Ribs are simple, crossing the venter straight and uninterrupted . " Pleurocephalites ", another possible subgenus of " Macrocephalites, is quite similar.
2.
""'Macrocephalites " "'is a genus of the ammonite family Macrocephalitidae, diagnostic of the Callovian stage of the Middle Jurassic.
3.
""'Indocephalites " "'is a true ammonite ( order Ammonitida ) and a possible subgenus of " Macrocephalites ", belonging to the stephanoceratacean family, Macrocephalitidae.
4.
The base of the Callovian is defined as the place in the stratigraphic column where the ammonite genus " Kepplerites " first appears, which is the base of the biozone of " Macrocephalites herveyi ".
5.
""'Kamptokephalites " "'is more globose than " Macrocephalites "'proper, with a depressed whorl section, wider than high, broadly arched venter, coarse plicate ribbing and wider umbilicus.
6.
"Xenocephalites " can be recognized by its coarsly ribbed, prominently umbilicate, involute shell where in ribs are widely splayed, tending to bifurcate high on the flanks . " Macrocephalites " is similar except that its ribbing is finer and more dense.
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