Posted Online : July 22 Th , 2020

Submitted : March 2 nd , 2020 – Accepted : July 15 th , 2020 – Posted online : July 22 th , 2020

To link and cite this article:

doi: 10.5710/AMGH.15.07.2020.3345

1 EARLY-MIDDLE ORDOVICIAN GRAPTOLITES FROM THE ARGENTINE

2 PUNA: QUANTITATIVE PALEOBIOGEOGRAPHIC ANALYSIS BASED ON

3 A SYSTEMATIC REVISION

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

1 6 A. TORO

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

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

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

10 Sarsfield 1611, X5016CGA, Córdoba, Argentina. [email protected];

11 [email protected]; [email protected]

13 58 pages; 5 figures

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

16 ARGENTINE PUNA.

17 Short Description: Quantitative paleobiogeographic analysis based on the updated

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

19 Argentina.

21 Corresponding author: GERARDO A. LO VALVO [email protected]

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

24 graptolites from the eastern Argentine Puna allows describing Sigmagraptus

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

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

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

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

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

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

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

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

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

34 Northwestern Argentina. Quantitative paleobiogeographic analyses of clusters and

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

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

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

38 results are discussed and compared with those formerly obtained in

39 paleobiogeographic analyses based on different fossil groups from Northwestern

40 Argentina.

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

42 Paleobiogeography.

43 Resumen. GRAPTOLITOS DEL ORDOVÍCICO TEMPRANO–MEDIO DE LA

44 PUNA ARGENTINA: ANÁLISIS PALEOBIOGEOGRÁFICO CUANTITATIVO

45 BASADO EN UNA REVISIÓN SISTEMÁTICA. La revisión taxonómica actualizada

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

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

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

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

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

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

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

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

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

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

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

57 paleobiogeográficos cuantitativos de agrupamiento y de coordenadas principales, que

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

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

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

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

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

63 Noroeste argentino.

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

65 Taxonomía. Paleobiogeografía.

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

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

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

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

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

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

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

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

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

76 A new bibliometric analysis involving graptolites from Northwestern

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

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

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

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

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

82 (6.8%) are underdeveloped.

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

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

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

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

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

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

89 stratigraphic sections.

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

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

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

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

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

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

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

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

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

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

100 deposits are also present in this area.

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

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

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

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

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

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

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

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

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

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

111 Muñayoc area.

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

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

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

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

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

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

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

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

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

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

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

123 Oriental, closer paleobiogeographic relations with Baltoscandia were successively

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

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

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

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

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

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

130 Tremadocian and Floian species.

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

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

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

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

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

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

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

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

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

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

141 the described taxa.

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

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

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

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

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

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

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

149 Anatomical abbreviation. th, thecae.

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

151 [FIGURE 1] Location map and fossiliferous sections

152 GEOLOGICAL FRAMEWORK

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

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

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

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

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

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

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

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

161 synsedimentary lavas and subvolcanic rocks. These successions constitute two

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

196 SYSTEMATIC PALEONTOLOGY

197 Phylum HEMICHORDATA Bateson 1885

198 Class PTEROBRANCHIA Lankester, 1877

199 Subclass GRAPTOLITHINA Bronn, 1849

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

201 Suborder SINOGRAPTINA Mu, 1957

202 Family SIGMAGRAPTIDAE Cooper & Fortey, 1982

203 Genus Sigmagraptus Ruedemann, 1904

204 Type species. Sigmagraptus praecursor Ruedemann, 1904.

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

206 progressive branching followed by monoprogressive branching, forming two main

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

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

209 apertural elaborations.

210 Sigmagraptus praecursor Ruedemann, 1904

211 Figure 3.1–2

212 1902. Coenograptid Ruedemann, p. 566.

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

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

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

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

217 61a-k.

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

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

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

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

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

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

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

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

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

227 CEGH-UNC 24977–24978.

228 Geographic and stratigraphic provenance. Sigmagraptus praecursor is here

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

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

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

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

233 corresponding from the Tshallograptus fruticosus Biozone to the Isograptus victoriae

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

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

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

237 Zalasiewicz et al., 2009).

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

253 Suborder DICHOGRAPTINA Lapworth, 1873

254 Family DICHOGRAPTIDAE Lapworth, 1873

255 Genus Clonograptus Hall & Nicholson, in Nicholson 1873

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

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

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

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

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

261 Clonograptus flexilis (J. Hall, 1858)

262 Figure 3.3

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

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

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

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

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

268 text-figs. 2A, 6A–E.

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

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

271 identified as CEGH-UNC 24979.

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

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

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

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

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

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

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

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

280 akzharensis Biozone (Lindholm & Maletz, 1989).

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

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

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

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

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

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

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

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

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

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

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

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

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

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

295 Family DIDYMOGRAPTIDAE Mu, 1950

296 Genus Baltograptus Maletz, 1994

297 Type species. Didymograptus vacillans Tullberg, 1880.

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

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

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

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

302 missing.

303 Baltograptus deflexus (Elles & Wood, 1901)

304 Figure 3.4

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

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

307 II, figs. 9, 14–15.

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

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

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

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

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

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

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

315 5, 7.

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

317 8.

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

319 D, H.

320 Referred material. Numerous specimens corresponding to different stages of

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

322 CEGH-UNC 24980, 24996, 24997.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

339 13 thecae in 10 mm.

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

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

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

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

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

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

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

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

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

349 Baltograptus extremus Maletz & Slovacek, 2013

350 Figure 3.5

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

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

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

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

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

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

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

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

359 previously known only from deposits corresponding to the Baltograptus minutus

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

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

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

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

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

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

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

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

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

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

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

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

372 Baltograptus geometricus (Törnquist, 1901)

373 Figure 3.6

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

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

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

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

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

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

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

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

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

383 N.

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

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

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

387 illustrated material is identified as CEGH-UNC 24982.

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

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

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

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

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

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

394 Baltoscandia from levels corresponding to the Cymatograptus protobalticus and

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

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

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

398 2019).

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

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

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

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

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

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

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

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

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

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

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

410 Baltograptus vacillans (Tullberg, 1880)

411 Figure 3.7

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

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

414 fig. 9.

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

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

417 G.

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

419 1, figs. A–E.

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

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

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

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

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

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

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

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

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

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

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

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

432 illustrated material is identified as CEGH-UNC 24983.

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

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

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

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

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

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

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

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

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

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

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

444 Description. Declined tubaria showing isograptid proximal development. Slender

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

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

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

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

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

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

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

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

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

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

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

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

457 width distally.

458 Genus Cymatograptus Jaanusson, 1965

459 Type species. Didymograptus undulatus Törnquist, 1901.

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

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

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

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

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

465 origin of th11.

466 Cymatograptus protobalticus (Monsen, 1937)

467 Figure 3.8

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

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

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

471 F–H.

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

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

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

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

476 3.18.

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

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

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

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

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

482 6.

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

484 L.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

506 the stipes.

507 Genus Expansograptus Bouček & Příbyl, 1951

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

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

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

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

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

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

514 isograptid suture variable.

515 Expansograptus constrictus (J. Hall, 1865)

516 Figure 3.9

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

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

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

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

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

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

523 48, pl. 12, fig. 13; figs. 34I–Q.

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

525 4, 8.

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

527 10, 11.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

552 Expansograptus holmi (Törnquist, 1901)

553 Figure 3.10

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

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

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

557 D–I, 3 A–B.

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

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

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

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

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

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

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

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

566 Referred material. Numerous specimens corresponding to different stages of

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

568 identified as CEGH-UNC 24986.

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

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

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

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

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

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

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

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

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

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

579 references therein).

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

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

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

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

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

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

586 thecae in 10 mm.

587 Discussion. The studied material presents the general characteristics previously

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

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

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

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

592 Expansograptus pusillus (Tullberg, 1880)

593 Figure 3.11

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

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

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

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

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

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

600 illustrated material is identified as CEGH-UNC 24976.

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

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

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

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

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

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

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

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

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

610 type development and the characteristic symmetrical appearance described for the

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

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

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

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

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

616 Discussion. The studied material presents isograptid type development and

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

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

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

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

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

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

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

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

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

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

627 and narrower stipes.

628 Expansograptus similis (J. Hall, 1865)

629 Figure 3.12

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

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

632 figs. 73–74.

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

634 figs. 45a–c.

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

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

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

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

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

640 3E–F.

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

642 3.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

671 Family PHYLLOGRAPTIDAE Lapworth, 1873

672 Genus Corymbograptus Obut & Sobolevskaya, 1964

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

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

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

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

677 Tshallograptus with mitre-shaped prosicula.

678 Corymbograptus v-fractus tullbergi (Monsen, 1937)

679 Figure 3.13

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

681 figs. 9–10.

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

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

684 fig. 3E.

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

686 6A.

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

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

689 4–5.

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

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

692 illustrated specimen is identified as CEGH-UNC 24988.

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

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

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

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

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

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

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

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

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

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

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

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

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

706 mm.

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

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

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

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

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

712 close to theca 7 as occurs in our material.

713 Genus Tetragraptus Salter, 1863

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

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

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

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

718 development of rutellum.

719 Tetragraptus reclinatus Elles & Wood, 1901

720 Figure 3.14

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

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

723 19, fig. 5.

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

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

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

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

728 figs. 11–14.

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

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

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

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

733 Referred material. Numerous specimens corresponding to different stages of

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

735 identified as CEGH-UNC 24989.

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

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

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

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

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

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

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

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

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

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

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

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

748 angles of 70°.

749 Discussion. The studied material presents the main characteristics originally

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

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

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

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

754 Tetragraptus serra (Brongniart, 1828)

755 Figure 3.15

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

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

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

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

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

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

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

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

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

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

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

767 Referred material. Numerous specimens corresponding to different stages of

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

769 identified as CEGH-UNC 24990.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

785 thecae in 10 mm.

786 Discussion. The studied material presents the general characteristics previously

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

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

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

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

791 serra.

792 [FIGURE 3] Relevant graptolite taxa

793 PALEOBIOGEOGRAPHIC ANALYSIS

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

811 differentiate the planktic graptolite faunas into endemic and pandemic faunal

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

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

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

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

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

817 graptolite distribution.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

847 thermal gradient.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

868 paleobiogeographic graptolites affinities of the Central Andean Basin.

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

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

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

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

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

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

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

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

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

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

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

880 which were used in previous paleobiogeographical analyses based on other

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

882 multivariate analyses allow similar interpretations.

883 [FIGURE 4] Dendrogram and PCoA of paleobiogeographic affinities

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

912 [FIGURE 5] Early–Middle Ordovician paleogeographic reconstruction

913 The results obtained from the multivariate analysis are also confirming

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

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

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

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

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

919 FINAL REMARKS

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

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

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

923 and three species constitute new records for South America.

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

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

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

927 paleobiogeographic relation with Baltoscandia, previously postulated based on

928 Tremadocian and Floian taxa from Northwestern Argentina.

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

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

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

932 Basin and Baltoscandia, documenting that paleobiogeographic relation between the

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

934 The strong paleobiogeographic relations between the Central Andean Basin,

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

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

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

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

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

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

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

942 Paleobiogeographic relations based on planktic graptolites from the eastern

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

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

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

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

947 bivalves, and brachiopods.

948 ACKNOWLEDGMENTS

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

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

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

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

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

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

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

956 Biodiversification Event-.

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1347 Zhang, Y. D., & Chen, X. (2003). The Early–Middle Ordovician graptolite sequence

1348 of the Upper Yangtze region, South China. Ordovician from the Andes.

1349 INSUGEO, Serie Correlación Geológica, 17, 173–180.

1350 Zhang, Y. D., Chen, X., & Goldman, D. (2007). Diversification patterns of Early and

1351 Mid Ordovician graptolites in South China. Geological Journal, 42(3–4), 315–

1352 337.

1353

1354 FIGURE CAPTIONS

1355 Figure 1. 1, Location map showing the geomorphological regions comprised in the

1356 Central Andean Basin. 2, Fossiliferous sections studied in the eastern Argentine Puna

1357 (Modified from Astini, 2003).

1358 Figure 2. Biostratigraphic ranges and provenance of the described taxa (black dots

1359 represent records from Muñayoc section, squares from Santa Rosa section, and

1360 triangles from both sections).

1361 Figure 3. Relevant graptolite taxa from the eastern Puna, Argentina. Arrows are

1362 pointing to the specimens of interest. 1–2, Sigmagraptus praecursor. 1, mature

1363 specimen preserving the zig-zag shape stipes and numerous monoprogressive

1364 branching, Santa Rosa section, CEGH-UNC 24978; 2, flattened proximal end

1365 exhibiting the long sicula and asymmetrical appearance of the proximal end, Santa

1366 Rosa section, CEGH-UNC 24977; 3, Clonograptus flexilis, mature specimen with

1367 the characteristic short second-order stipes, Muñayoc section, CEGH-UNC 24979; 4,

1368 Baltograptus deflexus, three specimens exhibiting typical slender and deflexed stipes,

1369 Santa Rosa section, CEGH-UNC 24980, 24996, 24997; 5, Baltograptus extremus,

1370 juvenile specimen showing the long and slender sicula, Santa Rosa section, CEGH-

1371 UNC 24981; 6, Baltograptus geometricus, slightly declined tubarium with slender

1372 sicula, Muñayoc section, CEGH-UNC 24982; 7, Baltograptus vacillans, young

1373 declined specimen, Muñayoc section, CEGH-UNC 24983; 8, Cymatograptus

1374 protobalticus, complete tubarium showing the characteristic conspicuous sicula and

1375 strong stipes, Muñayoc section, CEGH-UNC 24984; 9, Expansograptus constrictus,

1376 mature specimen that exhibits a robust tubarium and slightly reflexed stipes, Muñayoc

1377 section, CEGH-UNC 24985; 10, Expansograptus holmi, complete tubarium showing

1378 the characteristic prominent sicula and horizontal stipes, Muñayoc section, CEGH-

1379 UNC 24986; 11, Expansograptus pusillus, mature declined tubarium showing the

1380 symmetric proximal end, Muñayoc section, CEGH-UNC 24976; 12, Expansograptus

1381 similis, complete specimen in semi-relief preserving the short sicula and horizontal

1382 stipes, Muñayoc section, CEGH-UNC 24987; 13, Corymbograptus v-fractus

1383 tullbergi, deflexed tubarium with a long and slender sicula, Muñayoc section, CEGH-

1384 UNC 24988; 14, Tetragraptus reclinatus, complete specimen showing the four strong

1385 reclined stipes, Muñayoc section, CEGH-UNC 24989; 15, Tetragraptus serra,

1386 flattened mature specimen with strong stipes, CEGH-UNC 24990. Scale bar equals 1

1387 mm.

1388 Figure 4. 1, Dissimilarity dendrogram obtained with the Modified Forbe’s Index (F’),

1389 in which the cluster, including the Puna region (NOA), Baltoscandia, and Great

1390 Britain is highlighted. 2, Principal Coordinate Analysis grouping the Puna region

1391 (NOA), Baltoscandia, and Great Britain. P (NOA), Puna region (NOA); GB, Great

1392 Britain; B, Baltoscandia; NA, North America; SWCH, SW China.

1393 Figure 5. Early-Middle Ordovician palaeogeographic reconstruction (Modified from

1394 Maletz, 2020) in which the Puna region (NOA), Baltoscandia, and Great Britain

1395 grouping are highlighted.