Early Tremadocian cephalopods from Santa Rosita Formation in NW Argentina: the oldest record for South America
We describe early Tremadocian (Kainella meridionalis Biozone) cephalopods from the Cordillera Oriental, Jujuy, NW Argentina. They consist of numerous small specimens collected at the Quebrada de Arenal, Trancas section, near the town of Tilcara, in the Alfarcito Member of the Santa Rosita Formatio...
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| Format: | Article |
| Language: | English |
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Institute of Paleobiology PAS
2023-12-01
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| Series: | Acta Palaeontologica Polonica |
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| Online Access: | https://www.app.pan.pl/archive/published/app68/app011032023.pdf |
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| author | MARCELA CICHOWOLSKI N. EMILIO VACCARI ALEXANDER POHLE DANIEL A. MORÓN ALFONSO ROMAIN VAUCHER BEATRIZ G. WAISFELD |
| author_facet | MARCELA CICHOWOLSKI N. EMILIO VACCARI ALEXANDER POHLE DANIEL A. MORÓN ALFONSO ROMAIN VAUCHER BEATRIZ G. WAISFELD |
| author_sort | MARCELA CICHOWOLSKI |
| collection | DOAJ |
| description | We describe early Tremadocian (Kainella meridionalis Biozone) cephalopods from the Cordillera Oriental, Jujuy, NW
Argentina. They consist of numerous small specimens collected at the Quebrada de Arenal, Trancas section, near the
town of Tilcara, in the Alfarcito Member of the Santa Rosita Formation. All but three specimens were assigned to a new
species of Ellesmeroceras (Family Ellesmeroceratidae), E. humahuacaensis sp. nov., based on its slightly endogastric
curvature, the characteristics of the siphuncle and chambers dimensions. Micro CT scanning of one specimen aided in
the description of the apex and facilitated the construction of a 3D model of the species. A single, similar specimen was
assigned to Ellesmeroceras sp. pending the availability of additional material. Two specimens differ from the rest, being
exogastric with a lower angle of expansion. They are tentatively assigned to Bassleroceras sp. This material indicates
that Cambrian and early Tremadocian cephalopods are not as different as previously thought. “Diversification” and
“extinction” events during the late Cambrian may be attributed to taxonomic “over-splitting” and taphonomic and/or
sampling biases, respectively. These specimens are currently the oldest recorded in the Central Andean Basin and of
West Gondwana, and probably represent the first migration of cephalopods into the region, when the water column was
still poorly colonized. During the middle Tremadocian, subsequent immigrations and originations of several cephalopod
orders accounted for a rise in diversity and expansion into new niches during this interval. Some of these taxa persisted
into the middle Floian, at which time, a second increase in diversity is recorded. Ellesmeroceras humahuacaensis sp.
nov. is interpreted as a sub-vertical nektobenthic organism. |
| first_indexed | 2024-03-08T11:10:44Z |
| format | Article |
| id | doaj.art-bfffe6382b3b4fd58fd51fce69e0bb27 |
| institution | Directory Open Access Journal |
| issn | 0567-7920 1732-2421 |
| language | English |
| last_indexed | 2024-03-08T11:10:44Z |
| publishDate | 2023-12-01 |
| publisher | Institute of Paleobiology PAS |
| record_format | Article |
| series | Acta Palaeontologica Polonica |
| spelling | doaj.art-bfffe6382b3b4fd58fd51fce69e0bb272024-01-26T11:07:29ZengInstitute of Paleobiology PASActa Palaeontologica Polonica0567-79201732-24212023-12-0168458360110.4202/app.01103.2023Early Tremadocian cephalopods from Santa Rosita Formation in NW Argentina: the oldest record for South AmericaMARCELA CICHOWOLSKI0https://orcid.org/0000-0002-9079-6350N. EMILIO VACCARI1https://orcid.org/0000-0003-4897-3111ALEXANDER POHLE2https://orcid.org/0000-0001-7396-0334DANIEL A. MORÓN ALFONSO3https://orcid.org/0000-0002-2882-0874ROMAIN VAUCHER4https://orcid.org/0000-0001-9122-1818BEATRIZ G. WAISFELD5https://orcid.org/0000-0002-6267-3927Instituto de Estudios Andinos “Don Pablo Groeber” (IDEAN), Universidad de Buenos Aires-CONICET, Intendente Güiraldes 2160, Ciudad Universitaria- Pabellón II C1428EGA, CABA, Argentina.Centro de Investigaciones de Ciencias de la Tierra (CICTERRA), Universidad Nacional de Córdoba-CONICET, Av. Vélez Sarsfield 1699, X5016GCB, Córdoba, Argentina.Institute of Geology, Mineralogy, and Geophysics, Ruhr University Bochum, Universitätsstrasse 150, 44801 Bochum, Germany.Instituto de Estudios Andinos “Don Pablo Groeber” (IDEAN), Universidad de Buenos Aires-CONICET, Intendente Güiraldes 2160, Ciudad Universitaria- Pabellón II C1428EGA, CABA, Argentina.Department of Earth Sciences, University of Geneva, Rue des Maraîchers 13, 1205 Geneva, Switzerland; Institute of Earth Sciences (ISTE), University of Lausanne, Geopolis, CH-1015 Lausanne, Switzerland.Centro de Investigaciones de Ciencias de la Tierra (CICTERRA), Universidad Nacional de Córdoba-CONICET, Av. Vélez Sarsfield 1699, X5016GCB, Córdoba, Argentina.We describe early Tremadocian (Kainella meridionalis Biozone) cephalopods from the Cordillera Oriental, Jujuy, NW Argentina. They consist of numerous small specimens collected at the Quebrada de Arenal, Trancas section, near the town of Tilcara, in the Alfarcito Member of the Santa Rosita Formation. All but three specimens were assigned to a new species of Ellesmeroceras (Family Ellesmeroceratidae), E. humahuacaensis sp. nov., based on its slightly endogastric curvature, the characteristics of the siphuncle and chambers dimensions. Micro CT scanning of one specimen aided in the description of the apex and facilitated the construction of a 3D model of the species. A single, similar specimen was assigned to Ellesmeroceras sp. pending the availability of additional material. Two specimens differ from the rest, being exogastric with a lower angle of expansion. They are tentatively assigned to Bassleroceras sp. This material indicates that Cambrian and early Tremadocian cephalopods are not as different as previously thought. “Diversification” and “extinction” events during the late Cambrian may be attributed to taxonomic “over-splitting” and taphonomic and/or sampling biases, respectively. These specimens are currently the oldest recorded in the Central Andean Basin and of West Gondwana, and probably represent the first migration of cephalopods into the region, when the water column was still poorly colonized. During the middle Tremadocian, subsequent immigrations and originations of several cephalopod orders accounted for a rise in diversity and expansion into new niches during this interval. Some of these taxa persisted into the middle Floian, at which time, a second increase in diversity is recorded. Ellesmeroceras humahuacaensis sp. nov. is interpreted as a sub-vertical nektobenthic organism.https://www.app.pan.pl/archive/published/app68/app011032023.pdfcephalopodaellesmeroceratidaeellesmerocerasstem cephalopodstremadocianordoviciansanta rosita formationcordillera oriental |
| spellingShingle | MARCELA CICHOWOLSKI N. EMILIO VACCARI ALEXANDER POHLE DANIEL A. MORÓN ALFONSO ROMAIN VAUCHER BEATRIZ G. WAISFELD Early Tremadocian cephalopods from Santa Rosita Formation in NW Argentina: the oldest record for South America Acta Palaeontologica Polonica cephalopoda ellesmeroceratidae ellesmeroceras stem cephalopods tremadocian ordovician santa rosita formation cordillera oriental |
| title | Early Tremadocian cephalopods from Santa Rosita Formation in NW Argentina: the oldest record for South America |
| title_full | Early Tremadocian cephalopods from Santa Rosita Formation in NW Argentina: the oldest record for South America |
| title_fullStr | Early Tremadocian cephalopods from Santa Rosita Formation in NW Argentina: the oldest record for South America |
| title_full_unstemmed | Early Tremadocian cephalopods from Santa Rosita Formation in NW Argentina: the oldest record for South America |
| title_short | Early Tremadocian cephalopods from Santa Rosita Formation in NW Argentina: the oldest record for South America |
| title_sort | early tremadocian cephalopods from santa rosita formation in nw argentina the oldest record for south america |
| topic | cephalopoda ellesmeroceratidae ellesmeroceras stem cephalopods tremadocian ordovician santa rosita formation cordillera oriental |
| url | https://www.app.pan.pl/archive/published/app68/app011032023.pdf |
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