Megaraptor
Encyclopedia
Megaraptor is a genus
of large theropod dinosaur
that lived in the Coniacian
stage of the Late Cretaceous
. Its fossils have been discovered in the Patagonian region of Argentina
. Initially thought to have been a giant dromaeosaur-like coelurosaur, it is now classified as a neovenatorid
allosauroid
.
, known primarily from a single claw (about 30 cm long) that resembled the sickle-shaped foot claw of dromaeosaurids. The discovery of a complete front limb, however, showed that this giant claw actually came from the first finger of the hand. The hands were unusually elongated, bearing sickle-shaped claws even more recurved than those of spinosaurids
. The hand is quite distinct from other basal tetanurans, so it was not initially clear whether Megaraptor was an allosaurid, a carcharodontosaurid, a spinosauroid, or something else entirely. Subsequent studies, as well as the identification of close relatives with similar large claws on the forelimbs (see below), have helped identify Megaraptor as a highly advanced and lightly built allosauroid, and a member of the family Neovenatoridae
.
When first discovered and prior to publication, the spinosaurid
Baryonyx
was also reported to be a dromaeosaurid, and the allosauroid Chilantaisaurus
was reported to be a possible spinosaurid, both based on the large hand claws.
, was discovered in Australia during 2009, helping to solve the mystery of its identity. An additional dinosaur believed to be related to Megaraptor was found in southeastern Australia, Dinosaur Cove. The creature is believed to be around half the size of Megaraptor. It has not yet been named. These finds may show that the breakup of Gondwana
was later than once thought.http://news.nationalgeographic.com/news/2008/06/080610-australia-dinosaur.html
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...
of large theropod dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
that lived in the Coniacian
Coniacian
The Coniacian is an age or stage in the geologic timescale. It is a subdivision of the Late Cretaceous epoch or Upper Cretaceous series and spans the time between 89.3 ± 1 Ma and 85.8 ± 0.7 Ma...
stage of 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...
. Its fossils have been discovered in the Patagonian region of Argentina
Argentina
Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...
. Initially thought to have been a giant dromaeosaur-like coelurosaur, it is now classified as a neovenatorid
Neovenatoridae
Neovenatoridae is a family of large carnivorous dinosaurs. The group is a branch of the allosauroids, a large group of carnosaurs that also includes the sinraptorids, carcharodontosaurids, and allosaurids...
allosauroid
Allosauroidea
Allosauroidea is a superfamily or clade of theropod dinosaurs which contains four families — the Sinraptoridae, Allosauridae, Carcharodontosauridae, and Neovenatoridae...
.
Classification
Megaraptor was initially described as a giant dromaeosaurDromaeosauridae
Dromaeosauridae is a family of bird-like theropod dinosaurs. They were small- to medium-sized feathered carnivores that flourished in the Cretaceous Period. The name Dromaeosauridae means 'running lizards', from Greek dromeus meaning 'runner' and sauros meaning 'lizard'...
, known primarily from a single claw (about 30 cm long) that resembled the sickle-shaped foot claw of dromaeosaurids. The discovery of a complete front limb, however, showed that this giant claw actually came from the first finger of the hand. The hands were unusually elongated, bearing sickle-shaped claws even more recurved than those of spinosaurids
Spinosauridae
Spinosauridae is a family of specialised theropod dinosaurs. Members of this family were large, bipedal predators with elongated, crocodile-like skulls, sporting conical teeth with no or only very tiny serrations. The front dentary teeth fanned out, giving the animal a characteristic look...
. The hand is quite distinct from other basal tetanurans, so it was not initially clear whether Megaraptor was an allosaurid, a carcharodontosaurid, a spinosauroid, or something else entirely. Subsequent studies, as well as the identification of close relatives with similar large claws on the forelimbs (see below), have helped identify Megaraptor as a highly advanced and lightly built allosauroid, and a member of the family Neovenatoridae
Neovenatoridae
Neovenatoridae is a family of large carnivorous dinosaurs. The group is a branch of the allosauroids, a large group of carnosaurs that also includes the sinraptorids, carcharodontosaurids, and allosaurids...
.
When first discovered and prior to publication, the spinosaurid
Spinosauridae
Spinosauridae is a family of specialised theropod dinosaurs. Members of this family were large, bipedal predators with elongated, crocodile-like skulls, sporting conical teeth with no or only very tiny serrations. The front dentary teeth fanned out, giving the animal a characteristic look...
Baryonyx
Baryonyx
Baryonyx is a genus of carnivorous saurischian dinosaur first discovered in clay pits just south of Dorking, England, and later reported from fossils found in northern Spain and Portugal. It is known to contain only one species, Baryonyx walkeri...
was also reported to be a dromaeosaurid, and the allosauroid Chilantaisaurus
Chilantaisaurus
Chilantaisaurus is a genus of neovenatorid theropod dinosaur from the late Cretaceous Ulansuhai Formation of China . The type species, C. tashuikouensis, was described by Hu in 1964. Chilantaisaurus was a large theropod, estimated as weighing between and...
was reported to be a possible spinosaurid, both based on the large hand claws.
Australian relatives
A close relative of Megaraptor, AustralovenatorAustralovenator
Australovenator is a genus of allosauroid theropod dinosaur from late Albian -age rocks of Australia...
, was discovered in Australia during 2009, helping to solve the mystery of its identity. An additional dinosaur believed to be related to Megaraptor was found in southeastern Australia, Dinosaur Cove. The creature is believed to be around half the size of Megaraptor. It has not yet been named. These finds may show that the breakup of Gondwana
Gondwana
In paleogeography, Gondwana , originally Gondwanaland, was the southernmost of two supercontinents that later became parts of the Pangaea supercontinent. It existed from approximately 510 to 180 million years ago . Gondwana is believed to have sutured between ca. 570 and 510 Mya,...
was later than once thought.http://news.nationalgeographic.com/news/2008/06/080610-australia-dinosaur.html