Late Paleozoic Trilobites from Kansas and Nebraska

A Thesis

Presented in Partial fulfillment of the requirements for the degree Bachelor of Science

in Geological Sciences

by

Robert E. Swisher

The Ohio State University 2007

Table of Contents

Abstract. ............................................................................................... 2

Acknowledgments .................................................................................... 3

Introduction ............................................................................................ 4

Geologic Setting ....................................................................................... 5

Geographic Locations .............................................................................. 11

Systematic Paleontology ........................................................................... 11

Graphs ................................................................................................ 24

References ............................................................................................ 27

Abstract

Species of late Paleozoic trilobites reported from Nebraska and Kansas include

Ameura missouriensis, Ditomopyge decurtata, Ditomopyge scitula, and Anisopyge whitei.

Restudy indicates that A. whitei is a subjective junior synonym of D. decurtata. Species

of Ditomopyge seem to represent end members in a gradational evolutionary series. The

earlier species, D. scitula (Carboniferous: Pennsylvanian) may have given rise to D.

decurtata (Permian: Cisurialian) through evolutionary processes.

2

Acknowledgments

My sincerest appreciation and thanks go to Dr. Loren Babcock for his guidance, assistance, and understanding for the completion of this thesis. I would also like to thank all those who collected the specimens used in this study, including Dr. Babcock. For assistance with preparations of the specimen figures used I thank Dr. Babcock for help with the set up and use of equipment, and Brad Walls for assistance on presentation and formatting of the pictures.

3

Introduction

The goal of this study is to evaluate and systematically review four species of

trilobites from Carboniferous and Permian strata of Kansas and Nebraska. The species of

late Paleozoic trilobites examined in this study are: Ameura missouriensis, Ditomopyge

decurtata, Ditomopyge scitula, and Anisopyge whitei.

Ameura missouriensis, has the mostly clearly defined and distinguishable features

making it the easiest of the four species to identify. Distinguishing D. decurtata, D.

scitula, and A. whitei is more complicated. Ditomopyge scitula and D. decurtata can

often be difficult to separate based on morphological characteristics, with variations

present often being gradational (Brezinski, 1988), leaving few examples of clearly

identifiable specimens. Often the stratigraphic position of specimens has factored into the'

identification with D. scitula occurring in the Carboniferous (Pennsylvanian Series) and

D. decurtata occurring in the Permian (Cisuralian Series). Temporal end members are

distinct enough to recognize separate species (Brezinski, 1988) but it is also possible that

the two forms represent a single gradational series. Ditomopyge scitula represents the

earlier form. Ditomopyge decurtata may have evolved from D. scitula during the early

part of the Permian through phyletic gradualism. The presence of forms transitional

between the temporal end members supports this assumption. As described below, A.

whitei seems to represent a synonym of D. decurtata.

4

Geologic Setting

Ditompyge scitula-

Summit coal bed

Member

ldenbro limestone Mbr Perry Farm Shale Mbr

Norfleet ls. Mbr.

Walter Johnson Ss. Mbr

Worland Limestone Mbr ...,_,...,.........._,,.~--··-·-·""".

Lake Neosho Sh. Mbr.

Laberdie Ls. Mbr. Mine Creek Shale Mbr.

-· -:::;.--\: Myrick Station ls. Mbr. C::::i::=I::> ·-- \ Anna Shale Member

(nglevale Ss. Mbr.

Higginsville ls. Mbr.

little Osage Sh Mbr.

Blackjack Cr. ls. Mbr.

Formation Holdenville Shale

Lenapah Limestone

Nowata Shale

Altamont Cl..

limestone :::i

e CJ

Bandera Shale c: 0 -Pawnee ~

E limestone

\...,

ro ~

Labette Shale

Fort Scott Limestone

Figures 1. Generalized Marmaton Group (Carboniferous: Pennsylvanian Series) stratigraphy of eastern Kansas showing lithologic units bearing trilobites. From Zeller

1968.

5

~-.. :·-.. ~ .. ~:-;.A A ,., y v- y y

Ditompyge scitula- l

Ameura missouriensis-

____ .. -..., _..,-__ ,....- --- -

_,, -- '. •' ,.

_,. -·-_..---:.:.·: - -- -I -- -

Ameura missouriensis- _,.

Member

Farley limestone Mbr

Island Creek Sh. Mb1

Frisbie limestone Mbr

Raytown Limestone Mbr.

Formation Bonner Sprin~s Sh .

Wyandotte

limes lone

lane Shale

_ Muncie Creek Sh Mbr. Iola limestone -~/._:._:.·:::···-~ ., Paola Limestone Mbr.

Th mi · ::.:. ::.; '::·~ :..__=--==_ Cottage Grove Ss. Mbr.

coat bed ]_.:-_ _ -:~ Chanute Shale

Q. :I

Ameura missouriensis-

Ameura missouriensis-

~~l:/~\~_\·:~L~\~t~·?·~L~t§:~~::::~:~;:~1:~;,~::~;~;;~:;~;:~M~~~:j· Orum Limestone

_f,j, ,,,___~ 0 " Quivira Shale Member

0 ... bO .0 :I

Cl)

c: c: :.J

Westemlle ls. Mbr

Wea Shale Member Cherryvale Shale Block Limestone Mb1.

f ontana Shale Member

... " " Winterset ls. Mbr.

:1~~~~1

~-1~<~=--Tff,g-fff~ff~~~ Dennis limestone _ , .. Slark Shale Member

- ~-;::;_ -:::._-· _______ Canvill_e ls. Mb--+-r. ~ g. ) --:.... ---· _.:-- 0

Yt<·~=~:\:--0-od-ds-C-re-ek_S_s_. M-b-1-1 Galesburg Shale ~ Bethany falls Ls. Mbr. Hushpuckney Shale Mbr. Swope limestone §

'J---~- .. :-:.~: ~ Middle Creek Ls. Mbr. g F=:-iif Sniahar limestone Mbr. Ladore Shale cXl ., ___ _

Mound City Shale Mbr. Hertha limestone 1. ) l Critzer limestone Mbr

0. :::I 0 ...

<.:> >-..... u V) ('() V)

c: ('()

::s:::

Figures 2. Generalized Kansas City Group (Carboniferous: Pennsylvanian Series) stratigraphy of eastern Kansas showing lithologic units bearing trilobites. From Zeller

1968.

6

Member Formation South Bend Ls. Mbr.

Ameura missouriensis- Rock lake Shale Mbr.

Ditompyge scitula-Stoner limestone Mbr. Stanton Limestone

a. ::::>

Eud0r1 Shale Member 0 ... Captain Creek Ls. Mbr.

(.!)

0.0

Vilas Shale c: 'iii c:

Ameura missouriensis-

Ditompyge scitula-

S rin Hill ls. Mbr. (\! ...J

H1ckor Creek Sh. Mbr Plattsburg Limestone Mernam limestone Mbr.

Figures 3. Generalized Lansing Group (Carboniferous: Pennsylvanian Series) stratigraphy of eastern Kansas showing lithologic units bearing trilobites. From Zeller

1968.

7

Ameura missouriensis-

Ditomopyge scitula _ Ameura missouriensis

Ameura missouriensis-

Ditomopyge decurtata Ameura missouriensis

Ditompyge decurtata-

Member i Coal Creek ls. Mb1.

/// Holt Shale Member '!! Du Bois Limestone Mbr.

' Turner Creek Sh. Mbr. ,, Sheldon limestone Mbr.

CT~~~~~~~ Jones Point Shale Mbr. <:; , Curzon limestone Mbr.

:::·. -c. .:::::\ "\ Iowa. Point Shalt Mbr. · :__--:_ ~ \' Hartford Ls. Mbr. ··-.--· - ---- ----

\ ·-·- • E1Vtne Creek Ls. Mbr. L " Larsh & Burroak Sh. Mbrs.

_ / Rock Bluff Ls. Mbr.

( ~~ .. ··. .-. . .. -·;

--· --- -··-- ·-- --~ _,,.,.

. -~=-- =~.~-~;~ '-:::-.-

Oskaloosa Shalt Mbr.

Ozawkie limestone Mbr.

Avoca Limestone Mbr. - -- - -- ·-~-Kina Hill Shale Mbr. I

~;;2§--;~~-~--~-~~/ Beil limestone Member C ,.. / Queen Hill Shale Mbr.

= ( Big Springs Ls. Mbr.

Doniphan Shale Member Spring Branch Ls. Mbr.

Stull Shale Member

Formation

Topeka limestone

Calhoun Shale

Deer Creek Limestone

Tecumseh Shale

Lecompton Limestone

' . Clay Creek Ls Mbr. Kanwaka Shale

13:§~~-~·:~JtE··~~-J_a_ck_s_on_Pa_r_k _S_h._M_b_' ________ --1

( l Keretord Ls. Mbr.

Heumader Shale Member

Plattsmouth Ls. Ml>r. Heebner Shale Member Oread Limestone Leavenworth ls. Mbr. Snyderville Shale Mbr.

Toronto limestone Mbr.

Figures 4. Generalized pre-Wabau.nsee Group (Carboniferous: Pennsylvanian Series) stratigraphy of eastern Kansas showing lithologic units bearing trilobites. From Zeller

1968.

8

Stormont Is. bed

Ditompyge decurtata-

:---:_:_--:--_:_-:-- ...:_-:- . --:-:--. ::-~ .-:-- :"'""-: -

:::Lli~~(5:~

-'~ -------=--~'

fl{~1

Member Brownville Ls. Mbr

Pony Creek Shalt Mbr.

Grayhorse ls. Mbr

Plumb Shale Member

Nebmka City Ls. Mbt.

French Creek Sh Mbr. Jim Creek Ls. Mbr.

Friedrich Shale Mbr. Grandhaven Ls. Mbr.

Ory Shale Member Dover Limestorni Mbr.

Maple Hill Ls. Mbr Wamego Shale Member Tarkio limestone Mbr.

Elmont limestone Mbr. Harveyville Shale Mbr.

Reading limestone Mbr

Wakarusa ls. Mbr.

Soldier Cleek Sh. Mbr. Burlingame Ls. Mbr.

Silver lake Shale Mbr.

Rulo Limestone Member

Cedar Vale Shale Mbr

Happy Hollow Ls Mbr.

White Cloud Shale Mbr.

Utopia limestone Mbr.

Winzeler Shale Member

Church limestorni Mbr. l\aide Shale Mtmber

Bachelor C1. Ls. Mbr.

Formation

Wood Siding Formation c.

::::i 0 .... t:>D ..0

Root Shale :::I (/)

c: 0 VI

Stotler Limestone -e "' .c: u

Pillsbury Shale 0:::

Zeandale Limestone

Willard Shale a. c. :::I :::I 0 0

Emporia ire ... ..0

<.!)

Limestone ::J QJ (/) QJ .,,

<'O c: Auburn Shale .s::. ::::i

ro "' E ..0 QJ <'O

Bern limestone z !:

Scranton Shale 0. ::::J 0

ire ..0 :::I

(/)

>< 0

<:; <'O

Howard limestone (/)

Severy Shale

Figures 5. Generalized Wabaundsee Group (Carboniferous: Pennsylvanian Series) stratigraphy of eastern Kansas showing lithologic units bearing trilobites. From Zeller

1968.

9

Member Formation Speiser Shale

Funston Limestone Blue Rapids Shale Crouse limestone Easly Creek Shale

Middleburg Ls. Mbr

Hooser Shale Member Bader limestone £ iss limestone Member

Stearns Shale Ditomopyge decurtata-Morrill limestone Mbr. 0.

Ditomopyge decurtata (revised)- Fk>rena Shale Member Beattie Limestone ::s 0 ...

Cottonwood Ls 11br. (.!>

CV >

Eskridge Shale 0 ... (.!>

Neva limes lone Mbr. ·u Salem Point Shale Mbr. r:

::s Burr Limestone Mbr Grenola Limestone 0

u Legion Shale Member

Sallyards Ls. Mbr.

Roca Shale Howe Limestone Member Red Eagle limestone Bennett Shale Member

----------- --Glenrock Ls. Mbr.

Johnson Shale long Creek Ls. Mbr.

Ameura missouriensis- Hughes Creek Sh. Mbr. Foraker Limestone Americus Ls. Mbr

Figure 6. Generalized Permian (Cisuralian) stratigraphy of eastern Kansas showing lithologic units bearing trilobites. From Zeller 1968.

Ameura missouriensis ranges from the Carboniferious (Pennsylvanian Series) to

the Permian (Cisuralian Series) It usually occurs in limestone. Specimens referable to D.

decurtata from the Carboniferious (Pennsylvanian Series) through the Permian

(Cisuralian Series). They are mostly in shale units. Ditomopyge scitula occurs only in the

Carboniferous (Pennsylvanian Series) and is found in shale and limestone units.

IO

Geographic Locations

Trilobite Species Geographic Localities of Specimens

Ameura missouriensis: Coffey Co. KS, Greenwood Co. KS, Lawrence Co. KS, Lecompton KS, Riley Co. Ks, Sunpy Co NE.

Ditomopyge decurtata: Elk Co. KS, Eudora KS, Greenwood Co. KS, Lecompton KS, Osage Co. KS, Wabaunsa Co. KS, Richardson Co. NE.

Ditomopyge scitula: DeSota KS, Montgomery Co. KS, Cass Co. NE.

Systematic Paleontology

Genus AMEURA Weller, 1936

AMEURA MISSOURIENSIS (Shumard, 1858)

Figure 7

Phillipsia missouriensis Shumard, 1858, p. 225.

Ameura missouriensis Shumard. Chamberlain, 1969, p. 60-62; Pabian and Fagerstrom,

1972, p. 811-813; Brezinski 1988, p. 941 (see for further synonymy).

Material. - 3 3 pygidia, 3 cephalons, 5 free cheeks.

Description. - Chamberlain ( 1969, p. 60-62).

Remarks. - Specimen proportions are slightly smaller than usual. Free checks and genal

spines are slightly shorter, while pygidia are also slightly smaller compared to other

described A. missouriensis specimens. However these variations fall within the range

11

described (Chamberlain, 1969). Some specimens show a reduction in the posterior

pygidal boarder.

Occurrence. - Clay Creek Limestone Member of the Kanwaka Shale; Curzon Limestone

Member of the Topeka Limestone; Drum Limestone; Farley Limestone Member of the

Wyandotte Limestone; Raytown Limestone Member of the Iola Limestone; Winterset

Limestone Member of the Dennis Limestone; Stoner Limestone Member of the Stanton

Limestone; Spring Hill Limestone Member of the Plattsburg Limestone; Deer Creek

Limestone; Beil Limestone Member of the Lecompton Limestone.

12

:~

.. L

Figure 7.

13

Figure 7. Ameura missouriensis, from the Carboniferous of Kansas. Specimens are

reposited in the University of Kansas Museum of Invertebrate Paleontology (KUMIP).

1. Cephalon and anterior thorax; x2. Curzon Limestone Member of the Topeka

Limestone, Coffey County, Kansas; KUMIP _.

2. Complete pygidium x2. Drum Limestone, SW of Coffeyville, Kansas; KUMIP _.

3. Complete pygidium; x2. Clay Creek Limestone Member of the Kanwaka Shale,

Greenwood County, Kansas; KUMIP _.

14

Genus D1TOMOPYGE Newell, 1931

DITOMOPYGE DECURTATA (Gheyselinck, 1937)

Figure 8

Phillipsia (Neophillipsia) decurtata Gheyselinck, 1937, p. 56.

Ditomopyge decurtata (Gheyselinck) Weller, 1944, p. 320-321; Shimer and Shrock,

1944, p. 645; Mudge and Y ochelson, 1962, p. 96-97; Hahn and Hahn, '1970, p.

175; Owens, 1983, p. 26; Brenzinski, 1988, p. 941-942.

Material.- 122 enrolled specimens, 5 cephalons, 33 pygidia, and 4 free cheeks

Description.- See Brezinksi (1988, p. 941-942).

Remarks. - The studied Ditomopyge decurtata specimens cited above are from the

following localities; the Kanwaka shale of the Carboniferous Pennsylvannian Series and

the Florena Shale Member of the Beattie Limestone (Permian: Cisuralian Series).

Specimens from the Kanwaka Shale are slightly smaller than average. Cephalic

proportions in the glabella, preoccipital lobes, and other measurable features are almost

identical to those of Ditomopyge scitula. The main deviations are a decrease in genal

spine length; shorter with a more triangular appearance with the spine reaching the

second through third thoracic segments. While being less consistent with D. scitula, these

lengths are similar to those seen in Anisopyge whitei, with genal spines reaching the

second through third thoracic segments and showing a triangular appearance. Pygidia are

semicircular in appearance, they resemble those of D. scitula. Pleural regions show a lack

of geniculation seen more predominantly in D. scitula, and also have a more uniform

15

width throughout the length of the pygidium and occur in a ratio of 6 pleural lobes to 10-

11 axial lobes. Along the axial profile a subrounded appearance is present.

Specimens from the Florena Shale Member of the Beattie Limestone (Permian:

Cisuralian Series) have a relatively large variance in size and measurable features. Many

of the specimens are enrolled, accounting for some of the variation. Cephalic proportions

in the gaballer region, preoccipital lobes, and other measurable features are almost

identical to those of D. scitula. Differences are in the length of genal spines, with a

relatively shorter length resulting in a more triangular appearance than that of the longer

D. scitula specimens. Lengths of genal spines range from the second through fourth

thoracic segments. While being less consistent with D. scitula, these lengths are similar to

those seen in the Anisopyge whitei, with genal spines reaching the second through third

thoracic segments and showing a triangular appearance. A large degree of variation is

seen the anterior glabeller borders of the specimens. Narrow to wide anterior borders are

not present in D. scitula, and are similar to the borders in A. whitei.

Pygidia also show a large degree of variation in the D. decurtata specimens. The

axial profile ranges from subrounded to a slightly longer and less rounded form than

those of D. scitula (see Brezinski, 1982). Pleural lobes in the pygidium range from seven

to eight, and axial rings range from fifteen to sixteen. Pleural regions lack the

geniculations of the pleural lobes seen more predominantly in D. scitula, and also have a

more uniform width along the length of the pygidium. Granules on top of the axial lobes

run the length of the pygidium in some specimens. Pygidial shape outline tends to be

subrounded to triangular.

16

The variations seen between the two sets of D. decurtata specimens are consistent

with findings on other specimens described. The Kanwaka Shale specimens show 10

through 11 to six pygidial lobes and ribs ratio and smaller pygidal sizes similar to those in

Appalachian D. decurtata specimens (Brezinski. 1988); while the Florena specimen are

similar to the Wolfcampian Series specimens of mid continental North America with a

ratio of 15 through 16 to eight for lobes to ribs. Explanations of variation include phyletic

size increase of holaspid individuals, or ecophenotypic responses (Brezinski, 1988).

Anisopyge whitei and D. scitula have been associated together in the past, with D.

scitula being considered a probable ancestor of Permian A. whitei (Pabian and

Fagerstrom, 1972). While many morphological characteristics and biometric

measurements have been taken to show the similarities between the two, variances where

present provide distinction, between the species. D. scitula lacks or has a very narrow

anterior gabellar lobe, while A. whitei has a relatively wide anterior border. Genal spines

of D. scitula extend to the fourth to fifth thoracic segments, while those of A. whitei

extend to the second to the third segment. Also D. scitula has a larger range of pygidial

lobes ranging from 11 to 14 axial and seven to eleven pleural ribs, A. whitei shows a

similar but more stable count fourteen to fifteen axial and seven to eight pleural ribs, with

the pleural ribs showing a more uniform width (Pabian and Fagerstrom, 1972). While

these differences are minor they do offer some distinction.

The range of variation in A. whitei is entirely consistent with D. decurtata.

Ditomopyge decurtata specimens do have variation in the anterior gabellar lobe. Some

specimens have a narrow border, other specimens have anterior borders of comparable in

thickness to that of A. whitei specimens. Genal spines are also reduced in D. decurtata

17

extending to the second to the fourth thoracic segments, comparable to the second to the

third seen in A. whitei. Ditomopyge decurtata and A. whitei 's pygidia are comparable

both in a subrounded to triangular outline and in counts of axial and pleural lobes and

ribs. Based on these similarities and near indistinguishablity it seems likely that the two

are actually the same species. Anisopyge whitei has been noted to share more

characteristics with the genus Ditomopyge than Anisopyge (Pabian and Fagerstrom, 1972)

and upon comparison with D. decurtata it seems the two are actually one in the same.

Occurrence. - Clay Creek Limestone Member of the Kanwaka Shale; Florena Shale

Member of the Beattie Limestone; Plattsmouth Limestone Member of the Dread

Limestone; Church Limestone Member of the Howard Limestone.

18

Figure 8.

19

Figure 8. Ditomopyge decurtata from the Permian of Kansas and Nebraska. Specimens in

figures 8.2, 8.3, 8.7, and 8.8 were previously referred to as Anisopyge whitei; specimen in

figure 8.2is the holotype of A whitei. Specimens are reposited in the University of Kansas

Museum of Invertebrate Paleontology (KUMIP) and the University of Nebraska State

Museum (UNSM).

1,4. Dorsal (1), Ventral (4) portion of broken cephlon from an enrolled trilobite; x3. In

( 4) hypostome is visible with rostral plate. Florena Shale Member of the Beattie

Limestone, Grand Summit, Cowley County, Kansas, KUMIP _.

2. Cephalon ofrevised D. decurtata; x3. Damage to upper left of anterior border, slight

distortion from burial. Cottonwood Limestone Member of the Beattie Limestone,

Richardson Co., Nebraska, UNSM 8092.

3. Gabella of revised D. decurtata; x3. Cottonwood Limestone Member of the Beattie

Limestone, Richardson Co., Nebraska, UNSM 8094.

5. Pygidium of enrolled specimen; x3. Florena Shale Member of the Beattie Limestone,

Grand Summit, Cowley Co. Kansas, KUMIP _.

6. Pygidium of enrolled specimen; x3. Florena Shale Member of the Beattie Limestone,

Grand Summit, Cowley Co. Kansas, KUMIP _.

7. Pygidium ofrevised D. decurtata; x3. Cottonwood Limestone Member of the Beattie

Limestone, Richardson Co., Nebraska, UNSM 8121.

8. Pygidium ofrevised D. decurtata,- x3. Cottonwood Limestone Member of the Beattie

Limestone, Richardson Co., Nebraska, UNSM 8113.

20

9. Pygidium; x4. Clay Creek Limestone Member of the Kanwaka Shale, Greenwood Co.,

Kansas, KUMIP _.

21

DITOMOPYGE SCITULA (Meek and Worthen, 1865)

Figure 9

Phillipsia (Griffithides) scitula Meek and Worthen, 1865, p. 270, 271.

Ditomopyge scitula (Meek and Worthen). Brezinski and Stitt, 1982, p. 1242-1248 (see for

additional synonymy).

Material.- 5 cephala, 25 pygidia, 9 free cheeks.

Description.- See Brezinski (1988, p. 941 ).

Remarks. - Genal spines on average are longer and more slender in appearance than in

D. decurtata, with lengths extending to the fourth and fifth thoracic segments. Other

cephalic proportions are almost identical. Slight variation in maximum glabeller width,

are present; the border is slightly wider in D. scitula.

Occurrence. - Haynies Limestone Member of the Deer Creek Limestone; Perry Farm

Shale Member of the Lenapah Limestone; Farley Limestone Member of the Wyandotte

Limestone; Stoner Limestone Member of the Starton Limestone; Merriam Limestone

Member of the Plattsburg Limestone.

22

Figure 9.

23

Figure 9. Ditomopyge scitula from the Carboniferous of Nebraska. Specimens are

reposited in the University of Nebraska State Museum (UNSM).

1. Complete specimen, damage to left side of cephalon; x3. Haynies Li~estone Member

of the Deer Creek Limestone, Cass County Nebraska, UNSM 7299.

2. Ventral view of cephalon and thoracic segments, pygidium missing; x3. Haynies

Limestone Member of the Deer Creek Limestone, Cass County Nebraska, UNSM 7300.

3. Cephalon and thoracic segments; x3. Haynies Limestone Member of the Deer Creek

Limestone, Cass County Nebraska, UNSM 7283.

24

E 8

E_ 7 ra Cl) s...

6 ra

ra -5 c: 0 s... -- 4 0

..c: 3 -"'O

3: 2 E :::s E 1 >< ~ 0

0 2

Graphs

: ... ,,.I•\.

• • t •.• •••• ~· • •

4 6 8

Palpebral cranidial width, mm

10

+ D. decurtata

II A. OOif ej

Figure 10. Comparison of cranidal measurements between D. decurtata and A. whitei.

25

6 Q)

~ Q)

~ E 5 :!: E Q) a) 4 O> 0

c: ~ 3 <(-

en ctl ·-c: c 2 Q) Q) (!) ..c >< 0 1 Q) _J -....

• • • • If • •

•

~ 0 +--~~~~~~~~~~--~~~~~~

0 5 10 15

Total Length of Free Cheek, mm

• D. decurtata

11 A. whitei

Figure 11. Comparison of measurements of liberigenae between D. decurtata and A. whitei.

26

--·------

14 l

12 -

E 10 E

-..c: 8 ~ -"'C I

I • 0. decurtata

3:: 6· ca 11 A. ooi~~~_J

·-"'C

C> 4 >- •

i::i.. 2

0 ---~--···----

0 2 4 6 8 10 12

Pygidia Length, mm

Figure 12. Scatter plot of pygidial length vs. width comparing D. decurtata to A. whitei.

27

References

Brezinski, D. K. 1988. Appalachian Carboniferous trilobites. Journal of Paleontology, 62:934-945.

Brezinski, D. K., Stitt, J. H. 1982. Ditomopyge scitula (Meek & Worthen) from the lower Pennsylvanian of Central Missouri and Central Texas. Journal of Paleontology, 56: 1242-1250.

Chamberlain, C. K. 1969. Carboniferous trilobites: Utah species and evolution in North America. Journal of Paleontology, 43 :41-68.

Meek, F. B., and Worthen, A.H. 1865. Contributions to the paleontology of Illinois and other western states. Academy of Natural Sciences of Philadelphia, Proceedings, p. 245-273.

Moore, R. C., Frye, J.C., Jewett, J.M., Lee, W. and O'Connor, H. G. 1951. The Kansas Rock Column. Geological Survey of Kansas Bulletin 89. p. 42-63

Pabian, R.K., and Fagerstrom, J. A. 1972. Late Paleozoic trilobites from southeastern Nebraska. Journal of Paleontology, 46:789-816.

Zeller, P. 1968. KU, Kansas Geological Survey, The University of Kansas. 18 June 2007. <http://www.kgs.ku.edu/General/Strat/Chart/index.html>

28