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MemberAllosaurusJul-03-2017 10:10 AMHello, guys. This is somewhat of a follow-up on my last topic regarding Tyrannosaur evolution. I discussed a possible ancestry from Lythronax argestes to Daspletosaurus torosus to Tyrannosaurus rex. However, a new discovery may have just turned my theory upside down...
Take a look at this size chart of Tyrannosaurs discovered in Northwest America.
This image shows, from smallest to largest, Nanuqsaurus hoglundi, Gorgosaurus libratus, Albertosaurus sarcophagus, Daspletosaurus torosus, and Tyrannosaurus rex. D.torosus is clearly the second-largest after T.rex, which has led many, myself included, to believe that Daspletosaurus was the evolutionary forerunner to Tyrannosaurus. However, things get a bit different if we take a look at the Tyrannosaurs of Southwest America...
This shows, from smallest to largest, Teratophoneus curriei, Lythronax argestes, Bistahieversor sealeyi, and a possible new species of Tyrannosaur; Alamotyrannus/Tyrannosaurus brinkmani. This may be the key to our understanding in Tyrannosaur evolution. In my last topic regarding this subject, I speculated that L.argestes may be a possible ancestor to T.rex. However, it is quite possible that Lythronax evolved into this new species, and quite possibly new genus, of theropod. The southern Tyrannosaurs had similar builds to those of Daspletosaurus and Tyrannosaurus, while in the north, Albertosaurus and Gorgosaurus were built differently. However, it is quite possible that this dinosaur is just a rex found much more south than most specimens. Personally, I am conflicted on the possiblity of a new Tyrannosaur, but it is possible, considering that Lythronax and Daspletosaurus lived in different parts of North America, and for the former, evolution could have taken a different path--leading to the speculative Alamotyrannus/Tyrannosaurus brinkmani. But, like I said, it could just be a T.rex found far more south than most specimens.
Another important piece of evidence to note is that the specimen of this new Tyrannosaur was 70 million years old; older than any known Tyrannosaurus individual. It is possible that this is a transitional species, and the animal began to move north, where it evolved into Tyrannosaurus rex. This is plausible because Eotriceratops xerinsularis, an ancestor of the famous Triceratops, was found in the south as well, while the Trike lived in the north. In addition, Torosaurus utahensis, an ancestor to T.latus lived here, so it's possible that this new Tyrannosaur preyed upon the two species of ceratopsian dinosaur! Feel free to share your thoughts in the comments below!
"Part of the journey is the end..."
