A new late Carboniferous coleoid from Oklahoma, USA: implications for the early evolutionary history of the subclass Coleoidea (Cephalopoda)

摘要: The limited record of the bactritoid-like coleoid cephalopods is here expanded due to discovery a late Carboniferous (Moscovian) orthocone comprising phragmocone and body chamber with proostracum-like structure, sheath-like rostrum, an ink sac, muscular mantle preserved on top conch. specimen comes from Wewoka Formation in vicinity city Okmulgee, Oklahoma, which previously yielded indicative evolutionary branch described as order Donovaniconida Doguzhaeva, Mapes, Mutvei, 2007a within subclass Coleoidea Bather, 1888. Here, we describe that site coleoid, Oklaconus okmulgeensis n. gen. sp. Oklaconidae fam. A broad lateral lobe suture line compressed conch narrowed dorsal side broadly rounded ventral distinguish this genus Donovaniconus 2002b. dense sheet-like crisscross pattern globular-lamellar ultrastructure. Recent knowledge early coleoids discussed. show high morphological plasticity capacity for being altered create diverse combinations ‘bactritoid’ ‘coleoid’ structures. This could be principle driver their radiation Carboniferous.