''Eowellerites'' is genus of
ammonoid
Ammonoids are extinct, (typically) coiled-shelled cephalopods comprising the subclass Ammonoidea. They are more closely related to living octopuses, squid, and cuttlefish (which comprise the clade Coleoidea) than they are to nautiluses (family N ...
cephalopods belonging to the
Welleritidae
Welleritidae is one of five families of the Schistoceratoidea superfamily. They are an extinct group of ammonoids, which are shelled cephalopods related to squids, belemnites, octopuses, and cuttlefish, and more distantly to the nautiloid
Nau ...
family
Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...
. Species belonging to this genus lived in middle
Pennsylvanian Pennsylvanian may refer to:
* A person or thing from Pennsylvania
* Pennsylvanian (geology)
The Pennsylvanian ( , also known as Upper Carboniferous or Late Carboniferous) is, on the International Commission on Stratigraphy, ICS geologic timesc ...
(
Moscovian
Moscovian may refer to:
*An inhabitant of Moscow, the capital of Russia
*Something of, from, or related to Moscow
*Moscovian (Carboniferous)
The Moscovian is in the International Commission on Stratigraphy, ICS geologic timescale a stage (strat ...
). Its fossils were found in USA and Japan.
It had thinly discoidal shells with a quite wide umbilicus (U/D = 0.3 - 0.5). While in juvenile stages (up to 15 mm in diameter) venter is moderately rounded, it becomes slightly rounded to flattened when becoming mature (100 mm in diameter). 12-lobed suture has adventitious lobe on the first lateral saddle and is also characterized by an addition of an umbilical lobe. Sutural formula is (V
1 V
1) L
1 L (U
1 U
2): I D. It has evolved from ''
Winslowoceras henbesti'' and gave rise to genus ''
Wellerites''.
[Mapes, Royal H., and Furnish W. M. "The Pennsylvanian Ammonoid Family Welleritidae." Journal of Paleontology 55.2 (1981): 317-30. Web.]
Species and distribution
''Eowellerites quinni''
Evolutionary first member of genus ''Eowellerites'' that has evolved from ''Winslowoceras henbesti''. Most diagnostic character of its suture is its weakly developed adventitious lobe in the first lateral saddle. Degree of its evolution is intermediate between ''Winslowoceras henbesti'' and ''Eowellerites moorei''. Weak development of this lobe distinguishes this species from both ''E. moorei'' and ''E. mccalebi''. ''Winslowoceras'' is more primitive in this character.
[
This species has been found in USA (Arkansas) and Japan (Honshu island).]
''Eowellerites mccalebi''
This is species of ''Eowellerites'' with asymmetrical prongs on ventral lobe. It also has broad and nearly symmetrical umbilical lobe. It can be distinguished from ''E. moorei'' by asymmetry of ventral prongs and more symmetrical and inflated umbilical lobe. From ''E. quinni'' it distinguishes by more developed adventitious lobe of first lateral saddle. It has evolved from ''E. quinni''[
It is known from only one locality, which is in USA (Arkansas, Crawford county).]
''Eowellerites moorei''
Type species of this genus. It has evolved from ''E. mccalebi'' and gave rise to genus ''Wellerites''. It differs from ''E. quinni'' by much more developed adventitious lobe of first lateral saddle and longer ventral lobe. ''E. mccalebi'' has more pounch-shaped prong of ventral lobe and more asymmetrical umbilical lobe. Specimens of this species shows two types of shell ornamentation. Sometimes, there is revolving ornamentation that becomes moderately reticulate near, or at the venter. In other cases, there is coarse ventral ornamentation and umbilical ribs. These different forms might be due to sexual dimorphism.[ Eowellerites discoidalis Gordon, 1965 is a synonym of this species based on the same type specimen.]
References
Goniatitida genera
Schistocerataceae
Pennsylvanian ammonites
Ammonites of Asia
Ammonites of North America
Moscovian life
{{Goniatitida-stub