Presbyornis
Encyclopedia
Presbyornis is an extinct genus of anseriform
bird. It contains two unequivocally accepted species
; the well-known P. pervetus and the much lesser-known P. isoni. P. pervetus was approximately the size and shape of a goose
, but with longer legs; P. isoni, known from a few bones, was much larger, more than swan
-sized. Other fossils, more doubtfully assigned to this genus, are also known.
sites (Early Eocene
), suggesting that the birds nested in colonies and possibly were liable to succumb to botulism, similar to many colony-nesting waterfowl
or shorebirds today. P. isoni is known from the Late Paleocene
Aquia Formation
(Maryland
, 61-62 MYA) humerus (USNM
294116) and a fingerbone (USNM 294117) that were initially described, as well as from the humeri that were initially believed to be from Headonornis (BMNH
PAL 3686, 5105, 6240). As these are Late Eocene or even Early Oligocene
(BMNH PAL 5105, Bembridge Marls) in age, they possibly belong to a distinct taxon.
P. recurvirostris is a disputed species possibly synonymous with P. pervetus; it is known from a partial wing (KUVP
10105) found in Colton Formation Eocene
sediments of the Wasatch Plateau near Ephraim, Utah
. Undescribed fossils are also known from the Paleocene of Utah
and possibly the Early Eocene of Mongolia
. The coracoid still assigned to Headonornis may also belong into this genus.
. Because of its long legs and neck, Presbyornis was initially mistaken for a flamingo
, but it was reclassified as an anseriform when the duck
-like anatomy of its skull
and bill
was found. Later, it was believed to represent a transitional stage between the anseriforms and the shorebirds, but it is now considered a member of an extinct group of anseriforms
which was most closely related to ducks and geese
. Judging from numerous fossil
findings, Presbyornis is presumed to have lived in colonies around shallow lakes. Its broad, flat bill was used to filter food (small plants and animals) from the water, in the manner of today's dabbling ducks.
Anseriformes
The order Anseriformes contains about 150 living species of birds in three extant families: the Anhimidae , Anseranatidae , and the Anatidae, which includes over 140 species of waterfowl, among them the ducks, geese, and swans.All species in the order are highly adapted for an aquatic existence at...
bird. It contains two unequivocally accepted species
Species
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...
; the well-known P. pervetus and the much lesser-known P. isoni. P. pervetus was approximately the size and shape of a goose
Goose
The word goose is the English name for a group of waterfowl, belonging to the family Anatidae. This family also includes swans, most of which are larger than true geese, and ducks, which are smaller....
, but with longer legs; P. isoni, known from a few bones, was much larger, more than swan
Swan
Swans, genus Cygnus, are birds of the family Anatidae, which also includes geese and ducks. Swans are grouped with the closely related geese in the subfamily Anserinae where they form the tribe Cygnini. Sometimes, they are considered a distinct subfamily, Cygninae...
-sized. Other fossils, more doubtfully assigned to this genus, are also known.
Fossils
The fossil record of P. pervetus includes many complete skeletons from Green River FormationGreen River Formation
The Green River Formation is an Eocene geologic formation that records the sedimentation in a group of intermountain lakes. The sediments are deposited in very fine layers, a dark layer during the growing season and a light-hue inorganic layer in winter. Each pair of layers is called a varve and...
sites (Early 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...
), suggesting that the birds nested in colonies and possibly were liable to succumb to botulism, similar to many colony-nesting waterfowl
Waterfowl
Waterfowl are certain wildfowl of the order Anseriformes, especially members of the family Anatidae, which includes ducks, geese, and swans....
or shorebirds today. P. isoni is known from 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...
Aquia Formation
Aquia Formation
The Aquia Formation is a Paleocene fossil site located near the Potomac River in Maryland and Virginia.-Sharks:*Carcharias hopei*Cretolamna*Otodus obliquus*Paleohypotodus rutoti*Striatolamia striata*Squalus...
(Maryland
Maryland
Maryland is a U.S. state located in the Mid Atlantic region of the United States, bordering Virginia, West Virginia, and the District of Columbia to its south and west; Pennsylvania to its north; and Delaware to its east...
, 61-62 MYA) humerus (USNM
Smithsonian Institution
The Smithsonian Institution is an educational and research institute and associated museum complex, administered and funded by the government of the United States and by funds from its endowment, contributions, and profits from its retail operations, concessions, licensing activities, and magazines...
294116) and a fingerbone (USNM 294117) that were initially described, as well as from the humeri that were initially believed to be from Headonornis (BMNH
Natural History Museum
The Natural History Museum is one of three large museums on Exhibition Road, South Kensington, London, England . Its main frontage is on Cromwell Road...
PAL 3686, 5105, 6240). As these are Late Eocene or even Early Oligocene
Oligocene
The Oligocene is a geologic epoch of the Paleogene Period and extends from about 34 million to 23 million years before the present . As with other older geologic periods, the rock beds that define the period are well identified but the exact dates of the start and end of the period are slightly...
(BMNH PAL 5105, Bembridge Marls) in age, they possibly belong to a distinct taxon.
P. recurvirostris is a disputed species possibly synonymous with P. pervetus; it is known from a partial wing (KUVP
University of Kansas Natural History Museum
The University of Kansas Natural History Museum is part of the University of Kansas Natural History Museum and Biodiversity Research Center, which is itself part of the KU Biodiversity Institute....
10105) found in Colton Formation 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...
sediments of the Wasatch Plateau near Ephraim, Utah
Ephraim, Utah
Ephraim is a city in Sanpete County, Utah, United States. The population was 6,135 at the 2010 census, making it the largest city in Sanpete County. It is the location of Snow College and is located along U.S. Route 89.-History:Ephraim was founded in 1854...
. Undescribed fossils are also known from the Paleocene of Utah
Utah
Utah is a state in the Western United States. It was the 45th state to join the Union, on January 4, 1896. Approximately 80% of Utah's 2,763,885 people live along the Wasatch Front, centering on Salt Lake City. This leaves vast expanses of the state nearly uninhabited, making the population the...
and possibly the Early Eocene of Mongolia
Mongolia
Mongolia is a landlocked country in East and Central Asia. It is bordered by Russia to the north and China to the south, east and west. Although Mongolia does not share a border with Kazakhstan, its western-most point is only from Kazakhstan's eastern tip. Ulan Bator, the capital and largest...
. The coracoid still assigned to Headonornis may also belong into this genus.
Description
Presbyornis was one of the first anseriformsAnseriformes
The order Anseriformes contains about 150 living species of birds in three extant families: the Anhimidae , Anseranatidae , and the Anatidae, which includes over 140 species of waterfowl, among them the ducks, geese, and swans.All species in the order are highly adapted for an aquatic existence at...
. Because of its long legs and neck, Presbyornis was initially mistaken for a flamingo
Flamingo
Flamingos or flamingoes are gregarious wading birds in the genus Phoenicopterus , the only genus in the family Phoenicopteridae...
, but it was reclassified as an anseriform when the duck
Duck
Duck is the common name for a large number of species in the Anatidae family of birds, which also includes swans and geese. The ducks are divided among several subfamilies in the Anatidae family; they do not represent a monophyletic group but a form taxon, since swans and geese are not considered...
-like anatomy of its skull
Skull
The skull is a bony structure in the head of many animals that supports the structures of the face and forms a cavity for the brain.The skull is composed of two parts: the cranium and the mandible. A skull without a mandible is only a cranium. Animals that have skulls are called craniates...
and bill
Beak
The beak, bill or rostrum is an external anatomical structure of birds which is used for eating and for grooming, manipulating objects, killing prey, fighting, probing for food, courtship and feeding young...
was found. Later, it was believed to represent a transitional stage between the anseriforms and the shorebirds, but it is now considered a member of an extinct group of anseriforms
Presbyornithidae
Presbyornithidae were a family of waterbirds with an apparently global distribution that lived until the Earliest Oligocene, but are now extinct...
which was most closely related to ducks and geese
Anatidae
Anatidae is the biological family of birds that includes ducks, geese and swans. The family has a cosmopolitan distribution, occurring on all the world's continents except Antarctica and on most of the world's islands and island groups...
. Judging from numerous fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
findings, Presbyornis is presumed to have lived in colonies around shallow lakes. Its broad, flat bill was used to filter food (small plants and animals) from the water, in the manner of today's dabbling ducks.
