Introduction The Morrison Formation of western North America is one of the most well-studied geological formations within the world. These rock layers, which extend from Montana to New Mexico and from Utah to South Dakota, are dated to the late… Read More ›
Morrison Formation
Ornitholestes
Ornitholestes, “the bird thief”, was a small meat-eating dinosaur which lived in western North America during the late Jurassic Period about 154 million years ago. Since its discovery in the year 1900, Ornitholestes has come to be regarded as the… Read More ›
Kepodactylus
Kepodactylus was a species of pterosaur which lived in western North America during the late Jurassic Period 150 million years ago. In 1992, a nearly-complete Stegosaurus skeleton was discovered in Garden Park, Colorado within the rocks of the Morrison Formation…. Read More ›
Goniopholis: The Typical Mesozoic Crocodile
Dinosaurs ruled the land during the Mesozoic Era, but crocodiles and their relatives unquestionably ruled the water. Prehistoric crocodiles are usually relegated to the background as supporting actors or extras in our imagined Mesozoic dramas, but the truth is that… Read More ›
Polyacrodus
NOTE: This article was originally published on May 4, 2022. On December 30, 2025, it was updated and re-uploaded. Polyacrodus was a genus of prehistoric shark, composed of several species, with fossils found in North America, South America, Europe, Asia, and… Read More ›
Gargoyleosaurus
When people think of “armored dinosaurs”, they generally think of two kinds of creature: the stegosaurs and the ankylosaurs. Both of these groups belong to the dinosaur sub-order Thyreophora, which means “armor-bearing” in ancient Greek. The dinosaur group Ankylosauria or… Read More ›
Brachiosaurus
There are some dinosaurs that everybody thinks of when they hear the word “dinosaur”. Among these is a very large sauropod which was the reptilian analog of a giraffe. I am, of course, talking about Brachiosaurus. Brachiosaurus is one of… Read More ›
List of Articles about the Morrison Formation
The Morrison Formation of western North America is my favorite geological / paleontological formation to study. Within these rock layers, which are dated to the late Jurassic Period from approximately 155 to 145 million years ago, are found the fossils… Read More ›
Ceratodus: The Iconic Lungfish of the Mesozoic Era
Ceratodus was a genus of prehistoric lungfish which existed on Earth for a surprisingly long time, from the middle of the Triassic Period approximately 227 million years ago to the beginning of the Eocene Epoch of the Tertiary Period about… Read More ›
Fruitachampsa, the crocodile-bear-cat of the Morrison Formation
Meet the Jurassic Period’s analog of the common house cat. This is Fruitachampsa callisoni, a prehistoric reptile which inhabited western North America during the late Jurassic Period. However, this was not a dinosaur. In fact, Fruitachampsa was a distant relative… Read More ›