''Promicroceras'' is an extinct

ammonite Ammonoids are a group of extinct marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs, commonly referred to as ammonites, are more closely related to living coleoids (i.e., octopuses, squid and cuttlefish) ...

genus from the upper Sinemurian ( Lower Jurassic) of Europe, named by Leonard Spath in 1925. ''Promicroceras'' is included in the family

Eoderoceratidae Eoderoceratidae is the ancestral and most primitive family of the Eoderoceratoidea; lower Jurassic ammonite cephalopods, characterized by evolute, commonly serpenticonic, shells that had long body chambers and would have had no stable floating ...

, which is part of the ammonitid superfamily

Eoderoceratoidea Eoderoceratoidea is a superfamily of true ammonites (suborder Ammonitina) from the Lower Jurassic, comprising seven phylogenetically related families, characterized in general by having ribbed evolute shells that commonly bear spines or tubercle ...

. Shells are evolute with an open umbilicus; strongly ribbed, ribs flattened on the venter, and with small spines without distinct tubercles.

Distribution

''Promicroceras'' species are commonly found in South West England, particularly along the Dorset coast. Pyritic ''Promicroceras'' fossils are commonly found along the coast of Lyme Regis and Charmouth where they are well preserved in the Lower Jurassic (Sinemurian)

Black Ven Black Ven is a cliff in Dorset, England between the towns of Charmouth and Lyme Regis. The cliffs reach a height of . It is part of the Jurassic Coast World Heritage Site. Nearby is an undercliff with an ammonite pavement. The area is popular wit ...

Marl Marl is an earthy material rich in carbonate minerals, clays, and silt. When hardened into rock, this becomes marlstone. It is formed in marine or freshwater environments, often through the activities of algae. Marl makes up the lower part o ...

. Fossil shops in the area commonly sell cleaned and polished ''Promicroceras''.

References

;Notes ;Bibliography * Treatise on Invertebrate Paleontology, Part L Ammonoidea ; Geological Society of America and Univ of Kansas press, 5th printing,1990. (L345-347) * Die Ammoniten des süddeutschen Lias. Ein Bestimmungsbuch für Fossiliensammler und Geologe.

External links

Nature article on promicroceras growth

Blogs about: Promicroceras Marstonensis
Jurassic ammonites Early Jurassic ammonites of Europe Fossil taxa described in 1925 Ammonitida genera Eoderoceratoidea {{ammonite-stub