Back to Basics

Look at this cladogram. You'll notice that group of fish from Madagascar come right off the base of the tree. This is called a basal taxon.

These fish are especially important for conservationists because they retain many of the characteristics believed to be present in the ancestral species. This can help biologists identify the factors responsible for variations in groups that have appeared more recently. For its small size, Madagascar is home to many basal taxa (forms of organisms that have retained many of their primitive characteristics).


What is a derived characteristic?

The hoof of a horse is a derived characteristic that evolved from hand-like feet. The fossil record shows how the multiple 'fingers' of a horse slowly became reduced until horses ran on a single digit with a giant fingernail, the hoof.

  • What are basal taxa? Why are these animals so important for evolutionary biologists?
  • Do you think a whale flipper is a primitive or derived characteristic? A bat wing?