Cetancodontamorpha

Cetancodontamorpha is a clade of even-toed ungulates that includes modern cetaceans (whales, dolphins, and porpoises) and hippopotamuses. The name refers to the close evolutionary relationship between these two seemingly disparate groups, a connection that was not widely accepted until relatively recently. Fossil evidence, particularly from the early Eocene, has been crucial in understanding this lineage. Key fossil groups like the raoellids, small amphibious artiodactyls, are considered among the earliest ancestors of cetaceans. The inclusion of hippos within this group, alongside the obligate aquatic cetaceans, highlights the complex and sometimes surprising pathways of evolutionary history. This classification is based on morphological and molecular data, with genetic studies strongly supporting the monophyly of Cetancodontamorpha. The extinct cetancodonts, such as Andrewsarchus, were once thought to be closely related to hippos, but current phylogenetic analyses place them in a broader context. The study of Cetancodontamorpha continues to shed light on the diversification of mammals and the evolutionary transitions that have occurred over millions of years.