A new species of carnivorous dinosaur — one of the three largest ever discovered in North America — lived alongside and competed with small-bodied tyrannosaurs 98 million years ago. This newly discovered species, Siats meekerorum, (pronounced see-atch) was the apex predator of its time, and kept tyrannosaurs from assuming top predator roles for millions of years.
The find was a juvenile stretching more than 30 feet long and weighing about four tons. How big is that?
“The huge size difference certainly suggests that tyrannosaurs were held in check by carcharodontosaurs, and only evolved into enormous apex predators after the carcharodontosaurs disappeared,” says Makovicky. Zanno adds, “Contemporary tyrannosaurs would have been no more than a nuisance to Siats, like jackals at a lion kill. It wasn’t until carcharodontosaurs bowed out that the stage could be set for the evolution of T. rex.”
“It’s been 63 years since a predator of this size has been named from North America,” says Lindsay Zanno, a North Carolina State University paleontologist with a joint appointment at the North Carolina Museum of Natural Sciences, and lead author of a Nature Communications paper describing the find. “You can’t imagine how thrilled we were to see the bones of this behemoth poking out of the hillside.”
Oh yes, we can imagine…
Let’s not lose sight of this: Before the Siats fossil was found, a whole narrative existed of late Cretaceous ecology that got started entirely in ignorance of this top predator. That would be like trying to understand the northern wilderness without the wolf or the bear.
We really don’t know enough to know as much as we think.
Note: The illustration shows a hairy (feathery) Siatz; new fashion among science artists.