What is Acanthodii?
{{Taxobox | name = Acanthodii | fossil_range = [[Silurian|Early Silurian]] - [[Permian]] | image = Mesacanthus_Parexus_Ischnacanthus.JPG | image_width = 250px | image_caption = Different extinct fishes of Early Devonian | regnum = [[Animal]]ia | phylum = [[Chordate|Chordata]] | subphylum = [[Vertebrata]] | infraphylum = [[Gnathostomata]] | unranked superclassis = [[Teleostomi]] | classis = '''Acanthodii''' | subdivision_ranks = Orders | subdivision = [[Climatiiformes]]<br/> [[Ischnacanthiformes]]<br/> [[Acanthodiformes]] }} '''Acanthodii''' (sometimes called '''spiny sharks''') is a class of extinct [[fish]]es, having features of both bony fish ([[Osteichthyes]]) and cartilaginous fish ([[Chondrichthyes]]). They appeared in the early [[Silurian]] (430 mya) and lasted until the late [[Permian]] (250 mya). The earliest ancanthodians were marine, but during the [[Devonian]], freshwater species became predominant. They are distinguished in two respects: they were the first known jawed [[vertebrate]]s, and they had stout spines supporting their fins, fixed in place and non-movable (like a [[shark]]'s dorsal fin). ==Other websites== {{commons-inline}}<br/> {{wikispecies-inline}} {{taxonbar|from=Q130955}} {{authority control}} [[Category:Extinct fish]] {{biology-stub}}