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| Alamitosphenos mineri Agnolín, Rolando, Chimento & Novas, 2024 |
Abstract
Sphenodontids are a group of reptiles that were diverse and global for much of the Mesozoic but today they are only represented by the New Zealand tuatara. Here we describe new sphenodontid remains coming from the Cretaceous (Maastrichtian) Los Alamitos Formation, at Río Negro province, Argentina. Previous reports in the stratigraphical unit included an indeterminate sphenodontid and the enigmatic Kawasphenodon. The new material here reported includes an isolated and incomplete dentary and a palatine bone. The dentary belongs to a small taxon having quadrangular teeth and an interlocked mandibular symphysis. The palatine shows compressed teeth and a fang-like canine. These specimens probably belong to two new taxa. These, together with Kawasphenodon, suggest that Maastrichtian sphenodontians from northern Patagonia were at least as diverse as those reported from Cenomanian beds. This contrasts with the poorer record of lizards in the same beds. However, the record of Maastrichtian sphenodonts in southern Patagonia is restricted to a single finding of a Sphenodontine sphenodontid. In Australasia the sphenodont record is also restricted to Cenozoic sphenodontines, very similar to extant Sphenodon species. The currently available fossil record suggests that northern Patagonian rhynchocephalians were more morphologically diverse than those of southern Patagonia and Australasia during the Cretaceous, probably reflecting another faunistic particularity of the 'Weddelian Bioprovince'.
Lepidosauria Dumeril and Bibron, 1839.
Sphenodontidae Günther, 1867.
Opisthodontia sensu Apesteguía and Novas, 2003.
Alamitosphenos mineri nov. gen. et nov. sp.
Holotype. MPMIK 1759/p/23, incomplete left dentary with three pre-served hatchling teeth (Fig. 2). The specimen was found by Mr Santiago Miner.
Etymology. The name Alamitosphenos comes from the old name of the farm ('Los Alamitos') that yielded the materials here described, and 'Sphenos' means 'wedged' but also refers to the tuatara (Sphenodon punctatus) and all its kin. The specific epithet mineri honours Santiago Miner, a technician and the member of the crew that found the holotype specimen.
Federico L. Agnolín, A. Mauro Aranciaga Rolando, Nicolás R. Chimento and Fernando E. Novas. 2024. New Small Reptile remains from the Late Cretaceous of Patagonia increase Morphological Diversity of sphenodontids (Lepidosauria). Proceedings of the Geologists' Association. 135(1); 36-44. DOI: doi.org/10.1016/j.pgeola.2023.09.007
Descubren fósiles de dos lagartos que habitaron la Patagonia hace 70 millones de años
