The ammonite Stoliczkaia from the Cenomanian of England and northern France
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Stoliczkaia Neumayr, 1875, a predominantly Upper Albian genus of world-wide occurrence, is represented in the Lower Cenomanian of England and northern France by a species of the subgenus S. (Shumarinaia) Matsumoto and Inoma, 1975, and by two species referred to a new subgenus, S. (Lamnayella) Wright and Kennedy nov. This new subgenus is shown to include the previously described S. texana (Cragin), S. uddeni Bose, S. crotaloides (Stoliczka), and S. clavigera Neumayr. S. (Lamnayella) probably evolved from S. (Stoliczkaia) by development of juvenile stages with a more markedly fastigiate venter, a feeble siphonal tubercle, middle growth stages with markedly bullate narrow strong ribs which either branch from bullae or are intercalated between primaries, and a mature stage with strong, distant, narrow, predominantly long ribs. It is an independent development parallel to, but distinct from, the contemporaneous Paracalycoceras Spath, 1925.
Palaeontology - Volume 21 Part 2 Pages 393-409Palaeontology - Volume 21 Part 2 Pages 393-409
Citations
WRIGHT, C. W., KENNEDY, W. J. 1978. The ammonite Stoliczkaia from the Cenomanian of England and northern France. Palaeontology, 21, 2, 393–409.