We are all familiar with many of the animal classifications such as mammals, insects, arachnids, mollusks, etc. But I sometimes wonder, are there fossil records of animal classifications that no longer exist today?

Datsmeharse

Going up the Taxonomic Scale, http://en.wikipedia.org/wiki/Taxonomic_rank obviously there's thousands of extinct ranks at the bottom with numerous fossil records. Towards the top, differences in the classification process make it debatable as to whether a certain fossil record is of an extinct rank or not: Even as high as the Kingdom level, fossil records of Vendobionta and Psammocorallia are argued by some to be an entire extinct Kingdom: http://jgs.lyellcollection.org/cgi/content/abstract/149/4/607 Another link: http://74.6.239.67/search/cache?ei=UTF-8&p=%22extinct+kingdom%22+of+animals&fr=yfp-t-501&u=www.sciencenews.org/pages/pdfs/data/1998/154-06/15406-20.pdf&w=%22extinct+kingdom%22+animals&d=Zupq9xlMS8aC&icp=1&.intl=us But even a rank down at Phyla, some dispute that known fossils belong to a distinct Phylum at all: http://palaeo-electronica.org/2001_1/editor/pe_ed.htm But the large majority of sources state there are numerous phyla extinct, with fossil record. It appears that the dispute comes from the classification process, since the higher up you go, the easier it is to lump a Family with a Class, a Class with a Phylum, a Phylum with a Kingdom, etc. http://www.fossilmuseum.net/Paleobiology/CambrianFossils.htm So if one agrees that there are numerous extinct Phyla, then certainly there'd be numerous extinct Class, the rank which you referenced in your question. Keep in mind that new classifications can be made only with known fossils, which can be as small as a single cell. http://en.wikipedia.org/wiki/Fossil Jun 19 09, 2:17 PM