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| Terastiodontosaurus marcelosanchezi Georgalis & Smith, in Georgalis, Smith, Marivaux, Herrel, Essid, Ammar, Marzougui, Temani et Tabuce, 2024. Artwork by Jaime Chirinos. |
Abstract
We here describe Terastiodontosaurus marcelosanchezi, a new amphisbaenian genus and species from the Eocene of Chambi, Tunisia. Using micro-computed tomography (μCT), we document the peculiar anatomy of the new taxon, which is characterized by extreme dental morphology, including one massive tooth on the maxilla and dentary, flat cheek teeth, and an array of other diagnostic features that readily differentiate it from all other amphisbaenians. We also redescribe the oldest named African amphisbaenian, Todrasaurus gheerbranti, from the late Palaeocene of Morocco, using μCT. Phylogenetic analysis recovers Terastiodontosaurus and Todrasaurus as sister taxa and provides strong support for a sister-group relationship of those two large-toothed amphisbaenians with extant Trogonophis. Accordingly, Todrasaurus shows that the divergence of crown Trogonophidae occurred much earlier than currently thought. Our survey of μCT scans reveals that Terastiodontosaurus, Todrasaurus, and Trogonophis are characterized by a great enamel thickness on their teeth, a feature that is absent in other examined amphisbaenians. Size estimates show that Terastiodontosaurus was the largest known amphisbaenian ever to have lived, with an estimated skull length of >5 cm. Based on new muscle data of Trogonophis, we estimate very high bite forces for Terastiodontosaurus, which would allow it to crush a wide variety of snails.
new genus and species, Palaeogene, North Africa, phylogenetic analysis, bite force, size, autecology
Systematic palaeontology
Squamata Oppel 1811,
Amphisbaenia Gray, 1844,
Trogonophidae Bonaparte, 1838
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| Figure 2.Holotype right maxilla (ONM CBI-1-645) of Terastiodontosaurus marcelosanchezi. Photographs of the specimen in labial (A), medial (B), dorsal (C), and ventral (D) views. |
Terastiodontosaurus Georgalis & Smith gen. nov.
Etymology: The genus name derives from the Greek words ‘τεράστιος’ (‘terastios’), meaning ‘huge’/‘enormous’, ‘ὀδούς’ [in genitive: ‘ὀδόντος’ (‘odontos’)], meaning ‘tooth’, and ‘σαύρα’ (‘saura’), meaning ‘lizard’. The gender of the new genus name is masculine.
Terastiodontosaurus marcelosanchezi Georgalis & Smith gen. et sp. nov.
Etymology: The species epithet is named after Professor Marcelo Sánchez-Villagra, director of the Palaeontological Institute of the University of Zurich, as an honour for his major contributions to palaeontology, zoology, and evolutionary biology, in addition to the kind friendship and his great support to the first author (G.L.G.) for many years.
Diagnosis:
Terastiodontosaurus marcelosanchezi can be referred to Amphisbaenia based on the prominent and enlarged median premaxillary tooth, the large anterior premaxillary foramina, the low tooth count on the maxilla and dentary, the ventral extension of the mandibular symphysis below Meckel’s groove, the broad insertion fossa for mandibular adductor muscles on the posterolateral surface of the dentary, and the strong and elevated coronoid process of the dentary. Terastiodontosaurus marcelosanchezi can be referred to Trogonophidae based on the presence of acrodont dentition, closely appressed (‘fused’) teeth, the interdigitating suture between the frontal and the facial process of the maxilla, and ectopterygoid abutting the posteromedial corner of the maxilla.
Terastiodontosaurus marcelosanchezi is united with Trogonophis wiegmanni by: thick enamel on marginal teeth, and ‘twinning’ of paired premaxillary teeth, with median tooth separated by a diastema from paired teeth. Terastiodontosaurus marcelosanchezi is united with Todrasaurus gheerbranti by: thick enamel on marginal teeth, extremely enlarged (>60% longer than ...
Type locality and horizon: Chambi 1 (CBI-1), Djebel Chambi, Kassérine region, western part of Central Tunisia, Tunisia; late early to early middle Eocene (late Ypresian to early Lutetian).
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| Life reconstruction of Terastiodontosaurus marcelosanchezi ready to prey on a large snail of the family Bulimulidae. Artwork by Jaime Chirinos. |
Georgios L Georgalis, Krister T Smith, Laurent Marivaux, Anthony Herrel, El Mabrouk Essid, Hayet Khayati Ammar, Wissem Marzougui, Rim Temani and Rodolphe Tabuce. 2024. The World’s Largest Worm Lizard: A New giant trogonophid (Squamata: Amphisbaenia) with extreme Dental Adaptations from the Eocene of Chambi, Tunisia. Zoological Journal of the Linnean Society. 202(3), zlae133. DOI: doi.org/10.1093/zoolinnean/zlae133
