section_path: Phylogeny/External phylogeny
section_name: External phylogeny
paragraph_text: External phylogeny
  
  Animals are monophyletic, meaning they are derived from a common ancestor. Animals are the sister group to the choanoflagellates, with which they form the Choanozoa. The dates on the phylogenetic tree indicate approximately how many millions of years ago (mya) the lineages split.
  
  Ros-Rocher and colleagues (2021) trace the origins of animals to unicellular ancestors, providing the external phylogeny shown in the cladogram. Uncertainty of relationships is indicated with dashed lines.