Holmiceras is one of two ancestral lituitids from the late Early Ordovician (Arenigian). The other being Ancistroceras.
Holmiceras begins with about 1.5 to 2 loosely coiled whorls followed by a rapidly expanding orthocone, much like Ancistroceras except for the apical whorls and that Holmiceras is known only from the late Early Ordovician whereas Ancestroceras extends through the middle of the period.
Holmiceras may have given rise to Angelinoceras which begins with an expanding open spiral.
Holmiceras is one of two ancestral lituitids from the late Early Ordovician (Arenigian). The other being Ancistroceras. Holmiceras begins with about 1...
described, all from the Baltic region of northern Europe. One genus, Holmiceras, is limited to the Lower Ordovician and one, Ancistroceras, comes from...
groups, based on general form. One is represented by Ancistroceras and Holmiceras and probably includes Angelinoceras. The other is represented by Litoceras...
lituitids from the late Early Ordovician (Arenigian). The other being Holmiceras. The shell is weakly annulate, starts off with 1.5 to 2 contiguous or...
straight-shelled adult portion. Angelinoceras is most likely derived from Holmiceras by a further opening of the initial spiral and a reduction in the expansion...
member of the family Rhiphaeoceratidae. The type species is E. venustum. Holmiceras havelense Sp. nov Valid Aubrechtová & Korn Ordovician (Darriwilian) Upper...
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