The Earliest Tyrannosaur

Since the tyrant lizards have been in the news so much lately, I figured I'd write a bit on our best known of the early tyrannosaurs, a beast discovered in Late Jurassic rock in China and named Guanlong. The other Jurassic tyrannosaurs are not nearly as well known. We have two relatively complete Guanlong specimens, an adult and a juvenile. While many tyrannosaurs feature head ornamentation of some sort - bumps, spikes, or small crests, Guanlong's head bore a large, delicate crest which in profile looks somewhat like that of Dilophosaurus.

Like the early Cretaceous Chinese tyrannosaur Dilong, it's likely that Guanlong was covered, at least partially, in hairy "proto-feathers." These would have been for warmth and display purposes, and the later giants of the family show no evidence of them, and would not have needed them to maintain their temperature as their large size would have done that job just fine. Both Guanlong and Dilong had three fingers; recently described Raptorex is the earliest tyrannosaur to bear the distinctive two-fingered hand.

National Geographic published a nice article on Guanlong in July of 2008, and the site also features a gallery dedicated to the fossilized mud trap where Guanlong was discovered with a whole mess of tasty fossils.


Drawing by Renato Santos.

Raptorex, Raptorex

Whoa! News outlets and the paleoblogosphere have blowed up mightily over last 24 hours with the news of the new tyrannosaurid Raptorex kriegsteini. Brian Switek wrote a thorough description at Dinosaur Tracking. Chinleana's Bill Parker took a detour from his Triassic stomping grounds to mention it. At DinoGoss, Matt Martyniuk poked fun at its silly name. Beyond the dino-blog world, Jerry Coyne wrote it up on Why Evolution Is True and PZ Myers nodded his head Raptorex's way at Pharyngula. Sports Illustrated hasn't commented on it yet, but the NFL season just started, and there's that NL wild card race to keep an eye on--their plate is pretty full.

Raptorex by Todd Marshall

There's a reason Paul Sereno and his team at the University of Chicago picked a name like "Raptorex," and it was to garner the kind of immediate sensation that causes CNN.com to feature the story on its front page, as it did yesterday. Like the name or not - it strikes me a bit Saturday-Morning-Cartoony - it certainly caused a splash, and in a much more tasteful way than the Ida debacle. So what is the big deal about what appears, on the surface, to simply be another small, basal tyrannosaurid from the early Cretaceous?

Raptorex, as noted by Sereno, is almost exactly proportioned like its late Cretaceous relative, Tyrannosaurus rex. Unlike other early tyrannosaurids found in China, Dilong and Guanlong, Raptorex bears the signature stubby, two-fingered arms that have been amusing us since the discovery of T. rex. Previously thought to be a later development, this indicates that it was an adaptation that had use for small predators as well as the giant tyrannosaurids to come.

PS. It helps if you sing the title of this post to tune of "Birthday Sex" by Jeremih. Weird Al, you have your marching orders. Hop to.