smooth shafts. Theornamentation of the external plate surfaces stronglyresembles the structure of the internal side of the ft6tof Receptaculites neptuni (Rietschel, 1969, pl. 2, fig.6). A concave external plate surface and stronglyexpressed gr9w1h .lines are unusual. In most otherspecres, e.g: Ischadites barcandei the surfaces are con-lrb* and glowth lines, if present at all, are fine andfaint. The taxonomic value of surface ornamentationsis unclear, however. It is also possible that the unusu-al plate morphology ?trd ornamentation of our spec-imen is preservational.

Ischadites hoenigii Murchison, 1939 and Ischaditeslindstroemi Hinde, f 884, both from the Silurian of theBritish Isles (Rietschel, 1969, pl. 3, figr. 14-15) or" Ischadites sp." from erratics of the Backiteinkalk, Jovi

Stage, of northern Germany (Neben & lirueger, 1973,p1.36, fig. 12) show srro"dly expressed radialwrinklescreating crenulate plate margins which clearly differsfrom the inconspicuous structures in Ischad.ites sp. a.

The shaft morphology may be a valuable specificcharacter. As a general rule the shafts become longerand slimmer towards the apex, and shorter andstouter towards the nucleus. In our specimen theshafts are uniform comprising only a straight, needle-like type. As .the specimen is incomplete, however, acertain variation may have existed, though.

Ordovician species of Laurentia, e.g. Ischaditesdixonensis (Miller & Gurley, 1896), from the GalenaGroup, Il l inois (Fisher & Nitecki, 1978) andIschalites mammillaris ('Walcott, 1884), from theAntelope Valley Limestone,'Whiterockian, California(Foster, 19,73) are. probabff , diffgrent. The ,ryp.,, ofIschadites dmonensts ls a steinkern of an ovoid thalluswith a very regular merom arrangement in whorls. Asthe -orphol;ry of shafts and .it..nal plate surfacesare unknowo, comparison is not possible. Ischaditesmammilkris differs by " turnip-shaped thallus, thick,strongly calcified nucleade shafts and a granularexternal plate surface.

Among North American Silurian species mono-graphed b| Nitecki (1972), Ischadites lemisphaericus(Hall, l86l ) resembles in having needle-like shafts

and hexagonal plates around the apex. Details of theexternal plate surfaces are not described, but theyseem to be convex and lack clear growth lines(Nitecki, 1972, text-fig. 3 I ).

Accordirg to Nitecki et al. (1999) all OrdovicianBaltic species previously assigned to Ischadires belongto Tettragonis. Possible synonymy with Ischadites,howevet is not yet fully clarified. All species formallydescribed, e.g. Tettragonis murchisoni Eichwald, 1842,Tbttragonis sulcata Eichwald, 1855 and TbttragonisparuiporaEichwald, 1855 are more reminiscent of ther..otrd Sardinian form, Ischadites sp. b. No furtherinformation, however, is available about

" Ischadites

sp. n." from the Jovi and Oanda stages of Estonia(itoomusoks 1976, pp. 249,332) and

nlschadites sp."

from the Keila Stage of Estonia (Roomusoks, 1970,p. 298).

IscHnoITES sp. blext-fig. 5

Material - From "Ovile

Cannamenda", Can lc,level BH4 of the Portixeddu Formation, I incompletespecimen, IPUM 25604.

Description - The well-preserved specimen, froma siliceoui nodule, lacks. th. apical pole. Sg:g acleavage a transverse section can be observed (Text-fig. 5At ) The iron oxide which replaced the originalskeletal matter has been removed by treatment withconcentrated hydrochloric acid.

The 2.5 cm long, incomplete nucleade part of thethallus is turnip-shaped, subcircular in cross-sectior,slightly curved and gently expandi.g apically. Theacute end corresponds to the nucleus, as is indicatedby the direction- of the apicade arms of the stellatestructures. The meroms are arranged in regularwhorls. The massive, rhombic plates do not imbri-cate. The external plate surface is apparently orna-mented with irregular tubercles and depressions,which cannot be attributed to a regular pattern asplate sutures are not discernable (Text-fig. 5C). Theinternal plate sides are poorly preserved either and donot show any details. The stellate structure consists offour arms of which the apicade arm is inclined. Theshafts are needle-like, straight and thin and do notshow any proximal expansions. They extend inwardto the central caviry which occupies about I 5-20o/o ofthe thallus diametre. An irregularitiy in the arrange-ment of the shafts seen in the central upper half(Text-fig. 5Al) indicates bifurcation of parastichiesand the existence of a triangulum-interpositum unit.

Discussion - Both specimens of Ischadites found atlocaliry Can I c are diFficult to compare as they areincomplete and represent different parts of thalliwhich are different in size. Thxonomic separation isproposed because of differences in thallus shape andexternal plate ornamentation.

1 4

$

/r! 7ttl'ri

82

Isc l tadi t r i sp. a. IPUM 25(103, f rorn ( .an lc .(A1) ( ) r ,e r i l l r , , iew o f inconrpr le te , par t l v c l i s : r r t i cu la tec l tha l lus enc losed i t t , r nodu le , in te rnrfaces o f 'heads w i th s te l la te , i ru lc tL l r . r , * 2 . (A2) l -a tex cas t o f 'A ] , overa l l v iew, x 4 . (A i ) ( ,1

s ide o f th ree p la tes anc l s te l l : r te s t ru lc tu res , x ( r . (A4) As A3, r ( r . (B l ) ( ) r ,e ra l l v iew o f specsu r f aces o f heads w i t h p l a t cs and s re l l a t c s t r uc t r l r es , x 2 . ( 82 ) La tex cas t o f - 81 , c l ose up ,growth l ines , x 5 .

H; I

H?

DASYCLADALES AND RECEPruCULITIDAE FROM L. ORDOVICIAN OF SARDINII:

Conical thalli and needle-like shafts are commoncharacters of many species of kchadites and the BalticTenragonis. Our specimen most closely resembles the

rype species Tbnragonis murcbisoni from the Jovi andIdavere stages of Estonia (Roomusoks, 1970, pp. 221,249) and questionably from glacial erratics of theBacksteinkalk, Jovi Stage, of northern Germany (Ne-ben & Krueger, 1973: cf,, murcltisoni, pL.56, figr. 7,8,9) in having similar long, thin, needle like shafts and aregular merom arrangement in whorls. Our specimenseems to differ, however, in havitg more massive stel-late structures and plates, which may allow placing itin Ischadites. Tettragonis sulcata differs in having imbri-cating plates, tribrachiate stellate structures and a spi-ral merom arrangement (Brummer, 1979).

Plate imbrication is also seen in Ischadites sp.from the Balclatchie Group, Caradoc, of Scotland(Elliott, 1972), known by thin sections only. Simila-rities with American specimens of Ischadites koenigiidescribed by Nitecki (1972) only concern the gener-al shape of the thallus.

Order DnsycLADALES Pascher, l93IFamily ?SEI-EToNELLACEAE Korde, 1950

tibus CycIocRINITEAE Pia, 1920

Genus Cvct-ocRINITES Eichwald, I 840

Synonyms - Cyclocrinus Bronn, 1848; ?MastoporaEichwald, 1840;iwiditlrrs Saltet l85l; ?Cerionites Meek &-'Worthen, 1868.

Tlpt species - Cyclocrinites spaskii Eichwald, 1840,from

'Wesenbergische Schichten, Stage E (Ralcvere),

Munalaskme, Estonia.

Remarks Since the first description ofCyclocrinites by Eichwald (l 840) from UpperOrdovician limestones of Estonia, morpholory, tax-onomy and systematic placement of this genus havebeen a problem. As the name suggests, Eichwald(1840) regarded i t a pelmatozoan echinoderm.Because of its very particular morpholory and differ-ences of skeletal material this was rejected by mostsubsequent authors. Possible attr ibut ions ofCyclocrinites and of several other Ordovician toSilurian genera with a similar bauplan, e.g. MastoportEichwald, 1840 , Nidulites Salter, 1851, PasceolusBillings, 1857 , Cerionites Meek &

'Worthen, 1868

and Coelosphaeridium Roemer, 1885, to eithersponges, bryo.zoa, corals, rhizopodr,, gastrop.od,.gg:,tunicates and algae were proposed (see Nitecki &Spjeldnaes, 1992).

Today there is general agreement that ryclocrini-tids are calcareous algae, as was first suspected bySteinmann (1880, pp. 138- 139), and that they are clo-sely related to dasyclads as proposed by Stolley ( I 896).Subsequently Pia's (1920) classification of cyclocrini-tids as a tribe of the order Dasycladales found accep-tance with many authors (Osgood 6c Fisher, 1960;

Johnson, 196l; Riding, 1977; Bassoullet et al., 1979;Beadle Sc Johnson, 1986; Beadle, 1988, 1991).

Starting with Kesling 6( Graham (1962) andByrnes ( 1968), who considered receptaculitids also asa group of dasyclads, a slightly different line of sys-tematic thinking evolved, which took up Roemer's(1876) idea of"a relationship of Cyclociinittt withreceptaculitids (Nitecki, 1972; Nitecki & Toomey,1979; Spjeldnaes & Nitecki, 1990a, 1992; Nitecki S{Spjeldnaes, 1992). In fact, our observations on thegrowth cycles of Cyclorinites also contradict this con-E pr, which has tJ..trtly been abandoned (Nitecki etdl., 1999).

As the name Cyclocrinus Bronn, 1848 is an unjus-tifiable amendment and therefore a synonym ofCyclouinites Eichwald, 1840 (Nitecki, 1970, p. 74),the spelling of the tribe Cyclocrineae Pia, 1920 (basedon Cyclorinus) is incorrect and has to be amendedinto Cyclocriniteae Pia, 1920 (ICBN: article l8l3).

The Cyclocriniteae are characterized by " simple,spherical to pyriform hollow body enclosing a cenlralcaviry. The outer wall is composed of more or lessheavily calcified, aragonitic or calcitic, tightly packedelements, the laterals. These consist of cup-like, gen-erally hexagonal globella which extend towards the..ntrrl cavi-'ry in tHe form of a hollow, conical to rod-like shaft (for terminolory see Texvfig. 4).

There has always been considerable uncertainryhowever, as to whether the genera CyclocrinitesEichwald, I 840 , Mastopora Eichwald, I 840 , NidulitesSalter, 1851 and Cerionites Meek & Vorthen, 1868,are all valid taxa or are partly or fully synonyms whichare based on ecophenorypic variations or differencesof preservation. Solving this problem is beyond ther.op. of this paper ".d requiies revision of the rypematerial. In some recent publications Mastopora hasbeen treated without explication as an independentgenus (Spjeldnaes & Nitecki, 1990; Nitecki 6{ Spjel-dnaes, 1992). According to Stolley ( 1896) , Mastoportmay differ from CyclocVinites by'the possession of aring-like swelling of the distal globella walls. Pia(1920) founded a separate subtribe, Mastoporinae,on this. Nevertheless, we tentatively follow the argu-ments !y Nitecki (1970, pp. ry-75) considering allgenera in question synonyms of Cyclocrinites.

Thxonomic uncertainties also concern numerousspecies of Cyclocrinites s. l. \7hile revision of NorthAmerican species has reduced their number to a fewnames (Nitecki, 1970), the validiry of Baltic Ordovi-cian species proposed by Stolley (1896, 1 898) remainsunclear. In fact, Stolley's meticulous differenciation ofspecies based on the structure of the cribellum isincomprehensible in less well-preserved material.

Cvcr-ocRINITES sp.Text-fi g. 7

Material - From "Brggerru

old road", Por 10, 1specimen. Figured: IPUM 25617 (Text-fig. 7C). -

G II t ' r f l i g .

- ( ) ' t ' 1 1 , ' t ' / 2 / / r ' , � s l ) . . l ) l ' t ' s t ' t ' r t ' r l , t r , t l l , , t t t , , t l r l l t , . s l l ' t l t 1 1 1 1 ' 1 ' s . l t I r , t s t ' o f l l l r . l ' t l \ l l l l g l r t ' r . ' , ,

r l ) t ' t l l l l t ' l l , r , , f , t r l . ' l l l ) l ' ( ' \ ( ' t r , . ' r . i r t t [ r r . ' . , , 1 r l l l ) ( l l , l ' [ J ' I l ' t \ l ] i ( r l l ' l ' t ' t ' l ' r l

l ' t , l l l . l l t ' l \ o f t ' l ' i i r e l i . l : l l t . l r l l l n . r l z , , l l t ' \ \ r t l l I l l ' \ ' ( ) , / ( ) . l l l ' t t I l r ' t i ) l ( ' \ ( ' t ' r r . ' r . 1 . ' ( I I l ' [ \ l ) :

( ) , / ( ) . t p ( ) \ r , r g r ( ) \ \ ' t l t . r l t p 1 1 r p q ( \ t l ' 1 t t ' / 2 / t r ' , , 1 ) I l ' t \ l ] 5 ( . , l ] . I ' , , t - , t .

r . i . ( \ t l ' r t ,

t , l ' 6 t i t , t j 1 r , r 1 i r , , 1 l r ; r ' , , / ( ) , 1 1 . , , i . , , , r I I I ' t \ 1 - ' i ( r I { . l ' , , t . 1 . ( 1 t t t t , t / ) t / l ( ' , . l l t t t t

: t ' r ' r t ' t i . i l l n . l t ' q l t t . t l z , r t t t ' . i l ' I i l i . i l t \ t ( ' \ \ r t l : p t ' 1 l l l l t ' l r . r i : l ] i . i o s t ' t l l ) ( ) t l ' , t ' r O z

l r i l l ' t \ 1 l S f . , l l t . l ' 6 r ' - , r .

r l . r l . r ' n I r r r ' , ) , / ( ) , u l ( ) \ ( ' r g l ' ( , n t l t r . ( ) \ t ' t l t t ! . , t l t t t , r s l t ' l l t l l ' t '

r l r i t , \ l t ' \ \ r ( , r I l ' [ \ 1 ] i ( ' , l ( . l . I ' r , l I i . r l . r . n r t ( ) l t ' l r l . ' t , . ' . , . 1 , ' t o t ' l t t t ' r l : p t ' t t t t t t ' t l . l r t '

DASYCLADALES AND RECEPTACULITIDAE FROM L. ORDOVICIAN OF SARDINI/

From "Cabo

de FigLlS", Por 13, I specimen. Figured:IPUM 25616 (Text-fig. 7G) - From

"Punta Pedrona",

Por 7a, 5 specimens. F'igured: IPUM 25686 (Text-fig.7A); IPUM 25511 (Text-fig. 7B); IPUM 25614(Text-fig. 7E); IPUM 25612 (Text-fig. 7D); IPUM25610 Gxt-fig. 7F). Not figured: IPUM 25613 (leg.A. M. Maccagno).

Desription - This form of Cyclocrinites is alwayspreserved'with an overgrowth of ^ cystoporate brv-Lro^n colony which, "6.rtd the .qr'r"tor of the tttb-globular thallus, gererally extends as a horizontal5rim. The thallus Is always incomplete and only thesteinkern of maximally one hemisphere is preseryed.The surface shows the rypical cyclocrinitid pattern ofhexagonal, concave elobella. About eleven globellaare aTigned per thallils diametre which r"ngds from16-25

-mm. ^A peduncular opening is not dbserved.

The shafts of the laterals are not preserved. Theirinsertions at the bottoms of the globella in form of asmall hole are rarely seen and generally covered byremnants of the cribellum. The globella generallyrlroy regular hexagonal outlines but some irregulari-ues rn slze and shape exist in most specimens. Theelobella diametres range berween 1.2-2.7 mm and arei.r.t"llv larger than i.0 mm. The average size of theilob.lla' incftase with increasing size of the thallus.F.or.ttes have not been observed

Remnants of cribella are always preserved and rel-atively frequently the silicified t.ttft.. of the cribel-lum can be seen. Nevertheless, the paftern of tubes isvery difficult to decipher and a clear hexameral sym-metry cannot be observed. The tubes seem to bearranged in two circles, the inner with 6, the outerwith i2 (or ? 18) tubes, which are grouped around acentral tube of equal size. The surfaces of the cribellaare weakly con'oei, showi.g the tube endings as small,round tubercles.

Discussion This form is confined to BH4.Hence it is slightly younger than Cyclocrinites cf. uAn-hoeffeni fromJrorirotr gl:F.ztgH:L ?rom which it dif-feri-merely by generally larger thalli and globella andby the absence of rosettes. The structure of the cribel-lum seems to be similar as well. Therefore both formsm"I be identical and . possib.ly represent ecopheno-rypic variants of a single species.J L

In BH4 Cycloriiittt sp. only occurs with bry-ozoan overgrowth while unsettled thalli, as are presentin BH21BH3, have not yet been found. Overgrowthon cyclocrinitids by various organisms, e. g. differentbryozoa, craniacea and (?) algae was described byNitecki (1970, pp. 53-56, figs. 30-32) and Nitecki &Spjeldnaes (1992, p. 28, fig. 16) ,and both possibili-ties, in vivo or post mortem settlement, were takeninto consideration. In some instances the aragoniticcyclocrinitid skeleton was selectively leached awayleaving its paftern at the base of the calcitic epizoa.E*tensive internal and external overgrowth of dead

thalli of the Jurassic dasyclad Goniolina hexagonaD'Orbigty, 1850 by bivalves, serpulids and bryozoawas also described by Cherchi 6c Schroeder (1993).There, too, the form of the "lg"l cortex is preserved asan allomorphic structure at the epizoans.'We

conclude that in our cise early diageneticsolution destroyed the aragonitic algal skeletons andproduced an aliomorphic Jtructure It the base of theLalcitic bryozoan colonies. As the bryozoa was lateralso leached away by weathering, the present fossilrepresents the internal mould of-the external wall ofCyclocrinites. This interpretation also explains theabsence of unseffled thalii.

'We have no explanation,

however, why unsettled thalli are well preserved inBIdZIBH3.

As seftlement of the internal side has not beenobserved in our material, both in vivo or postmortem overgrowth is possible. The striking_ abseqceof roseffes may suggest^that active growth oT the algawas either ha-p."rEd or had alreidy ceased befoiebryozoan. settlement took place. In fact, it is difficultto concelve that extensive overgrowth could haveoccurred without having severel/dirt,rrbed the ilg .Strikin gly, in all specimens the cribella are preserved.The frInction of the cribellum remains unknown(Nitecki 6. Spjeldnaes, 1992, pp. 45-46). If thisstructure, however, represented a brittle, living organ,overgrowth must have occurred either on ^ livingCyclocrinites or shortly after death.J

The regular pattern of the bryozoan overgrowthpresent in ill rp.Lim.ns may be of some significance.Very probably

^the lateral extension of the

"bryoroans

fo[;wed the surface of the bottom sediment. Thus, thebryozoan colony achieved a more stable position whichminimized the danger of a turn-over by currents.

CvcIocRINITES aff vANHoEFFENI Stolley, 1898Text-figs. 8-12

Material -From "Via Pinna s'ombra" (VPO), Flu

4, 176 specimens. Figured: IPUM 25622 (Text-fig.l0B); IPUM 2565r (Text-fig. r2C); IPUM 25664IVPO-REC 93-253) (Text-fig. 8B); IPUM 25666MPO-REC 93-2601 (Text-fig. l2A); IPUM 25667IVPO-REC 93-269] (Text-fis. 8D); IPUM 25668tvpo-REC e3-2l8rl (Text-fig: l2D); IPUM 25679a,bMPO-REC 93-248A+Bl (Text-fig. 8A); IPUM 25680MPO-REC 93-2671 (Te*t-fis. 10A); IPUM 25685YPO-REC 93-2321 (Te*r-fi-g. l0C). Not figured:IPUM 25619 - 25621 , IPUM 25623 - 25650, IPUM25652 - 25663, IPUM 25665,IPUM 25669 - 25678,IPUM 25681 25684. - From "Piscina Suigxs", Por12, 1 specimen. Not figured. IPUM 2561 8: - From"Sa Siliqua", Gon 1, 20 specimens. Figured: IPUM25603 (Text-fig. I lC), IPUM 25604 (Text-fig. 8C),IPUM 25605 (Text-fig. 8E), IPUM 25606 (Gxt-fig.11A), IPUM 25607

"(Te*t-fig. llB). Not figured:

IPUM 2560I,IPUM 25602, IPUM 25608, IPUM25609 17.

r 8 f VI HAMMAAIA/, E. SERPAGLI

*-: s . . " ,

rex'�- n g 8 - ?:!::x" K:ir :i :(:,ff ,1 i,':i"'J;1,?i,'iix:i[ :ifftfiy#1,"ff l3;;i'm';of thallur. (C) IPUM 25604, Gon I, compressed, cushion-shaped thallus with(Cl) convex upper (?) side, internal mouli; (CZ\ side view, internal mould; (CCl, latex cast bFe*t.rnal mould. (D) IPUM 25667, Flu 4, deformed internalIPUM 25605, Gon l, hardly deformed internal mould of large thallus showirlatex cast of E2 showing base of shafts; (E2) convex upper side, slightly obliqu

Description - The original shape of the thallus wasprobably lpherical ot *Jtkly .,tthion-shaped with ailiehrly'flattened inferior side. The diameires (mean"f"-"i.imum and minimum diametres of deformedthalli) of 97 specimens measured vary berween 6.5

mm and 17.5 mm (specimen of 6.5 mm diametreText-f ig. 8D). The size distr ibut ion fol lows aGaussiin pattern with a maximum at 13 and 14mm(Text-fi g. 9). The wall has a honeycomb-like patternof predominantly hexagonal and rarely pentagonal

DASYCLADALES AND RECEPTACULITIDAE FROM L. ORDOVICIAN OF SARDINII

and quadrangular globella. The number of globellaalong- alignments over various diametres of a hemi-spheie ring.r from 10-16 (most frequently 13); itincreases wlth the size of the thallus. Many specimensshow rosettes, i. g. well defined, star-like groups up toeight elongate globella. The shafts are indicated by "ciicula, op".ni"E in the concave bottom of the globel-la. A peduncular opening has not been clearlyobserve-d. Several specimens from Gon I show pre-served cribella.

The individual laterals consist of a cup-shapedelobellum formins an element of the thallus wall andf thin, cylindrical"shaft that extends from the base ofthe globellum towards the central caviry. The shaftsare

"rarely preserved. They are radialiy arranged,

straight, thin, hollow tubes, which very weakly widento*a"rds the base of the elobellum. Ai the mouth ofthe shaft the bottom of the elobellum abrubtly opensto form a wide cup. The tri"-.tr. of the th"ftt isabout I0o/o of the diametre of the elobellum. Theirlength corresponds to about five tiries the depth ofthe"globellum and to about one third of the averagediametre of the thallus, respectively.

The globella are cup-shaped with an evenly con-cave, rounded bottom, which distally merges intovertical lateral walls. The walls, which are shared withneiehbouring globella, form polygones with thin andrhJp margitrl The depth of ih". globella approxi-

6 7 I I 10 11 12 13 14 15 16 17

mean diametreText-fig. 9 - Size distribution of 97 specimens of Cyclorinites

aff. uanhoffini Srclley, l89S from localities Flu 4and Gon f"showi ng a Gaussian pattern. The size isthe mean between iraximum ".d minimum diame-tres; mean diametres within one mm are combinedto a single column, e.g. l6 and 16.6 mm = 16 mm.

mately corresponds to their diametre. The high vari-at ion of elobel la diametres (0.8-1.8 mm; mean 1.3mm) and"shapes frequently observed within an indi-vidual specimen is partly due to deformation butoften primary and related to growth processes (seebelow)^. The average diametre oT the globella statisti-cally correlates with *. size of the thallus: small.spec-imens possess conspicuously smaller globella diame-tres than large ot.i. In many specimJtt the globellahave a nearly regular hexagonal outline. This regularpattern is often disrupted and globella with quadran-

[ular or pentagonal outlines may be intercalated,5ft.tr showine c;nsiderable variation of size.

Rosett.r it. star-like arrangments of rypically fiveand six or, less frequently, seven and eight drop-shaped globella, here called petals, which meet at anelotrg"td acute angle at a common centre (Text-fig.I}CZ). Often the-rosette contains a small, ..r,ttilelobellum (Text-fiss 12C2, IzDr. The radial diame-ire of the petals is

-generally larger than the diametres

of "normal"

globella and may attain up to 2 mm inlength. The normal, regular hexagonal honeycombpattern of the globella surrounding the rosettes isoften irregular.

ln 49"out of 162 sufficiently well-preserved spec-imens a hexameral rosette is present. Pentameralrosettes have been observed in 28 cases. Two speci-mens show rosettes of seven or eight globella, respec-tively. In addition, rosette-like clu"rt.rf of four globel-la are very frequent. The number of rosettes observedin ole specimen mly va.ry.from 0 to 3. As in mostspecimens only one hemisphere can be observed, it isprobable that rosettes are present at each completespecimen.

Cribella are frequently preserved in specimensfrom Gon l, but are lacking in Flu 4 and Por 12. Invertical cross sections the glSbell a are filled with thin,silicified subvertical tubes which proximately seem toconverge towards the centre of the globellum. Thisstructure largely resembles figures by Eichwald( 1860, fig. Zla, pl. 1 I ) and Nitecki 6{ Spjeldnaes(1992, fig-. 7), respectively. In vertical view the surfaceof the cribellum seems to be covered by a slightly con-vex

"skin" with a granular structure. A well preserved

external surface showin g a perfect hexagonal patternof tubes, as known from Baltic species of Cyclocrinites,has never been observed. In some few instances, how-ever, a hexameral arrangement is indicated suggestingan inconspicuous central tube surrounded by rwo cir-cles of 6 and l2 tubes, respectively.

There is no indication of a calcified wall enclos-irg the central caviry, which is merely marked by theproximal tips of the shafts. The caviry occupies aboutone third of the thallus diametre. In some steinkernsa circular opening interrupts the regular globella pat-tern, suggesting the possible presence of a pedunculus(IPUM 25622, Text-fig. l0B). In other specimens,however, a similar structure may exist on the internalmould, while on the corresponding external mould

QcoE 1 5

t -ooo-Q

F

; 1 0o-oEfc

20

Text-fig. l0

t TTI HAMMAAII/, E. SERPAGLI

Cyclocrinites aff. uanhoffini Srcl\ey, 1898, shafts and (?) peduncular opening; all from Fsteinkern (Al) and latex cast (A2) of compressed, broken thallus showing interior with parnote also large rosette. (B) IPUM 25622, x 3.5, compressed steinkern of thallus showing traopening_ (C) IPUM 25685, x4, compressed steinkern of thallus showing traces of the shaftsment o-f thallus showing laterals wit lr empry globella and shafts; (D 1) sleinkern; (D2) latex

the globella form a closed wall. There is evidence thatweathering of pyrit ic concretions is responsible forsuch an

"opening". As none of the halves of thall i nor

the specimens, which were prepared from all sides,show a well-defined gap, it is more likely that apeduncular opening was lacking.

Discussion - Due to unconstricted globella wallsand cribella with a pattern of tube circles, the presentspecies belongs to Stolley's (L896, p. 258) speciesgroup of Cyclocrinites porosus. Thus comparison withOrdovician species with constricted globella walls("MastoporA"-group), e.g. the Baltic species MastoporaconctuA Eichwald, 1840 , Cyclocrinites multicauus

Stolley, 1896 and Cyclocrinites plrformis Stolley,1896, 2s well as Mastopora nAnA Gnilovskaja, 1972,from beds with Amsassia c/taetetoides, Pleurograptuslinearis Zone of Dulanka Stage of the KulanbulakFormation, Thrbagatay Range, eastern Kazakhstan, isout of quest ion.

The same applies to the species group with radialridges of cribella around Cyclocrinites spasskii Eich-wald, 1840 which also includes Cyclocrinites roemeriStolley, 1896, Cyclocrinites subtilis Stolley, 1896,Cyclocrinites planus Stolley, 1896 and Cyclocrinitesmembrannceus Stolley, I 896.

Cyclocrinites bilobatus Lee & Caldwell , 1977 fromthe Irene Bay Formation, Caradocian, Cornwallis

DASYCLADALES AND RECEPruCULITIDAE FROM L. ORDOVICIAN OF SARDINI.I

Island, Northwest Territories, Canada, differs in hav-i.g a small, elongated, medianly constricted thallus.

The porosu.r-group includes three varieties ofCyclocrinites porosu.r as well as the species Cyclocrinitesoilandicus Siolley, 1898 and Cyclocrinites uanhoeffeniStolley, 1898. Among these Cyclocrinites uanhoffiniseems to be most closely related to our species in hav-ine convex cribella surfaces with rwo circles of indis-tirictly defined pores. Cyclocrinites uanhoffini wasbased on only rwo specimens from glacial erratics ofthe Marurus Limestone or the Kegelsche Schicht(Keila Stage, DII), respectively, of Poland (Stolley1898). The holorype, an almost complete globularthallus, was refigured by Neben & Krueger (1979, pl.125, figr. 25, 26). It cle arly shows the strongly con-vex cribellum surfaces with rwo circlets of 6 and 12indistinct pores, respectively. The thallus is relativelysmall and has a diametre of 9-10 mm. The hexagonalglobella with average diametres of 0.9- I mm are

arranged in relatively regular rows of about I I perdiametre. Though being relatively low, these valuessti l l fall within the range of our specimens. Accordingto Stolley (1898) the globella of Cyclocrinites uanhoef-

ftri are only weakly calcified, which does not seem tob. the case in our material. Apart from the existingmorphological similarities, the relatively young strati-graphical occurrence of Cyclocrinites uanhoffini isalso most comparable. However, a definite attribu-tion of the Sardinian material to Cyclocrinites uan/to-effeni does not seem possible at the-moment.

According to Stolley (l 898) Cyclocrinites oelandi-cus Stolley, 1598, which also o..u?r in erratics of theMacrurus Limestone of Oeland and northernGermany, differs from Cyclocrinites uanhoeffeni main-ly by the presence of plan cribella surfaces.

Cyclorinites porosu.r which is the stratigraphicallyoldest and best known species of this group, occurs inthe Jovi Stage, DI, of Estonia as well as in coeval

Cyclocrinites aff. uanhoeffeni Stolley, 1898, with cribellum; all from Gon l.(A) IPUM 256Cingglobel la part lywi th cr ibel la preserved; (Al) latex cast ; (M) ste inkern. (B) IPUM 25607,imen with part ly preserved cribella; (B I ) overall view, x 3; (82) close up of cribella, x 7 . ((plete thallus; (C1) steinkern marginally showing globella walls and rwo globella with remnaprotruding interior mould of ,ositte; (C21.*t. ini l mould, note disart icJlated part of cribelhence of three rosettes.

Text-fig. I I

22 t W HAMMANN, E. SERPAGLI

glacial erratics from the southern shores of the BalticL" (Stolley, 1896; Neben 6{ Krueger, 1973, 1979;Roomusoks, 1970). It may also exist in erratics ofIdavere age, C3 (Neben & Krueger, 197 ?, pl . 57 , cf.porosus). The species is characterized by generallystrongly calcified globella and cribella, clearly show-i.g tK. concentriiube arrangement around a slight-ly larger central tube.-

One of the rype specimens (? the holorype) ofCyclocrinites porosui Stoll.y, 1896, refigured by N.ebena Krueger (tgll,_ pl. gi, figt. l-2)-and Nitecki 6{Spjeldr""., (1992, fi!. M) frot-t Ordovician erratics oftl i . Pliocene Kaolinsand of the Island of Sylt,Germany, shows a small protuberance formed by "central elevation and six surrounditg globella, whichwas interpreted as a pedunculus (Nitecki &Spjeldnaes, 1992, p. 34). As the specimen is an inter-rr"i mould, the stiucture may ai well represent theprotruding centre of a rosette. The thallui diametresbf the rype and of other specimens of Cyclocrinitesporosus figured by Neben 6{ Krueger (197 3) rangeb.r*. rn 7.5 and i 6 --. The globeJla are about 0,8-1.2 mm in diametre and the n"umber of globella perthallus diametre is 10-16. These values are comPara-ble with the Sardinian material, though the averageglobella size may be slightly larger in the latter. TheSardinian species differi howevJr, by a less distinctlymarked hexameral pore pattern.

North American Ordovician species are more dif-ficult to compare as well-preserved cribella are alwayslacking . Cyclocrinites globosrs (Billings, 1857) ftqhtthe 6ttr*" and E-rindale Formition, MiddleOrdovician, Canada, is clearly larger than the presentspecies. The globular thalli exce ed 40 mm in diame-tie and also rf,o* a higher number (about t 5) of glo-bella per diametre. Cyclorinitel flrformis (Bassler,1915) (non Cyclocriiites pytformlt

- Stolley, 1896)

from tlre Charirplainian of" tli. USA differs by anelongate, pyriform thallus and smaller and deeperglobElla. X..ording ro Nitecki (1970, p. I 34)Cyclocrinites pyrfo/mis appears to be similar toMatnpora paiia Nicholson & Etheridg., 1878 fromthe Iialcla'tchie Group, Caradoc, of the GirvanDistrict, Scotland.

Cyclocrinit ids reported from East Asia, e.g.Pasceolus? shianensis Reed, 1912from Pin Limestone,? Caradoc, Spiti, India, and Cyclocrinites tibetensisMu, 1982 from ? Lower Caradoc strata, of

'West

Sichuan, China, belong to Coelosphaerid.ium (Spjel-dnaes & Nitecki, 1990).

OBSERVATIONS ON THE GRO\TTH OF CYCLOCRINITES

Possible models for the growth of the thdlus inCyclocrinites were discussed on the basis of well-pre-served, three-dimensional North American and Balticmaterial but details of this process are still poorly under-stood (Nitecki, 1970, pp.32-35; Nitecki S( Spjeldnaes,1992, pp. 46-48). Clearly the growth of the thallus is

controlled by rwo interacting processes. As small speci-mens possess smaller globellae than large ones, contin-uous iadial growth Jf the laterals co'-ntribute to thesrowth of thE thallus on the one hand. On the othetIddition of new laterals must have occurred as the num-ber of laterals, indicated by the number of globella perdiametre, is hieher in large specimens.

Unlike rec"eptaculitids and most recent dasyclads,where small, new lateral elements are added in whorlsaround the apical pole, in cyclocrinitids the locus ofthe formation of new laterals remains unkno'wn. Infact, in Cyclouinites a well-defined apical growth zonehas nevei been observed, although this has been sus-pected (Nitecki, 1970). The laterals rather show aiandom size distribution over the thallus wall andmay even become slightly larger at the suppos.ed api-cal'region. The alignilrents oflthe hexagonif glgbefia,which are traceable as parastichies or whorls, arenever completely regulir and generally becomeincreasingladisruptedln large speiimens (Nitecki &Spjeldnaes, 1992, p. 46).

These observaiions largely apply to our materialas well. As our specimens are compressed, the paffernof laterals can only be observed at one side. Beingabout globular and lacking a peduncular pole, an api-cal region cannot be defined a priori. 4 p"r,ern. s.ug-gesting apical growth has nol been found, either.eon.."rniirg the"regulariry of whorls and parastichies,there are .L", indlviduai differences indlpendent ofthe absolute size of the thallus. Specimens of all sizesmay be completely irregular, predominantly regular,or, most frequently, show a mixture of regular andirregular "r.ir. Tlie irregular disruptions bf par1s:tichles suggest that interfalation of^new laterals didnot take p'1".. at a well-defined region, but was ran-domly diitributed over the whole t-hallus.

Newly intercalated laterals are likely to be recog-nized by their smaller size. The rosettes, often containa remarkably small, central globellum (Text-fig.I2C2) which may vary in size from very tiny to slight-ly smaller than an average-sized globellum. This wasalready observed and described by Stolley ( 1896, pp.190-191, figt. 26, 30, 34) for species of Cyclorinitesand MastoporA. Obviously Stolley, who very cautious-ly talked

- of possible

"'Wachsthumserscheinungen"

(manifestations of growth), found the correct iriter-pretatioh, but did not elaborate on it further. A simi-Iar proposal was made by Nitecki (1969, p. 371), buthe,

^ as

^well, did not diaw any further ionclusions.

Rosettes have as well been observed in NorthAmerican specimens of Cyclocrinites dnctiloides and inthe genus

^Coehsphaeridium (Spjeldnaes 6{ Nitecki,

1990, p. 31), showi^g that these structures were com-mon and of some significance in ryclocrinitids.

In the followinf we suggest th"t rosettes are theplace of intercalatioil of " .."'# lateral and that they aresecond ary structures which were specifically formedfor thir p.ttpose. The numerous diferent geometricalconfigurations of globella observed in our specimens

DASYCLADALES AND RECEPACULITIDAE FROM L. ORDOVICIAN OF SARDINI/ 23

globella involved are called "petals".

Particulars of thisprocess seem to be more complex, however. The pat-terns observed indicate that the shortening of wallsdoes not occur synchronously but successively, whichwould also explain the formation of various otherradial symmetries. The frequent quadromeral constel-lation can be understood as the first step towards anhexameral rosette, where only one wall has disap-peared. A p.ntameral structure may be derived froma quadromeral structure by the shortening of a fur-ther wall, etc. In contrast to rosettes with higher sym-metries, intercalation of new globella have never beenobserved in quadromeral structures, which thereforeare probably mere transitional patterns. Clearly, hexa-

represent "snapshots"

of this dynamic, cyclic process,which, put into a hypothetical order, may comprizethree stages: a) formation of a rosette, b) formation ofa new lateral and c) growth of the new lateral and dis-appearance of the rosette (Text-fig. I 3).

a) FonrvrerloN oF A RoSETTE (steps 1-3 in Text-fig. 13).Starting from a pattern of regular hexagonal glo-

bella a hexameral rosette may hypothetically form byshorteTirg of three radiating globella walls andmigration of the inner angle of the three outer glo-bella towards the centre. At the same time the innerthree globella adjust in size and shape so that finally ahexameral symmetry of rosette is achieved. The six

I:i

Wt , .

fl&9"3i

PgCyclocrinites aff. uanhoffini Stolley, 1898, rosettes and intercalation of new laterals; all fromcompressed thallus showing various growth stages of several rosettes; (Al) steinkern, overgential view showing protruding centre of a rosette. (B) IPUM 25679b, x 3.5, external motthree rosettes; (B I ) latex cast, note large rosette (a) of six petals (upper half) with initial peas Bl, steinkern. (C) IPUM 25639, laiex cast of extemal mould; '(Cl ) * 4, overall view rh'o'(C2) x 8, c lose up of hexameral roset te (a of Cl)wi th smal l daughter g lobel lum; (C3), X 8,(b of Cl) showing init ial petal. (D) IPUM 25668, latex cast of external mould showing rw<all view; (D2) x 8, close up of hexameral rosette (a of Dl); inir ial globellum showing begiglobellum; (D3) * 8, close up of heptameral rosette (b of Dl) showing daughter globellum

Text-fig. 12

meral rosettes are most frequent. As is explainedbelow this symmetry allows the immediate formationof a globellum with the ideal hexagonal outline.

'We

r.tpp6se that the purpose of the roiette is to providethe space where an additional new lateral can grow.

b) FonMATIoN oF A NE\r LATERAL (steps 4-5 of Text-f ig. 13).

In this stage of development the centre of therosette plays ; crucial role. In a fully-developedrosette the deepest concaviry of the petals with theshafts is situat.d excentrically. Centraily the bottomsof the globella rise gendy so that the radial wallsbecomes less fused towards the centre. In contrast totriradiate crossings of normal gobella walls, the cen-tres of rosettes are hollow up to the tip, as is indicat-ed by the clearly protruding pyramidal steinkerns(Text-fig. I2A2). In external moulds, however, thecentres of rosettes are not elevated. In well-preservedspecimens it can be observed that the centre is notcbmpletely radially symmetrical: one of the petals,the

"initial petal", has a slightly longer tip which sur-

passes the centre (Text-fie. I2C3; Stolley, 1896, fig.fOl. In the followirg hyp"othetical step the tip of tli.initial petal slightly widens and deepens, formi.g !h.init ial

^ site oI a'

"daughter globil lum' (Text-fig.

l2D2). Subsequendy a ffansverse wall is formed, sep-arating the daughter globellum from the initial petal.

wfril. the "'bor,..-described transformatiott ,if theinitial petal is well established, interpretation of the

24

processes occurring in the _soft tissue involved remain

the petals and surrounding globella which may be

1 - 3 F o r m a t i o n o f r o s e t

achieved by resorption and redeposition of the cal-careous skeietal mitter. In fact, Stblley (1 896, p. 191)interprets the frequent presence of small gaps in thecentrts of rosettes as possible sites of non-preserved,still uncalcified, smafl laterals. In our material thedaughter globella are silicified and always preserved.

Itrothi"'tre is known about the formation of theshaft and .r-lb.llum in the new lateral. The new shaftdoes not seem to result from a branchitg and cen-tripetal, longitudinal spliming of the shaft of the ini-tial petal. Fiist traces oT " sec6nd shaft in the form ofe very tiny basal depression are seen in the daugthterglobellum at an , rfy stage of separation from di. ini-iirl petal (Text-fig. l2b2). dr"nched shafts havenever been observed in Cyclocrinites (Nitecki, 1970).Division of the cribellum is not documented in ourspecimens but was mentioned by Stolley ( 1896, p.191) "r well. In a specimen of Cyclocrinites cf . Porosusfigured by Neben & Krueger (1979, pl . 145, fig. 3)the cribella of a rosette with a small daugther globel-lum can be seen. The number and arrangement ofpores in the daughter globellum is unclear, however.

c) GnovrH oF THE NE\r LATERAL AND DISAIIEAR-ANCE oF THE ROSETTE (steps 6-7 of Text-fig. 13).

Once established in the centre of the rosette, thedaughter globellum seems to grow rapidly, expanditgcentlifu gilly at the expense oF the petals. The centraltips of t.-he'petals "t. p,rshed back until, finally, thepitals and the daughter globellum have achiev.d th.ror*"1 size. Startine frJm a hexameral rosette thisprocess would result Ttt a pattern of equal-sized hexag-onal globella, showing a disruption of parastichies(Text-fig. I 3).

t W. HAMMANN, E. SERPAGLI

processes occurnng lnspeculative. The .["ttg. of outlines taking place dur-ins the formation of the rosettes recuires olasticiw ofi"g the formation of the rosettes requires plasticiry ofthe oetals and surrounding slobella which mav be

4 - 5 F o r m a t i o n o fd a u g h t e r g l o b e l l u m6 - 7 G r o w t h o f d a u g h t e r g l o b e l l u m

\ reT .

(.;...;.'.i

Text-fig . 13 - Growth rycle of rosette with intercalation of a new laterals (see explanation ir

DASYCLADALES AND RECEPTACULITIDAE FROM L. ORDOVICIAN OF SARDINU

APPENDIXBiometric data of cyclocrinitids

Localiry Por 7aIPUIvt No. | 225610 22t37 Q9., r4t23 (18.5)25611 22133 (27.5) 16122 (19)25612 17124 (20.5) r2lr4 (r3)2j6r3 20t27 (23.5)

25

The supposed irregular interstitial intercalation ofsingle, rapiily growin{daughter plobella.well :*Pl*ltthe geornetrical patterns observed in Cyclocrinites. I heoort-'ttlated .otttittuous changes of globella symmetriesiequires a high plasticiry oF the J"l."t.o.ti skeleton.Teinpo rary dEcaf.ification may be supposed for areasof intercalation of new globella.

CONCLUSIONS

Receptaculitid growth and the patterns of inter-calation

'of -.ro-", have extensivily been studied

(Rietschel, 1970; Gould & Katz, 1975; Fisher 6cNitecki, 1982) and are considered an importent sys-tematic criterion. In receptaculitids bifurcation ofparastichies happg",t T

interposita, a glotlP of two or^tht.. meroms which form an entiry of a large rhom-

bic element. This rype of intercalaiion is "Jty differ-ent from intercalaiion bV means of rosettes incyclocrinitids. Most significandy, roseftes were alsodtscribed in well-pt.r.ft.d specimens of the dasycladGoniolina hexagoiaD'Orbigny, 1850 from ,hg UpPqt

Jurassic of Pommerania, Poland, and similarities withcyclocrinit ids were pointed out (Cherchi 6(Schroeder, 1993, pp. l2-I3, pl. 2, figt. 3-r. Othersimilarities of Gonlol;na hexagona wirli cyclocrinitids,concern the morphology of tle thallus, possession ofsimple, unbranched literals and of hexigonal headswith a constricted external margin (reminiscent of" MastoporA").In fact, ?r unrelat.{ develoPment of all

these r^tt,t.t.tr.t seems to be highly unlikely and canbe taken as a strong, further argument for an attribu-tion of cyclocrinititrs to Dasycl"adales.

In Goniolina the sametangia are known and situ-ated laterally (Cherch'i 6c Schloeder, 1993) rypical ofthe family Dasycladaceae. ln Cyclocrinites, however,gametangla ha"e never been obslrved but, in analogyIo the cyilocrinitid genera Apidium Srcll9y, 1896 andCoelosphaeridium {oemer 1885, may be suPPosedinternilly (Nitecki 6. Spjeldnaes, l9?2, pp: 58-59).Therefoie, in agreemenfwith Bassoullet et Al. (1979) 2Cyclocrinites is-tentatively retained in the dasycladfamily Seletonellaceae Korde, 1950.

ACKNO\TLEDGEMENTS

'We are grateful to I uciano Menghi who kindly supplied his

large collecti-on of fossils from the Fluminimaggiore-Portixedu^r{^ including specimens of Cychminites, to Enrique Villas,Zaragoza, whd kihdly read the.siratigrlpfical chapter, further toStefaio Conti, Modena, who identifild the bryozoan overgrowthof Cyclocrintes and to our colleagues.from Modena "tt+ CgJtqliUniversiries who assisted us in tlie field work.

'W'e also thank Nils

*********************************************************************************************rl*'j;3*,?:fi:f #,i"*"3*ln:iiH',Hi'',;;I;material of his ryclocrinitid col-lection. H. Muwei, Stockholm,kindly showed to one of us (E.S.,.sePt. 1994) cyclocrinidd sPec-imeni housed at the Naturhistoriska iiksmuseet. Some figures aredrafted by the artist Giancarlo Leonardi, Modena.

This research was supported by MURST 600/o and COFINgranrs (resp. E. Serpagli). This report is a late contribution to theiCCp Project 410 'TFe grear Ordovician biodiversification event".

1. Cyclocrinites sp.

Explanation. First column: IPUM-No of specimen. I = Diame-tres of bryozoan colony: minimum/ma:rimum (mean), in mm.2 - Diametre of Cyclocrinites: minimum/ma:rimum (mean), inmm. 3 = Range of globella diametres in mm:

3r .5 -2 .52.0-2.5r.3-r.92.0-3.0

Localiry Por 13IPUM No. I25616 -134

2 317128 (22) 2.0-3.0

2. Cyclorinites aff. uanhffini

Explanation. First column: IPUM-No of specimen. I = Thallusdiametres: minimum/ma:rimum (mean), in mm. 2 - Range ofelobella diametres in mm. 3 = Rosettes with number of petalsfnd, if present, with small daughter globellum (e.g. 6+ I ) . 4 -Presenci of cribellum (cr), shafti(sha)"or possible o[ening (op?)and other fossils.

Locality Flu4IPUM256r9256202562r25622256232562425625 |256252256262562725628125628225629256302563r2563225633125633i l25634256352563625637 |25637 225637 325637 425637,25637 625637 725637 825637 e25637 rc25637 n25637 B25637 1a25637 525637 6256381256382256383

Ir2 t r5 (13 .5 )rLt16 (13.5)

to /15 (12 .5)etrs ( 13.5)r4 l 18L3 l17r2 l16rr lrT

6)5)4)4)

r2lrg 5.5)

2r.2-r.6r .0 l r .3r .0 l r .4-t- (-)r .2 l r .5r .2 l r . 5r . U L . 5r .4 l r .7r .0 l r .4r .2 l r . 5r .2 l r .5

-t-r . 2 l r . 5r . r l r . 3r .3 l r .6r .2 l r .4r.3t-

r .0 l r .7T,OIT,2r . r l r . 6-1r.4

r . r l r . 4L .2 l r .40.81r .4r . r l r . 5r .2 l r .4r .0 l r .51 .0 / 1 .5r .2 l r .4r .0 l r .4r . r I r . 50.91r .3r .3 l r . 5r .0 l r .4r .0 lL .30.91r .4r .0 l r .4

-t-r .4 t r .5

4

sha

hexact.

r2 l16r2 l17r2l19r2l18

r4 l19l0 / 18

r2 l13r0 l16

4)4.5), .5)5)

6.5)

3514

615_14

4444

44

6

7

elq

6t4

u:,

6

eis64

shashashasha

bryoz.bivalvelingul.

oP?

shacr?

r4)2.5)3)

r0l-t3 t17 ( r5)8l12 (10)1 l /17 ( r4 )

-t--t--t--t--t--t--t--t--t--t--t--t--t-

t 1 / 1 5 ( 1 3 )l 1 / l l ( l l )10/ l 4 (r2)

-t-continued

26

25638425638525638625638725638825638e25638rc25638n256381225638l:'25638M25638$25638rc25638v2563818256392025638212563922256382625638272563928256382e2563qiJo2563q: ' l2563qi.42563ql , ,2563U62563U82563\e256394025639412563842256384325639 |25639325639425639525639725639825639e2564r2564225643256442564525646256472564825649256502565r256522565312565322565r256522565525656256572565825659256602566r2566225663256642566525666256672566825669 |

-t-I 1 / 16 ( l 3 .5)

-t--t--t-

1o/15 (12.5)-t-

1o/ 1 4 (r2)-t-

8 t13 (10.5)-t--t--t-

- / 1.8-t--t--t-

1 r /16 (13 .5 )lo/14 (r2)

-t--t-

rzt18 (15)_t 17

rr I 13 ( r2)9 t 1 4 ( 1 1 . 5 )r2t18 (15)

-t--t--t--t-

ntr6 (13.5)_t13

r2t17 ( r4.5)-t-

r3t17 (r5)11 /18 (14 .5)r3t 19 ( 16)

- l12rzt17 ( r4.5)

-t-1 r /16 (13 .5 )I r /16 (13 .5)lo /15 (12.5)l1 /17 ( r4 )

r3t20 (16.5)ntr6 (13.5)lo /13 (1 1 .5 )15t18 (16.5)gt r r ( lo)

- t 17-t-

r3t17 (r5)8t13 (1 1)8/ r l (e.5)

I l /18 (14 .5)11 /15 ( r3 )I 1 /17 ( r4)

I 1 / l 8 ( l 4 .5 )-t-

8 /18 (13)r4t 17 (r5.5)9 t 1 3 ( 1 1 )

r5t20 (r7.5)r2t16 ( r4)1o /16 (13)

10/ 1 7 (r3.5)8 t15 ( I 1 .5 )1o /13 (11 .5 )

5t8 (6.5)1 l / 1 5 ( 1 3 )

1o /13 (1 1 .5 )

r .U r .3r.3t--r.3-I.2-t--t--t-

r .0 l r .3r .2 l r .5r . U r . 31,.21r.6L .2 l r .5

25669225669325669425669,25669625669725669825669s25669rc25669 n25669 n25669li�25669 v25669$25669rc2566917256702567r25672125672225672325673256742567525676125676225676325676425676525676625677256782567925680256822568325684125684225685

I Vf HAMIUL,4 IN, E. SERPAGLI

1 . 1 / l1 .0 / lr .2 lrr .3 lrr .3 lr

L.2 l

-t- (1 . 1 / l

:

6t5t5464

5t4t464

5t5t56t_5

4

-5 t545

46

6+ l l 4615146+l6

6t76t5t4?614

66t6t6

7-4

4

6t5t45

615146

617 +l

sha

sha

sha

sha

sha

cr?

1o/13 (11 .5) r .L l r .3-l- -t.21t.9

- / 18 r .0 l r .47l13 (10) 0.9/ l .o

r2l- 1.0/1.3lo/15 (12.5) r .2 l r .5

- l - r .5lr .71 l /14 ( r2 .5 ) r .2 l r .3L3l18 (15. , r .o lL .4

r3 l - r .2 l r .5l0 /15 (12. , r .2 l r .6

- l - r .2lr .57 l r r (9) r .o l r .3

r2 l18 (15) r . r l r .6n l - r . r l r . 5

9 l12 (10.5) o.9 l r .21 l / 16 (13 . ' r . o l r . 4r3lrg ( l6) r .2lL.5r2 l14 ( r , r . r l r .4

l1 /18 (14 .5) r .2 l r .5r2l- -l-

l 1 /19 (15 ) r . r l r . 5r2 l16 ( r4) r . r l r .2

r2l19 (15., r .3lr .6- l - l . l l r .4

1 l /17 04) L.0 l r .2etr5 02) -t-9 l13 (11) 0 .8 /1 .3

- l- r .2lr .6- l - r . r l r .3rc l - r .L l r .3- t - - l -

11 /19 (15 ) r . o l r . 5g116 ( r2.5) r .2 l r .310/14 (r2) r .ur.315l19 (r7) r.3lr.4

- / l8 r .0 l r .3-t- L.3lr .5

1l /17 04) - t-

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r .3r .31.5

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4

514

i

-;

6+L4

6t45t4

615t461514 sha

6 cr?6t5- graPt.

6t5

4 sha66

61514

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r.3r.3

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66

r .2 lr1 . 1 / 1r .2 lr1 . 1 / 1. ,1 .3-1.4

r .2 lr1.0 / l1 .0/ lr .2 lr1.0/ I1 .0 / I0 .91 r1 . 1 / 1

-I .41 . 1 / 11.0/ l1 . 1 / r0 .91r

Locality GonIIPUM I25601 I 3lr5 04)25602 -l-25603 r4lr7 (r5.5)25604 -l-25605 12116 (r4)25606 -l-25607 1o/14 (r2)25608 I l /15 (13)25609t -lr42560924 -l-256092-2 -l-256091 -l-2560e; 6te (7.5)256097 1o/l I (10.5)

Locality Porl2IPUM I25618 r2l-

2 3r.3 l r .7

4cr

46 c r6 c r

614 sha- c r- c r- c r-t- (

1 . 1 / l1 . 1 / l1 . 1 / l1 .0/ l

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| 6173 614

0| 6t5t5

444

DASYCIADALES AND RECEPTACULITIDAE FROM L. ORDOVICUN OF SARDINI}

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YouNc, T.P., 1990, Ordovician sedimentary facies and faunas ofsouthwest Europe: palaeogeography and tectonic implica-tions. In McKeriow,-'V7.S. S{ Scotese, C.R. (eds.), PdaeozoicPalaeogeography ?nd Biogeography: Geological SocieryMemoir, 12: 421-430.

(manuscript receiued October 10, 2002accipted March 20, 2003)

\Tolfgang HnrrlrraeNN

Ahornstr. 3, D-97535 'Wasserlosen

(Germany)(deceased Sept. 23'h, 2002)

Enrico Snnpnclt

Dipartimento del Museo di Paleobiologia e dell'Orto Botanico(Paleontologia)"

Universit)r di Modena e-Reggio Emilia,via unnflTi ^;;:;;32#;i;na (Ldv)