''Graculavus'' is a prehistoric

bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweigh ...

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

that was described in the 19th century by American paleontologist

O. C. Marsh Othniel Charles Marsh (October 29, 1831 – March 18, 1899) was an American professor of Paleontology in Yale College and President of the National Academy of Sciences. He was one of the preeminent scientists in the field of paleontology. Among h ...

. Its remains were found in the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger 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 ''creta'', the ...

Austin Chalk of

Texas Texas (, ; Spanish language, Spanish: ''Texas'', ''Tejas'') is a state in the South Central United States, South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2 ...

, USA, and Lance Formation (late

Maastrichtian The Maastrichtian () is, in the ICS geologic timescale, the latest age (uppermost stage) of the Late Cretaceous Epoch or Upper Cretaceous Series, the Cretaceous Period or System, and of the Mesozoic Era or Erathem. It spanned the interval from ...

faunal stage, or

Lancian The Lancian was a North American faunal stage of the Late Cretaceous. It was the final stage of the Cretaceous period in North America, lasting from approximately 70.6 to 66 million years ago. Geology Terrestrial sedimentary strata from the Judit ...

land mammal age), and the controversial

Hornerstown Formation The Hornerstown Formation is a Paleogene or latest Mesozoic geologic formation in New Jersey.Weishampel, et al. (2004). "Dinosaur distribution." Pp. 517-607. The age of these deposits have been controversial. While most fossils are of animals typ ...

which straddles the

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...

–

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), E ...

boundary, possibly dating to the

Danian The Danian is the oldest age or lowest stage of the Paleocene Epoch or Series, of the Paleogene Period or System, and of the Cenozoic Era or Erathem. The beginning of the Danian (and the end of the preceding Maastrichtian) is at the Cretaceous� ...

stage. These birds lived on the shores of the northwestern

Atlantic The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe an ...

and the Western Interior Seaway some .

Classification

''Graculavus'' is the namesake for the form taxon "Graculavidae", a

plesiomorph 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, and ...

ic assembly of unrelated birds that were believed to hold a key position in avian evolution as "transitional shorebirds." Two

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

are known: ''Graculavus augustus'' from the Western Interior Seaway and ''Graculavus velox'' from the

Atlantic Seaboard The East Coast of the United States, also known as the Eastern Seaboard, the Atlantic Coast, and the Atlantic Seaboard, is the coastline along which the Eastern United States meets the North Atlantic Ocean. The eastern seaboard contains the coa ...

.Chiappe, Luis M. and Witmer, Lawrence M. (2002): ''Mesozoic Birds: Above the Heads of Dinosaurs'', University of California Press, 2002. , Several species have been named, but most are considered synonyms of ''G. velox'' or have been referred to other genera. Most scientists considered ''G. velox'' the only valid ''Graculavus'' species until 1999, when ''G. augustus'' was described. An additional name, ''Graculavus'' "idahensis", was included erroneously in a table of species by Shufeldt in 1915. ''"Graculavus" lentus'' was for some time placed in '' Ichthyornis'' or ''

Pedioecetes The sharp-tailed grouse (''Tympanuchus phasianellus''), also known as the sharptail or fire grouse, is a medium-sized prairie grouse. One of three species in the genus ''Tympanuchus'', the sharp-tailed grouse is found throughout Alaska, much of ...

'' after being removed from the present genus. It is not related to either however and is nowadays considered an early galliform or close relative and placed in the genus ''

Austinornis ''Austinornis'' is a genus of prehistoric birds related to Galliformes. It is known from a fossil partial tarsometatarsus from the Late Cretaceous of Texas Texas (, ; Spanish: ''Texas'', ''Tejas'') is a state in the South Central regio ...

''.Clarke, Julia A. (2004): Morphology, Phylogenetic Taxonomy, and Systematics of ''Ichthyornis'' and ''Apatornis'' (Avialae: Ornithurae). ''Bulletin of the American Museum of Natural History'' 286: 1–17
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References

Charadriiformes Bird genera Late Cretaceous birds of North America Extinct birds of North America Paleogene birds of North America Fossil taxa described in 1872 {{paleo-bird-stub