THE TETRAPOD ASSEMBLAGE FOR THE EARLIEST CRETACEOUS OF THE NEUQUINA BASIN

GALLINA, PABLO; CANALE, JUAN; APESTEGUÍA, SEBASTIÁN; CARBALLIDO, JOSÉ LUIS; GARDERES, JUAN MANUEL; RIGUETTI, FACUNDO

Mendoza

Jornada; 34 Jornadas Argentinas de Paleontología de Vertebrados; 2021

Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales, Museo de Historia Natural de San Rafael y Museo de Ciencias Naturales y Antropológicas ?Juan Cornelio Moyano?

In 2004, H. Leanza and colleagues identified six tetrapod assemblages for the Cretaceousof the Neuquina Basin, being the earliest the Amargan assemblage (Barremian?EarlyAptian), considered as representing late Pangean fauna. At that time, no fossil vertebrateswere yet found from the earlier Bajada Colorada and Mulichinco formations. Along thelast decade both units have been enriching our knowledge on the earliest Cretaceousdinosaurian fauna. Then we consider it is time to propose a new tetrapod assemblage, theBajadan assemblage, mainly represented by the combination of both formations. Thisassemblage groups tetrapods recovered from units deposited by Berriasian?EarlyHauterivian times, as part of the Lower and Middle Mendoza Group, underneath theCoihuequical unconformity. So far, its content is understood as characterized by the cooccurrence of globally distributed clades of dinosaurs as originated previous to thePangean spread in Laurasia and Gondwana by Late Jurassic times (i.e. neosauropods,basal neotetanurans and neoceratosaurian theropods, eurypodan and basal iguanodontianornithischians), devoid of suprageneric Gondwanan endemisms. The Bajadan assemblagethus includes flagellicaudatan (Diplodocidae, Dicraeosauridae) and basal titanosauriansauropods; abelisauroid ceratosaurian, megalosauroid, and carcharodontosaurid tetanurantheropods; and thyreophoran (either a eurypodan form or a new lineage), as well as basaliguanodontian ornithischians. Although still solely represented by dinosauriancomponents, the potential of preservation of the Bajada Colorada Formation with wellpreserved remains of two meters long theropods allows the possibility of finding othersmall tetrapod components in the future. The Bajadan fauna shows strong similaritieswith the Late Jurassic-earliest Cretaceous African fauna