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Spinosauridae is a family of unusual theropod dinosaurs. Members of this group were large, bipedal predators with elongated, crocodile-like skulls, sporting conical teeth with no or only very tiny serrations. The front dentary teeth fanned out, giving the animal a characteristic look. The name of this family alludes to the typically conspicuous sail-like structure protruding from the back of species in the type genus, Spinosaurus. The purpose of the sail is disputed, but popular explanations are that it may have served as a thermoregulator, a threat display, or as a sexual display during courtship.
All spinosaurids appeared during the Cretaceous period without ever, judging by the scarce findings, becoming abundant. Spinosaurid fossils have been recovered in Africa, Europe, South America, and Asia.
Taxonomy
The family Spinosauridae was named by Ernst Stromer in 1915 to include the single genus Spinosaurus. The family was expanded as more close relatives of Spinosaurus were uncovered. The first cladistic definition of Spinosauridae was provided by Paul Sereno in 1998 (as "All spinosaurids closer to Spinosaurus than to Torvosaurus).
Spinosauridae contains two subfamilies--Spinosaurinae and Baryonychinae. The subfamily Spinosaurinae was named by Sereno in 1998, and defined by Holtz et al. (2004) as all taxa closer to Spinosaurus aegyptiacus than to Baryonyx walkeri. The subfamily Baryonychinae was named by Charig & Milner in 1986. They erected both the subfamily and the family Baryonychidae for the newly discovered Baryonyx, before it was referred to the Spinosauridae. Their subfamily was defined by Holtz et al. in 2004, as the complementary clade of all taxa closer to Baryonyx walkeri than to Spinosaurus aegyptiacus.
Classification
- Indeterminate spinosaurids
Diet
Evidence shows that spinosaurids fed on fish as well as a variety of other small to medium sized animals, including small dinosaurs. Baryonyx was found with fish scales and the digested bones of a young Iguanodon in its stomach cavity, one specimen of Spinosaurus had a fish bone lodged in one tooth socket, and there is one documented example of a spinosaurid having eaten a pterosaur.[2]
References
- ^ Buffetaut, Eric; Suteethorn, Varavudh; Tong, Haiyan; and Amiot, Romain (2008). "An Early Cretaceous spinosaurid theropod from southern China". Geological Magazine 145 (5): 745-748. doi:10.1017/S0016756808005360.
- ^ Buffetaut, E., Martill, D., and Escuillié, F. (2004). "Pterosaurs as part of a spinosaur diet." Nature, 430: 33.
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