What is Archaeothyris?
{{italictitle}} {{Taxobox | name = ''Archaeothyris'' | fossil_range = Upper [[Carboniferous]] | image = Archaeothyris_BW.jpg | image_width = 250px | image_caption = ''Archaeothyris'' | regnum = [[Animal]]ia | phylum = [[Chordate|Chordata]] | superclassis = [[Tetrapod]]a | classis = [[Synapsid]]a | ordo = [[Pelycosauria]] | genus = '''''Archaeothyris''''' | species = '''''A. florensis''''' | binomial = ''Archaeothyris florensis'' | binomial_authority = [[Reisz]], 1972 }} '''''Archaeothyris''''' was one of the earliest definite [[synapsid]]s. It lived in the late [[Carboniferous]] period, 306 million years ago.<ref>Falcon-Lang H.J; Benton M.J. & Stimson M. 2007. Ecology of early reptiles inferred from Lower [[Pennsylvanian]] trackways. ''Journal of the Geological Society'', London, '''164''', #6. 1113-1118 </ref> It shares this fame with another species ('''''Echinerpeton''''') about which little is known. '''''Protoclepsydrops''''' is even slightly older, but only fragments have been found. ''Archaeothyris'' was found in [[Nova Scotia]], in the same area as several other species which were probably [[sauropsid]]s: ''[[Hylonomus]]'', and ''[[Petrolacosaurus]]''. ''Archaeothyris'' belonged to a group of early [[pelycosaur]]s which evolved early in the [[Pennsylvanian]]. It is thus seen as the precursor of all synapsids (which include [[mammal]]s). == Appearance and lifestyle == Unlike the early [[sauropsid]]s, ''[[Hylonomus]]'' and its kin, ''Archaeothyris'' was relatively large, measuring {{convert|50|cm|in}} head to tail. It was also more advanced than the early sauropsids (~[[reptiles]]), with strong jaws that could open wider than those of the sauropsids. Its sharp teeth were all of the same shape, and it had a pair of enlarged [[canine tooth|canine]]s, suggesting that it was a carnivore.<ref name=EoDP>{{cite book |editor=Palmer, D.|year=1999 |title= The Marshall illustrated encyclopedia of dinosaurs and prehistoric animals|url=https://archive.org/details/illustratedencyc0000unse_y8e7|publisher= Marshall