''Amylodon'' is an extinct

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

chimaera Chimaeras are Chondrichthyes, cartilaginous fish in the order (biology), order Chimaeriformes (), known informally as ghost sharks, rat fish (not to be confused with rattails), spookfish, or rabbit fish; the last two names are also applied to B ...

. It consists of four described species. ''A. karamysh'' is known from the latest early

Campanian The Campanian is the fifth of six ages of the Late Cretaceous epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campa ...

Russia Russia, or the Russian Federation, is a country spanning Eastern Europe and North Asia. It is the list of countries and dependencies by area, largest country in the world, and extends across Time in Russia, eleven time zones, sharing Borders ...

, the name being derived from the Karamysh River which runs near the type locality. In the

Eocene The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes ...

, two species are known. ''A. venablesae'' and ''A. eocenica'' are both known from the

Ypresian In the geologic timescale the Ypresian is the oldest age (geology), age or lowest stage (stratigraphy), stratigraphic stage of the Eocene. It spans the time between , is preceded by the Thanetian Age (part of the Paleocene) and is followed by th ...

-aged

London Clay The London Clay Formation is a Sediment#Shores and shallow seas, marine formation (geology), geological formation of Ypresian (early Eocene Epoch, c. 54-50 million years ago) age which outcrop, crops out in the southeast of England. The London C ...

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 ...

. A mandibular plate originally ascribed to the latter was found in the

Bartonian The Bartonian is, in the International Commission on Stratigraphy's (ICS) geologic time scale, a stage or age in the middle of the Eocene Epoch or Series. The Bartonian Age spans the time between . It is preceded by the Lutetian and is follow ...

of the Barton Beds of

, though later found not to fit with any described species. ''A. delheidi'' is known from the

Rupelian The Rupelian is, in the geologic timescale, the older of two age (geology), ages or the lower of two stage (stratigraphy), stages of the Oligocene epoch (geology), Epoch/series (stratigraphy), Series. It spans the time between . It is preceded b ...

-aged Boom Clay of

Belgium Belgium, officially the Kingdom of Belgium, is a country in Northwestern Europe. Situated in a coastal lowland region known as the Low Countries, it is bordered by the Netherlands to the north, Germany to the east, Luxembourg to the southeas ...

. All species are known mainly from isolated mandibles. They show a slow progressing towards increased shearing ability. ''Amylodon'' was considered to be a member of

Chimaeridae The Chimaeridae, or short-nosed chimaeras, are a family (biology), family of cartilaginous fish. They resemble other Chimaeriformes, chimaeras in general form and habits, but have short, rounded snouts, without the modifications found in relate ...

in Nessov and Averianov, 1996 but other studies have either been assigned to the "Edaphodontidae", or to the

Rhinochimaeridae The Rhinochimaeridae, commonly known as long-nosed chimaeras, are a family (biology), family of cartilaginous fish. They are similar in form and habits to other chimaeras, but have an exceptionally long conical or paddle-shaped snout. The snout h ...

References

Chimaeridae Prehistoric cartilaginous fish genera {{paleo-holocephalan-stub