👉 The term "liassic" refers to a group of fossilized organisms that lived during the Late Cretaceous period, approximately 65 million years ago. This group includes fossils such as ammonites, which are characterized by their long, slender bodies with sharp teeth and claws, and were one of the first groups of vertebrates to evolve in this time frame. The term "liassic" is derived from the Latin word "ligia," which means "to be" or "of the