Arthropterygius, “jointed fin”, was a genus of ichthyosaur which lived in the Arctic Ocean during the Jurassic/Cretaceous transition period about 150 to 140 million years ago. Fossils of it have been found in Canada, Scandinavia, and Russia, and bones which… Read More ›

Paleontology
Semionotus
Semionotus was a genus of prehistoric fish which lived throughout the world during much of the Mesozoic Era. It was named by the famous Swiss ichthyologist and paleontologist Louis Agassiz in 1843 (type species: Semionotus bergeri). Semionotus first appeared during… Read More ›
The Cedar Mountain Hypsilophodont Dinosaur
The Cedar Mountain Formation of the western United States, which is dated to the early Cretaceous Period, has produced fossils of numerous dinosaur species. Several of these are still not officially classified, and this post concerns one of them. In… Read More ›
An Ornithocheirid Pterosaur
An ornithocheirid pterosaur. © Jason R. Abdale (February 13, 2022). The “ornithocheirids” were a group of pterosaurs which dominated the skies during the early and middle parts of the Cretaceous Period from about 140 to 90 million years ago. They… Read More ›
The Sail-Backed Dinosaur from the Cedar Mountain Formation
Greetings. A few days ago, I learned of a remarkable discovery. In east-central Utah within the rock layers of the Cedar Mountain Formation, dated to the early Cretaceous Period about 135 million years ago (the same time and place where… Read More ›
Gracilisuchus
Gracilisuchus, meaning “the slender crocodile”, was a 2-foot-long reptile which lived in South America during the middle of the Triassic Period. Its remains were discovered in northwestern Argentina within the rocks of the Chañares Formation, which are dated to about… 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 ›
The Lives of Raptor Dinosaurs: A Series of Mistaken Preconceptions
Introduction If you were to approach most people who possess a familiarity with paleontology, and ask them about what they know about raptor dinosaurs and how they lived their lives, these people would almost certainly tell you the following four… Read More ›
Zephyrosaurus
Zephyrosaurus was a small ornithopod dinosaur which lived in Montana during the middle Cretaceous Period. The first fossils of this animal were discovered by Charles R. Schaff, who worked at Harvard University’s Museum of Comparative Zoology. Schaff was prospecting for… Read More ›
Deinonychus: The Dinosaur that Changed the World
The skull of Deinonychus. This is the very first thing that appears on-screen in the first episode of the 1992 PBS documentary series The Dinosaurs! It’s a great series, by the way. You should watch it. Right now. Seriously. Get… Read More ›