Carnian genus first appearances

Placerias (meaning 'broad body') is an extinct genus of dicynodonts that lived during the Carnian and Norian stages of the Triassic period (230–215 million years ago). Placerias belongs to a clade of dicynodonts called Kannemeyeriiformes, which was the last known group of dicynodonts before the taxon became extinct at the end of the Triassic.

Shastasaurus ("Mount Shasta lizard") is an extinct genus of ichthyosaur from the Late Triassic. Specimens have been found in the United States, Canada, and China.

Poposaurus is an extinct genus of pseudosuchian archosaur from the Late Triassic of the southwestern and eastern United States. It belongs to the clade Poposauroidea, an unusual group of Triassic pseudosuchians that includes sail-backed, beaked, and aquatic forms. Fossils have been found in Wyoming, Utah, Arizona, Texas, and Virginia. Except for the skull, most parts of the skeleton are known. The type species, P. gracilis, was described and named by Maurice Goldsmith Mehl in 1915. A second species, P. langstoni, was originally the type species of the genus Lythrosuchus. Since it was first des

thumb|350x350px|Silicified Gryphaea sp. from the Lower Jurassic. Le Liquier, Aveyron, France. Max Rouger collection. Gryphaea, one of the genera known as '''devil's toenails''', is a genus of extinct oysters, marine bivalve mollusks in the family Gryphaeidae.