Gaviiformes
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Gaviiformes () is an
order Order, ORDER or Orders may refer to: * A socio-political or established or existing order, e.g. World order, Ancien Regime, Pax Britannica * Categorization, the process in which ideas and objects are recognized, differentiated, and understood ...
of
aquatic bird A water bird, alternatively waterbird or aquatic bird, is a bird that lives on or around water. In some definitions, the term ''water bird'' is especially applied to birds in freshwater ecosystems, although others make no distinction from seab ...
s containing the
loon Loons (North American English) or divers (British English, British / Irish English) are a group of aquatic birds found in much of North America and northern Eurasia. All living species of loons are members of the genus ''Gavia'', family (biolog ...
s or divers and their closest extinct relatives. Modern gaviiformes are found in many parts of
North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...
and northern
Eurasia Eurasia ( , ) is a continental area on Earth, comprising all of Europe and Asia. According to some geographers, Physical geography, physiographically, Eurasia is a single supercontinent. The concept of Europe and Asia as distinct continents d ...
(Europe, Asia and debatably Africa), though prehistoric species were more widespread.


Classification and evolution

There are five living species, and all are placed in the genus '' Gavia''. The loons were formerly often considered to be the most ancient of the northern hemisphere bird families; this idea grew basically out of the perceived similarity of shape and (probably) habits between loons and the entirely unrelated extinct
Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...
order Hesperornithiformes. In particular '' Enaliornis'', which was apparently an ancestral and
plesiomorphic In phylogenetics, a plesiomorphy ("near form") and symplesiomorphy are synonyms for an ancestral character shared by all members of a clade, which does not distinguish the clade from other clades. Plesiomorphy, symplesiomorphy, apomorphy, an ...
member of that order, was sometimes used to support claims of
Albian The Albian is both an age (geology), age of the geologic timescale and a stage (stratigraphy), stage in the stratigraphic column. It is the youngest or uppermost subdivision of the Early Cretaceous, Early/Lower Cretaceous epoch (geology), Epoch/s ...
(
Early Cretaceous The Early Cretaceous (geochronology, geochronological name) or the Lower Cretaceous (chronostratigraphy, chronostratigraphic name) is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 143.1 ...
) Gaviiformes. More recently, it has become clear that the
Anseriformes Anseriformes is an order (biology), order of birds also known as waterfowl that comprises about 180 living species of birds in three families: Anhimidae (three species of screamers), Anseranatidae (the magpie goose), and Anatidae, the largest f ...
(waterfowl) and the
Galliformes Galliformes is an order (biology), order of heavy-bodied ground-feeding birds that includes turkey (bird), turkeys, chickens, Old World quail, quail, and other landfowl. Gallinaceous birds, as they are called, are important in their ecosystems ...
are the most ancient groups of modern birds, and these being distinct by the end of the Albian 100
million years ago Million years ago, abbreviated as Mya, Myr (megayear) or Ma (megaannum), is a unit of time equal to (i.e. years), or approximately 31.6 teraseconds. Usage Myr is in common use in fields such as Earth science and cosmology. Myr is also used w ...
(Ma), while just possible, is not at all well-supported. Loons belong to a more modern radiation. They were once believed to be related to grebes, which are also foot-propelled diving birds, and both groups were once classified together under the order Colymbiformes or in even older classifications as the Urinatores. The family name Urinatoridae was used for the family Gaviidae. This was derived from Latin ''Urinator'' meaning "diver". However, as recently as the 1930s, it was determined that the two groups (grebes and divers) are not that closely related at all and are merely the product of
convergent evolution Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last comm ...
and adapted in a similar way to a similar
ecological niche In ecology, a niche is the match of a species to a specific environmental condition. Three variants of ecological niche are described by It describes how an organism or population responds to the distribution of Resource (biology), resources an ...
. The similarity is so strong that even the most modern
cladistic Cladistics ( ; from Ancient Greek 'branch') is an approach to biological classification in which organisms are categorized in groups ("clades") based on hypotheses of most recent common ancestry. The evidence for hypothesized relationships is ...
analyses of general
anatomical Anatomy () is the branch of morphology concerned with the study of the internal structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old scien ...
features are easily misled into grouping loons and grebes. Mayr (2009) The Sibley-Ahlquist taxonomy still allied the loons with the grebes in its massively
polyphyletic A polyphyletic group is an assemblage that includes organisms with mixed evolutionary origin but does not include their most recent common ancestor. The term is often applied to groups that share similar features known as Homoplasy, homoplasies ...
"Ciconiiformes", and it is almost certain that the relationships of loons lie with ''some'' of the orders placed therein. Namely, other recent authors have considered loons to share a rather close relationship with
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 ...
s such as
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 (Sphenisciformes), tubenoses (
Procellariiformes Procellariiformes is an order (biology), order of seabirds that comprises four family (biology), families: the albatrosses, the Procellariidae, petrels and shearwaters, and two families of storm petrels. Formerly called Tubinares and still call ...
),
wader 245px, A flock of Red_knot.html" ;"title="Dunlins and Red knot">Dunlins and Red knots Waders or shorebirds are birds of the order Charadriiformes commonly found wikt:wade#Etymology 1, wading along shorelines and mudflats in order to foraging, ...
s (Charadriiformes) – and perhaps the newly discovered
clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...
Mirandornithes Mirandornithes () is a clade that consists of flamingos and grebes. Many scholars use the term Phoenicopterimorphae for the superorder containing flamingoes and grebes. Determining the relationships of both groups has been problematic. Flaming ...
which unites grebes (Podicipediformes) and their closest living relatives, the
flamingos Flamingos or flamingoes () are a type of wading bird in the family Phoenicopteridae, which is the only extant family in the order Phoenicopteriformes. There are four flamingo species distributed throughout the Americas (including the Caribbe ...
(Phoenicopteriformes). It is perhaps notable that some early penguins had skulls and beaks that were in many aspects similar to those of the known living and fossil Gaviiformes.


Fossil record

In prehistoric times, the loons had a more southerly distribution than today, and their fossils have been found in places such as
California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...
,
Florida Florida ( ; ) is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. It borders the Gulf of Mexico to the west, Alabama to the northwest, Georgia (U.S. state), Georgia to the north, the Atlantic ...
and
Italy Italy, officially the Italian Republic, is a country in Southern Europe, Southern and Western Europe, Western Europe. It consists of Italian Peninsula, a peninsula that extends into the Mediterranean Sea, with the Alps on its northern land b ...
. The conflicting molecular data regarding their relationships is not much resolved by the
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 ...
record; though they seem to have originated at the end of the
Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the more recent of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''cre ...
like their presumed relatives, modern loons are only known with certainty since the
Eocene The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes ...
. By that time almost all modern bird orders are at least strongly suspected to have existed – if not known from unequivocally identified specimens – anyway. The oldest known stem-gaviiform is '' Nasidytes'' from the
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 ...
aged
London Clay The London Clay Formation is a Sediment#Shores and shallow seas, marine formation (geology), geological formation of Ypresian (early Eocene Epoch, c. 54-50 million years ago) age which outcrop, crops out in the southeast of England. The London C ...
of England, dating to around 55 million years ago. '' Colymboides'' is widely known from early
Priabonian The Priabonian is, in the ICS's geologic timescale, the latest age or the upper stage of the Eocene Epoch or Series. It spans the time between . The Priabonian is preceded by the Bartonian and is followed by the Rupelian, the lowest stage ...
– about 37
million years ago Million years ago, abbreviated as Mya, Myr (megayear) or Ma (megaannum), is a unit of time equal to (i.e. years), or approximately 31.6 teraseconds. Usage Myr is in common use in fields such as Earth science and cosmology. Myr is also used w ...
(Ma) in the
Late Eocene The Priabonian is, in the International Commission on Stratigraphy, ICS's geologic timescale, the latest age (geology), age or the upper stage (stratigraphy), stage of the Eocene epoch (geology), Epoch or series (stratigraphy), Series. It spans ...
– to
Early Miocene The Early Miocene (also known as Lower Miocene) is a sub-epoch of the Miocene epoch (geology), Epoch made up of two faunal stage, stages: the Aquitanian age, Aquitanian and Burdigalian stages. The sub-epoch lasted from 23.03 ± 0.05 annum, Ma to ...
(late
Burdigalian The Burdigalian is, in the geologic timescale, an age (geology), age or stage (stratigraphy), stage in the early Miocene. It spans the time between 20.43 ± 0.05 annum, Ma and 15.97 ± 0.05 Ma (million years ago). Preceded by the Aquitanian (sta ...
, less than 20 Ma)
limnic Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. The term excludes seawater and brackish water, but it does include non-salty minera ...
and marine rocks of western
Eurasia Eurasia ( , ) is a continental area on Earth, comprising all of Europe and Asia. According to some geographers, Physical geography, physiographically, Eurasia is a single supercontinent. The concept of Europe and Asia as distinct continents d ...
north of the
Alpide belt The Alpide belt or Alpine-Himalayan orogenic belt,K.M. Storetvedt, K. M., ''The Tethys Sea and the Alpine-Himalayan orogenic belt; mega-elements in a new global tectonic system,'' Physics of the Earth and Planetary Interiors, Volume 62, Issues 1 ...
, between the
Atlantic The Atlantic Ocean is the second largest of the world's five oceanic divisions, with an area of about . It covers approximately 17% of Earth's surface and about 24% of its water surface area. During the Age of Discovery, it was known for se ...
and the former Turgai Sea. It is usually placed in the Gaviidae already, but usually in a
subfamily In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end botanical subfamily names with "-oideae", and zo ...
Colymboidinae, with the modern-type loons making up the Gaviinae. But the ''Colymboides'' material is generally quite distinct from modern loons, and may actually belong in a now-extinct family of primitive gaviiforms. Furthermore, the supposed genus could well be paraphyletic, so that for example ''Dyspetornis'' – which is now contained therein – might have to be separated again. A leg of an undescribed small diver was found in the
Late Oligocene The Chattian is, in the geologic timescale The geologic time scale or geological time scale (GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating that uses chronostratigraphy (the pro ...
deposits at Enspel (
Germany Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...
); it too may or may not belong to ''Colymboides''. Of the crown genus ''Gavia'', nearly ten prehistoric species have been named to date, and about as many undescribed ones await further study. The genus is known from the Early Miocene onwards, and the oldest members of them are rather small (some are smaller than the red-throated loon). Throughout the late
Neogene The Neogene ( ,) is a geologic period and system that spans 20.45 million years from the end of the Paleogene Period million years ago ( Mya) to the beginning of the present Quaternary Period million years ago. It is the second period of th ...
, the genus by and large follows Cope's Rule. Brodkorb (1953), 1963: pp. 223–225, Olson (1985: pp. 212–213), Mlíkovský (2002: pp. 63–64), Mayr (2009: pp. 75–76) Some older fossils are sometimes assigned to the Gaviiformes. From the
Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the more recent of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''cre ...
, the genera '' Lonchodytes'' (
Lance Formation The Lance (Creek) Formation is a division of Late Cretaceous (dating to about 69–66 Ma) rocks in the western United States. Named after Lance Creek, Wyoming, the microvertebrate fossils and dinosaurs represent important components of the lates ...
, Wyoming) and '' Neogaeornis'' ( Quinriquina Formation,
Chile Chile, officially the Republic of Chile, is a country in western South America. It is the southernmost country in the world and the closest to Antarctica, stretching along a narrow strip of land between the Andes, Andes Mountains and the Paci ...
) have been described; both are usually allied with orders which are considered related to loons. In particular the latter is still sometimes explicitly proposed as a primitive loon as they both were initially, but other authors consider ''Neogaeornis'' a
hesperornithiform Hesperornithes is an extinct and highly specialized group of aquatic avialans closely related to the ancestors of modern birds. They inhabited both marine and freshwater habitats in the Northern Hemisphere, and include genera such as ''Hesperorn ...
; note however that neither Gaviiformes nor Hesperornithiformes are known from the Southern Hemisphere or anywhere near it. ''Lonchodytes'' was more certainly quite close to loons, but probably closer still to some of the loons' relatives. '' Eupterornis'' from the
Paleocene The Paleocene ( ), or Palaeocene, is a geological epoch (geology), epoch that lasted from about 66 to 56 mya (unit), million years ago (mya). It is the first epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), ...
of Châlons-sur-Vesle (
France France, officially the French Republic, is a country located primarily in Western Europe. Overseas France, Its overseas regions and territories include French Guiana in South America, Saint Pierre and Miquelon in the Atlantic Ocean#North Atlan ...
) has some features reminiscent of loons, but others seem more similar to
Charadriiformes Charadriiformes (, from '' Charadrius'', the type genus of family Charadriidae) is a diverse order of small to medium-large birds. It includes about 390 species and has members in all parts of the world. Most charadriiform birds live near water ...
such as gulls ( Laridae). A piece of a
carpometacarpus The carpometacarpus is a bone found in the hands of birds. It results from the fusion of the carpal and metacarpal bone, and is essentially a single fused bone between the wrist and the knuckles. It is a smallish bone in most birds, generally fla ...
supposedly from
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 ...
rocks near
Lusk, Wyoming Lusk is a town in and the county seat of Niobrara County, Wyoming. It is located in the High Plains (United States), High Plains. The town was founded in July 1886, by Frank S. Lusk, a renowned Wyoming rancher, partner in the Western Live Stock ...
was described as '' Gaviella pusilla'', but this handbone also shows some similarities to the plotopterids which were flightless wing-propelled divers and if these are
apomorph In phylogenetics, an apomorphy (or derived trait) is a novel character or character state that has evolved from its ancestral form (or plesiomorphy). A synapomorphy is an apomorphy shared by two or more taxa and is therefore hypothesized to ha ...
ic would make an unconvincing member of the Gaviidae (though it still could be a small-winged gaviiform in a yet-undescribed family "Gaviellidae"): while the carpometacarpus in ''Gavia'' is somewhat convergent to that of wing-propelled divers, enabling the wings to be used as rudders for quick underwater turns, ''Colymboides'' still had an unspecialized
plesiomorph In phylogenetics, a plesiomorphy ("near form") and symplesiomorphy are synonyms for an ancestral Phenotypic trait, character shared by all members of a clade, which does not distinguish the clade from other clades. Plesiomorphy, symplesiomorph ...
ic hand. ''Parascaniornis'', sometimes allied to the loons by early authors, was eventually determined to be a
junior synonym In taxonomy, the scientific classification of living organisms, a synonym is an alternative scientific name for the accepted scientific name of a taxon. The botanical and zoological codes of nomenclature treat the concept of synonymy differently. ...
of the hesperornithiform '' Baptornis''. A supposed mid-
Eocene The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes ...
diver fossil form Geiseltal (
Germany Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...
) was erroneously assigned to ''Gavia''. Brodkorb (1963: pp. 220–223), Olson (1985), Mlíkovský (2002: pp. 64, 259–261), Mayr (2009: p. 20)


See also

* List of Gaviiformes by population


References


Bibliography

* * * * * * *


Further reading

* * * Heinrichs, Ann (2003): ''Minnesota''. Compass Point Books. * * Linnaeus, Carl (1758): 68.1. ''Colymbus arcticus. In:
Systema naturae ' (originally in Latin written ' with the Orthographic ligature, ligature æ) is one of the major works of the Sweden, Swedish botanist, zoologist and physician Carl Linnaeus (1707–1778) and introduced the Linnaean taxonomy. Although the syste ...
per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis'' (10th ed., vol. 1): 190 atin book Lars Salvius, Stockholm ("Holmius")
Digitized version
* Minnesota Pollution Control Agency (2007)
Let's Get the Lead Out! Non-lead alternatives for fishing tackle
Version of June, 2007. Retrieved 2007-July-23. * Montana Fish, Wildlife & Parks (Montana FW&P) (2007)
Animal Field Guide: Common Loon
Retrieved 2007-May-12. * Moran, Mark; Sceurman, Mark; Godfrey, Linda S. & Hendricks, Richard D. (2005): ''Weird Wisconsin: Your Travel Guide to Wisconsin's Local Legends and Best Kept Secrets''. Sterling Publishing. * Piper, W.H.; Evers, D.C.; Meyer, M.W.; Tischler, K.B. & Klich, M. (2000a): Do common loons mate for life?: scientific investigation of a widespread myth. ''In'': McIntyre, J. & Evers, D.C. (eds.): ''Loons: old history and new findings – proceedings of a symposium from the 1997 meeting of the American Ornithologists' Union'': 43–49. North American Loon Fund, Meredith, New Hampshire. * * * * * * Stewart, Barry D. (2004): ''Across The Land: A Canadian Journey Of Discovery''. Trafford Publishing. * *
United States Fish and Wildlife Service The United States Fish and Wildlife Service (USFWS or FWS) is a List of federal agencies in the United States, U.S. federal government agency within the United States Department of the Interior which oversees the management of fish, wildlife, ...
(USFWS) (2005)
Common Loons at Seney NWR
, June 2005. *


External links

* * {{Authority control Bird orders Extant Maastrichtian first appearances Late Cretaceous taxonomic orders Paleocene taxonomic orders Eocene taxonomic orders Oligocene taxonomic orders Miocene taxonomic orders Pliocene taxonomic orders Pleistocene taxonomic orders Holocene taxonomic orders