PHRYNOPS (TESTUDINES, CHELIDAE) IN THE LATE MIOCENE OF PALO PINTADO FORMATION, NORTHWESTERN ARGENTINA

LUNA, CARLOS A.; LANDA RAMIREZ, ENZO M.; ZURITA, ALFREDO E.; GALLI, CLAUDIA I.

Simposio; VII Simposio del Mioceno-Pleistoceno del Centro y Norte de Argentina; 2023

UNLar

The Palo Pintado Formation (ca. 10–5 Ma; Late Miocene) shows a wide diversity of fossilvertebrates including mainly mammals, turtles, and caimans. Although turtles are quitefrequent in the fossil record of the formation, they have not been described in detail. Theonly previous record reported for this unit corresponds to an undetermined Chelidae fromthe Quebrada de Piscuyacu, near of Angastaco, Salta Province. In the present contributionwe report from a cuspidal level of Palo Pintado Formation a part of the posterior regionof the carapace (with five neurals, seven costals, suprapigal and pigal) and plastron (hio,hipo and xifoplastrón) of a turtle [CNS-V-038], which may have reached up to 32 cm inlength, and whose characteristics allow us to refer it to the genus Phrynops Wagler, 1830.When compared to different genera of Chelidae recorded for the Neogene of SouthAmerica (Acanthochelys, Mesoclemmys, Phrynops, and Hydromedusa), the carapacediffers from Acanthochelys and Mesoclemmys in the presence of a continuos series ofneural plates, from Hydromedusa in lacking upturned lateral margins, and presents, as insome extant and extinct species of Phrynops, peripheral plates of the posterior marginwith ornamentation with fine grooves forming irregular polygons. This genus has beenpreviously recorded from the Late Miocene of Catamarca, Tucumán and Entre Ríosprovinces in Argentina, and Uruguay. Phrynops currently inhabits freshwater lowlandsin tropical to humid temperate climates. In consequence, the presence of this genus in thestudied levels is consistent with environmental conditions previously interpreted for thisunit.-Project subsidized by PIP-2022-11220210100300CO and CIUNSA 2722/0.