Thursday, February 13, 2020

[Paleontology • 2020] Stupendemys geographicus • The Anatomy, Paleobiology, and Evolutionary Relationships of the Largest Extinct Side-necked Turtle

Stupendemys geographicus Wood, 1976

in Cadena, Scheyer, Carrillo-Briceño, et al., 2020. 
 Art: Jaime Chirinos

Despite being among the largest turtles that ever lived, the biology and systematics of Stupendemys geographicus remain largely unknown because of scant, fragmentary finds. We describe exceptional specimens and new localities of S. geographicus from the Miocene of Venezuela and Colombia. We document the largest shell reported for any extant or extinct turtle, with a carapace length of 2.40 m and estimated mass of 1,145 kg, almost 100 times the size of its closest living relative, the Amazon river turtle Peltocephalus dumerilianus, and twice that of the largest extant turtle, the marine leatherback Dermochelys coriacea. The new specimens greatly increase knowledge of the biology and evolution of this iconic species. Our findings suggest the existence of a single giant turtle species across the northern Neotropics, but with two shell morphotypes, suggestive of sexual dimorphism. Bite marks and punctured bones indicate interactions with large caimans that also inhabited the northern Neotropics.

Systematic paleontology
Testudines Batsch, 1788.
Pleurodira Cope, 1864 sensu Joyce et al., 2004.

Podocnemididae Cope, 1868.
Eymnochelyinae sensu Ferreira et al., 2018.

Stupendemys geographicus Wood, 1976.

Synonymy: Caninemys tridentata (Meylan et al., 2009)
Stupendemys souzai (Lapparent de Broin et al., 1993; Bocquentin et al., 2006)
Stupendemys sp. (Gaffney et al., 1998)
Podocnemididae indet. (Gaffney et al., 1998)

Reconstruction of Stupendemys geographicus male (front) and female (middle-left),
 together with the giant caimanine 
Purussaurus mirandai and the large catfish Phractocephalus nassi
Art: Jaime Chirinos

E.-A. Cadena, T. M. Scheyer, J. D. Carrillo-Briceño, R. Sánchez, O. A Aguilera-Socorro, A. Vanegas5, M. Pardo, D. M. Hansen and M. R. Sánchez-Villagra. 2020. The Anatomy, Paleobiology, and Evolutionary Relationships of the Largest Extinct Side-necked Turtle. Science Advances. 6(7); eaay4593. DOI: 10.1126/sciadv.aay4593

Extinct giant turtle had horned shell of up to three meters via @physorg_com
Fossils shed new light on car-sized turtle that once roamed South America