Hell Creek

hell creek
The Hell Creek formation. Wikimedia Commons


Hell Creek



Date of Fossil Sediments:

Late Cretaceous (70-65 million years ago)

Dinosaurs Discovered:

Tyrannosaurus Rex, Triceratops, Ornithomimus, Troodon


About Hell Creek

If you've ever wondered why so many dinosaurs date from oddly specific time periods--say, 70 to 65 million years ago--the answer lies in formations like Hell Creek in Montana, the sediments of which date from the late Cretaceous period, right before the dinosaurs were rendered extinct by the K/T Meteor Impact.

Discovered in 1902 by the famous American paleontologist Barnum Brown, Hell Creek has yielded dozens of dinosaur genera, of all different kinds of families, including ceratopsians (horned, frilled dinosaur), hadrosaurs (duck-billed dinosaurs), ankylosaurs (armored dinosaurs), ornithomimids ("bird-mimic" dinosaurs) and pachycephalosaurs (thick-headed dinosaurs).

What did Hell Creek look like 70 million years ago? To judge from the relatively small dinosaurs that have been discovered there (this part of North America wasn't exactly a hotbed of multi-ton sauropods or tyrannosaurs), it seems likely that the area was thickly forested, which would have imposed natural size limits on its inhabitants. This conclusion is supported by the numerous non-dinosaur fossils that have been discovered in Hell Creek, including the remains of prehistoric turtles, pterosaurs (including, possibly, Quetzalcoatlus), monitor lizards, and tree-dwelling mammals like Cimexomys.

At this time, apparently, Hell Creek was part of a coastal plain that bordered the great Western Interior Sea covering much of western and central North America, which helps explain its diversity of wildlife.

Hell Creek also offers paleontologists valuable insight into the plant life of the late Cretaceous period--and remember, without plants, there wouldn't have been any plant-eating dinosaurs, and without plant-eating dinosaurs, there wouldn't have been any meat-eating dinosaurs.

This area of North America was thickly carpeted with ferns, mosses, sycamores, and even ancient palm trees and magnolias. In particular, these latter two plants indicate that Hell Creek was a much warmer and more humid ecosystem than it is today!

Hell Creek is famous for a reason besides its plant and animal fossils: the deposits of iridium, a rare element, in its uppermost layer of sediment offer firm support for the hypothesis that a meteor impact 65 million years ago caused the extinction of the dinosaurs (the only way to scatter iridium is to blast it out of the deep layers of the earth's mantle). Some paleontologists have interpreted the geologic evidence as showing that some hardy dinosaurs survived for as long as a couple of million years after the impact, but this theory doesn't enjoy wide support (although it is possible that some genera survived for thousands of years after the disaster).