''Phocavis'' is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

genus of

flightless Flightless birds are birds that through evolution lost the ability to fly. There are over 60 extant species, including the well known ratites (ostriches, emu, cassowaries, rheas, and kiwi) and penguins. The smallest flightless bird is the ...

seabird, belonging to the family

Plotopteridae Plotopteridae is an extinct family of flightless seabirds with uncertain placement, generally considered as member of order Suliformes. They exhibited remarkable convergent evolution with the penguins, particularly with the now extinct giant peng ...

, and distantly related with modern

cormorant Phalacrocoracidae is a family of approximately 40 species of aquatic birds commonly known as cormorants and shags. Several different classifications of the family have been proposed, but in 2021 the IOC adopted a consensus taxonomy of seven ge ...

s. Its fossils, found in the

Keasey Formation The Keasey Formation is a geologic formation in northwestern Oregon. It preserves fossils dating back to the Paleogene period Period may refer to: Common uses * Era, a length or span of time * Full stop (or period), a punctuation mark Arts, en ...

in Oregon, are dated from the Late Eocene.

History and taxonomy

The holotype of ''Phocavis'', LACM 123897, an isolated right

tarsometatarsus The tarsometatarsus is a bone that is only found in the lower leg of birds and some non-avian dinosaurs. It is formed from the fusion of several bones found in other types of animals, and homologous to the mammalian tarsus (ankle bones) and meta ...

, was collected in Late Eocene rocks belonging to the

, near

Vernonia, Oregon Vernonia is a city in Columbia County, Oregon, United States. It is located on the Nehalem River, in a valley on the eastern side of the Northern Oregon Coast Range that is the heart of one of the most important timber-producing areas of the sta ...

, by James L. Goedert in 1979. The fossil was only described in 1988 as a new genus and species of

, ''Phocavis maritimus''. Due to the lack of existing material on the two described genera of

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

n plotopterids, ''

Tonsala ''Tonsala'' is an extinct genus of Plotopteridae, a family of flightless seabird similar in biology with penguins, but more closely related to modern cormorants. The genus is known from terrains dated from the Late Oligocene of the State of Washi ...

'' and ''

Plotopterum ''Plotopterum'' is an extinct genus of flightless seabird of the family Plotopteridae, native to the North Pacific during the Late Oligocene and the Early Miocene. The only described species is ''Plotopterum joaquinensis''. History and Etymology ...

'', the validity of the genus was only assumed due to the assumed size of the living bird, estimated to be intermediate between the two later genera, and its much older geological age. Comparison could however be made with the then undescribed remains of ''

Copepteryx ''Copepteryx'' is an extinct genus of flightless bird of the family Plotopteridae, endemic to Japan during the Oligocene living from 28.4 to 23 mya, meaning it existed for approximately . Taxonomy ''Copepteryx'' was named by Olson and Hasegawa ...

'' from

Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...

to verify the identity of the bone as a fossil of plotopterid. The genus name, ''Phocavis'', is constructed with the Latin prefix “''Phoca''-”, meaning seal, and the suffix “''-avis''”, meaning bird, as a reference of its supposed adaptation towards swimming. The type species name, ''maritimus'', means in Latin “from the sea”.

Description

''Phocavis'' is only known from its holotype tarsometatarsus, which could be identified as belonging to a new genus of plotopterid thanks to comparison with fossil remains of large plotopterids from

. The tarsometatarsus was much smaller than its Japanese counterparts, but larger than its later relative '' Plotopterum maritimus''. It was also more elongated, and anatomically distinct from the Japanese plotopterids.

Paleoenvironment

''Phocavis'' is the earliest known genus of plotopterid, dating from the Late Eocene. The Keasey Formation, in which it was found, represents deep sea deposits, at an approximate deposition depth of 500 to 1000 m, possibly indicating that plotopterids were able to venture far from the coast early in their evolution. In the Eocene of this formation are also represented a pseudodontorn, a marine turtle, a

cetacean Cetacea (; , ) is an infraorder of aquatic mammals that includes whales, dolphins, and porpoises. Key characteristics are their fully aquatic lifestyle, streamlined body shape, often large size and exclusively carnivorous diet. They propel them ...

teleost fish Teleostei (; Greek ''teleios'' "complete" + ''osteon'' "bone"), members of which are known as teleosts ), is, by far, the largest infraclass in the class Actinopterygii, the ray-finned fishes, containing 96% of all extant species of fish. Tel ...

and sharks. The cohabitation between plotopterids and early cetaceans since the Eocene goes against an earlier theory justifying the extinction of the plotopterids during the Miocene by an unequal concurrence with

porpoise Porpoises are a group of fully aquatic marine mammals, all of which are classified under the family Phocoenidae, parvorder Odontoceti (toothed whales). Although similar in appearance to dolphins, they are more closely related to narwhals an ...

s, and may designate other culprits, such as the dramatic climatic and oceanographic changes in the North Pacific during the Early and Middle Miocene, affecting

phytoplankton Phytoplankton () are the autotrophic (self-feeding) components of the plankton community and a key part of ocean and freshwater ecosystems. The name comes from the Greek words (), meaning 'plant', and (), meaning 'wanderer' or 'drifter'. Ph ...

ic communities and causing the extinction of the specialized plotopterids, in favor of other group such as the enaliarctine pinnipeds.

References

{{Taxonbar, from=Q114608103 Fossil taxa described in 1988 Plotopteridae Extinct flightless birds Prehistoric bird genera