LATE CRETACEOUS

HELL CREEK FORMATION

Tyrannosaurus

update 062516

The Hell Creek large carnivores are less diverse than Late Jurassic Morrison formation. There is only one large predator. Tyrannosaurus was one of the largest ever theropods.

mouse over diorama pics for figure information.

There is some evidence that tyrannosaurs may have been social. The model suggested is an analogue of modern hawks where a mated pair and their sub adult offspring form a unit.The most complete skeleton of a T. rex yet found, nicknamed ‘Sue’ was found with a mix of younger fossils. The younger animals seemed to have more agile proportions. This may have allowed them to run down hadrosaurs and other more fleet footed animals. They may have acted like a lion pride chasing prey towards the larger adults.

The level of parental care is debated. The size difference between hatchings and adults must have effected how they interacted.

Tyrannosaurs are from the same branch of the theropod line as birds and predatory birds are known for investing a lot of effort in raising their young.

Crocodiles and their relatives the close living relatives of dinosaurs tend both eggs and hatchlings. They show complex behavioral hierarchies.

It is reasonable to expect at least that level of care and social behavior from most dinosaurs.

 

 

 

 

 

Large and small herbivores are associated with particular areas, but tyrannosaurs seem to be fairly widespread. Juvenile, sub adult, and adult animals may have favored different habitats to avoid completion. Adults were more common in open floodplains.

 

 

 

 

 

 

 

 

 

 

Lambeosaurs are know from fossils in Europe and Asia are contemporary with Hell Creek. They may have been seasonal visitors passing through Hell Creek on their way to environments they favored.

 

 

 

 

 

 

 

 

 

 

Its feet had 3 clawed toes pointing forwards with a smaller one at the back. Although the arms may appear tiny and puny, they were in fact quite strong and very well designed for holding struggling prey, and ended in clawed, 2-fingered hands. The jaw was 4.5 ft long with saw-like teeth. There has been considerable debate as to whether it was a relatively slow scavenger or a fast predator.

 

 

 

 

 

 

 

 

The traditional view was tyrannosaurs were solitary predators that only came socialized in the breeding season.

The bits of fossilized skin and impressions of skin seem to show that was scaly.
There is indirect evidence for the possibility of feathers in Tyrannosaurus as several earlier tyrannosaurs did have feathers.

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