Siats
| Key | Value |
|---|---|
| Name Meaning | “Siats” |
| Location | United States (Utah) |
| Time Period | c. 95 million years ago (Late Cretaceous) |
| Length | 36 ft (11 m) |
| Weight | 4.5 tons (4,000 kg) |
| Locomotion | Biped |
| Diet | Carnivore |
| Described | 2013 (Zanno & Makovicky) |
| Geological Formation(s) | Cedar Mountain |
| Valid Species | Siats meekerorum (type) |
Phylogeny: Dinosauria > Saurischia > Theropoda > Neotheropoda > Tetanurae > Avetheropoda > Coelurosauria (?) > Tyrannosauroidea (?) > Megaraptora (?)
Overview: In 2008, paleontologists operating in Utah came across the partial skeletal remains of a massive theropod dinosaur, recognized as a taxon then unknown to science. Over the next couple of years, the fossils were recovered from the site, consisting of some partial vertebrae, portions of the pelvis, and a few leg bones. This is unfortunately not a lot to work with, but the bones do have a number of unique features. Using these features, Siats was formally described as a genus in 2013. Siats takes its generic name from that of a monster in the folklore of the Ute people, native to the area where the bones were found. It’s a fitting name, as the Siats monster had an insatiable hunger for human flesh, while Siats the dinosaur was likely an apex predator. The only known specimen of this genus wasn’t fully grown, but adults may’ve been ten to twelve meters long. Siats was among the largest theropods in North America prior to the appearance of Tyrannosaurus.
With only a handful of bones being known, it’s not too surprising that some controversy surrounds Siats, specifically in regards to its phylogeny. Paleontologists aren’t entirely sure of how the animal should be classified, though there are some suggestions based on its anatomy. It was at first placed within the clade Megaraptora, which if accurate, would’ve easily made it the largest member. This same study classified the megaraptorans as allosauroids, closely related to the genus Neovenator. Siats did have a lot in common with Neovenator, so artistic restorations are often inspired by the anatomy of said genus. Recent studies, however, have classified megaraptorans not as allosaurs, but as coelurosaurs, potentially close to the tyrannosauroid superfamily. Siats could, of course, be from a lineage separate from the Megaraptora. All known fossils of Siats appear to come from the geologically youngest layers of Utah’s famous Cedar Mountain Formation.