Mesozoic

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 ›

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 ›

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 ›