Oryctos
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Accès privé :
| volume 1, 1998 |
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Zoltan Csiki & Dan Grigorescu, Small Theropods from the Late Cretaceous of the Hateg Basin (Western Romania) - an unexpected diversity at the top of the food chain. Oryctos 1, 87-104.
The Late Maastrichtian deposits of the Hateg Basin have yielded numerous remains of herbivorous dinosaurs (titanosaurids, ornithopods, nodosaurids); but those of theropods are scarce, represented mostly by teeth and hindlimb elements. New material allows the recognition of an unexpected diversity of these predators in the Hateg fauna. Teeth of various morphologies are reported here to represent several distinct taxa of small theropods: a velociraptorine dromaeosaurid, a "troodontid-like" small theropod, cf. Euronychodon and perhaps a fourth, peculiar small theropod with sharp, but unserrated carinae on the teeth. Re-examination of previously published theropod material also suggests such diversity. Femora, previously referred to Elopteryx, probably belong to a derived maniraptoran. A distal end of a femur seems to document a small ceratosaur, while some tibiotarsi (holotypes of Bradycneme and Heptasteornis) may represent a non-maniraptoran tetanuran theropod. Without diagnostic remains of small theropods, it is inappropriate to give the reported material generic names; consequently informal use of the published names 'Elopteryx' and 'Bradycneme' is recommended. Moreover, for most part of the isolated theropod remains from Hateg there are no reasons to group them under the same name; one such case may be represented, however, by some skull elements and the velociraptorine teeth. The diversity of the small theropods in the Hateg fauna, together with the absence of a large "top" theropod, represents the first such case reported for Late Cretaceous faunas. This phenomenon is probably linked to the restricted, insular habitat of the Hateg fauna, which could not accommodate and support any larger sized predator.
Keywords : Hateg Basin, Late Maastrichtian, ceratosaurs, maniraptorans, dromaeosaurids, Euronychodon, diversity, insular habitat.
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