Cretaceous Period

Gastonia

Introduction Gastonia was an armored dinosaur measuring approximately 16.5 feet long which lived in western North America during the early Cretaceous Period approximately 135-130 million years ago. The first specimens were found in eastern Utah in 1989, and more have… Read More ›

Thalassomedon

Thalassomedon, meaning “lord of the sea”, was a 38 foot long elasmosaurid plesiosaur which lived within the Mowry Sea, the shallow sea that covered North America during the middle of the Cretaceous Period 97-95 million years ago. In March 1939,… Read More ›

Edgarosaurus

Edgarosaurus was a 12 foot long short-necked plesiosaur which lived within the Mowry Sea during the middle Cretaceous Period 105-100 million years ago. In 1993, a well-preserved fossil specimen consisting of the skull, neck, and one front flipper (collection ID… Read More ›

Brachauchenius

Brachauchenius was a 15 foot long pliosaur which lived in the shallow sea that once covered the middle of North America during the middle Cretaceous Period 100-90 million years ago. Fossils of this animal were first found by Charles H…. Read More ›

Strophodus

Strophodus was a 10 foot long hybodont shark which specialized in eating shellfish. It appeared during the early Jurassic Period and went extinct during the early Cretaceous Period, making it one of the longest-lived shark genera in the fossil record…. Read More ›

Trinacromerum

Trinacromerum was a 12 foot long plesiosaur which lived within the Mowry Sea, the shallow sea that covered North America during the middle of the Cretaceous Period 95 million years ago. The holotype specimen was found in 1888 within the… Read More ›

Cimoliopterus

Introduction Cimoliopterus was pterosaur with a supposed wingspan of 16 feet or thereabouts, which inhabited Europe and North America during the middle of the Cretaceous Period approximately 100-94 million years ago. There are presently two species of this pterosaur genus:… Read More ›

Coloborhynchus

Coloborhynchus was a species of pterosaur which lived in England (and possibly elsewhere) during the early Cretaceous Period approximately 140 million years ago. The first specimen of this animal was found in the 1800s within the Hastings Beds of the… Read More ›

Halecodon

Halecodon denticulatus was a species of prehistoric saltwater fish, which is estimated to have measured 20 inches long, and which lived around 105-98 million years ago within the Mowry Sea which once covered the center of North America during the… Read More ›