Promicroceras
Encyclopedia
Promicroceras is an extinct ammonite
genus from the upper Sinemurian
(middle Lower Jurassic) of Europe, named by Leonard Spath
in 1925. Promicroceras is included in the family Eoderoceratidae
, which is part of the ammonitid superfamily Eoderocerataceae
. The type is P. planicosta from England.
Shells are evolute with an open umbilicus; strongly ribbed, ribs flattened on the venter, and with small spines without distinct tubercle
s.
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
where they are well preserved in the Lower Jurassic (Sinemurian) Black Ven
Marl
. Fossil shops in the area commonly sell cleaned and polished Promicroceras.
Ammonite
Ammonite, as a zoological or paleontological term, refers to any member of the Ammonoidea an extinct subclass within the Molluscan class Cephalopoda which are more closely related to living coleoids Ammonite, as a zoological or paleontological term, refers to any member of the Ammonoidea an extinct...
genus from the upper Sinemurian
Sinemurian
In the geologic timescale, the Sinemurian is an age or stage in the Early or Lower Jurassic epoch or series. It spans the time between 196.5 ± 2 Ma and 189.6 ± 1.5 Ma...
(middle Lower Jurassic) of Europe, named by Leonard Spath
Leonard Frank Spath
Leonard Frank Spath was a British paleomalacologist and an ammonitologist, a specialist of ammonites.He gained a B.Sc in geology at Birkbeck College in 1912 and obtained employment at the British Museum as an assistant curator in the geology department...
in 1925. Promicroceras is included in the family Eoderoceratidae
Eoderoceratidae
The Eoderoceratidae is the ancestral and most primitive family of the Eoderocerataceae; lower Jurassic ammonite cephalopods, characterized by evolute, commonly serpenticonic, shells that had long body chambers and would have had no stable floating position; and thus resemble contemporary...
, which is part of the ammonitid superfamily Eoderocerataceae
Eoderocerataceae
Eoderocerataceae is a superfamily of true ammonites from the Lower Jurassic, comprising seven phylogenetically related families, characterized in general by having ribbed evolute shells that commonly bear spines or tubercles...
. The type is P. planicosta from England.
Shells are evolute with an open umbilicus; strongly ribbed, ribs flattened on the venter, and with small spines without distinct tubercle
Tubercle
A tubercle is generally a wart-like projection, but it has slightly different meaning depending on which family of plants or animals it is used to refer to....
s.
Promicroceras species are commonly found in South West England
South West England
South West England is one of the regions of England defined by the Government of the United Kingdom for statistical and other purposes. It is the largest such region in area, covering and comprising Bristol, Gloucestershire, Somerset, Dorset, Wiltshire, Devon, Cornwall and the Isles of Scilly. ...
, particularly along the Dorset
Dorset
Dorset , is a county in South West England on the English Channel coast. The county town is Dorchester which is situated in the south. The Hampshire towns of Bournemouth and Christchurch joined the county with the reorganisation of local government in 1974...
coast. Pyritic
Pyrite
The mineral pyrite, or iron pyrite, is an iron sulfide with the formula FeS2. This mineral's metallic luster and pale-to-normal, brass-yellow hue have earned it the nickname fool's gold because of its resemblance to gold...
Promicroceras fossils are commonly found along the coast of Lyme Regis
Lyme Regis
Lyme Regis is a coastal town in West Dorset, England, situated 25 miles west of Dorchester and east of Exeter. The town lies in Lyme Bay, on the English Channel coast at the Dorset-Devon border...
where they are well preserved in the Lower Jurassic (Sinemurian) Black Ven
Black Ven
Black Ven is a cliff in Dorset, England. It is part of the Jurassic Coast World Heritage site. The cliff is famous for its mudslides, in fact, it has the largest mudslides in Europe. The area is popular with tourists because a number of fossils are found in the area.- History :The Black Ven has...
Marl
Marl
Marl or marlstone is a calcium carbonate or lime-rich mud or mudstone which contains variable amounts of clays and aragonite. Marl was originally an old term loosely applied to a variety of materials, most of which occur as loose, earthy deposits consisting chiefly of an intimate mixture of clay...
. Fossil shops in the area commonly sell cleaned and polished Promicroceras.