Sturia
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''Sturia'' is a genus of
ceratitid Ceratitida is an order that contains almost all ammonoid cephalopod genera from the Triassic as well as ancestral forms from the Upper Permian, the exception being the phylloceratids which gave rise to the great diversity of post-Triassic ammon ...
ammonoid Ammonoids are extinct, (typically) coiled-shelled cephalopods comprising the subclass Ammonoidea. They are more closely related to living octopuses, squid, and cuttlefish (which comprise the clade Coleoidea) than they are to nautiluses (family N ...
s from the Lower Triassic with an ammonitic suture. ''Sturia'' produced a robust, laterally compressed, high whorled, involute shell; whorls strongly embracing. the surface is without ribs or constructions but does have sharp spiral lines. the suture is ammonitic, deeply digitate; lobes and saddles narrowly V-shaped overall. The ventral lobe is divided, 1st lateral lobe is larger than the second, which is followed by a series of auxiliary lobes decreasing in size toward the umbilicus. J.P Smith, 1932, included ''Sturia'' in the
Thalassoceratidae Thalassoceratidae a family of late Paleozoic ammonites included in the goniatitid superfamily Thalassoceratoidea along with the Bisatoceratidae. Some eight genera are included, although the specific number and exactly which depends on the parti ...
, but only tentatively. The American
Treatise on Invertebrate Paleontology The ''Treatise on Invertebrate Paleontology,'' published from 1953–2007 by the Geological Society of America and the University of Kansas, then 2009–present by the University of Kansas Paleontological Institute, is a definitive multi-authore ...
, Part L, 1957, includes ''Sturia'' in the
Ptychitidae The Ptychitidae is a family of ceratitid ammonites (''ammonites sensu lato''). They are combined with the Eosagenitidae and Sturiidae in the superfamily Ptychitoidea. Ptychitid genera have compressed, involute shells in which the inner whorls ...
, along with such genera as '' Ptychites'', '' Discoptychites'', '' Aristoptychites'', and '' Parasturia''. ''Sturia'' is now included in the Sturiidae, established by Kipsarova. 1958, for genera such as already mentioned ''Sturia'', ''Parasturia'', and ''Discoptychites'', notably distinct from genera retained in the Ptychitidae, like ''Ptychites''.


References

* Arkell, W.J. et al., 1957. Mesozoic Ammonoidea. Treatise on Invertebrate Paleontology Part L. Geological Society and University of Kansas Press. * Smith, J.P. 1932. Lower Triassic Ammonoids of North America. US Geological Survey Professional Paper 167.
''Sturia''
in Fossilworks. Ceratitida genera Triassic ammonites Ammonites of Europe {{Ceratitida-stub