Tooth morphotypes from the Cañadón Asfalto Formation (Middle Jurassic) of Patagonia

HOLWERDA, F.; POL, D.; GROCKE, D.; RAUHUT, O.W.

Las Vegas

Congreso; 70th Meeting of the Society of Vertebrate Paleontology; 2011

Society of Vertebrate Paleontology

The sauropod fossil record of the Cañadón Asfalto Formation (Middle Jurassic) of Patagonia includes two described taxa (Patagosaurus and Volkheimeria) and two undescribed taxa. Both named taxa plus one of the undescribed species occur at the locality of Cerro Cóndor Sur. The taxa are mainly known from postcranial materials. For this study, cranial material and isolated teeth recovered at Cerro Cóndor Sur and isolated teeth recovered at the nearby Las Chacritas locality were used. The teeth are here described in terms of size, shape, and enamel wrinkling, presence and orientation of wear facets and microwear. The aim of this study is to present an analysis of teeth morphotypes to assess the sauropod dental diversity at these sites.The analysis reveals the presence of three different teeth morphotypes in the sample taken from the Cerro Cóndor Sur locality, which are characterized by a unique combination of characters related to the pattern of enamel wrinkling and crown shape measurements. The presence of three dental morphotypes at Cerro Cóndor Sur matches the known sauropod diversity of this site based on postcranial evidence.The cranial material studied included fragmentary cranial and mandibular remains that have been assigned to Patagosaurus in previous studies. The teeth present in the maxilla originally referred to Patagosaurus are markedly different to those present in the mandibular remains referred to the same taxon, and represent different morphotypes, and thus probably different taxa. The latter interpretation is supported by the association of the maxilla with postcranial remains that also differ from the postcranium of Patagosaurus.Finally, statistical microwear analysis on the only tooth that has a mesial and a distal wear facet revealed different directions of the striae located on the mesial and distal facet. There are no further statistically significant differences in microwear between the wearfacets of different teeth. The low variance between them may suggest the absence of clear niche dif- ferentiation for the Middle Jurassic sauropods known from the Cañadón Asfalto Formation.