Leptocleidus was a genus of plesiosaur which lived in the oceans during the early Cretaceous Period about 135 to 125 million years ago. It measured just 10 feet long, which is quite small for a plesiosaur. Three species of Leptocleidus… Read More ›

Paleontology
Lissodus
Lissodus was a prehistoric shark which lived from the early Triassic to the middle Cretaceous Period, about 250 to 110 million years ago, give or take. Named in 1835, it was a member of a group of sharks called the… Read More ›
Polyacrodus
Polyacrodus was a genus of prehistoric shark, composed of several species, with fossils found in North America, South America, Europe, Asia, and Africa. The name Polyacrodus means “tooth with many bumps”, and it was officially named by the German paleontologist… Read More ›
Cretaceous Stegosaurs in North America? Maybe
Stegosaurus stenops. © Jason R. Abdale (August 1, 2020) Stegosaurus is one of the most famous dinosaurs in the world. With its large back plates and spiked tail, it’s commonly seen in every child’s dinosaur book and is one of… Read More ›
The Cedar Mountain Allosaur
The Cedar Mountain Formation is a geological formation located in the western United States, mostly within the state of Utah, with rocks dating to the early and middle parts of the Cretaceous Period. The Cedar Mountain Formation is most well-known… Read More ›
List of articles about the Hell Creek Formation
Since I started this blog in the Summer of 2013, I have written several articles and I have posted several examples of my artwork associated with the Hell Creek Formation. This geological formation, dated to the very end of the… Read More ›
Nedcolbertia: A North American elaphrosaur?
IntroductionNedcolbertia (named in honor of the American paleontologist Dr. Edward “Ned” Colbert, 1905-2001) was a mysterious and intriguing creature which inhabited western North America during the early Cretaceous Period about 140-130 million years ago. When it was officially named and… Read More ›
Lepisosteus occidentalis – the Western Gar
Introduction The Hell Creek Formation of the western United States is understandably known for its dinosaur fossils, including Tyrannosaurus and Triceratops. However, in terms of sheer physical numbers, there are other species found here which surpass them by far. One… Read More ›
Arthropterygius
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 ›
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 ›