Graculavus
Encyclopedia
Graculavus is a prehistoric bird
genus
that was described by O. C. Marsh. Its remains were found in the Late Cretaceous
Austin Chalk
of Texas
and Lance Formation
(late Maastrichtian
faunal stage
, or Lancan land mammal age
), and the controversial Hornerstown Formation
which straddles the Cretaceous
–Paleocene
boundary, possibly dating to the Danian
stage. These birds lived on the shores of the northwestern Atlantic and the Western Interior Seaway
some .
"Graculavidae", a plesiomorphic assembly of unrelated birds that were believed to hold a key position in avian evolution as "transitional shorebirds." Two species
are known: Graculavus augustus from the Western Interior Seaway
and Graculavus velox from the Atlantic Seaboard
.
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 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.
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
that was described by O. C. Marsh. Its remains were found in the Late Cretaceous
Late Cretaceous
The Late Cretaceous is the younger of two epochs into which the Cretaceous period is divided in the geologic timescale. Rock strata from this epoch form the Upper Cretaceous series...
Austin Chalk
Austin Chalk
The Austin Chalk is an upper Cretaceous geologic formation in the Gulf Coast region of the United States. It is named after type section outcrops near Austin, Texas...
of Texas
Texas
Texas is the second largest U.S. state by both area and population, and the largest state by area in the contiguous United States.The name, based on the Caddo word "Tejas" meaning "friends" or "allies", was applied by the Spanish to the Caddo themselves and to the region of their settlement in...
and Lance Formation
Lance Formation
The Lance Formation is a division of Late Cretaceous rocks in the western United States. Named after Lance Creek, Wyoming, the microvertebrate fossils and dinosaurs represent important components of the latest Mesozoic vertebrate faunas...
(late Maastrichtian
Maastrichtian
The Maastrichtian is, in the ICS' geologic timescale, the latest age or upper stage of the Late Cretaceous epoch or Upper Cretaceous series, the Cretaceous period or system, and of the Mesozoic era or erathem. It spanned from 70.6 ± 0.6 Ma to 65.5 ± 0.3 Ma...
faunal stage
Faunal stage
In chronostratigraphy, a stage is a succession of rock strata laid down in a single age on the geologic timescale, which usually represents millions of years of deposition. A given stage of rock and the corresponding age of time will by convention have the same name, and the same boundaries.Rock...
, or Lancan land mammal age
Nalma
Nalma is a village development committee in Lamjung District in the Gandaki Zone of northern-central Nepal. At the time of the 1991 Nepal census it had a population of 2082 people living in 409 individual households.-External links:*...
), and the controversial Hornerstown Formation
Hornerstown Formation
The Hornerstown Formation is a Paleogene or latest Mesozoic geologic formation. The age of these deposits have been controversial. While most fossils are of animals types known from the earliest Cenozoic era, several fossils of otherwise exclusively Cretaceous age have been found...
which straddles the Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
–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...
boundary, possibly dating to the Danian
Danian
The Danian is the oldest age or lowermost stage of the Paleocene epoch or series, the Paleogene period or system and the Cenozoic era or erathem. The beginning of the Danian age is at the Cretaceous-Tertiary extinction event...
stage. These birds lived on the shores of the northwestern Atlantic and the Western Interior Seaway
Western Interior Seaway
The Western Interior Seaway, also called the Cretaceous Seaway, the Niobraran Sea, and the North American Inland Sea, was a huge inland sea that split the continent of North America into two halves, Laramidia and Appalachia, during most of the mid- and late-Cretaceous Period...
some .
Classification
Graculavus is the namesake for the form taxonForm taxon
Form classification is the classification of organisms based on their morphology, which does not necessarily reflect their biological relationships...
"Graculavidae", a plesiomorphic assembly of unrelated birds that were believed to hold a key position in avian evolution as "transitional shorebirds." Two 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...
are known: Graculavus augustus from the Western Interior Seaway
Western Interior Seaway
The Western Interior Seaway, also called the Cretaceous Seaway, the Niobraran Sea, and the North American Inland Sea, was a huge inland sea that split the continent of North America into two halves, Laramidia and Appalachia, during most of the mid- and late-Cretaceous Period...
and Graculavus velox from the Atlantic Seaboard
Atlantic Seaboard
The Atlantic seaboard watershed is a watershed of North America along both*the Atlantic Canada coast south of the Gulf of Saint Lawrence Watershed &*the East Coast of the United States north of the watershed of the Okeechobee Waterway....
.
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
Ichthyornis
Ichthyornis is a genus of toothed seabirds from the Late Cretaceous of North America. Its fossil remains are known from the chalks of Alberta, Alabama, Kansas, New Mexico, Saskatchewan, and Texas, in strata that were laid down in the Western Interior Seaway during the Turonian-Campanian ages,...
or Pedioecetes after being removed from the present genus. It is not related to either however and is nowadays considered an early galliform
Galliformes
Galliformes are an order of heavy-bodied ground-feeding domestic or game bird, containing turkey, grouse, chicken, New and Old World Quail, ptarmigan, partridge, pheasant, and the Cracidae. Common names are gamefowl or gamebirds, landfowl, gallinaceous birds or galliforms...
or close relative and placed in the genus Austinornis.