An isolated tooth found in an outcrop of the Gorno Formation (Carnian, Late Triassic) in the locality of Zambla Alta (Bergamo, Lombardy, Italy) is described. The ziphodont morphology and the characters of the serrations allow to consider it as belonging to an archosaur, possibly a rauisuchian.
Material: Specimen MCSNB 6167 of the collection of the Museo Civico di Scienze Naturali "E. Caffi" Bergamo, consisting in an isolated crown of a ziphodont tooth.
Horizon age and locality
Uppermost level of the Gorno Formation, Middle Carnian (Late Triassic), Zambla Alta (Bergamo, Lombardy, Northern Italy)
The following measurements have been taken: maximum height of the crown 15mm; anteroposterior width at the crown base 9 mm
The overall morphology of the crown permits its recognition as a ziphodont tooth , adapted for slicing and cutting flesh. Ziphodont teeth are typical of the lateral tooth row of carnivorous archosaurs. During the Carnian, Three main groups of archosaurs had a ziphodont dentition, eterodont phytosaurs, rauisuchians and basal theropods. A comparison among the morphologies of the teeth of these three groups allows to exclude the belonging of MCSNB 6167 to phytosaurs with some confidence, due to the labiolingually flattened crown and its sub-ellipitical cross section. It is perhaps more difficult to distinguish between rauisuchian and theropods, but the tooth morphology, however, is different from the one of the teeth of the basal theropod Eoraptor which is Middle Carnian in age, and SD is much lower than in later coelophysids. Taking also into account that theropods were a minor element in the Carnian faunas, while rauisuchians were abundant and diversified , it may be more probable that specimen MCSNB 6167 belonged to a rauisuchian.
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