Abstract
Some structural features of the suture line of adult representatives of the family Parkinsoniidae are analyzed. It has been established that in the genera Caumontisphinctes, Pseudocosmoceras, Sokurella and most Rarecostites, the ventral lobe (V) is deeper than the first lateral lobe (U). On the contrary, in the microconchs of the later Rarecostites, as well as in the genera Parkinsonia and Oraniceras, lobe V is smaller than lobe U; in macroconchs they can be of approximately equal depth. Based on data on shell morphogenesis, ornamentation, and the chronostratigraphic succession of taxa, a phylogenetic scheme for the Parkinsoniidae, including Parkinsoniinae Buckman (genera Caumontisphinctes, Rarecostites, Parkinsonia, and Oraniceras), and Pseudocosmoceratinae Sasonov (genera Pseudocosmoceras and Sokurella), is proposed. The assignment of the genus Djanaliparkinsonia to the subfamily Garantianinae (Stephanoceratidae), based on similarity of the sutural outline, is confirmed.
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