Acerosodontosaurus

Acerosodontosaurus
Temporal range: Late Permian, 260–252 Ma
Skull diagram
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Family: †Tangasauridae
Genus: †Acerosodontosaurus
Currie 1980
Type species
†Acerosodontosaurus piveteaui

Acerosodontosaurus is an extinct genus of neodiapsid reptiles that lived during the Late Permian of Madagascar.[1][2] The only species of Acerosodontosaurus, A. piveteaui, is known from a natural mold of a single partial skeleton including a crushed skull and part of the body and limbs. The fossil was discovered in deposits of the Lower Sakamena Formation. Based on skeletal characteristics, it has been suggested that Acerosodontosaurus individuals were at least partially aquatic.[2]

Acerosodontosaurus has generally been considered a "younginiform", part of a paraphyletic grade of Permian diapsids which linked the most basal ("primitive") diapsids (araeoscelidians such as Petrolacosaurus) to more derived ("advanced") diapsids, including the earliest ancestors of modern reptiles such as crocodilians and lizards (Sauria).[2] However, its position within the grade is controversial. Initially considered a specimen of the contemporaneous Tangasaurus, Acerosodontosaurus was later described as a younginid in 1980[1] and a tangasaurid in 2009.[2] More recent studies have even supported the hypothesis that it was not a "younginiform" at all, but rather that it was an early member of Pantestudines, the reptile lineage that would lead to modern turtles.[3][4] However, this theory is still controversial,[5] and other studies have continued to support the "younginiform" interpretation.[6]

  1. ^ a b Currie, Philip J. (1980). "A new younginid (Reptilia: Eosuchia) from the Upper Permian of Madagascar" (PDF). Canadian Journal of Earth Sciences. 17 (4): 500–511. Bibcode:1980CaJES..17..500C. doi:10.1139/e80-046. Archived from the original (PDF) on 2023-04-21.
  2. ^ a b c d Bickelmann, Constanze; Müller, Johannes & Reisz, Robert R. (22 September 2009). "The enigmatic diapsid Acerosodontosaurus piveteaui (Reptilia: Neodiapsida) from the Upper Permian of Madagascar and the paraphyly of "younginiform" reptiles". Canadian Journal of Earth Sciences. 46 (9): 651–661. Bibcode:2009CaJES..46..651S. doi:10.1139/E09-038.
  3. ^ Cite error: The named reference :5 was invoked but never defined (see the help page).
  4. ^ Cite error: The named reference :4 was invoked but never defined (see the help page).
  5. ^ Nathan E. Van Vranken. "The Permian diapsid reptiles Acerosodontosaurus and Claudiosaurus are not stem-turtles: Morphological and fossil phylogenetic analyses must take a cautious, holistic approach toward turtle origins". 95th Annual Meeting Abstracts. doi:10.55632/pwvas.v92i1.626.
  6. ^ Simões, Tiago R.; Kammerer, Christian F.; Caldwell, Michael W.; Pierce, Stephanie E. (2022-08-19). "Successive climate crises in the deep past drove the early evolution and radiation of reptiles". Science Advances. 8 (33): eabq1898. Bibcode:2022SciA....8.1898S. doi:10.1126/sciadv.abq1898. ISSN 2375-2548. PMC 9390993. PMID 35984885.