''Stemec'' is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

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 ...

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 ...

, a family of

flightless Flightless birds are birds that cannot fly, as they have, through evolution, lost the ability to. There are over 60 extant species, including the well-known ratites ( ostriches, emus, cassowaries, rheas, and kiwis) and penguins. The smal ...

seabird Seabirds (also known as marine birds) are birds that are adaptation, adapted to life within the marine ecosystem, marine environment. While seabirds vary greatly in lifestyle, behaviour and physiology, they often exhibit striking convergent ...

similar in biology with

penguin Penguins are a group of aquatic flightless birds from the family Spheniscidae () of the order Sphenisciformes (). They live almost exclusively in the Southern Hemisphere. Only one species, the Galápagos penguin, is equatorial, with a sm ...

s, but more closely related to 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 International Ornithologists' Union (IOU) ado ...

s. The genus is known from terrains dated from the Late

Oligocene The Oligocene ( ) is a geologic epoch (geology), epoch of the Paleogene Geologic time scale, Period that extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that defin ...

Sooke Formation of

British Columbia British Columbia is the westernmost Provinces and territories of Canada, province of Canada. Situated in the Pacific Northwest between the Pacific Ocean and the Rocky Mountains, the province has a diverse geography, with rugged landscapes that ...

History and etymology

Although the fossil remains of large marine birds like the

Pelagornithid The Pelagornithidae, commonly called pelagornithids, pseudodontorns, bony-toothed birds, false-toothed birds or pseudotooth birds, are a prehistoric family (biology), family of large seabirds. Their fossil remains have been found all over the wor ...

'' Cyphornis'' are known from the Sooke Formation of the

Vancouver Island Vancouver Island is an island in the northeastern Pacific Ocean and part of the Canadian province of British Columbia. The island is in length, in width at its widest point, and in total area, while are of land. The island is the largest ...

since 1894, the first remains of plotopterids from the formation were only discovered in 2013 in the vicinity of

Sooke Sooke () is a district municipality on the southern tip of Vancouver Island, Canada, by road from Victoria, the capital of British Columbia. Sooke, the westernmost of Greater Victoria's Western Communities, is to the north and west of t ...

by Leah and Graham Suntok. In 2015, those remains were described by Gary Kaiser,

Junya Watanabe Junya Watanabe (born 1961) is a Japanese people, Japanese fashion designer, a protégé of Comme des Garçons designer Rei Kawakubo. He continues to work for Comme des Garçons: His atelier is located on the second floor of its Tokyo headquarters, ...

and Marji Johns as the new genus and species ''Stemec suntokum'', using as

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

the specimen RBCM.EH2014.032.0001.001, a nearly complete coracoid.

Etymology

The genus name, ''Stemec'', designate an indefinite long-necked black waterbird in the

Coast Salish The Coast Salish peoples are a group of ethnically and linguistically related Indigenous peoples of the Pacific Northwest Coast, living in the Canadian province of British Columbia and the U.S. states of Washington and Oregon. They speak on ...

language native of the area in which the holotype was discovered. The type species name, ''suntokum'', honours the family name of Leah and Graham Suntok, the discoverers of the holotype.

Description

''Stemec'' was a relatively small plotopterid, comparable in size with its

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

relative ''

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 ...

''. It is only known from a single right

coracoid A coracoid is a paired bone which is part of the shoulder assembly in all vertebrates except therian mammals (marsupials and placentals). In therian mammals (including humans), a coracoid process is present as part of the scapula, but this is n ...

belonging to an adult bird, as proven by the smooth surface of the shaft, although two fragmentary

tibiotarsi The tibiotarsus is the large bone between the femur and the tarsometatarsus in the leg of a bird. It is the fusion of the proximal part of the tarsus with the tibia. A similar structure also occurred in the Mesozoic Heterodontosauridae. These sm ...

found in the same locality and similar to those of modern

s might have belonged to the genus, or to another small-sized plotopterid. The holotype coracoid is 74.8 mm long, 12.8 mm wide, and fairly complete, although

erosion Erosion is the action of surface processes (such as Surface runoff, water flow or wind) that removes soil, Rock (geology), rock, or dissolved material from one location on the Earth's crust#Crust, Earth's crust and then sediment transport, tran ...

had damaged part of its surface. It shared more similarities with the known coracoid of ''Plotopterum'' than with those of the larger Tonsalinae plotopterids like ''

Copepteryx ''Copepteryx'' is an extinct genus of flightless bird, flightless bird of the family Plotopteridae, endemic to Japan during the Oligocene living from 28.4 to 23 Annum, mya, meaning it existed for approximately . History and Etymology Remains of ...

'' and ''

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 ...

''. It was although mostly differenced from ''Plotopterum'' by several osteological specificities, including the raised and flat platform formed by the facies articularis humeralis, and the absence of a prominent groove formed by the sulcus supracoracoideus typical of the later genus.

Palaeobiology

During the

, ''Stemec'' lived alongside the Desmostylian ''

Cornwallius ''Cornwallius'' is an extinct herbivorous marine mammal of the family Desmostylidae. ''Cornwallius'' lived along the North American Pacific Coast from the Early Oligocene (Chattian) through the Oligocene (28.4 mya—20.6 Mya) and existing for ap ...

'', the Aetiocetid ''

Chonecetus ''Chonecetus'' is an extinct genus of primitive baleen whale of the family Aetiocetidae that lived in the Oligocene period. Its fossils have been found in Canada, in the northeast Pacific. It was first named by L.S. Russell in 1968, and contain ...

'' and the

'' Cyphornis'' in a shallow marine environment rich in sessile fauna. The discovery of ''Stemec'' and its close relative ''

'' in coastal deposits indicate that the latest and smallest plotopterids had costal habits, when the larger and older tonsalin plotopterids where

pelagic The pelagic zone consists of the water column of the open ocean and can be further divided into regions by depth. The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or water column between the sur ...

feeders. Elements of their osteology indicates that they were not proficient swimmer like their larger, open sea specialist relatives, which may explain both the apparent lack of competition between larger and smaller plotopterids and the later survival of the latter form.

References

{{Taxonbar, from1=Q87701598 Fossil taxa described in 2015 Paleogene British Columbia Plotopteridae Extinct flightless birds Prehistoric bird genera