vertebrate

Any animal with a backbone. The 41,000 species of vertebrates include mammals, birds, reptiles, amphibians, and fishes. They include most of the larger animals, but in terms of numbers of species are only a tiny proportion of the world's animals. The zoological taxonomic group Vertebrata is a subgroup of the phylum Chordata.

In 2003, palaeontologists in Australia reported the discovery of the world's earliest vertebrate. Discovered in the Flingers Ranges of South Australia, the 66-cm/26-in fishlike fossil was dated to at least 560 million years old, around 30 million years older than previously thought for a vertebrate fossil. Prior to this find, a giant fossil conodont (an eel-like organism from the Cambrian period), discovered in South Africa in 1995, was thought to be one of the first vertebrates; conodonts evolved 520 million years ago, pre-dating the earliest fish by about 50 million years.