Saniwa is an extinct genus of varanid lizard from the Eocene of North America and Europe. It is the sister taxon to the crown-group Varanus. Up to now, only one poorly known species is recognized from Europe, Saniwa orsmaelensis from the earliest Eocene of Dormaal, Belgium. This species originally named by Louis Dollo nearly a century ago, is the earliest varanid of Europe. Unfortunately, the material was limited to vertebrae with only preliminary description and no figure provided, except for one dorsal vertebra that later has been designated as the lectotype. Here we describe and illustrate new fossil specimens collected from Dormaal and other early Eocene localities of the Paris Basin, France, including dentary and maxilla fragments as well as skull material, allowing to reassess the validity of the European taxon. These fossils allow further comparisons with the type-species, Saniwa ensidens, from the late early Eocene Bridger and Green River formations of Wyoming and to propose a new diagnosis for S. orsmaelensis. The occurrence of S. orsmaelensis is restricted to the early Eocene of Northwest Europe and its geographic origin is unresolved because the earliest record of Saniwa in North America is also from the earliest Eocene. The brief presence of varanid lizards in the European Paleogene could result from two major climatic events. At the Paleocene Eocene Thermal Maximum, large biotic interchanges occurred in the northern hemisphere allowing new dispersals into Europe. However, at the end of the Eocene, thermophilic lizards disappeared due to cooler conditions. Another hypothesis for their disappearance could be the competition that occurred with other anguimorph lizards. Grant Information: This abstract is a contribution to the Belspo Brain network project BR/121/A3/PalEurAfrica funded by the Belgian Science Policy Office.
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Excavations since 2004 in the early Eocene Cambay Shale Formation at Vastan, Mangrol, and Tadkeshwar open-cast lignite mines in Gujarat, western India, have yielded thousands of vertebrate specimens of terrestrial mammals, lizards, snakes, frogs, and birds as well as elasmobranch and teleost fishes. Here we report new fossils from the currently active Tadkeshwar mine discovered from several layers intercalated at different heights between the two major lignite seams. Most of them belong to taxa already described from the nearby Vastan and Mangrol mines, such as the adapoid primate Marcgodinotius indicus, the hyaenodontan Indohyaenodon raoi, the tillodont Anthraconyx hypsomylus, the perissodactyl-like mammal Cambaytherium thewissi, the agamid lizard Tinosaurus indicus, the palaeophiid snake Palaeophis vastaniensis, the caenophidian snakes Procerophis and Thaumastophis, and the bird Vastanavis. The presence of these taxa in the three mines and at different levels suggests that the deposits between the two major lignite seams represent a relatively short time span and a single mammal age. Among the new specimens from Tadkeshwar are well-preserved jaws of a new condylarth-like mammal, a new adapoid primate, and a small tapiroid perissodactyl. Most vertebrate taxa of the Cambay Shale Formation are of west European affinities; some of them seem to be endemic to India, and a few are of Gondwanan affinities, such as mesoeucrocodylians and the giant madtsoiid snake Platyspondylophis, attesting that the early Eocene was an important period in India during which Laurasian taxa coexisted with relict taxa from Gondwana before the India-Asia collision. Grant Information: Funded by Leakey Foundation, National Geographic Society, Wadia Institute of Himalayan Geology, and Belgian Science Policy Office (project BR/121/A3/PalEurAfrica)
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