Late Cretaceous genus first appearances

Baculites is an extinct genus of heteromorph ammonite cephalopods with almost straight shells. The genus, which lived worldwide throughout most of the Late Cretaceous, and which briefly survived the K-Pg mass extinction event, was named by Lamarck in 1799.

Echinocorys is an extinct genus of echinoids that lived from the Late Cretaceous to the Paleocene. The genus belongs to the Holasteridae family. Its remains have been found in Asia, Europe, Australia (Oceania) and North America.

Groebertherium is a genus of dryolestoid mammal from the Late Cretaceous Los Alamitos and Allen Formations of Argentina. It is not closely related to other contemporary dryolestoids, all of which are part of the clade Meridiolestida.

Temnocidaris is an extinct genus of echinoids that lived from the Late Cretaceous to the Paleocene. Its remains have been found in Europe and North America.

Leonardus is an extinct mammal genus from the Late Cretaceous (Late Santonian to Maastrichtian) of South America. It is a meridiolestidan, closely related to the also Late Cretaceous Cronopio and the Miocene Necrolestes.