The axial biomechanics of Trigonosaurus pricei (Neosauropoda: Titanosauria) and the importance of the cervical–dorsal region to sauropod high-browser feeding strategy

Abstract

Trigonosaurus pricei is a small to medium-sized sauropod dinosaur (Sauropoda: Titanosauria) from the Late Cretaceous Bauru Group of Brazil that is known from a significant amount of recovered axial elements [four cervical vertebrae, 10 dorsal vertebrae, sacrum (MCT 1488-R), and 10 caudal vertebrae (MCT 1719-R)]. In this biomechanical work, we approach the hypothesis of the cartilaginous neutral pose and the range of motion of the axial series of Trigonosaurus. The results show that this sauropod could be capable of high elevation of the neck resulting from morphological adaptations of the cervicodorsal region on dorsal (D) vertebrae D2 and D3 (e.g. postzygapophyses of D2 positioned over the vertebral centrum and prezygapophyses of D3 over the anterior vertebral centrum). This implies that D2 articulates (cartilaginous neutral posture) with D3 only at a strong dorsally directed angle, resulting in a shift in the direction of the neck to a more elevated posture. Furthermore, the tail attributed to Trigonosaurus as a paratype could be oriented in the horizontal ‘direction’ and presented a sigmoidal ‘shape’. This work contributes generally to the understanding of variation in the body plan of sauropods and, more specifically, to the feeding strategy of small and medium-sized titanosaurs from semi-arid regions of Gondwana.