The lower Eocene (Ypresian) Cambay Formation at Vastan Lignite Mine in Gujarat, western India, has yielded a rich vertebrate assemblage including the earliest modern mammals and oldest birds of the Indian subcontinent. Among the herpetological faunas, snakes, lizards and amphibians are abundant, but, strangely, lizards are only represented by agamids. Here we describe the agamid assemblage based on numerous, diverse and well-preserved dentaries, premaxillaries, and maxillaries. At least four taxa are present at Vastan. Vastanagama susanae is characterized by dentaries with a large symphyseal facet, three anterior pleurodont teeth followed by acrodont teeth presenting a main cusp bordered by two lateral crests; the teeth increase in size posteriorly toward the coronoid process. Tinosaurus indicus exhibits a subdental ridge between the tooth row and the Meckelian canal, pleurodont symphyseal teeth including one that can be caniniform, and acrodont and tricuspid posterior teeth with poorly differentiated lateral cusps. Two other taxa represent two new genera and species. The first taxon presents multicuspid acrodont teeth with the main cusp surrounded by two or three progressively smaller lateral cusps. The second taxon presents pleurodont anterior teeth followed by a few acrodont teeth and ending with three or four subacrodont teeth near the coronoid process. Our results confirm that Agamidae (assigned to the Acrodonta) is the only lizard group present at Vastan, whereas many other groups are already present in the Early Eocene on the other continents. Agamidae is considered to have had a Gondwanan origin, with 52 genera and 420 species of extant agamids known from Asia, Australia, Africa and a few from Southern Europe. The oldest occurrence of formally recognized Acrodonta is found in the Jurassic of India. Other fossil agamids are known in the Upper Paleocene of Kazakhstan, Paleocene and Eocene of China, Early Eocene of Europe, Eocene of North America, and Middle Eocene of Pakistan. The diversity of the agamids in India and the absence of other lizard groups at Vastan tentatively support the Out-of-India hypothesis for agamids.
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RBINS Staff Publications
In the scope of the Belgo-Romanian excavation campaigns in Transylvania, the Royal Belgian Institute of Natural Sciences and the University Babeş-Bolyai excavated three Late Cretaceous vertebrate localities in the Haţeg Basin. Compared to other European localities, the studied sites show rich mammal remains, which are dominated by multituberculates. At three localities, more than five tons of fossiliferous sediments were screen washed (mesh width 0.5 mm) and yielded forty-three dental specimens. This material essentially provides new information on the enigmatic European family Kogaionidae. A new small species of the genus Kogaionon is recognized on the basis of four dental positions from the fluviatil deposits of Pui (excavation 2000). In the floodplain deposits of the new site Toteşti-baraj (excavation 2001) sixteen teeth representing seven different dental positions of two kogaionid genera were found (Codrea et al., 2002). One lower first molar is similar to that of Barbatodon transylvanicus Rădulescu & Samson, 1986. A nearly complete upper dental series of a new species of Kogaionon is particularly well preserved. In the floodplain deposits of the new site Nălaţ-Vad (excavation 2002), one of the exceptional fossiliferous marl pockets yielded twelve teeth and three dentary fragments of the genera Kogaionon and Barbatodon (Smith et al., 2002). A new small species of Barbatodon is represented by a dentary with a very long rounded fourth premolar, a small first molar, but with the third premolar absent. On the other hand, Kogaionon presents a lower fourth premolar with a typical triangle shape differing clearly from Barbatodon. The results reveal for the first time the morphology of all the upper and lower dental positions characteristic of the family Kogaionidae, which allows more precise discussion of the phylogenetic position of this family among the multituberculates. Comparisons with other kogaionid multituberculates from the Paleocene of Spain, Belgium, Romania and France permit analysis of the possible migration ways following the paleogeography of Europe during the end of the Cretaceous.
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RBINS Staff Publications 2016
