Terastiodontosaurus marcelosanchezi inhabited what is now Africa during the Eocene epoch, approximately 47 million years ago.
This newly identified species is part of the Trogonophidae family, a group of small, limbless, carnivorous, lizard-like reptiles within the Amphisbaenia clade.
“Amphisbaenians are a charismatic group of fossorial squamates, with bizarre morphological features and extreme anatomical modifications,” said lead author Dr. Georgios Georgalis from the Institute of Systematics and Evolution of Animals at the Polish Academy of Sciences and his colleagues.
“In particular, their unique skeletal anatomy has attracted and puzzled researchers since the 19th century.”
“Before the advent and broad acceptance of phylogenetic systematics, amphisbaenians were considered to be the third major group of Squamata, together with Serpentes and the paraphyletic ‘Lacertilia’.”
“Recent phylogenetic analyses, however, have placed them as the sister group of lacertid lizards, a topology that has been supported by both molecular and combined morphological and molecular evidence: a name, Lacertibaenia, was even proposed for the clade Amphisbaenia + Lacertidae.”
“Amphisbaenians have a relatively rich fossil record across the Cenozoic of Europe and North America, coupled with a few Neogene and Quaternary occurrences from South America, a few Palaeogene, Neogene, and Quaternary occurrences from Africa, a very few Neogene occurrences from the Arabian Peninsula, and a very few occurrences from the Neogene of southwestern Asia.”
“Trogonophidae are a rather distinctive group of amphisbaenians that are today distributed in northern and north-central Africa (including Socotra Island, Yemen) and the Middle East,” they added.
“Four living genera are currently recognized, i.e. Agamodon, Diplometopon, Pachycalamus, and the type genus, Trogonophis.”
The most distinctive feature of trogonophids is their acrodont dentition, a feature that, within squamates, is otherwise present solely in the iguanian group Acrodonta.”
“Trogonophids also possess other unique features among amphisbaenians, including locomotion and burrowing patterns, shoulder girdle or hemipenial morphology, chromosomes, vertebral arrangement, the absence of caudal autotomy, and a triangular body in cross-section.”
Multiple specimens of Terastiodontosaurus marcelosanchezi were discovered at a fossil-rich site in the Natural Park of Djebel Chambi in Tunisia.
“The Djebel Chambi National Park is situated in the Kasserine area, in the Central Western part of Tunisia,” the paleontologists said.
“The material of this study comes from a fossil-bearing site (Chambi locus 1), which consists of fluvio-lacustrine deposits situated at the base of the continental sequence of Chambi.”
“These localities have yielded a diverse assemblage of aquatic and terrestrial vertebrates, including fishes, amphibians, turtles, crocodiles, squamates, birds, and mammals, such as bats, primates, eulipotyphlans, hyaenodonts, hyracoids, an elephant shrew, a marsupial, a rodent, and a sirenian.”
Terastiodontosaurus marcelosanchezi reached over 90 cm (35 inches) in length, making it the largest amphisbaenian species known to have ever existed.
“Amongst extant amphisbaenians, Amphisbaena alba is the largest species, reaching a maximum total length of 81 cm (32 inches) and a skull length of over 3.1 cm (1.2 inches),” the researchers said.
Nearly all living amphisbaenians are burrowing animals, rarely seen above ground outside their subterranean habitats.
However, certain traits of Terastiodontosaurus marcelosanchezi appear to challenge this typical behavior, indicating that the species was likely a surface dweller.
This hypothesis is further reinforced by the species’ large size, which would make burrowing behaviors less plausible.
“Terastiodontosaurus marcelosanchezi represents a substantial contribution to the so far poorly known African fossil record of Amphisbaenia, representing only the fifth named extinct species from the continent,” the scientists concluded.
“Moreover, the new material from Chambi adds further to the extremely poor fossil record of Trogonophidae.”
The new species was described in an article published in the Zoological Journal of the Linnean Society.
