What is Acanthostega?
{{Italic title}} {{taxobox | colour = lightgreen | name = ''Acanthostega'' | fossil_range = [[Devonian]] 365 mya | image = Acanthostega gunnari.jpg | image_caption = ''Acanthostega gunnari'' skeleton reconstruction | regnum = [[Animal]]ia | phylum = [[Chordate|Chordata]] | subphylum = [[Vertebrate|Vertebrata]] | superclassis = [[Osteichthyes]] | classis = [[Sarcopterygii]] | subdivision_ranks = [[Tetrapodomorpha]] | subdivision = * [[Tetrapodomorpha]] – [[Tetrapod]]s | binomial = ''Acanthostega gunnari'' | binomial_authority = Jarvik, 1952 }} '''''Acanthostega''''' (meaning 'spiny roof') was an extinct [[fishapod]]. It was one of the first [[vertebrates]] to have recognizable [[limb]]s. It appeared in the Upper [[Devonian]] about 365 million years ago, and was anatomically intermediate between [[lobe-finned fish]]es and the first tetrapods fully capable of coming onto land.<ref name=SciAm>[[Jennifer Clack]], ''Scientific American'', [http://sciam.com/print_version.cfm?articleID=000DC8B8-EA15-137C-AA1583414B7F0000 ''Getting a leg up on land''] {{Webarchive|url=https://web.archive.org/web/20071018170618/http://sciam.com/print_version.cfm?articleID=000DC8B8-EA15-137C-AA1583414B7F0000 |date=2007-10-18 }} November 2005.</ref> ==Description== [[File:Acanthostega model.jpg|right|thumb|Model reconstruction of ''Acanthostega'' at State Museum of Natural History in [[Stuttgart]], Germany]] [[File:Acanthostega gunnari - head.JPG|thumb|Skull of ''Acanthostega gunnari''.]] ''Acanthostega'' had eight digits on each hand linked by webbing, and six digits on the rear legs. It had no wrists to support the animal's weight on land. ''Acanthostega'' also had a remarkably fish-like shoulder and forelimb.<ref>[http://www.devoniantimes.org/Order/re-acanthostega.html Acanthostega gunneri] {{Webarchive|url=https://web.archive.org/web/20100110072538/http://www.devoniantimes.org/Order/re-acanthostega.html |date=2010-01-10 }} ''Devonian Times''.</ref> The front foot of ''Acanthostega'' could not bend forward at the elbow, and so could