''Zenostephanus'' is true ammonite genus from the lower part of the Upper Jurassic of eastern

England England is a Countries of the United Kingdom, country that is part of the United Kingdom. It is located on the island of Great Britain, of which it covers about 62%, and List of islands of England, more than 100 smaller adjacent islands. It ...

and

Scotland Scotland is a Countries of the United Kingdom, country that is part of the United Kingdom. It contains nearly one-third of the United Kingdom's land area, consisting of the northern part of the island of Great Britain and more than 790 adjac ...

belonging to the ammonitid family,

Perisphinctidae Perisphinctidae is a family of Middle and Upper Jurassic discoidal ammonites in the order Ammonitida. They have a shell morphology that is mostly evolute, typically with biplicate, simple, or triplicate ribbing. Large forms have simple aperture ...

. ''Zenostephanus'' is revised from ''Xenostephanus'', a preoccupied name for a new genus of toxodont notoungulate from

Argentina Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...

.Zenostephanus new name
/ref> The type is ''Aulacostephanus ranbyensis''

''References''

* Perisphinctidae ''in the''

Treatise on Invertebrate Paleontology The ''Treatise on Invertebrate Paleontology,'' published from 1953–2007 by the Geological Society of America and the University of Kansas, then 2009–present by the University of Kansas Paleontological Institute, is a definitive multi-authore ...

, Part L, Mollusca 4. Ammonitida genera Perisphinctidae {{Ammonitina-stub