>>Tyrannosaurs are often seen as the kings of the prehistoric world. They’re among the largest and most charismatic of giant predators to stalk the Earth during the age of dinosaurs. But they weren’t the only voracious giants of the time. The “shark tooth lizards,” known to paleontologists as carcharodontosaurs, ruled all over the planet for tens of millions of years before and during the rise of tyrannosaurs, and a new find in southeast Asia helps fill in the backstory of these impressive carnivores.
Siamraptor now joins a bizarre and impressive array of carcharodontosaurs. Some members of this family bore strange ornaments on their backs, like the high-spined Acrocanthosaurus from the southern United States. Others, like Giganotosaurus from Argentina, grew to enormous sizes that matched or exceeded the great Tyrannosaurus rex. Carnivores like Siamraptor were apex predators in many of the places where tyrannosaurs failed to gain a claw-hold, and their anatomy underscores differences in how these dinosaurs behaved.
“At rough glance carcharodontosaurs and tyrannosaurs are broadly similar,” says University of Maryland paleontologist Thomas Holtz, Jr., as both are marked by “big heads, big bodies and short arms.” But digging into the details, the predators are very different. While the snouts of T. rex and kin are broad and round, Holtz says, carcharodontosaurs have “hatchet heads” with tall and narrow snouts fitted with blade-like teeth. The different snouts affect how these animals would have hunted and fed. “The bite in tyrannosaurids was bone-crushing like a hyena or an alligator, while that in carcharodontosaurs were more shark-like and slicing,” Holtz says.<<
https://www.smithsonianmag.com/science-nature/newly-discovered-dinosaur-was-giant-shark-tooth-predator-rival-tyrannosaurs-180973304