Saturday, December 4, 2021

[Paleontology • 2021] Taytalura alcoberi • A Triassic Stem Lepidosaur (Reptilia: Lepidosauromorpha) illuminates the Origin of Lizard-like Reptiles

 Taytalura alcoberi 
Martínez, Simões, Sobral & Apesteguía, 2021

The early evolution of diapsid reptiles is marked by a deep contrast between our knowledge of the origin and early evolution of archosauromorphs (crocodiles, avian and non-avian dinosaurs) to that of lepidosauromorphs (squamates (lizards, snakes) and sphenodontians (tuataras)). Whereas the former include hundreds of fossil species across various lineages during the Triassic period1, the latter are represented by an extremely patchy early fossil record comprising only a handful of fragmentary fossils, most of which have uncertain phylogenetic affinities and are confined to Europe. Here we report the discovery of a three-dimensionally preserved reptile skull, assigned as Taytalura alcoberi gen. et sp. nov., from the Late Triassic epoch of Argentina that is robustly inferred phylogenetically as the earliest evolving lepidosauromorph, using various data types and optimality criteria. Micro-computed tomography scans of this skull reveal details about the origin of the lepidosaurian skull from early diapsids, suggesting that several traits traditionally associated with sphenodontians in fact originated much earlier in lepidosauromorph evolution. Taytalura suggests that the strongly evolutionarily conserved skull architecture of sphenodontians represents the plesiomorphic condition for all lepidosaurs, that stem and crown lepidosaurs were contemporaries for at least ten million years during the Triassic, and that early lepidosauromorphs had a much broader geographical distribution than has previously been thought.

Lepidosauromorpha Benton, 1985 (sensu Gauthier et al., 1988)

Taytalura alcoberi gen. et sp. nov.

Etymology. Tayta, father (Quechua language, spoken by the Quechua peoples of the Andes in South America); lura, lizard (Kakán language, spoken by the Sherkai (or Diaguita) Nation of Northwestern Argentina). The species epithet refers to O. Alcober, for his sustained contribution to Late Triassic palaeontology.

Holotype. PVSJ 698, accessioned at Museo de Ciencias Naturales, Universidad Nacional de San Juan (PVSJ).


Ricardo N. Martínez, Tiago R. Simões, Gabriela Sobral and Sebastián Apesteguía. 2021. A Triassic Stem Lepidosaur illuminates the Origin of Lizard-like Reptiles. Nature. DOI: 10.1038/s41586-021-03834-3

Researchers describe a new fossil species representing the ancient forerunner of most modern reptiles