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 ›
Cretaceous Period
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 ›
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 ›
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 ›
Microvenator
In North America, dinosaur fossils are found in profusion in rocks dated to the late Triassic, late Jurassic, and late Cretaceous Periods. However, much of the rest of the Mesozoic Era’s time scale contains much sparser remains. The middle part… Read More ›
The Big Muddy: The Mowry Sea of the Early Cretaceous Period
Today the broad expanse of the Great Plains, which forms the central part of North America, is a vast area of farms, prairies, and deserts. Here, immense herds of buffalo once roamed and wild mustangs galloped. However, the land did… Read More ›
Astrodon
If you were to ask people if they know a good place to find dinosaur bones, many of them would say “Go west, young man!” There is a lot of truth to this. There are vast areas of western North… Read More ›
Altispinax: The Mysterious Meat-Eater of Early Cretaceous England
Introduction There are many dinosaur species which have been identified based upon very scant remains, and this article concerns one of them: a meat-eating dinosaur named Altispinax dunkeri. If you’ve never heard of this animal before, you’re not alone. It’s… Read More ›