Evolution of fish
The evolution of fish began about 530 million years ago during the Cambrian explosion. One of the earliest jawless fish include Haikouichthys, a craniate. The conodonts were another Agnatha. The earliest jawed vertebrates developed during the late Ordovician period.
During the Devonian period, a great increase in fish variety occurred, especially among the ostracoderms and placoderms, and also among the lobe-finned fish and early sharks, which meant that this was the age of fishes.
The Agnatha (meaning "no jaws") is a superclass of fish in the phylum Chordata, subphylum Vertebrata. Agnatha comes from the Greek. The first armoured agnathans were the ostracoderms, precursors to the bony fish and hence to the tetrapods.
Main article: Chondrichthyes
Extinct cartilaginous fishes change
Living fossils change
Main article: Living fossil
Bony fish change
Main article: Actinopterygii
Main article: Sarcopterygii
The first tetrapodomorphs, which included the rhizodonts, had the same general anatomy as the lungfish, who were their closest kin, but they appear not to have left their water habitat until the late Devonian epoch (385 - 359 Ma), with the first appearance of tetrapods.
Devonian fish change
Main article: Placoderm
Main article: Dunkleosteus
Main article: Materpiscis
Related pages change
- Lecointre, G; Le Guyader, H (2007). The Tree of Life: A Phylogenetic Classification. Harvard University Press Reference Library.
- Haines, Tim; Chambers, Paul (2005). The Complete Guide to Prehistoric Life. Firefly Books.
Other websites change
- Evolution of fish on English Wikipedia