Sinemurian genus first appearances

thumb|right|Arietites bucklandi fossil at the Geological Museum in Copenhagen

Eurysaurus (meaning "wide lizard") is an extinct genus of plesiosaur, originally classed as a nothosaur, from the Early Jurassic of Echenoz-la-Meline, France, named in 1878. The type material, consisting of a cranium, teeth and five vertebrae, is now lost. The type species is E. raincourti, and a second species, E. schafferi, was named in 1924 but it has since been absorbed into the unrelated genus Germanosaurus.

Lytoceras is an ammonite genus that was extant during most of the Jurassic and Cretaceous periods, and is the type genus for the family Lytoceratidae. These cephalopods were fast-moving nektonic carnivores.