North America

Platypterygius

Platypterygius, meaning “flat fin”, was a genus of ichthyosaur which lived during the middle of the Cretaceous Period approximately 115-95 million years ago. It was one of the last ichthyosaurs to exist before the entire group went extinct. Traditionally treated… Read More ›

Leptostyrax

Leptostyrax was a genus of prehistoric sand tiger shark measuring an impressive 20 feet long which lived in the oceans around North America, Europe, Africa, and Australia during the Cretaceous Period approximately 125-75 million years ago. Leptostyrax has a long… Read More ›

Radiodactylus

During the Mesozoic Era, dinosaurs ruled the land, but their flying cousins the pterosaurs ruled the sky. They first appeared during the late Triassic Period about 210 million years ago, and persisted until the reign of the reptiles came to… Read More ›

Acrocanthosaurus

Acrocanthosaurus, meaning “high-spined lizard”, was a large 35 foot long meat-eating dinosaur which lived in North America during the middle of the Cretaceous Period approximately 115-110 million years ago. It is distinctive for the unusually tall neural spines on the… Read More ›

Leucichthyops

Leucichthyops vagans was a species of prehistoric salmonid fish which lived in what’s now western North America during the middle of the Cretaceous Period approximately 100 million years ago. The species was named in 1919 by Theodore D. A. Cockerell,… Read More ›

Erythrinolepis

Erythrinolepis was a prehistoric freshwater fish which lived in western North America during the middle to late Cretaceous Period approximately 100-66 million years ago. The name Erythrinolepis was coined by the paleontologist Theodore D. A. Cockerell in 1919. The name… Read More ›

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 ›