''Aconeceras'' is an early

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...

ammonite included in the oppeliid subfamily Aconeceratidae, characterized by an involute, high-whorled, flat-sided shell that bears a finely serrate keel along the venter. Sutures have narrower and deeper elements than in '' Protaconeceras''. ''Aconeceras'' has been found in western Europe, South Africa, and eastern Australia. Its stratigraphic range is from the Upper Barramian to the Lower

Albian The Albian is both an age of the geologic timescale and a stage in the stratigraphic column. It is the youngest or uppermost subdivision of the Early/Lower Cretaceous Epoch/Series. Its approximate time range is 113.0 ± 1.0 Ma to 100.5 ± 0.9 M ...

References

Arkell ''et al.'', 1957 Mesozoic Ammonoidea, Treatise on Invertebrate Paleontology Part L. Geol Society of America and Univ Kansas Press R.C Moore (ed) 1957 Early Cretaceous ammonites Ammonitida genera Haploceratoidea Ammonites of Australia {{Ammonitina-stub