Tortoises and turtles from Huayquerías del Este (late Miocene–early Pliocene), Mendoza, Argentina

Abstract

We report new occurrences of Testudinidae and Chelidae from 11 different fossil sites in the Huayquerías and Tunuyán formations (late Miocene–Pliocene) in the Huayquerías del Este, Mendoza, Argentina. A total of 36 specimens were collected, representing at least three taxa from two different clades: 80.6% Testudinidae and 19.4% Chelidae. Testudinids are present throughout the stratigraphic succession, in alluvial, fluvial, and interdune sedimentary environments, represented by dorsal and plastron carapace plates, with some remains of the appendicular skeleton. A complete articulated plastron with some peripheral plates of the carapace was also recognized and is assigned to the extant species Chelonoidis chilensis, representing the oldest record for this taxon (late Miocene, Messinian). Another possible morphotype was recognized in the form of a large scapular girdle and femur that likely corresponded to an individual with a dorsal carapace of about 80 cm. This assemblage of small and large tortoise species is recognized for first time in the Messinian Age/Stage of Mendoza. Chelids are mostly restricted to fluvial deposits in the upper part of the Huayquerías Formation, except for two specimens which appear in the lower part. One specimen is represented by a right half plastron of an indeterminate Chelidae species which could correspond to a carapace of up to 24 cm in length with plastral lobes narrower than those observed in Phrynops species. Another specimen is characterized by a large costovertebral tunnel in the carapace, peripheral plates of the posterior margin of the carapace with ornamentation of fine grooves forming irregular polygons.

Redefining the Huayquerian Stage (Upper Miocene to Lower Pliocene) of the South American chronostratigraphic scale based on biostratigraphical analyses and geochronological dating

“…chilensis ; de la Fuente et al . 2022) also appears in both Huayquerías Fm. sections but not in the Tunuyán Fm.…”

“…6 m below the tuff level containing T10 (de la Fuente et al . 2022). Estimation based on the sedimentation rate at Los Pajaritos profile suggests an age for this specimen of c .…”

“…1 (de la Fuente et al . 2022) occur throughout the entire sequence from HLo to TUp. The armadillo Macroeuphractus and the rodent Caviinae gen. et sp.…”

“…2019; Gómez & Turazzini 2021; Vera & Romano 2021; de la Fuente et al . 2022; Cerdeño et al . 2023a; Turazzini & Gómez 2023).…”

A new old Budgett frog: an articulated skeleton of an Early Pliocene Lepidobatrachus (Anura, Ceratophryidae) from western Argentina

“…The first vertebrate fossils recovered at the Huayquerías (Mendoza Province) were collected by de Carles (1911) and described by Rovereto (1914), comprising ∼100 specimens. Scarce fossil findings were made in subsequent years at the Huayquerías del Este (Castellanos, 1957; Dessanti, 1946; Linares, 1981; Yrigoyen, 1993, 1994) and Huayquerías de San Carlos (Baulíes & Olazábal, 1950; Kraglievich & de Olazábal, 1959; Vera & Byrd, 2022), until ongoing systematic prospection fieldworks started in 2013 that have yielded more than 1000 new vertebrate specimens, most of which are still under study (Chiesa et al, 2019; de la Fuente et al, 2022; Forasiepi et al, 2015; Prevosti et al, 2019; Vera & Ercoli, 2018; Vera & Romano, 2022). Among the numerous fossils found in recent years, two represent ceratophryid frogs: a single isolated maxilla (IANIGLA-PV 104; Fig.…”