Biomechanics of the vertebral column and implications for the lifestyle of dinosaurs and certain pelycosaurs
by Klaus Ebel, Markdorf
EBEL, K. (2000): Biomechanics of the vertebral column and implications for the lifestyle of dinosaurs and certain pelycosaurs. - Paläontologie, Stratigraphie, Fazies - Heft 8; Freiberger Forschungshefte C 490: 27-50; Freiberg 2000.
The investigation of the vertebral column of extinct vertebrates by means of a biomechanical approach yields strong indications that length, distribution, and orientation of the spinous processes in the region between shoulder girdle and pelvis can be used as a reliable measure as to whether such animals were bipeds or not and whether they were adapted to live preferably on land or possibly had an amphibious lifestyle. In comparison to modern ungulate mammals, in which length and orientation of the spinous processes especially in the shoulder area can be regarded as an adaptation to the ability of running and jumping, the vertebral columns of vertebrates of previous epochs exhibit remarkable divergences from this design. These are considered as indications of different lifestyles and less specialized locomotory capabilities.
The most important results of these biomechanical considerations are that the dorsal sails of the pelycosaurs Dimetrodon and Edaphosaurus reflect an adaptation to quadrupedal locomotion on land. On the other hand, only few theropods and sauropods suggest a terrestrial lifestyle. Saurischian dinosaurs appear to have lived preferably in moderately shallow water, whereas most ornithischians were quadrupedal land-dwellers.