Contribución a La Diversidad Del Registro Fósil De Tortugas (Testudinata) De La Provincia De Chubut (Argentina) Y Su Significado en La Comprensión De La Evolución De Las Tortugas en El Sur De Sudamérica

Abstract

In this work we focus on the fossil record of turtles and tortoises from the Chubut Province, in Patagonia, Argentina. This record is the richest, most diverse, the longest and continuous in the country and one of the most important in the continent. In this work, we present and study new fossils from all known clades of turtles from the province, coming from targeted field campaigns, as well as from past investigations, placed in a comprehensive and detailed chronostratigraphic context. In Chubut, more than 241 occurrences of turtles from at least 223 collection points are known, spanning from the Toarcian (Jurassic) to the Tortonian (Miocene). we manage to fill some of the gaps in the fossil record, complete the anatomical knowledge of many taxa, explore new geographical areas, and present some important highlights. Among these, the record of the oldest pan-chelid turtles indicates the significant potential of the sedimentary deposits of Chubut. Furthermore, we discuss the changes in the diversity and faunal turnovers of the various turtle clades in this region during the last 180 Ma and across important events during the Cretaceous/Paleocene and Oligocene/Miocene boundaries.

A new large‐sized species ofChelonoidis(Testudinidae) without gibbosities from the middle Miocene of Aguada Escondida (NWChubut, Patagonia, Argentina)

“…; de la Fuente et al (2018): Chelonoidis sp. Type material: MLP‐46‐VIII‐21‐9, parts of the carapace and plastron and some isolated elements of a single tortoise individual. Type locality: Northeast of the Almacén de Don Justino Ojea (or Ojeda in some tags), Aguada La Escondida (or Aguada Escondida in some tags), Chubut, Argentina (Figure 1). Type horizon: Collón Curá Formation, Middle Miocene, Langhian–Serravalian, 14.6–11.6 ± 0.4 Ma (see Sterli, Vlachos, Krause, Puerta, & Oriozabala, 2021 and references therein for details on stratigraphy). The precise point of collection is not known. Etymology: The specific epithet comes from the Latin adjective merīdiānus‐a‐um, which means midday, noon or southern, as the new species is both the southernmost occurrence of a large‐sized Chelonoidis or testudinid in general, and because it has been discovered during the works of the Commission of the Measurement of a Meridian Arc (Comisión para la Medición de un Arco de Meridiano; see Introduction above). Diagnosis: A large‐sized testudinid, without cervical scute on nuchal bone and with a large entoplastron as in Chelonoidis , that exceeded 80 cm in carapacial length, which differs from all other extinct large‐sized species of this clade ( Ch.…”

“…meridiana sp. nov. in the Middle Miocene increases the raw turtle diversity in Chubut, permitting to reduce the gap between the raw and phylogenetic diversity recovered in Sterli et al (2021) for that period of time. Following their previous arrival in the continent, the diversity and range of testudinids during the Middle Miocene has been increasing in both Argentina and South America (Vlachos, Randolfe, Sterli, & Leardi, 2018).…”

“…Up to now, the only tortoise known from the Miocene deposits of the region was the small‐sized Ch. gringorum , known from the Early Miocene of Bryn Gwyn area in the lower Chubut River Valley (see de la Fuente, 1994; de la Fuente et al, 2018; Sterli et al, 2021; Vlachos & Sterli, in press), and the Middle Miocene of the Rio Chico area (Oriozabala, Sterli, & González Ruiz, 2018; Sterli et al, 2021). Specimens corresponding to Ch.…”

New findings on the evolution of turtles: A symposium in honor of Marcelo S. de la Fuente

“…The Chubutian record of extinct turtles is the most abundant, diverse, longest, and continuous in Argentina, and one of the most important in South America (Sterli et al, 2021). The Chubutian record accounts for 40% of the Argentinean turtle record.…”

A new chelid turtle, Prochelidella palomoi sp. nov., from campanian Anacleto Formation, Neuquén Basin, North‐Western Patagonia, Argentina

“…Prochelidella sp. from the Aptian–Cenomanian of Neuquén, Santa Cruz, Río Negro and Chubut provinces, and from the Campanian of Mendoza and Río Negro provinces (de Broin & de la Fuente, 1993; Maniel & de la Fuente, 2016 and references therein; Sterli et al, 2021) (Figure 1).…”