Karagandoceratids are a rare offshoot of the Prionoceratinae, resembling that subfamily in general conch form and sutural ontogeny, but differing by possession of an acute ventral margin and an increasingly trifid ventral lobe. The systematic position of the Karagandoceratidae has been controversial [see Bartzsch and Weyer (1988) for an exhaustive review]. The nominate genus, KaragandocerasLibrovitch, 1940 (type species, K. galeatum), possesses a weakly divided ventral lobe which has led authors to refer it to both the Praeglyphioceratina (Ruzhencev, 1960, 1962; Bogoslovsky, 1971; Ruzhencev and Bogoslovskaya, 1978; Bogoslovskaya et al., 1999; Kusina, 2000...
MASONOCERAS, A NEW KARAGANDOCERATID AMMONOID FROM THE LOWER MISSISSIPPIAN (LOWER OSAGEAN) OF KENTUCKY
DAVID M. WORK, WALTER L. MANGER; MASONOCERAS, A NEW KARAGANDOCERATID AMMONOID FROM THE LOWER MISSISSIPPIAN (LOWER OSAGEAN) OF KENTUCKY. Journal of Paleontology ; 76 (3): 574–577. doi: https://doi.org/10.1666/0022-3360(2002)076<0574:MANKAF>2.0.CO;2
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