Lithornis
Encyclopedia
Lithornis is a genus
of extinct paleognathous
birds. Lithornis were able to fly well, but are closely related to today's tinamou
s (which are poor flyers) and ratite
s (which are flightless bird
s).
Fossils of Lithornis are known from the Upper Paleocene
through the Middle Eocene. "Lithornis" is from ancient Greek for "stone bird", as it was one of the first fossil birds to become widely discussed. Presumably closely related genera are Paracathartes
, Pediorallus, Promusophaga and Pseudocrypturus
.
have been recognized in modern times, but not all may be valid; undescribed ones are also likely to exist. The supposed tarsometatarsus
piece from which "Lithornis" emuinus was described is actually a humerus
fragment of the giant pseudotooth bird Dasornis
.
Lithornis vulturinus
L. vulturinus was described by Owen (1840) from the holotype fossil 955 738 - TM 024 717. The fossil was collected from Early Eocene London Clay
deposits on the Isle of Sheppey, Kent, England by J. Hunter before 1793. This fossil was destroyed by bombing in World War II
. A neotype was erected by Houde in 1988, and the new fossil has catalog number BMNH A 5204. An exceptionally preserved specimen was collected from Denmark and cataloged as MGUH 26770.
Lithornis hookeri
L. hookeri was first described by Harrison (1984).
Lithornis nasi
L. nasi was described by Harrison (1984),also.
Lithornis celetius
L. celetius is from the Bangtail Quarry, Sedan Quadrangle, Park County, Montana, USA, and was described by Peter Houde (1988). It is from the Fort Union Formation
, which is earliest Tiffanian
, Late Paleocene
. The type fossil is USNM 290601.
Lithornis promiscuus
L. promiscuus has type specimen USNM 336535 and was described by Peter Houde (1988). It is from the Clark Quandrangle, Park County, Wyoming, USA. It is from the Willwood Formation, which is earliest Eocene
in age. An egg, USNM 336570, is known for L. celetius as well.
Lithornis plebius
L. plebius is from the same locality as L. celetius and was also described by Peter Houde (1988). The type specimen is USNM 336534.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of extinct paleognathous
Paleognathae
The Palaeognathae or paleognaths are one of the two living superorders of birds. The other living superorder is Neognathae. Together these two clades form the subclass Neornithes....
birds. Lithornis were able to fly well, but are closely related to today's tinamou
Tinamou
The tinamous are a family comprising 47 species of birds found in Central and South America. One of the most ancient living groups of bird, they are related to the ratites. Generally ground dwelling, they are found in a range of habitats....
s (which are poor flyers) and ratite
Ratite
A ratite is any of a diverse group of large, flightless birds of Gondwanan origin, most of them now extinct. Unlike other flightless birds, the ratites have no keel on their sternum—hence the name from the Latin ratis...
s (which are flightless bird
Flightless bird
Flightless birds are birds which lack the ability to fly, relying instead on their ability to run or swim. They are thought to have evolved from flying ancestors. There are about forty species in existence today, the best known being the ostrich, emu, cassowary, rhea, kiwi, and penguin...
s).
Fossils of Lithornis are known from the Upper Paleocene
Paleocene
The Paleocene or Palaeocene, the "early recent", is a geologic epoch that lasted from about . It is the first epoch of the Palaeogene Period in the modern Cenozoic Era...
through the Middle Eocene. "Lithornis" is from ancient Greek for "stone bird", as it was one of the first fossil birds to become widely discussed. Presumably closely related genera are Paracathartes
Paracathartes
Paracathartes is a genus of extinct bird from the Wasachtian horizon of lower Eocene Wyoming, USA. One species, Paracathartes howardae has been described....
, Pediorallus, Promusophaga and Pseudocrypturus
Pseudocrypturus
Pseudocrypturus is a genus of extinct paleognathous bird. One species is known, Pseudocrypturus cercanaxius. It is a relative of such modern birds as ostriches. It lived in the early Eocene....
.
Species
Six speciesSpecies
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
have been recognized in modern times, but not all may be valid; undescribed ones are also likely to exist. The supposed tarsometatarsus
Tarsometatarsus
The tarsometatarsus is a bone that is found in the lower leg of certain tetrapods, namely birds.It is formed from the fusion of several bones found in other types of animals, and homologous to the mammalian tarsal and metatarsal bones...
piece from which "Lithornis" emuinus was described is actually a humerus
Humerus
The humerus is a long bone in the arm or forelimb that runs from the shoulder to the elbow....
fragment of the giant pseudotooth bird Dasornis
Dasornis
Dasornis is a genus of the prehistoric pseudotooth birds. These were probably rather close relatives of either pelicans and storks, or of waterfowl, and are here placed in the order Odontopterygiformes to account for this uncertainty....
.
Lithornis vulturinus
L. vulturinus was described by Owen (1840) from the holotype fossil 955 738 - TM 024 717. The fossil was collected from Early Eocene London Clay
London Clay
The London Clay Formation is a marine geological formation of Ypresian age which crops out in the southeast of England. The London Clay is well known for the fossils it contains. The fossils from the Lower Eocene indicate a moderately warm climate, the flora being tropical or subtropical...
deposits on the Isle of Sheppey, Kent, England by J. Hunter before 1793. This fossil was destroyed by bombing in World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
. A neotype was erected by Houde in 1988, and the new fossil has catalog number BMNH A 5204. An exceptionally preserved specimen was collected from Denmark and cataloged as MGUH 26770.
Lithornis hookeri
L. hookeri was first described by Harrison (1984).
Lithornis nasi
L. nasi was described by Harrison (1984),also.
Lithornis celetius
L. celetius is from the Bangtail Quarry, Sedan Quadrangle, Park County, Montana, USA, and was described by Peter Houde (1988). It is from the Fort Union Formation
Fort Union Formation
The Fort Union Formation is a geologic unit containing sandstones, shales, and coal beds in Wyoming, Montana, and parts of adjacent states. In the Powder River Basin, it contains important economic deposits of coal, uranium, and coalbed methane....
, which is earliest Tiffanian
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 , typically set from 60,200,000 to 56,800,000 years BP lasting . It is usually considered to overlap the Selandian and Thanetian within the...
, Late Paleocene
Paleocene
The Paleocene or Palaeocene, the "early recent", is a geologic epoch that lasted from about . It is the first epoch of the Palaeogene Period in the modern Cenozoic Era...
. The type fossil is USNM 290601.
Lithornis promiscuus
L. promiscuus has type specimen USNM 336535 and was described by Peter Houde (1988). It is from the Clark Quandrangle, Park County, Wyoming, USA. It is from the Willwood Formation, which is earliest Eocene
Eocene
The Eocene Epoch, lasting from about 56 to 34 million years ago , is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era. The Eocene spans the time from the end of the Palaeocene Epoch to the beginning of the Oligocene Epoch. The start of the...
in age. An egg, USNM 336570, is known for L. celetius as well.
Lithornis plebius
L. plebius is from the same locality as L. celetius and was also described by Peter Houde (1988). The type specimen is USNM 336534.