In Depth
A member of the Silesauridae (and hence relative of Silesaurus), Sacisaurus was a late Triassic dinosauriform from South America. Although much of the skeleton of Sacisaurus is still unknown, the parts which have been recovered and studied have revealed traits that are similar to ornithischian dinosaurs. Better known as ‘bird hipped’ dinosaurs, ornithischians went on to produce such diverse groups as ornithopods, hadrosaurs, ceratopsians, ankylosaurs, stegosaurs and pachycephalosaurs. Paradoxically, the birds are believed to have evolved from the theropod line of ‘lizard hipped’ dinosaurs.
If the ancestral line of ornithischian dinosaurs can be traced back to Sacisaurus, then that would mean that the two main groups of saurischian and ornithischian dinosaurs actually became established before either group could technically be described as a dinosaur, which in turn could suggest that the two groups appeared as a convergent evolution derived from common ancestors.
Sacisaurus is known to have had quite small teeth which did not grow bigger than three millimetres long. These teeth seem to be best adapted to processing plants, which would suggest that Sacisaurus was a herbivore. What is known about the post cranial skeleton is that the legs of Sacisaurus were long in proportion to the length of the body. These legs indicate that Sacisaurus were fast runners and probably relied upon speed to outrun potential threats such as rauisuchians and predatory dinosauriformes.
Further Reading
- A Late Triassic dinosauriform from south Brazil and the origin of the ornithischian predentary bone. - Historical Biology 19(1):23-33 - J. Ferigolo & M. C. Langer - 2006.
