mammal
A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three ...
s that existed in the
late Paleocene
The Thanetian is, in the International Commission on Stratigraphy, ICS Geologic timescale, the latest age (geology), age or uppermost stage (stratigraphy), stratigraphic stage of the Paleocene epoch (geology), Epoch or series (stratigraphy), Serie ...
and
early Eocene
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 ...
epochs
In chronology and periodization, an epoch or reference epoch is an instant in time chosen as the origin of a particular calendar era. The "epoch" serves as a reference point from which time is measured.
The moment of epoch is usually decided by ...
. The
type species
In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...
Wyoming
Wyoming ( ) is a landlocked U.S. state, state in the Mountain states, Mountain West subregion of the Western United States, Western United States. It borders Montana to the north and northwest, South Dakota and Nebraska to the east, Idaho t ...
during the
Clarkforkian
The Clarkforkian North American Stage, on the geologic timescale, is the North American faunal stage according to the North American Land Mammal Ages chronology (NALMA), typically set from 56,800,000 to 55,400,000 years BP lasting .
Considered t ...
North American Land Mammal Age
The North American land mammal ages (NALMA) establishes a geologic timescale for North American fauna beginning during the Late Cretaceous and continuing through to the present. These periods are referred to as ages or intervals (or stages when ref ...
of the Paleocene and was originally proposed to be an early form of
insectivorous bat
A robber fly eating a hoverfly
An insectivore is a carnivorous animal or plant which eats insects. An alternative term is entomophage, which can also refer to the human practice of eating insects.
The first vertebrate insectivores wer ...
. Later re-examination of the material has put this alliance in doubt, and the genus has instead been proposed as belonging to the subfamily Placentidentinae, within the family
Nyctitheriidae
Nyctitheriidae is a family of extinct eulipotyphlan insectivores known from the Paleocene and Eocene Epoch, epochs of North America and Asia and persisting into the Oligocene of Europe. Several genera, including ''Nyctitherium'', ''Paradoxonycter ...
. Similar
fossil
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...
material of the same time period found in
Europe
Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...
was later discovered and described as new species, ''Wyonycteris richardi''.
Secord (2008) described the first known species of ''Wyonycteris'' from the
Tiffanian
The Tiffanian North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology (NALMA), typically set from 60,200,000 to 56,800,000 years BP lasting .
It is usually co ...
NALMA
The North American land mammal ages (NALMA) establishes a geologic timescale for North American fauna beginning during the Late Cretaceous and continuing through to the present. These periods are referred to as ages or intervals (or stages when ref ...
, ''Wyonycteris galensis'' and ''W. microtis'', although the status of both species as members of ''Wyonycteris'' has been questioned. The two largest species, ''W. primitivus'' and ''W. kingi'', are known from the early Eocene of
Mississippi
Mississippi ( ) is a U.S. state, state in the Southeastern United States, Southeastern and Deep South regions of the United States. It borders Tennessee to the north, Alabama to the east, the Gulf of Mexico to the south, Louisiana to the s ...
and
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 ...
, respectively.
Evolutionary relationships
''Wyonycteris'' is only known from dental remains. It is characterized by W-shaped crests on the outer side of the upper
molars
The molars or molar teeth are large, flat tooth, teeth at the back of the mouth. They are more developed in mammal, mammals. They are used primarily to comminution, grind food during mastication, chewing. The name ''molar'' derives from Latin, '' ...
, a trait that it shares with most insectivorous bats. However, ''Wyonycteris'' possesses a number of additional cusps on the upper molars that are not present in bats leading many researchers to conclude that it is more closely related to the extinct insectivorous family Nyctitheriidae. A recent
phylogenetic
In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...
analysis found most species of ''Wyonycteris'' to be within the family Nyctitheriidae, most closely related to the genus ''Pontifactor.'' ''Wyonycteris microtis'' was found to be very distantly related to the other species of ''Wyonycteris'', outside the family Nyctitheriidae and more closely related mammal to
bats
Bats are flying mammals of the order Chiroptera (). With their forelimbs adapted as wings, they are the only mammals capable of true and sustained flight. Bats are more agile in flight than most birds, flying with their very long spread-out ...
alongside genus '' Eosoricodon''.
Rose et al. (2012) compared ''Wyonycteris'' to the genus '' Plagioctenoides'' and concluded that the two may in fact belong to the same genus. If this is the case, the correct genus name would be ''Plagioctenoides'' since it was formally named first.
Distribution
;Paleocene
*
Tiffanian
The Tiffanian North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology (NALMA), typically set from 60,200,000 to 56,800,000 years BP lasting .
It is usually co ...
**
Polecat Bench Formation
The Polecat Bench Formation is a geologic formation in Montana.
It preserves fossils dating back to the Paleogene period.D. E. Russell. 1967. Le Paleocene continental d'Amerique du nord. Memoires du Museum National d'Histoire Naturelle. Serie C. ...
, Wyoming
*
Clarkforkian
The Clarkforkian North American Stage, on the geologic timescale, is the North American faunal stage according to the North American Land Mammal Ages chronology (NALMA), typically set from 56,800,000 to 55,400,000 years BP lasting .
Considered t ...
**
Willwood Formation
The Willwood Formation is a sedimentary sequence deposited during the late Paleocene to early Eocene, or Clarkforkian, Wasatchian and Bridgerian in the NALMA classification.Tienen Formation The Tienen Formation (; ; abbreviation: Ti) is a geologic formation in the subsurface of northern Belgium. The formation crops out in the province of Hainaut and the Hesbaye region in the province of Limburg. It has a late Thanetian (Paleocene) t ...
, Belgium
*
Woolwich
Woolwich () is a town in South London, southeast London, England, within the Royal Borough of Greenwich.
The district's location on the River Thames led to its status as an important naval, military and industrial area; a role that was mainta ...
Wasatchian
The Wasatchian North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology (NALMA), typically set from 55,400,000 to 50,300,000 years Before Present, BP lasting .
I ...