Newly discovered dino towered over T. Rex's ancestors

Despite what its name might suggest, the newly-discovered Siats meekerorum was probably anything but meek.

 

Estimated to have weighed 4 tons, the 30-foot-tall Siats meekerorum is believed to have been the apex predator during its time, sitting ferociously at the top of the dinosaur food chain way before Tyrannosaurus rex first reared its ugly—and likely feathered—head.

 

 

The animal was discovered in 2008 by Lindsay Zanno, a paleontologist from the North Carolina Museum of Natural Science. Zanno and a colleague, Peter Makovicky from the Field Museum of Natural History in Chicago, spotted the prehistoric carnivore’s fossilized bones jutting out of a hillside in the Cedar Mountain Formation in Utah.

 

The discovery was officially unveiled when the study was published on November 22 in the online science journal Nature Communications.

 

The 'top dog in his neighborhood'

 

Siats meekerorum derives its genus name from a man-eating monster in Ute tribal legends. Its species name, on the other hand, comes from the Meekers, a family from Evanston that has been providing support to the Field Museum’s early career paleontologists.

 

Despite its intimidating size, Siats did not belong to the same family as the infamous T. rex. Siats is from the Neovenatoridae branch of the carcharodontosaur family, a subgroup of allosaurs that also included some of the largest predatory dinosaurs discovered so far, such as Giganotosaurus and Mapusaurus.

 

According to Makovicky, Siats was probably the “top dog in his neighborhood,” dwarfing the smaller tyrannosaurs that populated the Early Cretaceous period.  “There’s simply nothing even close in this ecosystem to the size of this animal that could’ve been interpreted as an apex predator,” explained Zanno.

 

Paleontologists believe that it was Siats’s gigantic size and fearsome presence that stunted the development of the tyrannosaur family for about 30 million years.  "Contemporary tyrannosaurs would have been no more than a nuisance to Siats, like jackals at a lion kill," said Zanno.

 

A meat-eating mystery

 

Zanno calls the fossils “the most exciting thing [she’s] found so far,” and perhaps with good reason. Not only is this the first gigantic predator from North America unearthed in 63 years, but the discovery of Siats also sheds some much-needed light on the unexplored period of time between the late Jurassic and late Cretaceous periods.

 

Up until 65 million years ago, carcharodontosaurs ruled the prehistoric landscape. A “species turnover”, brought about by unknown circumstances, led to the rise of T. rex during the late Cretaceous period as North America's largest known predator.

 

The last gigantic carcharodontosaur to terrorize North America, Acrocanthosaurus, existed approximately 10 million years earlier than Siats. Thanks to the discovery of Siats, paleontologists now know that it was another member of the carcharodontosaur family that dominated the North American landscape during the early Cretaceous period.

 

Siats became extinct sometime between 98 million and 80 million years ago. The oldest known close relative of T. rex, the recently-discovered Lythronax argestes, is believed to have inherited the title of top predator from Siats after it disappeared from the Cretaceous landscape. 

 

A lucky find—and possibly more on the way

 

During Siats’s reign, the part of the world that would eventually become Utah was a marshland along the Western Interior Seaway, a shallow sea bisecting North America. This makes the likelihood of finding well-preserved fossils very low. However, this also means that discoveries in the area are more likely to be of previously unknown species.

 

The paleontologists are optimistic that there are more fossils and secrets to be revealed, and believe that discovering Siats was only the first step. “In the next three to five years we really hope to be able to bring to light more of what this lost ecosystem looked like.” — TJD, GMA News