A new sauropod discovered in Utah: Abydosaurus

Yes, it's official. A team of paleontologists and students from BYU has just dug up and described a new sauropod species at Utah's Dinosaur National Monument, and this one includes gorgeous complete skulls from four individuals!


Species: Abydosaurus mcintoshi
Taxonomy: Saurischia; Sauropoda; Macronaria; Brachiosauridae; ?Giraffatitanae? 
Time: Early Cretaceous (Albian epoch, 104.46 ± 0.95 million years ago)
Location: the Mussentuchit Member of the Cedar Mountain Formation in Dinosaur National Monument, Utah
Known material: holotype DINO 16488, a nearly complete skull and lower jaws with the first four neck vertebrae. Abundant skull and postcranial bones were found at the same site, including partial skulls from three additional individuals, a partial hip and associated tail vertebrae, a scapula, a humerus, and several metacarpals.
Unique features: narrow teeth relative to earlier brachiosaurs, very large eye sockets, unusually wide struts of bone separating the nares from the antorbital fenestrae, nares are unusually small for a brachiosaur (even smaller than the eye sockets), though this may be a temporary immature trait, as all the skull material is from juvenile specimens.

Abydosaurus mcintoshi is a brachiosaur which grew to about 80 feet long, though the skulls and most of the other remains found at the site are from juveniles that were only about 35 feet long at their time of death. It's a Cretaceous brachiosaur, one of many which evolved rapidly to steal the spotlight from the already extinct diplodocids and camarasaurs that didn't survive the end of the Jurassic. Cedarosaurus, Sonorasaurus, Astrodon, Pleurocoelus, and the gigantic Sauroposeidon round out the cretaceous brachiosaur A-list. And now for the first time, one of their own contemporaries has been found with perfectly preserved skull material!

Initial photo released upon discovery of the then-unnamed skull

More detailed photo of the same skull from both sides. Notice the hyoid bones in the throat.

The Abydosaurus skulls include, as you can see here, even the fragile hyoid bones of the throat which anchored the tongue muscles. These skulls also pack a decent set of teeth, nearly all of which are in place, and quite sharp. The teeth of Abydosaurus were narrower than those of earlier brachiosaurs, and show a marked trend toward thinner and more rod-shaped teeth, which is typical of the evolution patterns of cretaceous macronarian sauropods. This trend culminated in late-stage titanosaurs like Antarctosaurus and Nemegtosaurus, whose thin peg-like teeth, limited to only the front of the mouth, converged strongly with the dentition of then long-dead diplodocids.

Abydosaurus likely did not evolve into titanosaurs - they were already present - but it did manifest a tooth design that was convergent to many of the basal ones. This may reflect a change in cretaceous conifers as well, leading to a change in herbivore adaptations.

Here is a youtube video of the discovery, with a great high-nostriled restoration of the beast by Michael Skrepnick.



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