Stem-Bird Files: Siats meekerorum

Coelurosauria>Tyrannoraptora>Tyrannosauroidea>Megaraptora>Siats>S.meekerorum
Lindsay Zanno & Peter Makovicky, 2013
Time: Late Albian (105-98 million years ago)
Length: 9.8 meters (32.1ft) on the subadult holotype specimen.
Height: 3.1 meters (10.1ft) at the hip on the subadult holotype specimen.
Weight: 4t on the holotype specimen.
Habitat: Cedar Mountain Formation, Utah, U.S.
Ecology and hunting habits: Large terrestrial predator, most likely the apex predator of the region. Like other megaraptorans and their fellow primitive tyrannosauroids, it probably targeted smaller than itself, which hardly means much given that it was one of the largest animals in it's environment. Based on the proportions of smaller megaraptorans, it would have been a fairly fast runner for it's size.
Diet: Ankylosaurs Animantarx and juveniles of Cedarpelta and Peloroplites, the iguanodontians Eolambia and Tenontosaurus and sauropods such as Venenosaurus.
Competition: Hatchlings and juveniles would likely have faced competition and depredation from contemporary small theropods Deinonychus and Richardoestesia, as well as multiple indeterminate dromaeosaurids. Adults would have little to fear other than their own species.
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The giant that held back the tyrants... except it didn't. With the new classification of Megaraptora, it would seem that Siats itself was a tyrant. In fact, if we expand the definition to fit all large members of Tyrannosauroidea, it is the very first American tyrant - and one of the largest.
Another interesting thing I found while researching this guy is that Deinonychus sp. is found from the Mussentuchit member of the Cedar Mountain Formation, the same layer that contains Siats; interactions between these two are therefore not out of the question, even though these would be highly one-sided in favor of the megaraptoran (more on that on the Deinonychus file).
I do not take credit for the skeletal references or silhouettes of any of these animals (I only fill them out with the life reconstruction and complement it with the info sheets)