What a time to be a paleontologist; evidence for a carnivorous dinosaur that waded into the water for its prey has been discovered in St. George, Utah. According to a recent news report from the Discovery Channel, a new Dilophosaurus relative has been found in a lake environment, in addition to a new shark species, at least three new fish species, and three new tree species. This is absolutely wonderful, allowing us a look into the early Jurassic ecology of this area, and I hope the excavations and study of this area continues.
Perhaps more impressive than all these new species, however, are the preserved trackways. According to the report, the tracks seem to show the predatory dinosaur walking out into the water and even scrambling to get back onto dry land, proof that this dinosaur enjoyed fish dinners. Much to my dismay, there are no photographs of any of the skeletons, tracks, or anything else, so I guess I’ll have to keep my eyes peeled for updates and announcements about the discoveries.
Also, some of the paleontologists explain in the report that the new dinosaur has a head/mouth shape seen in spinosaurs, including nostrils moved back on the top of the skull and lots of small, sharp teeth for catching/holding onto fish. This got me wondering; could there be a relationship between Dilophosaurus and its relatives and later dinosaurs like Spinosaurus, Suchomimus, Baryonx, and Irritator? I pulled out my copy of The Dinosauria (2nd ed.) and did a quick search on Wikipedia to check out how things stand. Currently, spinosaurs have been folded into the Superfamily Megalosauroidea and Dilophosaurus and its kin belong to the Superfamily Coelophysoidea, although there seems to be some doubt as to the true affinities of spinosaurs. To get to the point, I’m wondering of these elongated skull shapes adapted for catching fish/holding onto prey evolved at least twice because of environmental pressures in these two different groups or there if there is an ancestor/descendant relationship here between some sort of coelophysid and the impressive spinosaurs. Maybe I’m way off base, but even if I’m wrong it would be worth it to determine if the piscivore skull evolved multiple times or belies an evolutionary relationship.
Update: Zeta was kind enough to bring to my attention a passage from Gregory S. Paul’s famed work Predatory Dinosaurs of the World (1988) which hints at a connection between dinosaurs like Dilophosaurus and the spinosaurids like Baryonx and Spinosaurus. Once again, I find that I am late to the party, but I think a re-evaluation of the relationship of the coelophysids and spinosaurs is needed now, especially given the discoveries made in recent years. Paul writes;
The kinked snouts, crests, and peculiar jaw supports show that coelophysids were an increasingly aberrant side branch that left no descendants. This means they paralleled other advanced theropods and birds in such details as extensive bone ossification and increasingly narrow cannon bones. Crests, peculiar jaw supports, and narrow cannon bones show that dilophosaurs are the most advanced of the bunch, so their reduced hips must be a secondary reversal to a more primitive condition. It may be that the extraordinarily aberrant Baryonx and Spinosaurus are extremely specialized developments of the dilophosaur branch; their deeply kinked snout and other similarities certainly suggest so.
If any of the above genera were new to you, why not check them out on DinoBase!