''Eowellerites'' is genus of

ammonoid 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) ...

cephalopods belonging to the Welleritidae

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

. Species belonging to this genus lived in middle Pennsylvanian (

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 (strati ...

). 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 (V₁ V₁) L¹ L (U₁ U₂): 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. Fossils of this species were found in USA (Arkansas and Texas) and Japan (Honshu island).

References

Goniatitida genera Schistocerataceae Pennsylvanian ammonites Ammonites of Asia Ammonites of North America Moscovian life {{Goniatitida-stub