Tyrannosaurus rex may have been the king of the dinosaurs at the Cretaceous's end but it was certainly not the first apex therapod. It took millions of years of theropod evolution to refine this family of ultimate predators.

Among the roots of this deadly family tree is the mighty Daspletosaurus, the "frightful lizard" that appeared in the Western Interior Seaway's costal fossil record around 77 million years ago.

Daspletosaurus clocked in at a massive 3 tons, with some evidence that members of the species could grow over 30 feet long. On the floodplains around the sea that split North America in two during the Cretaceous, this dinosaur hunted hadrosaurs and ceratopsids. To help get through the defenses of large herbivores, Daspletosaurus had a massive skull with an incredible bite force, over seven times that of a modern alligator. It could easily crack bone while delivering the killing blow to its prey, outclassing the bite of even larger and contemporary theropods.

Daspletosaurus's success set the blueprint that its descendant, Tyrannosaurus rex, would follow through the end of the Cretaceous.

This specimen is a fragment of a Daspletosaurus leg bone from Montana’s Two Medicine Formation. The study of Daspletosaurus specimens at this site has been foundational to understanding the evolution of the Tyrannosaurid family and their large appetites. Scars found on some Daspletosaurus fossils seem to have been inflicted by others of its own kind, suggesting the dinosaurs engaged in feeding frenzies so violent that they could even turn cannibalistic.

Each fossil fragment measures between 0.5-1" long. All specimens are enclosed in an acrylic specimen jar with a removable top which arrives in a handsome, glass-topped riker box case measuring 4x3x1".

The Daspletosaurus bone fossil comes complete with a informational card that serves as our statement of authenticity. It is a fantastic display item for those looking to expand their fossil collection!

How do we get to Tyrannosaurus rex? By the end of the Cretaceous, the Tyrannosaurid family had become the apex predators of the dinosaur world, but where did these carnivores come from? The terrifying frame of the massive theropod with an oversized set of jaws and teeth was millions of years in the making—Tyrannosaurus rex was not the first tyrannosaurid.

One of the earliest ancestors of the T. rex appeared 77 million years ago along the coastal floodplains of the Western Interior Seaway. This creature was smaller than its descendant, but still carried the same gigantic teeth and incredible bite force that all
tyrannosaurids did. Named Daspletosaurus, or “frightful lizard,” this early tyrannosaurid weighed 2.5 metric tons (5,500 lb) and measured over 8 m (25 ft) in length.

Daspletosaurus had the hallmarks of its fellow tyrannosaurids, with a massive set of jaws and small, two-fingered claws. However, its arms were a fair bit longer in proportion to its body, giving it an advantage when scavenging over fallen prey, and tearing flesh with its claws.

Like other tyrannosaurids, Daspletosaurus had an enormous head with a catastrophic bite. The power within these jaws was over seven times the bite force of a modern American alligator. Studies of tyrannosaurid fossils show that this family of dinosaurs had specific adaptations to resist torsion stress when biting down. Combined with a bite force that outpaced even larger theropods like Giganotosaurus, it is thought that Daspletosaurus could crack bone with its teeth, making even just one chomp from this predator fatal.

While its bite strength changed as it grew older, the actual mechanics of its jaws did not. This means a juvenile Daspletosaurus hunted in similar ways to an adult, and it likely did not depend on its parents’ help for very long. That said, Daspletosaurus was not always a lone hunter. A fossil bed in the Two Medicine Formation found a pack of at least three Daspletosaurus among a herd of Hadrosaurs, working together to break apart the defenses of the group.