Shape variation in presacral vertebrae of saltasaurine titanosaurs (Dinosauria, Sauropoda)

ZURRIAGUZ VIRGINIA; ALVAREZ ALICIA

Historical Biology

Taylor & Francis

Año: 2013 vol. 26 p. 801 - 809

0891-2963

Titanosaurs were small to giant-sized sauropods, highly derived and highly-pneumatic. Using morphometric analyses, we studied differences in shape of the presacral vertebral centra in some of these sauropods, especially in saltasaurines, and compared asymmetry patterns in lateral pneumatic foramina between these titanosaurs and avian and non-avian theropods. Geometric morphometric analyses showed that the cervical centra tend to be elongated and dorsoventrally short, with an elliptical lateral pneumatic foramen located in the middle of the centrum; dorsal centra tend to be short and higher than the cervical centra, with the lateral pneumatic foramen slightly displaced to the anterior region. Shape variation can be described as a result of the ordering of the vertebrae within both the cervical and dorsal sequences, and therefore these methods can be applied to predict the position of isolated vertebrae. A persistent pattern of asymmetry among lateral pneumatic foramina was observed when length/height indexes were plotted. The right lateral pneumatic foramina usually are larger than the left ones in cervical vertebrae (except in Saltasaurus loricatus) but variable in dorsal vertebrae. We propose an explanation of this asymmetry based on the asymmetric arrangement of viscera and late development of the respiratory (and air sacs) system.