Late Jurassic

Ornitholestes

Ornitholestes, “the bird thief”, was a small meat-eating dinosaur which lived in western North America during the late Jurassic Period about 154 million years ago. Since its discovery in the year 1900, Ornitholestes has come to be regarded as the… Read More ›

Caypullisaurus

Caypullisaurus was a 20 foot long ichthyosaur which lived off the coast of Argentina (and possibly elsewhere) during the late Jurassic and early Cretaceous Periods 150-140 million years ago. In 1989, the front half of a skeleton of a medium-sized… Read More ›

Cricosaurus

Cricosaurus was a genus of 5-10 foot long marine crocodylomorphs which swam in the shallow seas around Mexico, Argentina, and Germany from the late Jurassic Period to the early Cretaceous Period, approximately 152-132 million years ago. Cricosarus belonged to a… 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 ›

Pliosaurus

We all know that dinosaurs walked the earth in prehistoric times, and many of us are also aware that pterosaurs flew across the skies and fearsome marine reptiles swam in the oceans. Some of these marine reptiles (which weren’t dinosaurs,… 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 ›

Leedsichthys

Leedsichthys was a very large prehistoric saltwater fish which lived during the middle and late Jurassic Period, circa 165-150 million years ago. It was named in 1889 in honor of Alfred N. Leeds who found the first specimen. Leedsichthys belonged… Read More ›

Aegirosaurus

Aegirosaurus leptospondylus was a 6 foot long ichthyosaur which lived in the seas around Europe during the late Jurassic Period and early Cretaceous Period, roughly 147-135 million years ago. Aegirosaurus belonged to a family of ichthyosaurs called the ophthalmosaurids (Bardet… Read More ›