Submitted: March 2nd, 2020 – Accepted: July 15th, 2020 – Posted online: July 22th, 2020 To link and cite this article: doi: 10.5710/AMGH.15.07.2020.3345

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EARLY-MIDDLE ORDOVICIAN GRAPTOLITES FROM THE ARGENTINE 1

PUNA: QUANTITATIVE PALEOBIOGEOGRAPHIC ANALYSIS BASED ON 2

A SYSTEMATIC REVISION 3

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GERARDO A. LO VALVO 1, NEXXYS C. HERRERA SÁNCHEZ1, AND BLANCA 5

A. TORO1 6

1 Centro de Investigaciones en Ciencias de la Tierra (CICTERRA), Universidad 7

Nacional de Córdoba, Facultad de Ciencias Exactas, Físicas y Naturales, Consejo 8

Nacional de Investigaciones Científicas y Tecnológicas (CONICET), Av. Vélez 9

Sarsfield 1611, X5016CGA, Córdoba, Argentina. gerardolovalvo@gmail.com; 10

nexxys.herrera@unc.edu.ar; btorogr@mendoza-conicet.gov.ar 11

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58 pages; 5 figures 13

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Running Header: LO VALVO ET AL.: ORDOVICIAN GRAPTOLITES FROM THE 15

ARGENTINE PUNA. 16

Short Description: Quantitative paleobiogeographic analysis based on the updated 17

taxonomic revision of the Early–Middle Ordovician graptolites from the eastern Puna, 18

Argentina. 19

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Corresponding author: GERARDO A. LO VALVO gerardolovalvo@gmail.com 21

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Abstract. The updated taxonomic revision of the Early–Middle Ordovician 23

graptolites from the eastern Argentine Puna allows describing Sigmagraptus 24

praecursor, Baltograptus extremus, B. geometricus, B. vacillans, Cymatograptus 25

protobalticus, Expansograptus constrictus, E. pusillus, E. similis, and 26

Corymbograptus v-fractus tullbergi for the first time in this region. The analyzed 27

material was collected from the volcano-sedimentary deposits assigned to the 28

Cochinoca-Escaya Magmatic-Sedimentary Complex and exposed at the Muñayoc and 29

Santa Rosa sections, Jujuy Province. This taxonomic analysis confirms the occurrence 30

of 23 taxa in the studied region, from which S. praecursor, B. extremus, and E. 31

pusillus were not previously documented in South America. Additionally, it 32

contributes to the clarification of the faunal graptolite affinities earlier postulated for 33

Northwestern Argentina. Quantitative paleobiogeographic analyses of clusters and 34

principal coordinate were carried out, including the described species and previous 35

certain graptolite assignations for the Puna region, to quantify its faunal affinities with 36

Baltoscandia, Great Britain, North America, and Southwestern China. Finally, our 37

results are discussed and compared with those formerly obtained in 38

paleobiogeographic analyses based on different fossil groups from Northwestern 39

Argentina. 40

Keywords. Floian. Dapingian. Graptolites. Northwestern Argentina. Taxonomy. 41

Paleobiogeography. 42

Resumen. GRAPTOLITOS DEL ORDOVÍCICO TEMPRANO–MEDIO DE LA 43

PUNA ARGENTINA: ANÁLISIS PALEOBIOGEOGRÁFICO CUANTITATIVO 44

BASADO EN UNA REVISIÓN SISTEMÁTICA. La revisión taxonómica actualizada 45

de los graptolitos del Ordovícico Temprano–Medio de la Puna Oriental de Argentina 46

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permite describir por primera vez para esta región las especies: Sigmagraptus 47

praecursor, Baltograptus extremus, B. geometricus, B. vacillans, Cymatograptus 48

protobalticus, Expansograptus constrictus, E. pusillus, E. similis y Corymbograptus 49

v-fractus tullbergi. El material analizado fue coleccionado de depósitos asignados al 50

Complejo Magmático-Sedimentario Cochinoca-Escaya, expuesto en las secciones de 51

Muñayoc y Santa Rosa, en la Provincia de Jujuy. Este estudio taxonómico confirma la 52

presencia de 23 especies en la región estudiada, de las cuales S. praecursor, B. 53

extremus y E. pusillus no habían sido mencionadas previamente para América del Sur, 54

y contribuye a clarificar las afinidades faunísticas anteriormente sugeridas para los 55

graptolitos del Noroeste argentino. Se presentan además, los análisis 56

paleobiogeográficos cuantitativos de agrupamiento y de coordenadas principales, que 57

incluyen las especies descriptas en este trabajo y otras asignaciones seguras realizadas 58

previamente para la Puna, a fin de cuantificar sus afinidades faunísticas con 59

Baltoescandinavia, Gran Bretaña, América del Norte y el Suroeste de China. Por 60

último, se discuten y comparan nuestros resultados con aquellos análisis 61

paleobiogeográficos previos, obtenidos a partir de distintos grupos de fósiles del 62

Noroeste argentino. 63

Palabras clave. Floiano. Dapingiano. Muñayoc. Graptolitos. Noroeste argentino. 64

Taxonomía. Paleobiogeografía.65

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66

THE STUDY OF EARLY–MIDDLE ORDOVICIAN GRAPTOLITES from the Central Andean 67

Basin has been mainly focused on records from Argentina and Bolivia. It was a 68

valuable tool to develop and refine the biostratigraphic framework for the Cordillera 69

Oriental (Toro, 1997; Egenhoff et al., 2004; Toro & Vento, 2013; Toro et al., 2015; 70

Albanesi & Ortega, 2016; Toro & Herrera Sánchez, 2019; Herrera Sánchez et al., 71

2019; and references therein). Conversely, biostratigraphic analyses based on 72

graptolites from the northern part of the Central Andean Basin are scarcer. However, 73

although Gutiérrez-Marco et al. (2019) recently presented new advances regarding the 74

Early Ordovician graptolites from Peru (Fig. 1.1). 75

A new bibliometric analysis involving graptolites from Northwestern 76

Argentina (NOA) shows that 84.1% of the published papers comprise records from 77

the Cordillera Oriental. In contrast, only around 20% of them include fossils from the 78

Argentine Puna (Lo Valvo et al., 2019). The authors also observed that most of the 79

publications focused on biostratigraphy (87.5%) and taxonomy (31.8%) while other 80

aspects, such as paleoecology (1.1%), phylogeny (1.1%), and paleobiogeography 81

(6.8%) are underdeveloped. 82

Since the first findings of graptolites near of the Tafna-Toquero road, in the 83

northernmost eastern Argentine Puna (Loss, 1948), around thirty taxa have been 84

mentioned in this region by different authors. However, no significant taxonomic or 85

biostratigraphic revisions of the graptolites faunas from this area had been achieved 86

after the contributions of Toro & Brussa (2003) and Brussa et al. (2008), respectively, 87

mainly due to the high elevations, difficult access, and tectonic deformation of the 88

stratigraphic sections. 89

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Loss (1948, 1949) assigned graptolites from the Tafna area to the Early 90

Ordovician and recognized Aulograptus climacograptoides (Bulman, 1931) in the 91

deposits located to the west of this area. Later, Gutiérrez-Marco et al. (1996) reviewed 92

several early Darriwilian taxa associated with the mentioned species, which were 93

previously assigned to an older age by Aceñolaza (1980). After that, Toro & Brussa 94

(1997) and Toro & Lo Valvo (2017) confirmed the presence of equivalent deposits 95

with Levisograptus cf. L. austrodentatus in the area, and Toro & Brussa (2000) 96

recognized Expansograptus suecicus (Tullberg, 1880), Acrograptus filiformis 97

(Tullberg, 1880), Expansograptus holmi (Törnquist, 1901), and Tetragraptus 98

reclinatus Elles & Wood, 1901 in the Tafna section, establishing that early Floian 99

deposits are also present in this area. 100

Additionally, Bahlburg et al. (1990) analyzed the graptolite associations from 101

the northern and central parts of the ‘Cordón de Escaya’ section and the south of the 102

‘Sierra de Cochinoca/Cerro Queta’ section, and assigned them from the Early to Late 103

Ordovician ages, respectively. Later, Martínez et al. (1999) recognized eighteen taxa 104

in the Muñayoc area (Fig. 1.2), standing out the presence of Baltograptus minutus 105

(Törnquist, 1879), Didymograptellus bifidus (J. Hall, 1865), and Azygograptus 106

lapworthi Nicholson, 1875 (sensu Toro & Herrera Sánchez, 2019), and emphasizing 107

that this section constitutes the most continuous succession of the eastern Puna. 108

Farther east, in the Santa Rosa section (Fig. 1.2), the graptolite association described 109

by Toro et al. (2006) allowed correlating the bearer deposits with those from the 110

Muñayoc area. 111

From the paleobiogeographic point of view, pioneer discussions by Turner 112

(1960) suggested that an Andean Sub-province was developed in South America, as 113

part of the ‘Atlantic Graptolite Province’ during the Ordovician. This study was based 114

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on records from the Famatina Range and NOA, Bolivia, Paraguay, Peru, and 115

Colombia, but graptolite collections from the Argentine Precordillera (La Rioja, San 116

Juan, and Mendoza Province) were also included because its allochthonous origin was 117

unknown at that time. Different provenances of the Ordovician graptolites from the 118

Precordillera and the Central Andean Basin can explain most of the mixture affinities 119

analyzed by Turner (1960), and they were later discussed by Maletz & Ortega (1995). 120

Since Toro (1993) highlighted the occurrence of Cymatograptus balticus (Tullberg, 121

1880) and Acrograptus filiformis in the Floian deposits of the Argentine Cordillera 122

Oriental, closer paleobiogeographic relations with Baltoscandia were successively 123

documented. Toro (1994b, 1996) quantified for the first time the faunal affinities of 124

the Early Ordovician graptolites from the NOA, based on the records from the 125

Cordillera Oriental and the main results show faunal affinities with Baltoscandia and 126

SW China in the early–middle Floian interval, while the scarce paleobiogeographic 127

studies that include graptolites from the Puna region were quantitatively analyzed by 128

Vento et al. (2012, 2014) and Toro et al. (2014), based on the presence of 129

Tremadocian and Floian species. 130

This work aims to contribute to the knowledge and understanding of 131

graptolites from the eastern Puna, through a taxonomic study of the material collected 132

from Muñayoc and Santa Rosa sections, and to test its paleobiogeographic relations 133

with other regions around the world, during the early Floian to early Dapingian times 134

(Fl1-Dp1, sensu Bergström et al., 2009). It was developed on the framework of the 135

Ph.D. Thesis of one of the authors (N.C.H.S.), and the reviewed main results of the 136

Degree Thesis of the senior author (G.A.L.) were also included. 137

An exhaustive discussion of the biostratigraphic framework included in Fig. 2 138

is beyond the scope of this paper. It was modified from the outline recently proposed 139

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by Herrera Sánchez et al. (2019) to show the biostratigraphic range and provenance of 140

the described taxa. 141

The studied material is housed in the paleontological collection of the Centro 142

de Investigaciones en Ciencias de la Tierra (CICTERRA), CONICET and 143

Universidad Nacional de Córdoba, Argentina, under the prefix CEGH-UNC. 144

We used the suprageneric taxonomy recently proposed in different chapters of 145

the revised Treatise of Invertebrate Paleontology by Maletz (2017) and Maletz et al. 146

(2018a, b) to describe thirteen species and one subspecies of graptoloids for the first 147

time in the eastern Argentine Puna, at Muñayoc and Santa Rosa sections. 148

Anatomical abbreviation. th, thecae. 149

Regional abbreviation. NOA, Northwestern Argentina [Noroeste de Argentina] 150

[FIGURE 1] Location map and fossiliferous sections 151

GEOLOGICAL FRAMEWORK 152

The Argentine Puna is a geological province encompassed in the NOA (Fig. 153

1.1), which involves average highs above 3500 m, and differs from the Bolivian 154

Plateau by the higher elevations and different geological characteristics (Ramos, 155

2017). Together with the Cordillera Oriental and Sierras Subandinas, the region 156

represents the southern part of the Central Andean Basin (Fig. 1.1), which was 157

developed in a continental margin at western Gondwana during the Cambrian–158

Ordovician times (Astini, 2003). In the Puna region, fossiliferous siliciclastic marine 159

sediments assigned to the Cambrian and Floian ages, interdigitate with 160

synsedimentary lavas and subvolcanic rocks. These successions constitute two 161

submeridional belts: the eastern and western Puna (Turner, 1970) (Fig. 1.2), which 162

were developed from a Cambrian rifting margin to a Floian back-arc basin until a 163

Darriwilian turbidite sequence at a foreland basin system (Astini, 2003, 2008; and 164

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references therein). Coira et al. (2004) defined the Cochinoca-Escaya Magmatic-165

Sedimentary Complex (CEMSC) composed by volcaniclastic dacites intercalated with 166

medium to fine sandstones and massive pelites, which outcrops in the Cochinoca-167

Escaya, Queta, and Quichagua ranges, at the eastern Puna (Fig. 1.2). It is associated 168

with volcanic breaches, hyaloclastites, cryptodomes, massive spilitized basaltic levels, 169

or with padded structures and micro-gabbros forming layers or lacolites (Coira, 2008, 170

and references therein). The best outcrops of the CEMSC are exposed in the Muñayoc 171

section, located in the Quichagua range, Jujuy Province (Fig. 1.2). Martínez et al. 172

(1999) described in the area a volcano-sedimentary succession of 150 m thick, 173

composed by lavas and dacitic domes, pelites and quartz-sandstones, that evidence an 174

upwards progression from mudstone-dominated oxygen-poor outer shelf deposits to 175

sandstone-dominated deposits under storm and wave influence, with an upper sandier 176

part related to a general regressive trend. These authors constrained the age of the 177

lower portion of the studied succession to the late Floian and suggested a younger age 178

for the upper third of the Muñayoc section, based on the occurrence of Azygograptus 179

lapworthi (sensu Toro & Herrera Sánchez, 2019). The Santa Rosa section (Fig. 1.2), 180

located approximately 26 km to the northeast, consists of 20 m thick of alternating 181

deposits of sandstones and pelites affected by synsedimentary intrusive bodies, 182

corresponding to the eastern margin of the CEMSC. In this area, Toro et al. (2006) 183

recognized a graptolite association composed by Baltograptus minutus, B. cf. B. 184

deflexus, Sigmagraptus sp., and Tetragraptus serra (Brongniart, 1828). They 185

postulated a late Floian age and proposed the correlation of these levels with the lower 186

half of the Muñayoc section (Didymograptellus bifidus Biozone) and the upper part of 187

the Acoite Formation, in the Argentine Cordillera Oriental. More recently, Toro & 188

Herrera Sánchez (2019) confirmed a late Floian to early Dapingian age for the upper 189

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half of the Muñayoc section. Meanwhile, Lo Valvo (2019) reviewed additional 190

material coming from these sections, describing eleven new taxa for the region and 191

postulating an older age for the lower portion of the Muñayoc section. This author 192

also confirmed the correlation between the Muñayoc and Santa Rosa sections 193

previously proposed by Toro et al. (2006). 194

[FIGURE 2] Biostratigraphic ranges and provenance of the described taxa 195

SYSTEMATIC PALEONTOLOGY 196

Phylum HEMICHORDATA Bateson 1885 197

Class PTEROBRANCHIA Lankester, 1877 198

Subclass GRAPTOLITHINA Bronn, 1849 199

Order GRAPTOLOIDEA Lapworth, 1875 in Hopkinson & Lapworth, 1875 200

Suborder SINOGRAPTINA Mu, 1957 201

Family SIGMAGRAPTIDAE Cooper & Fortey, 1982 202

Genus Sigmagraptus Ruedemann, 1904 203

Type species. Sigmagraptus praecursor Ruedemann, 1904. 204

Diagnosis (sensu Maletz et al., 2018b). Sigmagraptines with a single order of 205

progressive branching followed by monoprogressive branching, forming two main 206

zigzag-shaped stipes and numerous lateral stipes; proximal end isograptid, dextral, 207

with long and slender sicula; thecae simple with low thecal overlap and without 208

apertural elaborations. 209

Sigmagraptus praecursor Ruedemann, 1904 210

Figure 3.1–2 211

1902. Coenograptid Ruedemann, p. 566. 212

1904. Sigmagraptus praecursor Ruedemann, p. 702, text-fig. 93; pl. 5, figs. 13–14. 213

1947. Sigmagraptus praecursor Ruedemann, Ruedemann, p. 300, pl. 49, figs. 17–20. 214

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1979. Sigmagraptus laxus (T. S. Hall), Cooper, p. 57, pl. 49; text-fig. 22. 215

1982. Sigmagraptus praecursor Ruedemann, Cooper & Fortey, p. 262, figs. 60a-d, 216

61a-k. 217

1988. Sigmagraptus praecursor Ruedemann, Williams & Stevens, p. 79, pl. 25, figs. 218

3, 6; pl. 26, figs. 12–15; pl. 28, figs. 2–6, 8, 9; text-figs. 75A–J; text-figs. 79L–N. 219

1992. Sigmagraptus praecursor Ruedemann, VandenBerg & Cooper, p. 41, fig. 5K. 220

2002. Sigmagraptus praecursor Ruedemann, Mu et al., p. 329, pl. 92, fig. 11. 221

2006. Sigmagraptus sp., Toro et al., p. 166. 222

2009. Sigmagraptus praecursor Ruedemann, Zalasiewicz et al., p. 802, fig. 8.11 223

2019. Sigmagraptus cf. S. praecursor Ruedemann, Lo Valvo, p. 44–45, pl. 1, fig. 5. 224

Referred material. Two specimens which respectively represent a young tubarium 225

and a mature tubarium. The material is preserved as flattened films and identified as 226

CEGH-UNC 24977–24978. 227

Geographic and stratigraphic provenance. Sigmagraptus praecursor is here 228

recognized for the first time in South America. The studied material comes from the 229

Santa Rosa section, at the Cochinoca range (Fig. 1.2). This species appears associated 230

with Baltograptus deflexus (Elles & Wood, 1901) in the Didymograptellus bifidus 231

Biozone (Fig. 2). S. praecursor has been recognized in North America from deposits 232

corresponding from the Tshallograptus fruticosus Biozone to the Isograptus victoriae 233

lunatus Biozone (Ruedemann, 1904; Williams & Stevens, 1988). Later, it was 234

recorded in Australia, Spitsbergen, the Jiangnan region in South China, and Great 235

Britain (Cooper & Fortey, 1982; VandenBerg & Cooper, 1992; Mu et al., 2002, 236

Zalasiewicz et al., 2009). 237

Description. The sicula is slender, 1.72 mm in length, with a small rutellum. The 238

apertural diameter of the sicula is about 0.3 mm, and a prominent basal free length of 239

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0.36 mm is observed. The first two thecae emerge from the sicula at different levels, 240

giving the characteristic asymmetrical appearance to the proximal end. Th11 241

originates high in the sicula at approximately 0.3 mm from the apex, while th12 grows 242

immediately below the point in which th11 leaves the sicula (Fig. 3.2). 243

The mature specimen shows a multiramous tubarium with two main zig-zag 244

shaped stipes and numerous monoprogressive branching up to the 13th order which are 245

spaced 1.16–2.0 mm in the proximal part and 2.5 mm distally (Fig. 3.1). The stipes 246

reach up 0.5 mm of width and possess goniograptid thecae without apertural 247

elaborations, which are spaced approximately 10 in 10 mm. 248

Discussion. Our material provides distinctive morphological patterns that agree with 249

previous descriptions of S. praecursor, particularly in the asymmetrical proximal end 250

illustrated by Cooper & Fortey (1982, fig. 60.d) and the general morphology of the 251

mature tubarium (Ruedemann, 1904; Rickards, 1974; Cooper & Fortey, 1982, fig. 60). 252

Suborder DICHOGRAPTINA Lapworth, 1873 253

Family DICHOGRAPTIDAE Lapworth, 1873 254

Genus Clonograptus Hall & Nicholson, in Nicholson 1873 255

Type species. Graptolithus rigidus J. Hall, 1858. 256

Diagnosis (sensu Maletz et al., 2018a). Multiramous, horizontal to subhorizontal 257

dichograptid with increasing distances of numerous distal, more irregularly placed 258

dichotomies; thecae simple widening tubes with moderate overlap and without 259

extended rutella; proximal development isograptid, dextral or sinistral. 260

Clonograptus flexilis (J. Hall, 1858) 261

Figure 3.3 262

1858. Graptolithus flexilis J. Hall, p. 119–120. 263

1865. Graptolithus flexilis J. Hall, J. Hall, p. 103–104, pl. 10, figs. 3–9. 264

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1947. Clonograptus flexilis (J. Hall), Ruedemann, p. 280–281, pl. 44, figs. 4–9. 265

1983. Clonograptus flexilis taipingensis (J. Hall), Li, p. 146, pl. 1, fig. 1. 266

1989. Clonograptus (Clonograptus) flexilis (J. Hall), Lindholm & Maletz, p. 723, 267

text-figs. 2A, 6A–E. 268

2002. Clonograptus cf. C. flexilis (J. Hall), Benedetto et al., p. 572–577, fig. 1. 269

Referred material. One specimen regularly preserved as a flattened film. It is 270

identified as CEGH-UNC 24979. 271

Geographic and stratigraphic provenance. The studied material comes from the 272

lower part of the Muñayoc section at the Quichagua range (Fig. 1.2), in which the 273

Tetragraptus akzharensis Biozone is developed (Fig. 2). Previous records of this 274

species were from the lower part of the Chiquero Formation at Huancar-Susques 275

region, in the eastern Puna, where Benedetto et al. (2002) recognized the presence of 276

Clonograptus cf. C. flexilis associated with Kiaerograptus cf. K. kiaeri. C. flexilis was 277

originally described in Quebec, Canada (J. Hall, 1858) and subsequently reviewed 278

based on low relief extra material coming from levels corresponding to the T. 279

akzharensis Biozone (Lindholm & Maletz, 1989). 280

Description. Although the tubarium is not well preserved, the most relevant 281

characteristics that enable us to assign our material to C. flexilis are still present. First-282

order stipes are very short and probably consist of one theca. The second dichotomy 283

encloses an angle of 60°–100°, and the corresponding second-order stipes vary within 284

1.0–2.5 mm in length. The next dichotomy encloses 50°–80°, and third-order stipes 285

are between 2.0–4.4 mm long. The thecae are straight tubes, with their apertures at 286

right angles to the dorsal margin of the stipes. The stipe width varies within 0.4–1.0 287

mm, and there are approximately 10 thecae in 10 mm. 288

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Discussion. The present material assigned to C. flexilis differs from the specimens of 289

Clonograptus multiplex (Nicholson, 1868) previously recognized in the Argentine 290

Cordillera Oriental (Toro, 1997), by the presence of shorter second-order stipes that 291

reach up to 2.5 mm in length; while in the latter species, they vary within 4.0–10.0 292

mm (sensu Lindholm & Maletz, 1989). The thecal spacing and thecal morphology are 293

comparable with the re-description of C. flexilis by Lindholm & Maletz (1989). 294

Family DIDYMOGRAPTIDAE Mu, 1950 295

Genus Baltograptus Maletz, 1994 296

Type species. Didymograptus vacillans Tullberg, 1880. 297

Diagnosis (sensu Maletz et al., 2018a). Horizontal to deflexed, declined, and pendent 298

didymograptids; sicula slender, with long supradorsal portion; proximal development 299

of isograptid or artus type with moderately low origin of th11 from metasicula and 300

comparably long free ventral apertural length of sicula; isograptid suture very short or 301

missing. 302

Baltograptus deflexus (Elles & Wood, 1901) 303

Figure 3.4 304

1901. Didymograptus deflexus Elles & Wood, p. 35, pl. 2, figs. 12a, c. 305

1994a. Didymograptus (Corymbograptus) deflexus (Elles & Wood), Toro, p. 217, pl. 306

II, figs. 9, 14–15. 307

2000. Didymograptus (s.l.) deflexus (Elles & Wood), Rushton, folio 1.29. 308

2006. Baltograptus cf. B. deflexus (Elles & Wood), Toro et al., p. 166. 309

2007. Corymbograptus deflexus (Elles & Wood), Zhang et al., p. 319, fig. 3. 310

2011. Baltograptus deflexus (Elles & Wood), Maletz & Ahlberg, p. 357, fig. 5A. 311

2011. Baltograptus deflexus (Elles & Wood), Rushton, p. 322, figs. 2A, B, C?, D–L. 312

2018. Baltograptus deflexus (Elles & Wood), Toro & Maletz, p. 64. 313

14

2019. Baltograptus deflexus (Elles & Wood), Lo Valvo, p. 50, fig. 16.1; pl. 2, figs. 3, 314

5, 7. 315

2019. Baltograptus deflexus (Elles & Wood), Herrera Sánchez et al., p. 72, figs. 2.2, 316

8. 317

2019. Baltograptus deflexus (Elles & Wood), Gutiérrez-Marco et al., p. 61, figs. 2C–318

D, H. 319

Referred material. Numerous specimens corresponding to different stages of 320

development are preserved as flattened films. The illustrated material is identified as 321

CEGH-UNC 24980, 24996, 24997. 322

Geographic and stratigraphic provenance. The studied material comes from levels 323

corresponding to the D. bifidus Biozone (Fig. 2). It was collected in the Muñayoc 324

section, the Quichagua range (Fig. 1.2). The records of B. cf. B. deflexus previously 325

mentioned by Toro et al. (2006) in the Santa Rosa section, at Cochinoca range (Fig. 326

1.2), are here assigned to B. deflexus, confirming the occurrence of this species in that 327

section. B. deflexus is mostly recorded at the Argentine Cordillera Oriental, as in the 328

Los Colorados and Santa Victoria areas (Toro et al., 2015; Herrera Sánchez et al., 329

2019; and references therein). Elles & Wood (1901) described this species for the first 330

time in levels corresponding to the Didymograptus (Expansograptus) extensus 331

Biozone in Great Britain. It was later recognized in Sweden, the Yangtze region in 332

South China, southern Bolivia and southern Peru (Zhang et al., 2007; Maletz & 333

Ahlberg, 2011; Toro & Maletz, 2018; Gutiérrez-Marco et al., 2019). 334

Description. Slender and deflexed tubaria with artus type development. Sicula 1.75–335

1.8 mm long, about 0.2–0.3 mm in width at the aperture, and with a free wall reaching 336

0.3 mm of length. The stipes make the outward bend at th4–th5 and constantly widen 337

15

along the stipe within 0.65–0.70 mm. The thecal inclination is 20°–25°, and there are 338

13 thecae in 10 mm. 339

Discussion. Our material agrees with the original description of B. deflexus (Elles & 340

Wood, 1901) in the characteristic deflexed tubarium, thecal density, thecal inclination, 341

and the stipes width. It also coincides with better-preserved material coming from the 342

Argentine Cordillera Oriental (Herrera Sánchez et al., 2019, figs. 2.2, 8) and the 343

redescription by Rushton (2011), in the proximal development of artus type. The 344

specimens here assigned to B. deflexus contrasts with the bigger proximal width 345

reached in Baltograptus vacillans (Tullberg, 1880), the longer sicula in B. extremus 346

which is more than 2 mm long, and the smaller sicula, slender stipes and more parallel 347

side thecae in B. kurcki (Törnquist, 1901) (Maletz & Slovacek, 2013). 348

Baltograptus extremus Maletz & Slovacek, 2013 349

Figure 3.5 350

2011. Baltograptus sp. 1, Maletz & Ahlberg, p. 357, fig. 5C. 351

2013. Baltograptus extremus Maletz & Slovacek, p. 13, figs. 2, 3B, 9–10. 352

2019. Baltograptus cf. extremus Maletz & Slovacek, Lo Valvo, p. 61, fig. 18.2. 353

Referred material. One specimen regularly preserved as a flattened film. The 354

material is stored under the prefix CEGH-UNC 24981. 355

Geographic and stratigraphic provenance. B. extremus is recorded here for the first 356

time in South America, from levels corresponding to the D. bifidus Biozone (Fig. 2) at 357

the Santa Rosa section, Cochinoca range, Jujuy Province (Fig. 1.2). This species was 358

previously known only from deposits corresponding to the Baltograptus minutus 359

Biozone in Sweden (Maletz & Slovacek, 2013). 360

Description. The specimen exhibits a slender and long sicula, which reaches 2.85 mm 361

in length, 0.41 mm in width at the aperture, and a long free wall of 0.67 mm. Pendent 362

16

stipes diverging from the sicula with angles of 125°–145°. They reach 0.94 mm of 363

width at the th1 aperture and gradually widen up to 1.08 mm at th4. The thecal length 364

varies within 1.72–2.05 mm, and the thecal width is 0.41 mm. The thecal inclination 365

is 20°–25°, and the thecae overlap in 1/2 to 1/3 of their length. 366

Discussion. The studied material matches with the characteristic morphology, 367

measurements of the sicula, and the thecal distribution originally described by Maletz 368

& Slovacek (2013) for B. extremus. Our specimen differs from B. deflexus because of 369

the longer sicula, and from Corymbograptus v-fractus (Salter, 1863), which presents 370

robust stipes up to 2.0 mm at th10 (sensu Rushton, 2011). 371

Baltograptus geometricus (Törnquist, 1901) 372

Figure 3.6 373

1901. Didymograptus geometricus Törnquist, p. 11, pl. 1, figs. 12, 14. 374

1937. Didymograptus aff. geometricus Törnquist, Monsen, p. 132, pl. 2, fig. 52. 375

1997. Baltograptus geometricus (Törnquist), Toro, p. 397, pl. I, figs. 7–8. 376

2008. Baltograptus geometricus (Törnquist), Toro & Maletz, p. 978, figs. 4. 2–3. 377

2011. Baltograptus geometricus (Törnquist), Maletz & Ahlberg, p. 357, fig. 5J. 378

2013. Baltograptus geometricus (Törnquist), Toro & Vento, p. 292, figs. 5. 3–4. 379

2017. Baltograptus geometricus (Törnquist), Li et al., p. 436, fig. 5J. 380

2018. Baltograptus geometricus (Törnquist), Toro & Maletz, p. 63. 381

2019. Baltograptus geometricus (Törnquist), Gutiérrez-Marco et al., p. 60, figs. 1M, 382

N. 383

2019. Baltograptus geometricus (Törnquist), Herrera Sánchez et al., p. 72, fig. 2.7. 384

2019. Baltograptus geometricus (Törnquist), Navarro et al., p. R65. 385

Referred material. Numerous specimens regularly preserved as flattened films. The 386

illustrated material is identified as CEGH-UNC 24982. 387

17

Geographic and stratigraphic provenance. Levels with B. geometricus are found in 388

the lower part of the Muñayoc section (Fig.1.2), T. akzharensis Biozone (Fig. 2). This 389

is the first record of the species for the Argentine Puna. It was previously recognized 390

at Cajas range, Aguilar range, Los Colorados, La Ciénaga de Purmamarca, and Santa 391

Victoria areas, in the Argentine Cordillera Oriental (Toro, 1997; Toro & Maletz, 392

2008; Toro et al., 2015; Navarro et al., 2019). This species is widely distributed in 393

Baltoscandia from levels corresponding to the Cymatograptus protobalticus and 394

Baltograptus vacillans biozones (Maletz & Ahlberg, 2011). More recently, B. 395

geometricus was documented in the Jiangnan region in South China, southern Bolivia, 396

and southern Peru (Li et al., 2017; Toro & Maletz, 2018; Gutiérrez-Marco et al., 397

2019). 398

Description. Slightly declined tubaria with a soft convexed dorsal margin of the 399

stipes. The sicula is slender and varies within 1.43–1.56 mm in length. The sicular 400

aperture is about 0.20–0.38 mm, and a free wall of 0.20–0.30 mm is observed. The 401

stipes width varies within 0.40–0.50 mm at th1 and remains constant along the stipes. 402

They diverge from the sicula at about 100°–112°. Thecae are simple with an 403

inclination of 15°–25°, and there are 11 thecae in 10 mm. 404

Discussion. The tubaria measurements, such as the length of the sicula, thecal 405

inclination, thecal density, and the stipes width, agree with those of B. geometricus 406

(Törnquist, 1901; Toro & Vento, 2013). Our material has a shorter sicula than 407

Cymatograptus rigoletto (Maletz, Rushton & Lindholm, 1991), which is greater than 408

2 mm in the latter species (sensu Maletz et al., 1991). 409

Baltograptus vacillans (Tullberg, 1880) 410

Figure 3.7 411

1880. Didymograptus vacillans Tullberg, p. 42, pl. 2, figs, 4–7. 412

18

1937. Didymograptus vacillans Tullberg, Monsen, p. 142, pl. 3, figs. 8, 35, 43; pl. 9, 413

fig. 9. 414

1951. Didymograptus vacillans Tullberg, Loss, p. 43, figs. 8–10; pl. 1, figs. 9–17. 415

1994. Baltograptus vacillans (Tullberg), Maletz, p. 38, figs. 6A–B; pl. 1, figs. B–D, 416

G. 417

1994. Corymbograptus aff. C. vacillans (Tullberg), Ortega & Rao, p. 23, figs. 3,4; pl. 418

1, figs. A–E. 419

1997. Baltograptus vacillans (Tullberg), Toro, p. 399, pl. II, figs. 2, 5. 420

2007. Baltograptus vacillans (Tullberg), Egenhoff & Maletz, p. 375–376, figs. 3–4. 421

2007. Baltograptus vacillans (Tullberg), Zhang et al., p. 319, fig. 3. 422

2011. Baltograptus vacillans (Tullberg), Maletz & Ahlberg, p. 357, fig. 5K. 423

2012. Baltograptus vacillans (Tullberg), Vento et al., p. 350, fig. 5H. 424

2013. Baltograptus vacillans (Tullberg), Toro & Vento, p. 292, figs. 5.10–11. 425

2017. Baltograptus vacillans (Tullberg), Li et al., p. 434–435, figs. 3–4. 426

2017. Baltograptus vacillans (Tullberg), Toro et al., p. 95, fig. 2.3. 427

2018. Baltograptus vacillans (Tullberg), Toro & Maletz, p. 63. 428

2019. Baltograptus vacillans (Tullberg), Navarro et al., p. R65. 429

2019. Baltograptus vacillans (Tullberg), Lo Valvo, p. 56, fig. 17; pl. 2, figs. 1–2. 430

Referred material. Few specimens regularly preserved as flattened films. The 431

illustrated material is identified as CEGH-UNC 24983. 432

Geographic and stratigraphic provenance. The studied material comes from the 433

lower portion of the Muñayoc section (Fig. 1.2), from the T. akzharensis Biozone 434

(Fig. 2). This is the first mention of B. vacillans in the Argentine Puna. The species 435

has been documented at the San Bernardo, La Ciénaga de Purmamarca, Los 436

Colorados, Aguilar range and Santa Victoria area, in the Argentine Cordillera Oriental 437

19

(Loss, 1951; Ortega & Rao, 1994; Toro & Vento, 2013; Toro et al., 2015; Toro et al., 438

2017; Navarro et al., 2019; and references therein). B. vacillans was originally 439

described by Tullberg (1880) in Sweden and later recognized by Egenhoff & Maletz 440

(2007) and Maletz & Ahlberg (2011). It was also mentioned for southern Bolivia 441

(Toro & Maletz, 2018) and South China, in the Yangtze and Jiangnan regions (Zhang 442

et al., 2007; Li et al., 2017). 443

Description. Declined tubaria showing isograptid proximal development. Slender 444

sicula of about 1.7–2 mm long, with an apertural diameter within 0.3–0.5 mm and free 445

wall of 0.3–0.4 mm. Stipes width is 0.8–0.9 mm at the th1 aperture and increases to 1 446

mm at th2 remaining constant along the rest of the stipes. The thecae are simple, with 447

1–1.4 mm in length. The thecal inclination varies within 25°–35°, and the overlapping 448

is 1/2 from the length of the thecae. 449

Discussion. The general morphology of the studied material agrees with those of B. 450

vacillans in Tullberg (1880) and Maletz & Ahlberg (2011). The proximal end 451

development, of isograptid type, and sicular parameters also coincide with better-452

preserved material from the Argentine Cordillera Oriental illustrated by Ortega & Rao 453

(1994, figs. 3.4; pl. 1), Toro (1997, pl. II.2, 5) and Toro & Vento (2013, fig. 5.10, 11). 454

Our material is clearly distinguished from other deflexed forms as B. deflexus with 455

artus type proximal development and slender stipes, which reach up to 0.7 mm in 456

width distally. 457

Genus Cymatograptus Jaanusson, 1965 458

Type species. Didymograptus undulatus Törnquist, 1901. 459

Diagnosis (sensu Maletz et al., 2018a). Slender, horizontal to subhorizontal or 460

declined tubarium; thecae simple with a moderate inclination and some species with 461

prothecal folds; sicula relatively long and slender, with small prosicula; supradorsal 462

20

portion of sicula prominent and with long free ventral side of the aperture; proximal 463

development type isograptid, dextral to artus type, dextral or sinistral; low prosicular 464

origin of th11. 465

Cymatograptus protobalticus (Monsen, 1937) 466

Figure 3.8 467

1933. Didymograptus patulus (J. Hall), Elles, p. 100, fig. 9. 468

1937. Didymograptus protobalticus Monsen, p. 138, pl. 3, figs. 2–3, 40; pl. 9, fig. 5. 469

1996b. Didymograptus (s.l.) protobalticus (Monsen), Maletz, p. 111, figs. 2A–E, 3C, 470

F–H. 471

1997. Didymograptus (s.l.) protobalticus (Monsen), Toro, p. 399, pl. II, fig. 11. 472

1998. Didymograptus protobalticus Monsen, Ortega et al., p. 238. 473

2004. Expansograptus protobalticus (Monsen), Egenhoff et al., p. 293, fig. 5j. 474

2009. Didymograptus (s.l.) protobalticus (Monsen), Zalasiewicz et al., p. 792, fig. 475

3.18. 476

2011. Cymatograptus protobalticus (Monsen), Maletz & Ahlberg, p. 353, fig. 3J. 477

2012. Cymatograptus protobalticus (Monsen), Vento et al., p. 352, fig. 6F. 478

2013. Cymatograptus protobalticus (Monsen), Toro & Vento, p. 292, fig. 5.1. 479

2018. Cymatograptus protobalticus (Monsen), Toro & Maletz, p. 64. 480

2019. Cymatograptus protobalticus (Monsen), Lo Valvo, p. 64, fig. 19.1; pl. 3, fig. 5–481

6. 482

2019. Cymatograptus protobalticus (Monsen), Gutiérrez-Marco et al., p. 60, figs. 1K, 483

L. 484

Referred material. One specimen with mold and counterpart is regularly preserved 485

as a flattened film. The illustrated material is identified as CEGH-UNC 24984. 486

21

Geographic and stratigraphic provenance. C. protobalticus is recognized here, for 487

the first time in the Argentine Puna, in the lower part of the Muñayoc section (Fig. 488

1.2), corresponding to the T. akzharensis Biozone (Fig. 2). It has been previously 489

recorded in equivalent levels from the Argentine Cordillera Oriental, at Los 490

Colorados, Aguilar range, and Cajas area (Toro, 1997; Ortega et al., 1998; Toro & 491

Vento, 2013). This species has been successively recognized in Baltoscandia, Great 492

Britain, Southern Bolivia, and Southern Peru (Egenhoff et al., 2004; Zalasiewicz et 493

al., 2009; Maletz & Ahlberg, 2011; Gutiérrez-Marco et al., 2019). 494

Description. Robust declined tubarium with slightly deflexed proximal portion. The 495

slender sicula is 3.3 mm long, with 0.4 mm in its aperture. The stipes continuously 496

widen from 1.3 mm at th1, up to 2.2 mm at th12. Thecal inclination and overlapping 497

could not be precisely measured because of the regular preservation of the material; 498

however, a thecal density of 13 thecae in 10 mm is presupposed. 499

Discussion. The characteristic parameters observed in the studied material, such as 500

the sicular length, stipes diverging angle, and the stipes width, are in agreement with 501

those reviewed by Maletz (1996b) for C. protobalticus. On the other hand, our 502

material differs from Cymatograptus balticus by the shorter sicula and wider stipes. 503

At the same time, it is distinguished from Corymbograptus v-fractus tullbergi 504

(Monsen, 1937) which possesses a more developed and marked deflexed portion of 505

the stipes. 506

Genus Expansograptus Bouček & Příbyl, 1951 507

Type species. Graptolithus extensus J. Hall, 1858. 508

Diagnosis (sensu Maletz et al., 2018a). More or less horizontal didymograptids with 509

isograptid, dextral proximal development; proximal portion of sicula perpendicular to 510

stipes; sicular and thecal apertures straight, without elaborations; origin of th11 low on 511

22

prosicula; stipe width variable; crossing canals more or less symmetrically placed on 512

sicula; crossing canal one is initially much wider than crossing canal two; length of 513

isograptid suture variable. 514

Expansograptus constrictus (J. Hall, 1865) 515

Figure 3.9 516

1865. Graptolithus constrictus J. Hall, p. 76–77, pl. 1, figs. 23–27. 517

1901. Didymograptus constrictus (J. Hall), Törnquist, p. 17–18, pl. 2, figs. 13–17. 518

1937. Didymograptus constrictus var. repandus Monsen, p. 102–103, pl. 1, fig. 20; pl. 519

7, fig. 5; pl. 8, fig. 4. 520

1979. Didymograptus constrictus (J. Hall), Cooper, p. 69–70, fig. 70; pl. 11d, f. 521

1988. Didymograptus (Expansograptus) constrictus (J. Hall), Williams & Stevens, p. 522

48, pl. 12, fig. 13; figs. 34I–Q. 523

1997. Didymograptus (Expansograptus) constrictus (J. Hall), Toro, p. 399, pl. II, figs. 524

4, 8. 525

2003. Expansograptus constrictus (J. Hall), Toro & Brussa, p. 476–477, pl. 2, figs. 526

10, 11. 527

2007. Expansograptus constrictus (J. Hall), Egenhoff & Maletz, p. 375, fig. 3. 528

2017. Expansograptus constrictus (J. Hall), Li et al., p. 436, fig. 5K. 529

Referred material. Two specimens regularly preserved as flattened films. The 530

illustrated material is identified with the prefix CEGH-UNC 24985. 531

Geographic and stratigraphic provenance. This material was collected for the first 532

time in the Argentine Puna from the lower part of the Muñayoc section, Quichagua 533

range (Fig. 1.2), in the T. akzharensis Biozone (Fig. 2). E. constrictus was previously 534

recorded at the Los Colorados area and Cajas range, in the Argentine Cordillera 535

Oriental (Toro, 1997; Toro & Brussa, 2003), from deposits of the Acoite Formation in 536

23

which the T. akzharensis Biozone was identified. This species was originally defined 537

in shales of the Quebec Group, Canada (J. Hall, 1865), and later recognized in 538

Baltoscandia, Australia, and the Jiangnan region, South China (Cooper, 1979; 539

Egenhoff & Maletz, 2007; Li et al., 2017). 540

Description. Robust tubaria with slightly reflexed stipes of 30 mm of length. The 541

sicula is 2.0–2.4 mm in length, straight and dorsally curved in the distal part. The 542

stipes diverges from the sicula with an angle of about 60°–80° and increases in width 543

from 1.6–1.7 mm up to 1.9–2.0 mm, distally. Thecae are straight with an inclination 544

angle of 35°–37°. There are 13 thecae in 10 mm. 545

Discussion. The measurements of the studied material agree with those of D. 546

(Expansograptus) constrictus described by Williams & Stevens (1988). It is also 547

similar to the specimens illustrated by Toro (1997) and Toro & Brussa (2003). The 548

specimens here assigned to E. constrictus are associated at the same stratigraphic level 549

with Expansograptus similis (J. Hall, 1865), which has a shorter sicula of about 1.5 550

mm and the stipes width does not exceed 1.4 mm, distally. 551

Expansograptus holmi (Törnquist, 1901) 552

Figure 3.10 553

1901. Didymograptus holmi Törnquist, p. 12, pl. I, figs. 15–18. 554

1937. Didymograptus holmi Törnquist, Monsen, p. 94, pl. 1, figs. 1, 9, 11, 14. 555

1996a. Didymograptus (Expansograptus) holmi (Törnquist), Maletz, p. 206, figs. 1B. 556

D–I, 3 A–B. 557

1997. Didymograptus (s.l.) holmi (Törnquist), Toro, p. 399, pl. II, figs. 6–7. 558

2003. Expansograptus holmi (Törnquist), Toro & Brussa, p. 446, pl. 2, figs. 8–9. 559

2008. Expansograptus holmi (Törnquist), Toro & Maletz, p. 978, fig. 5.1. 560

2011. Expansograptus holmi (Törnquist), Maletz & Ahlberg, p. 375–376, figs. 3–4. 561

24

2013. Expansograptus holmi (Törnquist), Toro & Vento, p. 292, fig. 5.12. 562

2017. Expansograptus holmi (Törnquist), Li et al., p. 434–435, figs. 3–4. 563

2018. Expansograptus holmi (Törnquist), Toro & Maletz, p. 66, fig. 4.4. 564

2019. Expansograptus holmi (Törnquist), Lo Valvo, p. 67, fig. 19.2; pl. 3, figs. 7–8. 565

Referred material. Numerous specimens corresponding to different stages of 566

development regularly preserved as flattened films. The illustrated material is 567

identified as CEGH-UNC 24986. 568

Geographic and stratigraphic provenance. E. holmi is recognized in the lower part 569

of the Muñayoc section, Quichagua range (Fig. 1.2), in the Baltograptus cf. B. 570

deflexus Biozone (Fig. 2). It has been previously recognized in the Cerro Tafna, in 571

eastern Puna (Toro & Brussa, 2000), and Los Colorados and Aguilar range areas, in 572

the Argentine Cordillera Oriental (Toro & Brussa, 2003; Toro & Vento, 2013). 573

Törnquist (1901) originally described the species from the T. phyllograptoides 574

Biozone from the Diabasbrottet section, Hunnerberg, Sweden. Later, Maletz (1996a) 575

and Maletz & Ahlberg (2011) extended its record through the C. protobalticus 576

Biozone of Baltoscandia. E. holmi has also been recorded in the Jiangnan region in 577

South China and southern Bolivia (Li et al., 2017; Toro & Maletz, 2018; and 578

references therein). 579

Description. The sicula is long and slender. It varies within 1.98–2.16 mm and 580

appears perpendicular to the dorsal side of the stipes. The apertural diameter of the 581

sicula is about 0.32–0.46 mm, and a basal free length of 0.4–0.45 mm is observed. 582

Stipes are nearly horizontal with a width of about 1.0–1.1 mm initially that increases 583

distally to 1.50–1.68 mm. Thecae are simple and right, with an inclination angle of 584

25°–40°. Thecal overlapping is about 1/2 to 2/3 of their length, and there are 14 585

thecae in 10 mm. 586

25

Discussion. The studied material presents the general characteristics previously 587

described by Maletz (1996a) for E. holmi. The slender and long sicula, and the stipes 588

width agree with those described for this species. Our material differs from 589

Expansograptus suecicus and E. similis, which have shorter siculas of about 1.4–1.8 590

mm in length (sensu Maletz, 1996a). 591

Expansograptus pusillus (Tullberg, 1880) 592

Figure 3.11 593

1880. Didymograptus pusillus Tullberg, p. 42, pl. 2, figs. 12, 14. 594

1987. Expansograptus pusillus (Tullberg), Maletz, p. 104–106, fig. 35.4. 595

1990. Acrograptus pusillus (Tullberg), Xiao & Chen, p. 134, pl. 20, figs. 5, 14, 15. 596

2003. Acrograptus pusillus (Tullberg), Zhang & Chen, p. 175, fig. 2K. 597

2012. Acrograptus pusillus (Tullberg), Li et al., p. 1117, figs. 5b, g–h. 598

Referred material. Numerous specimens regularly preserved as flattened films. The 599

illustrated material is identified as CEGH-UNC 24976. 600

Geographic and stratigraphic provenance. The studied material was collected for 601

the first time in South America, from the lower part of the Muñayoc section, 602

Quichagua range (Fig. 1.2), in the Baltograptus cf. B. deflexus Biozone (Fig. 2). 603

Tullberg (1880) originally described it from equivalent levels of the Cymatograptus 604

balticus Biozone in Sweden. More recently, Li et al. (2012) re-illustrated some 605

specimens from Baltoscandia and South China (Yangtze and Jiangnan regions). 606

Description. Complete tubaria that reaches a maximum of 30 mm of length in mature 607

specimens. Short sicula of about 1.0–1.2 mm in length with an apertural diameter of 608

0.18 mm. The free wall of the sicula is 0.2 mm. The proximal end shows an isograptid 609

type development and the characteristic symmetrical appearance described for the 610

genus Expansograptus (Maletz, 1987, Maletz et al., 2018a). The narrow stipes 611

26

diverge from the sicula with angles of 90°–120°, giving a sub-horizontal to slightly 612

declined aspect for the tubaria. The dorsal-ventral width of the stipes increases from 613

0.3–0.4 mm at th2 up to 0.5–0.6 mm at th12. Thecae are straight with an inclination of 614

10°–18°, and there are 12 thecae in 10 mm. 615

Discussion. The studied material presents isograptid type development and 616

symmetrical appearance of the proximal end, as well as most of the general 617

characteristics previously described in E. pusillus by Tullberg (1880), Maletz (1987), 618

and probably showed in the specimens more recently re-illustrated by Li et al. (2012). 619

For years, this species has been included in the Acrograptus genus (Xiao & Chen, 620

1990; Zhang & Chen, 2003; Li et al., 2012), but more recently, as part of the last 621

revision for the Treatise of Invertebrate Paleontology, Maletz et al. (2018b) redefined 622

the genus Acrograptus to include only the species with artus type of development. 623

Accordingly, we follow the generic assignation of the discussed species to 624

Expansograptus. E. pusillus is easily distinguished from other expansograptids, such 625

as E. holmi, E. constrictus, and E. similis described in this work, by the shorter sicula 626

and narrower stipes. 627

Expansograptus similis (J. Hall, 1865) 628

Figure 3.12 629

1865. Graptolithus similis J. Hall, p. 8–9, pl. 2, figs. 1–5. 630

1904. Didymograptus similis (J. Hall), Ruedemann, p. 677–679, pl. 14, figs. 25–29; 631

figs. 73–74. 632

1982. Didymograptus (Expansograptus) similis (J. Hall), Cooper & Fortey, p. 238, 633

figs. 45a–c. 634

1988. Didymograptus (Expansograptus) similis (J. Hall), Williams & Stevens, p. 46, 635

pl. 12, fig. 15; text-fig. 31O, P, T [non pl. 12, fig. 16, text-fig. 31L, Q, R = D. (E.) 636

27

holmi; non pl. 3, figs. 1–2, pl. 14, figs. 13–17, text-fig. 31M, N = D. (E.) grandis; non 637

text-fig. 31S = Didymograptus sp. indet]. 638

1996a. Didymograptus (Expansograptus) similis (J. Hall), Maletz, p. 208, figs. 2B–I, 639

3E–F. 640

1997. Didymograptus (Expansograptus) similis (J. Hall), Toro, p. 402–403, pl. III, fig. 641

3. 642

2003. Expansograptus similis (J. Hall), Toro & Brussa, p. 476, pl. 2, fig. 7. 643

Referred material. One complete specimen well preserved as internal mold in semi-644

relief. It is identified as CEGH-UNC 24987. 645

Geographic and stratigraphic provenance. This is the first record of E. similis in 646

the Argentine Puna. Previous findings of this species coming from the Argentine 647

Cordillera Oriental were summarized by Toro (1997) and Toro & Brussa (2003). The 648

studied material comes from the lower portion of the Muñayoc section, at Quichagua 649

range (Fig. 1.2), corresponding to the T. akzharensis Biozone (Fig. 2). E. similis was 650

originally described in Canada from levels of the Quebec Group in which the 651

Phyllograptus anna Biozone was identified (J. Hall, 1865). Later on, it was 652

recognized in Australia (Cooper & Fortey, 1982, and references therein) and 653

Newfoundland, where this species occurs from the T. akzharensis Biozone to the 654

Didymograptellus bifidus Biozone (Williams & Stevens, 1988). 655

Description. The specimen exhibits a short sicula of 1.5 mm in length inclined 656

approximately 14° respect to the dorsal margin of the tubarium. Two nearly horizontal 657

stipes slightly reflexed emerge from the sicula with an angle of 88°. They widen 658

slowly, from the proximal part from about 1.1 mm to 1.4 mm distally. The thecae are 659

straight with an inclination angle of 25°. There are 11 thecae in 10 mm. 660

28

Discussion. Although the records of E. similis from Argentine Cordillera Oriental 661

(Toro, 1997) reach longer siculas (ca. 2 mm) and distally wider stipes (ca. 1.7 mm), 662

probably as a result of tectonic deformation, the length of the sicula and the stipes 663

width of our material agree with those previously described by Cooper & Fortey 664

(1982), Williams & Stevens (1988), and Maletz (1996a) for the species. Our material 665

differs by the sicular inclination from E. holmi, which has a perpendicular sicula, and 666

also disagrees by the smaller sicula with E. holmi and E. suecicus in which it varies 667

from 1.8–2.4 mm and from 1.8–2.0 mm long, respectively (Maletz, 1996a). The last-668

mentioned expansograptids present a stipes width that reaches up to 1.7 and 1.8 mm 669

distally, which also differs from the illustrated material in Fig. 3.12. 670

Family PHYLLOGRAPTIDAE Lapworth, 1873 671

Genus Corymbograptus Obut & Sobolevskaya, 1964 672

Type species. Didymograpsus v-fractus Salter, 1863. 673

Diagnosis (sensu Maletz et al., 2018a). Deflexed, two-stiped phyllograptid with 674

distally distinctly widening stipes; proximal development isograptid, dextral; low 675

prosicular origin of th11; crossing canals low on sicula; sicula long and slender as in 676

Tshallograptus with mitre-shaped prosicula. 677

Corymbograptus v-fractus tullbergi (Monsen, 1937) 678

Figure 3.13 679

1937. Didymograptus v-fractus tullbergi Monsen, p. 144, pl. 3, figs. 12, 16, 23; pl. 10, 680

figs. 9–10. 681

1994. Corymbograptus v-fractus tullbergi (Monsen), Maletz, p. 34, figs. 4E–G. 682

1996b. Corymbograptus v-fractus tullbergi (Monsen), Maletz, p. 108, fig. 1I; p. 110, 683

fig. 3E. 684

29

2012. Corymbograptus v-fractus tullbergi (Monsen), Vento et al., p. 351, figs. 5J–K, 685

6A. 686

2017. Corymbograptus v-fractus tullbergi (Monsen), Li et al., p. 434–435, figs. 3–4. 687

2019. Corymbograptus v-fractus (Salter), Lo Valvo, p. 73, figs. 20.2–20.4; pl. 4, figs. 688

4–5. 689

2019. Corymbograptus v-fractus tullbergi? (Monsen), Gutiérrez-Marco et al., p. 59. 690

Referred material. Numerous specimens well preserved as flattened films. The 691

illustrated specimen is identified as CEGH-UNC 24988. 692

Geographic and stratigraphic provenance. Corymbograptus v-fractus tullbergi is 693

recognized for the first time in the Argentine Puna, from levels corresponding to the 694

T. akzharensis Biozone (Fig. 2) in the Muñayoc section (Fig. 1.2). This subspecies has 695

been previously recognized in the Argentine Cordillera Oriental, in the Quinilicán and 696

Agua Chica sections (Vento et al., 2012). It was originally described in Norway 697

(Monsen, 1937), more recently recognized in South China (Jiangnan region) (Li et al., 698

2017), and dubiously mentioned in southern Peru (Gutiérrez-Marco et al., 2019). 699

Description. Deflexed tubaria with a long and slender sicula ranging from 2.63 to 700

2.86 mm long. The sicular aperture is 0.28–0.44 mm in width, and the ventral free 701

wall reaches up to 0.5 mm. The studied material shows isograptid type development, 702

and th11 originates high in the sicula. The stipes are up to 8.2 mm in length. They 703

widen slowly from 0.70–1.10 mm at th1 to 1.30 mm at th6. The stipes diverging angle 704

is 105°–125°, thecal inclination varies within 30°–40°, and there are 13 thecae in 10 705

mm. 706

Discussion. The studied material was assigned to C. v-fractus tullbergi based on the 707

similar parameters of the sicula, the high origin of th11, and the deflexed attitude of 708

the tubarium. Following the recent redescription of C. v-fractus by Rushton (2011), 709

30

the latter has wider stipes of 2.2 mm, and the outward bend appears near to theca 13, 710

meanwhile in C. v-fractus tullbergi the outward bend is nearer to the proximal end, 711

close to theca 7 as occurs in our material. 712

Genus Tetragraptus Salter, 1863 713

Type species. Graptolithus bryonoides J. Hall, 1858. 714

Diagnosis (sensu Maletz et al., 2018a). Phyllograptid with four horizontal to reclined, 715

reflexed and scandent stipes; proximal end isograptid, dextral, with wide-crossing 716

canals and tetragraptid proximal end; thecae with considerable overlap and moderate 717

development of rutellum. 718

Tetragraptus reclinatus Elles & Wood, 1901 719

Figure 3.14 720

1901. Tetragraptus reclinatus Elles & Wood, p. 67, pl. VI, figs. 5a–e. 721

1937. Tetragraptus reclinatus Elles & Wood, Monsen, p. 174, pl. 4, figs. 3, 7, 23; pl. 722

19, fig. 5. 723

1960. Tetragraptus reclinatus Elles & Wood, Turner, p. 63, pl. III, fig. 8. 724

1988. Tetragraptus reclinatus reclinatus Elles & Wood, Williams & Stevens, p. 29, 725

pl. 2, fig. 9; pl. 10, fig. 1?, figs. 2–4, 6–8; pl. 11, figs. 3–5, 8–11; text-figs. 18A–F. 726

2003. Tetragraptus reclinatus reclinatus Elles & Wood, Toro & Brussa, p. 449, pl. 5, 727

figs. 11–14. 728

2007. Tetragraptus reclinatus Elles & Wood, Zhang et al., p. 319, fig. 3. 729

2009. Tetragraptus reclinatus Elles & Wood, Zalasiewicz et al., p. 792, fig. 3.32. 730

2011. Tetragraptus reclinatus ssp., Maletz & Ahlberg, p. 359, fig. 6I. 731

2019. Tetragraptus reclinatus Elles & Wood, Lo Valvo, p. 82, pl. 5, fig. 3. 732

31

Referred material. Numerous specimens corresponding to different stages of 733

development, regularly preserved as flattened films. The illustrated material is 734

identified as CEGH-UNC 24989. 735

Geographic and stratigraphic provenance. Levels containing T. reclinatus are 736

located in the middle and upper parts of the Muñayoc section, the Quichagua range 737

(Fig. 1.2). It was previously recorded in the Cuesta de Toquero and Cerro Tafna, in 738

eastern Puna (Gutiérrez-Marco et al., 1996; Toro & Brussa, 2000), the Argentine 739

Cordillera Oriental, and Precordillera (Turner, 1960; Toro & Brussa, 2003; and 740

references therein). This species has a worldwide distribution (Williams & Stevens, 741

1988; Zhang et al., 2007; Zalasiewicz et al., 2009; Maletz & Ahlberg, 2011). 742

Description. Tubaria with four robust second-order stipes. The sicula varies between 743

2.1 to 2.5 mm and 0.7–0.8 mm of apertural diameter. The initially reclined stipes 744

diverge with an angle of about 200°–240°, becoming straight distally. The dorsal-745

ventral width of the stipes increases from 0.88 mm up to 2.0 mm, and the thecal 746

density is 12.5 thecae in 10 mm. Thecae are straight and diverge from the stipes with 747

angles of 70°. 748

Discussion. The studied material presents the main characteristics originally 749

described by Elles & Wood (1901). The sicular length, reclined stipes, and thecal 750

density are agreeing with those in T. reclinatus. Our material is distinguished from 751

Tetragraptus bigsbyi (J. Hall, 1865) and T. amii Elles & Wood, 1901 by the stronger 752

stipes, and T. serra by the less robust tubarium. 753

Tetragraptus serra (Brongniart, 1828) 754

Figure 3.15 755

1828. Fucoides serra Brongniart, p. 71, pl. VI, figs. 7–8. 756

1858. Graptolithus bryonoides J. Hall, p. 126. 757

32

1875. Tetragraptus bryonoides (J. Hall), Nicholson, pl. 7, figs. 4–5. 758

1901. Tetragraptus serra (Brongniart), Elles & Wood, p. 65, pl. 6, figs. 4A–f. 759

1960. Tetragraptus serra (Brongniart), Turner, p. 62, pl. III, fig. 12. 760

1992. Tetragraptus serra (Brongniart), VandenBerg & Cooper, p. 41, fig. 5J. 761

2006. Tetragraptus cf. T. serra (Brongniart), Toro et al., p. 166. 762

2009. Tetragraptus serra (Brongniart), Zalasiewicz et al., p. 794, fig. 4.64. 763

2011. Tetragraptus serra (Brongniart), Maletz & Ahlberg, p. 355, fig. 4. 764

2018. Tetragraptus serra (Brongniart), Toro & Maletz, p. 69, fig. 3.4. 765

2019. Tetragraptus serra (Brongniart), Lo Valvo, p. 84, pl. 5, figs. 1–2. 766

Referred material. Numerous specimens corresponding to different stages of 767

development, regularly preserved as flattened films. The illustrated material is 768

identified as CEGH-UNC 24990. 769

Geographic and stratigraphic provenance. The studied material comes from the 770

Santa Rosa section, Cochinoca range (Fig. 1.2). It is associated with Baltograptus 771

minutus, B. deflexus, and B. extremus in the Didymograptellus bifidus Biozone (Fig. 772

2). These records confirm the occurrence of T. serra, which is dubiously mentioned 773

by Toro et al. (2006) at NOA. This species is a very ubiquitous form described 774

originally in Canada (Brongniart, 1828) and later recognized in the Argentine 775

Precordillera, Australia, Great Britain, and Baltoscandia (Turner, 1960; VandenBerg 776

& Cooper, 1992; Zalasiewicz et al., 2009; Maletz & Ahlberg, 2011). 777

Description. Robust tubaria with two first-order stipes that generate four second-778

order stipes. The funicular region is 2.5 mm long and 0.67 mm in width. Second-order 779

stipes width varies within 1.4–2.5 mm proximally and increases up to 4.50 mm in the 780

distal part. The stipes are initially reclined but become straight distally in mature 781

specimens. Sicula long and slender of about 3.2 mm with an apertural diameter of 0.4 782

33

mm. The free wall of the sicula varies between 0.70 mm to 0.88 mm. Thecae are 783

strongly curved to the distal part, developing apertural denticles. There are 10–11 784

thecae in 10 mm. 785

Discussion. The studied material presents the general characteristics previously 786

described by Elles & Wood (1901) and later discussed by Cooper & Fortey (1982). 787

The measurements of thecae, thecal density, and funicular dimensions agree with T. 788

serra. It is distinguished from T. amii, T. reclinatus, and T. bigsbyi by the wider 789

stipes. Additionally, T. reclinatus and T. bigsbyi have a greater thecal density than T. 790

serra. 791

[FIGURE 3] Relevant graptolite taxa 792

PALEOBIOGEOGRAPHIC ANALYSIS 793

Several physical and biotic controls have been proposed during a half-century 794

to explain the distribution patterns of the Ordovician graptolites (Goldman et al., 795

2013; Cooper et al., 2017; Maletz, 2020; and references therein). The surface 796

temperature model based on paleolatitude, as well as the depth stratification model, 797

were widely accepted. However, certain graptolite taxa may be restricted to a specific 798

paleocontinent or depositional basin and the consensus regarding the main factors that 799

control the graptolite distribution is still on debate (e.g., Vandenbroucke et al., 2009; 800

Goldman et al., 2013; Maletz, 2020). 801

Skevington (1973, 1974) proposed the surface water temperature model and 802

identified two major faunal provinces: the cool-temperature ‘Atlantic Province’ and 803

the paleotropical ‘Pacific Province’. This author concluded that latitudinal variation 804

influencing the surface water temperature was the primary control of the graptolite 805

distribution patterns. Later, Cooper et al. (1991, 2012, 2017) showed a lateral and 806

vertical partition in their multiple depth stratification models. These authors 807

34

recognized three graptolite species groups: 1) taxa restricted to the deep-water facies; 808

2) taxa present in both the neritic and deep-water facies; 3) taxa found only in the 809

neritic facies. Alternatively, Egenhoff & Maletz (2007) and Maletz et al. (2011) 810

differentiate the planktic graptolite faunas into endemic and pandemic faunal 811

elements, in an inshore-offshore lateral partition. More recently, Goldman et al. 812

(2013) proposed that both depth stratification and surface temperature distribution 813

models play an essential role in the biogeographical differentiation of graptolite 814

faunas. These authors also suggested using of low and medium to high latitudes 815

instead of the ‘Pacific’ and ‘Atlantic’ provinces of Skevington (1973, 1974) to discuss 816

graptolite distribution. 817

The faunal affinities between the Early Ordovician graptolites from the NOA 818

(Central Andean Basin) and those from other regions, such as Baltoscandia, SW 819

China, Australia, etc., have been quantified by several authors (Toro, 1994b, 1996; 820

Vento et al., 2012, 2014; Toro et al., 2014). Toro (1996) recognized a mixture of both 821

high and low latitude graptolite elements in deposits from the Acoite Formation 822

(Argentine Cordillera Oriental), mainly based on the coexistence of Corymbograptus 823

v-fractus, Baltograptus vacillans, B. deflexus, and B. minutus (high latitude) and 824

Tetragraptus akzharensis Tzaj, 1968 and Didymograptellus bifidus (low latitude). The 825

author statistically tested the faunal affinities between graptolites from the Cordillera 826

Oriental and several regions located at different paleolatitudes and postulated that 827

NOA was located in the transitional zone of intermediate latitudes during the Floian. 828

Later, Vento et al. (2012) determined the faunal affinities of the early Floian taxa 829

recorded in the Tetragraptus phyllograptoides and T. akzharensis biozones from the 830

Aguilar range, NOA. These authors observed a close paleobiogeographic relationship 831

between NOA and Baltoscandia, but weak affinities with SW China, concluding that 832

35

NOA was located in middle to high latitudes, corresponding to the high latitude fauna 833

of cold water. More recently, Vento et al. (2014) postulated that the 834

paleobiogeographic relationship between the NOA and the Yangtze region (SW 835

China) become more significant during the middle–late Floian (Baltograptus cf. B. 836

deflexus and Didymograptellus bifidus biozones). According to the authors, this 837

sudden change of the faunal affinities, represented by the occurrence of 838

geographically restricted forms as Baltograptus turgidus (Lee, 1974) and B. 839

kunmingensis (Ni, in Mu et al., 1979), can be explained by the paleoenvironmental 840

influence. Finally, Toro et al. (2014), based on the affinities of the Tremadocian 841

graptolites from the NOA and Bolivia documented a close relationship with 842

Baltoscandia, and successively higher similarities with the faunas from the ‘warm 843

water realm’ than the previously postulated for the Floian faunas. The authors 844

attributed these different results to the influence of the water depth, related to 845

paleoenvironmental controls, rather than the exclusive control of the paleolatitudinal 846

thermal gradient. 847

To contribute to the understanding of the paleobiogeographic relations of the 848

Central Andean Basin, we test the faunal affinities between Early–Middle Ordovician 849

graptolite records from the Argentine Puna and those from other selected regions of 850

the world. A presence-absence matrix (available online at the National University of 851

Córdoba Data Repository, http://hdl.handle.net/11086/15593) was built, including the 852

graptolite taxa above described for the first time in the studied areas, and previous 853

records from Muñayoc and Santa Rosa sections (Martínez et al., 1999; Toro et al., 854

2006; Toro & Herrera Sánchez, 2019) successively reviewed by Lo Valvo (2019) and 855

this work. We also integrated into the matrix, the graptolite fauna from the 856

Huaytiquina section, at western Puna (Monteros et al., 1996), recently reviewed by 857

36

Toro & Herrera Sánchez (2019). The quantitative analysis also comprises the first 858

mentions and certain assignations of species from equivalent deposits at Baltoscandia 859

(Egenhoff & Maletz, 2007; Maletz & Ahlberg, 2011), Great Britain (Zalasiewicz et 860

al., 2009), SW China (Zhang et al., 2007), and North America (Williams & Stevens, 861

1988; Jackson & Lenz, 2006). Moreover, we decided to exclude from this analysis 862

some conflictive taxa, previously described for the NOA, as Baltograptus sp. nov. 863

(sensu Toro & Maletz, 2007), Baltograptus kurcki, and B. turgidus ‘group’ (Vento & 864

Toro, 2014). We consider that until the revision of these deflexed species from the 865

Central Andean Basin will be accomplished in the framework of the Ph.D. Thesis of 866

one of the authors (N.C.H.S.), their inclusion may lead to misinterpretations of the 867

paleobiogeographic graptolites affinities of the Central Andean Basin. 868

The cluster analysis (Fig. 4.1) was carried out in the programming 869

environment R (R Core Team, 2019) using the Modified Forbe’s Index (F’) following 870

Alroy (2015a, b). The dissimilarity between the regions was calculated as 1-F’ and the 871

Unweighted Pair Group Method with Arithmetic Mean (UPGMA) analysis was used. 872

Also, we reproduced with our database the methodology applied in previous 873

paleobiogeographic analysis from NOA, in which the authors used the statistical 874

software PAST (Hammer et al., 2001) and different similarity indices, such as Jaccard 875

(Toro, 1996; Vento et al., 2012, 2014), Dice, and Raup-Crick (Benedetto et al., 2009; 876

Muñoz et al., 2017). The obtained results using PAST were qualitatively identical to 877

those achieved using F’ in R software. Finally, a Principal Coordinate Analysis 878

(PCoA) was tested applying F’ (Fig. 4.2), as well as Dice and Raup-Crick indices 879

which were used in previous paleobiogeographical analyses based on other 880

Ordovician fossil groups (Benedetto et al., 2009; Muñoz et al., 2017). Both 881

multivariate analyses allow similar interpretations. 882

37

[FIGURE 4] Dendrogram and PCoA of paleobiogeographic affinities 883

The cluster analysis (Fig. 4.1) shows a close relationship between the 884

Argentine Puna and Baltoscandia, with a cophenetic distance of 0.15, in concordance 885

with previous results obtained by Vento et al. (2012). This result is widely justified by 886

the presence of Baltograptus extremus, B. vacillans, B. geometricus, Expansograptus 887

holmi, E. pusillus, and Corymbograptus v-fractus tullbergi in the studied region. 888

Successively, Great Britain is grouped with the last cluster with a distance of 0.28 889

(Fig. 4.1), which means that it has a lower faunal affinity with Puna and Baltoscandia, 890

but it still reflects a significant similarity. On the other hand, species described here 891

for the first time in the Argentine Puna, at Muñayoc and Santa Rosa sections, such as 892

Expansograptus similis, E. constrictus and Clonograptus flexilis, sustain the vague 893

relationship between the latter cluster and North America (Fig. 4.1), with a 894

dissimilarity of 0.47. Moreover, the occurrence of typical low latitude faunal 895

elements, such as Didymograptellus bifidus, and typical high latitude faunal elements, 896

such as Baltograptus deflexus and B. minutus, support the mixed character of the 897

graptolite fauna from NOA formerly observed by Toro (1994b; 1996) and Vento et al. 898

(2014). The SW China was also considered a region with mixed affinities (Cooper et 899

al., 1991), and different authors previously recognized its close relation with the NOA 900

during the middle–late Floian (Toro, 1996, fig. 4c; Toro et al., 2011; Vento et al., 901

2014, fig. 6), but it does not appear to be significantly related to any regions 902

considered in this work (Fig. 4.1). This contrasting result could be related to the 903

exclusion of the robust deflexed baltograptids, previously assigned to the 904

Baltograptus turgidus ‘group’ (Vento & Toro, 2014), from our matrix. 905

The PCoA showed that the first two components (PC1 and PC2) explain 906

88.8% of the variation (Fig. 4.2). The Argentine Puna, Baltoscandia, and Great Britain 907

38

are closely related; meanwhile, SW China and North America are widely distanced 908

from the former group (Fig. 4.2). This result is in agreement with the cluster analysis 909

(Fig. 4.1) but contrasts with the previous idea that Puna, Baltoscandia, and SW China 910

shared similar mixed-faunas (Toro et al., 2011; Vento et al., 2014). 911

[FIGURE 5] Early–Middle Ordovician paleogeographic reconstruction 912

The results obtained from the multivariate analysis are also confirming 913

previous paleobiogeographical interpretations for the Early–Middle Ordovician (Fig. 914

5), based either on planktic graptolites from the NOA (Toro, 1994b, 1996; Vento et 915

al., 2012, 2014), chitinozoans assemblages and marine phytoplankton (Rubinstein & 916

Toro, 2001; de la Puente & Rubinstein, 2013); or benthic brachiopods, trilobites and 917

bivalves (Benedetto et al., 2009, fig. 6a, fig.7a; Muñoz et al., 2017). 918

FINAL REMARKS 919

The taxonomic revision of the graptolites coming from the Muñayoc and Santa 920

Rosa sections, at the eastern Argentine Puna, allows identifying twenty-three different 921

taxa. Fourteen of these taxa are described here, for the first time in the studied area, 922

and three species constitute new records for South America. 923

The presence of Baltograptus extremus, B. geometricus, B. vacillans, 924

Cymatograptus protobalticus, Expansograptus holmi, E. pusillus, and 925

Corymbograptus v-fractus tullbergi in the Argentine Puna emphasize the 926

paleobiogeographic relation with Baltoscandia, previously postulated based on 927

Tremadocian and Floian taxa from Northwestern Argentina. 928

The cluster and principal coordinate analyses based on Early–Middle 929

Ordovician taxa from the Argentine Puna, Baltoscandia, Great Britain, North 930

America, and SW China, show close faunal affinities between the Central Andean 931

39

Basin and Baltoscandia, documenting that paleobiogeographic relation between the 932

last regions can be extended up to the early Dapingian. 933

The strong paleobiogeographic relations between the Central Andean Basin, 934

Baltoscandia, and Great Britain are reflecting the main influence of the 935

paleolatitudinal control. However, the presence of taxa with warm water affinities in 936

the Argentine Puna suggests that the paleoenvironmental control cannot be discarded. 937

On the other hand, our results show less significant affinities between 938

Northwestern Argentina and SW China compared to previous conclusions based on 939

the late Floian taxa from the Argentine Cordillera Oriental. These differences could be 940

originated in the exclusion from this study of the deflexed problematic taxa. 941

Paleobiogeographic relations based on planktic graptolites from the eastern 942

Puna are pointing out that the Central Andean Basin was related to the western margin 943

of the Gondwana Paleocontinent, and located at high latitudes during the Early–944

Middle Ordovician. It is in agreement with the results independently obtained in 945

previous studies based on epipelagic chitinozoans, acritarchs, and benthic trilobites, 946

bivalves, and brachiopods. 947

ACKNOWLEDGMENTS 948

The authors thank the editorial revision of Alejandro Otero, Nestor Toledo, 949

and Juan L. Benedetto, and the valuable observations of Yuandong Zhang and Jörg 950

Maletz that greatly improved the manuscript. We also thank to D.F. Muñoz and F.J. 951

Lavié for their help and discussions in the field. This work was supported by the 952

Agencia Nacional de Promoción Científica y Tecnológica (PICT 2016-0558) and 953

Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET). It is a 954

contribution to 653 IUGS-IGCP project -The onset of the Great Ordovician 955

Biodiversification Event-. 956

40

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