Early Cretaceous genus first appearances

Adocus is an extinct genus of aquatic turtles belonging to the family Adocidae.

Tylocidaris is an extinct genus of sea urchins that lived from the Early Cretaceous to the Eocene. Its remains have been found in Europe and North America.

Holcodiscus is an extinct ammonite genus placed in the family Holcodiscidae. Species in this genus were fast-moving nektonic carnivores. The type species of the genus is Ammonites caillaudianus.