North America

Dakosaurus

There were numerous kinds of marine reptiles which swam in the oceans during the Mesozoic Era, including the ichthyosaurs, plesiosaurs, and mosasaurs. Less well known are the marine crocodilians, or more accurately, crocodylomorphs. These animals are known as the thalattosuchians,… Read More ›

Orthacanthus

Orthacanthus, meaning “straight spine”, was a 10 foot long freshwater shark-like fish which lived during the late Carboniferous Period and early Permian Period roughly 315-275 million years ago. The genus Orthacanthus is divided into twelve different species, two of which… Read More ›

Kepodactylus

NOTE: This article was originally published on August 3, 2023. It was substantially revised on February 3, 2026. Kepodactylus was a pterosaur which lived in western North America during the late Jurassic Period 155-152 million years ago. In 1992, a nearly-complete Stegosaurus skeleton… Read More ›

Gigantoraptor

Gigantoraptor was a massive 25-30 foot long oviraptorosaurian theropod dinosaur which lived in eastern Asia (and possibly in North America) during the middle of the Cretaceous Period. The fossils of this enormous bird-like dinosaur, consisting of a partial skeleton, were… Read More ›

Toxolophosaurus

Introduction Allow me to introduce you to Toxolophosaurus, “the bow-crested lizard”, which lived in Montana during the early to middle Cretaceous Period approximately 135-115 million years ago. Despite its name, Toxolophosaurus wasn’t either a dinosaur or a lizard. Instead it… Read More ›

Cifelliodon

Cifelliodon was a prehistoric mammal which lived in Utah during the early Cretaceous Period approximately 135 million years ago. The only specimen which we have of this animal is a single upper jaw measuring 2.75 inches (7 cm) long which… Read More ›

Synechodus

Synechodus was a genus of prehistoric saltwater shark which lived from the early Permian Period until the late Eocene Epoch of the Paleogene Period, 290 to 37 million years ago (Ivanov 2005, pages 127-138). Fossils of this animal reached around… Read More ›