Bambiraptor

Bambiraptor is a Late Cretaceous, 72-million-year-old, bird-like dromaeosaurid theropod dinosaur described by scientists at the University of Kansas, Yale University, and the University of New Orleans.

The holotype fossil is less than one meter long, although this specimen appears to be a juvenile,[1] and it is possible that Bambiraptor is really just a juvenile Saurornitholestes. Because of its small size, it was named Bambiraptor feinbergi, after the familiar Disney movie character (the name literally translates to "Bambi thief") and the surname of the wealthy family who bought and lent the specimen to the new Graves Museum of Natural History in Florida.

Bambiraptor
Temporal range: Late Cretaceous, 72 Ma
Dans l'ombre des dinosaures - Bambiraptor jeune - 04
Restored skeleton of the juvenile specimen
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Order: Saurischia
Suborder: Theropoda
Family: Dromaeosauridae
Clade: Eudromaeosauria
Subfamily: Saurornitholestinae
Genus: Bambiraptor
Burnham et al., 2000
Type species
Bambiraptor feinbergi
Burnham et al., 2000

Discovery

BambiraptorFeinbergi RoyalOntarioMuseum
Cast of the fossil slab

The Bambiraptor skeleton was discovered in 1993 by 14-year-old fossil hunter Wes Linster, who was looking for dinosaur bones with his parents near Glacier National Park in Montana, United States. Linster told Time Magazine that he uncovered the skeleton on a tall hill and was amazed at his discovery. "I bolted down the hill to get my mom because I knew I shouldn't be messing with it", he said. The bones that Linster discovered on that hilltop led to the excavation of a skeleton that was approximately 95 percent complete. Because of its completeness Florida Paleontology Institute Director Martin Shugar compared it to the 'Rosetta Stone' that enabled archaeologists to translate Egyptian hieroglyphics. Yale paleontologist John Ostrom, who reintroduced the theory of bird evolution from dinosaurs after his 1964 discovery of Deinonychus in Wyoming, agreed, calling the specimen a "jewel", and telling reporters that the completeness and undistorted qualities of the bones should help scientists further understand the dinosaur-bird link.

The fossil first was seen as the young of Saurornitholestes and in 1997 reported as belonging to a Velociraptor sp.[2] In 2000 it was named and described by David Burnham, Kraig Derstler, Phil Currie, Robert Bakker, Zhou Zhonge and John Ostrom as a separate species: Bambiraptor feinbergi. The generic name is derived from Bambi, in reference to the young age of the specimen, and a Latin raptor, "seizer". The specific epithet honours Michael and Ann Feinberg who acquired the specimen from a fossil dealer and made it available to science.[3] In 2000 George Olshevsky suggested the emended epithet "feinbergorum", the plural genitive, and this was followed by some authors but such emendations are no longer allowed by the ICZN.

The holotype specimen AMNH FR 30556 (previously AMNH 001 and FIP 001, sometimes wrongly referred to as AMNH FR 30554), was uncovered in layers of the Upper Two Medicine Formation dating to the late Campanian. It is currently housed at the American Museum of Natural History, New York. It consists of a partially articulated largely complete skeleton with skull of a juvenile individual. Though the right side of the skeleton is damaged, most bones are uncompressed and well-preserved. The end of the tail is lacking. Also a paratype was assigned in 2000, FIP 002-136, consisting of thirty-four skeletal elements of at least two adult individuals found near the holotype. In 2004 an upper jaw bone was referred to the species, specimen MOR 553S-7-30-91-274.[4]

Description

Bambiraptor feinbergi
Skeletal restoration

While adult specimens are known, only the type specimen, a juvenile, has been described. This juvenile Bambiraptor has a preserved length of 90 centimetres (3.0 ft),[5] and an estimated total length of one metre. It perhaps weighed only two kilograms (4.4 lb). In 2010 Gregory S. Paul estimated the adult length at 1.3 metres (4.3 ft), the weight at five kilogrammes.[6] It had long hindlimbs, indicating it could have been a fast runner. It also had very long arms and a well-developed wishbone.

Forelimbs

Bambiraptor2
Restored skeleton in Oxford University Museum

Research done by Phil Senter of the Lamar State College in Orange, Texas has indicated that Bambiraptor may have had mutually opposable first and third fingers and a forelimb maneuverability that would allow the hand to reach its mouth.[7] This would have given the animal the ability to "hold" food in its front limbs and place it in its mouth, in a similar manner to some modern-day small mammals.[8]

Brain

Bambiraptor had a brain size in the lower range of modern birds. Because of its enlarged cerebellum, which may indicate higher agility and higher intelligence than other dromaeosaurs, David A. Burnham has hypothesized that Bambiraptor feinbergi may have been arboreal. Life in the trees may have required evolutionary pressure that resulted in a larger brain. Burnham also offers an alternative hypothesis that a larger brain could be selected for as a result of hunting more agile prey items such as lizards and mammals. The Bambiraptor holotype had with 14 cm³ the largest brain for its size of any dinosaur yet discovered, although the brain size may be due to its age, because juvenile animals tend to have larger brain-to-body ratios compared to adults.

Feathers

Bambiraptor reconstruction
Artist's restoration of the juvenile specimen

During the conference where Bambiraptor was first introduced, the dinosaur reconstruction specialist Brian Cooley portrayed Bambiraptor as having feathers, despite the fact that no feathers were found with the fossil itself. His decision was influenced by the fact that because Bambiraptor within a cladistic analysis was a member of a group, Paraves, that contained feathered true birds and that was the sister taxon of Oviraptorosauria, a group that also had feathered forms (e.g. Caudipteryx), Bambiraptor most likely had feathers too due to phylogenetic bracketing. Most paleontologists support Cooley's view, and subsequent discoveries confirmed that small dromaeosaurid dinosaurs like Bambiraptor were fully covered in feathers (see Dromaeosauridae for more information).

Phylogeny

Bambiraptor was assigned to the Dromaeosauridae in 2000. Subsequent cladistic analyses differ in the position of Bambiraptor: it has been recovered in the Velociraptorinae, Microraptoria and most recently in the Saurornitholestinae.

See also

References

  1. ^ [1] Archived April 20, 2006, at the Wayback Machine
  2. ^ Burnham, D.A., Derstler K.L. and Linster, W., 1997, "A new specimen of Velociraptor (Dinosauria: Theropoda) from the Two Medicine Formation of Montana", Dinofest International Proceedings. pp 73-75
  3. ^ Burnham, D.A., Derstler, K.L., Currie, P.J., Bakker, R.T., Zhou Z. & Ostrom J. H., 2000. "Remarkable new birdlike dinosaur (Theropoda: Maniraptora) from the Upper Cretaceous of Montana", University of Kansas Paleontological Contributions 13: 1-14
  4. ^ Burnham, D. A. (2004). "New Information on Bambiraptor feinbergi from the Late Cretaceous of Montana". In Philip J. Currie; E.B. Koppelhus; M.A. Shugar; J.L. Wright (eds.). Feathered Dragons: Studies on the Transition from Dinosaurs to Birds. Indianapolis: Indiana University Press. pp. 67–111. ISBN 0-253-34373-9.
  5. ^ Holtz, Thomas R. Jr. (2011) Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages, ISBN 978-0375824197 Winter 2010 Appendix.
  6. ^ Paul, G.S., 2010, The Princeton Field Guide to Dinosaurs, Princeton University Press p. 135
  7. ^ Senter, P., 2006, "Comparison of forelimb function between Deinonychus and Bambiraptor (Theropoda: Dromaeosauridae)", Journal of Vertebrate Paleontology, 26(4): 897-906
  8. ^ [2] Archived September 30, 2007, at the Wayback Machine

External links

1993 in science

The year 1993 in science and technology involved many significant events, listed below.

Acheroraptor

Acheroraptor is an extinct genus of dromaeosaurid theropod dinosaur known from the latest Maastrichtian Hell Creek Formation of Montana, United States. It contains a single species, Acheroraptor temertyorum. A. temertyorum is one of the two geologically youngest known species of dromaeosaurids, the other being Dakotaraptor, which is also known from Hell Creek.

Achillobator

Achillobator ( ə-KIL-ə-BAY-tor) is a dromaeosaurid theropod dinosaur that lived roughly 93 to 80 million years ago during the Late Cretaceous in what is now Mongolia, in Asia. It was among the largest dromaeosaurs; the holotype and only known individual of Achillobator is estimated at 5 to 6 m (16.4 to 19.7 ft) long. Achillobator was a moderately-built, ground-dwelling, bipedal carnivore. It would have been an active predator, hunting with the enlarged, sickle-shaped claw on the second toe.

Atrociraptor

Atrociraptor (meaning "savage robber") is a genus of dromaeosaurid theropod dinosaur from the Late Cretaceous (Maastrichtian stage) of Alberta, Canada.

The type (and only) specimen of Atrociraptor, holotype RTMP 95.166.1, was discovered by Wayne Marshall in 1995, in layers of the Horseshoe Canyon Formation also containing an Albertosaurus bonebed, near Drumheller. This bonebed is located at the top of Unit 4 of the Horseshoe Canyon Formation, which dates to about 68.5 million years ago. The only known specimen consists of parts of the upper and lower jaws—both premaxillae, a right maxilla, both dentaries—teeth and numerous small fragments. The skull appears to have been unusually short and tall. The teeth are relatively straight, but they emerge from the tooth sockets at an angle to the jaw line, resulting in a strongly raked row of teeth. A number of isolated teeth (previously referred to Saurornitholestes) have also been recovered from the Horseshoe Canyon Formation; they can be recognized by their unusually large serrations.

In 2004 Philip J. Currie and David Varricchio named and described the type species of Atrociraptor: Atrociraptor marshalli. The generic name is derived from the Latin atrox, "savage", and raptor, "seizer". The specific name honours Marshall.In 2010 Gregory S. Paul estimated its length at two metres, its weight at fifteen kilogrammes. Atrociraptor differs from Bambiraptor and other velociraptorines in its more isodont dentition—the teeth have different sizes but the same form—and short deep snout. A skull opening, the maxillary fenestra, is relatively large and positioned right above another opening, the promaxillary fenestra, a condition not known from other species.

Atrociraptor was by its describers assigned to the Velociraptorinae within a larger Dromaeosauridae. However, in 2009 Currie published a cladistic analysis showing Atrociraptor to be a member of the Saurornitholestinae.

Dromaeosaurinae

Dromaeosaurinae is a subfamily of Dromaeosauridae. Most dromaeosaurines lived in what is now the United States and Canada, as well as Mongolia, and possibly Denmark as well. Isolated teeth that may belong to African dromaeosaurines have also been discovered in Ethiopia. These teeth date to the Tithonian stage, of the Late Jurassic Period.All North American and Asian dromaeosaurine dinosaurs from the Late Cretaceous were generally small, no more than 1.8 metres (5.9 ft) long, in Dromaeosaurus and Adasaurus. However, among the dromaeosaurines were the largest dromaeosaurs ever; Dakotaraptor was ~5.5 metres (18 ft) long, Achillobator 6 metres (20 ft), and Utahraptor up to ~7 metres (23 ft).

Eudromaeosauria

Eudromaeosauria ("true dromaeosaurs") is a subgroup of terrestrial dromaeosaurid theropod dinosaurs. They were relatively large-bodied, feathered hypercarnivores (with diets consisting almost entirely of other terrestrial vertebrates) that flourished in the Cretaceous Period.

Eudromaeosaur fossils are known almost exclusively from the northern hemisphere. They first appeared in the early Cretaceous Period (early Aptian stage, about 124 million years ago) and survived until the end of the Cretaceous (Maastrichtian stage, 66 Ma). The earliest known definitive eudromaeosaur is the dromaeosaurine Utahraptor ostrommaysorum, from the Cedar Mountain Formation, dated to 124 million years ago. However, the earlier (143-million-year-old) fossils such as those of Nuthetes destructor and several indeterminate teeth dating to the Kimmeridgian stage may represent eudromaeosaurs.

Gallery of Paleontology and Comparative Anatomy

The Gallery of Paleontology and Comparative Anatomy (in French, galerie de Paléontologie et d'Anatomie comparée) is a part of the French National Museum of Natural History (Muséum national d'histoire naturelle, MNHN). It is situated in the Jardin des plantes in Paris near the Gare d'Austerlitz.

The Gallery of Comparative Anatomy (occupying the ground floor), holds nearly a thousand skeletons and interprets their organization and classification. The Gallery of Paleontology (occupying the first and second floor) presents a famous collection of fossil vertebrates, fossil invertebrates and fossil plants. Among the most appreciated pieces by the public is worth mentioning a series of dinosaur skeleton casts (Diplodocus, Iguanodon, Allosaurus, Carnotaurus, Tarbosaurus, Unenlagia, Dromaeosaurus, Bambiraptor) but also a Tyrannosaurus skull (cast of specimen AMNH 5027), an authentic skull of Triceratops, an authentic Compsognathus skeleton, and some authentic fossilised skeletons of other extinct animals like Sarcosuchus, Cynthiacetus, Mammuthus meridionalis, Mammuthus primigenius, Megatherium, Thalassocnus, Ursus spelaeus, Panthera leo spelaea, Aepyornis and many others.

Halszkaraptor

Halszkaraptor (; meaning "Halszka's seizer") is a genus of dromaeosaurid dinosaur from Mongolia that lived during the Late Cretaceous period. It contains only one known species, Halszkaraptor escuilliei.Scientists compared the type specimen (holotype) to the bones of extant crocodilians and aquatic birds, and found evidence of a semiaquatic lifestyle. A phylogenetic analysis revealed it was a member of the basal subfamily Halszkaraptorinae along with Mahakala and Hulsanpes.

Halszkaraptorinae

Halszkaraptorinae is a basal ("primitive") subfamily of Dromaeosauridae that includes the enigmatic genera Halszkaraptor, Mahakala, and Hulsanpes. A comparison of the fossils of Halszkaraptor with the bones of extant crocodilians and aquatic birds revealed evidence of a semiaquatic lifestyle. The group is named after Polish paleontologist Halszka Osmólska.

Hulsanpes

Hulsanpes is a genus of dromaeosaurid theropod dinosaur from Mongolia that lived during the Late Cretaceous.

Itemirus

Itemirus is a genus of theropod dinosaur from the Turonian age of the Late Cretaceous period of Uzbekistan.

Luanchuanraptor

Luanchuanraptor (meaning "Luanchuan thief") is a genus of dromaeosaurid theropod dinosaur from the Late Cretaceous of China. It is based on a partial skeleton from the Qiupa Formation in Luanchuan, Henan. A medium-sized dromaeosaurid, it is the first Asian dromaeosaurid described from outside the Gobi Desert or northeastern China. The fossil material is cataloged as 4HIII-0100 in the Henan Geological Museum and includes four teeth, one frontal, a neck vertebra, one or two back vertebrae, seventeen tail vertebrae, ribs, chevrons, a humerus (upper arm bone), claw and finger bones, partial shoulder and pelvic girdles, and other fragmentary bones from a moderately sized dromaeosaurid. The type species is L. henanensis, described by Lü et al. in 2007.

Mahakala omnogovae

Mahakala (from Sanskrit, named for Mahakala, one of eight protector deities (dharmapalas) in Tibetan Buddhism) is a genus of basal dromaeosaurid dinosaur from the Campanian-age (about 80 million years ago) Upper Cretaceous Djadokhta Formation of Ömnögovi, Mongolia. It is based on a partial skeleton found in the Gobi Desert. Mahakala was a small dromaeosaurid (approximately 70 centimeters long (28 in)), and its skeleton shows features that are also found in early troodontids and avialans. Despite its late appearance, it is among the most basal dromaeosaurids. Its small size, and the small size of other basal deinonychosaurians, suggests that small size appeared before flight capability in birds.

Saurornitholestes

Saurornitholestes ("lizard-bird thief") is a genus of carnivorous dromaeosaurid theropod dinosaur from the late Cretaceous of Alberta, Montana, New Mexico, Alabama, North Carolina, and South Carolina.

Two species have been named: Saurornitholestes langstoni in 1978 and Saurornitholestes sullivani in 2015. Saurornitholestes was a small bipedal meat-eating dinosaur, equipped with a sickle-claw on the foot.

Saurornitholestinae

Saurornitholestinae is a subfamily of dromaeosaurid dinosaurs. The saurornitholestines currently include three monotypic genera: Atrociraptor marshalli, Bambiraptor feinbergorum, and Saurornitholestes langstoni. All are medium-sized dromaeosaurs from the Late Cretaceous of western North America. The group was originally recognized by Longrich and Currie as the sister taxon to a clade formed by the Dromaeosaurinae and Velociraptorinae. However, not all phylogenetic analyses recover this group.

Tsaagan

Tsaagan (meaning "white") is a genus of carnivorous dromaeosaurid theropod dinosaur from the Djadokhta Formation of the late Cretaceous of Mongolia.

The fossil of Tsagaan was discovered in 1996 and first identified as a specimen of Velociraptor. After a CAT-scan in May 1998 it was concluded that it represented a new genus. In December 2006 its type species was named and described by Mark Norell, James Clark, Alan Turner, Peter Makovicky, Rinchen Barsbold and Timothy Rowe. The species name, Tsaagan mangas, should be read as a whole with the generic name qualifying the specific epithet, and is derived from the Mongolian words for "white monster" (цагаан мангас), although with an accidental misspelling of the word Tsagaan.

The holotype specimen, IGM 100/1015, was found near Xanadu in Ömnögovi Province in layers of the Djadokhta Formation dating to the Campanian, about 75 million years ago. It consists of a well-preserved skull and series of ten neck vertebrae as well as a damaged left shoulder girdle. It is the only specimen found of Tsaagan and belonged to an adult individual.Tsaagan was a medium-sized dromaeosaurid. In 2010 Gregory S. Paul estimated its length at 2 metres (6.6 ft), its weight at 15 kilograms (33 lb). The skull in general appearance resembles that of Velociraptor but differs from it in many details. It is more robust and smooth on top; unique derived traits, autapomorphies, include long paroccipital processes and basipterygoids at the back of the skull and a jugal touching the squamosal.

Unenlagiinae

Unenlagiinae is a subfamily of dromaeosaurid theropods. Unenlagiines are known from South America and Antarctica.

Unquillosaurus

Unquillosaurus (meaning "Unquillo river lizard") is a genus of maniraptoran dinosaur from the Late Cretaceous Period, discovered in Argentina. Known only from a single fossilized pubis (a pelvic bone), its total body length may have reached 2 to 3 metres (6.6 to 9.8 ft).

Velociraptorinae

Velociraptorinae is a subfamily of the theropod group Dromaeosauridae. The earliest velociraptorines are probably Nuthetes from the United Kingdom, and possibly Deinonychus from North America. However, several indeterminate velociraptorines have also been discovered, dating to the Kimmeridgian stage, in the Late Jurassic Period. These fossils were discovered in the Langenberg quarry, Oker near Goslar, Germany.In 2007 paleontologists studied front limb bones of Velociraptor and discovered small bumps on the surface, known as quill knobs. The same feature is present in some bird bones, and represents the attachment point for strong secondary wing feathers. This finding provided the first direct evidence that velociraptorines, like all other maniraptorans, had feathers.While most velociraptorines were generally small animals, at least one species may have achieved gigantic sizes comparable to those found among the dromaeosaurines. So far, this unnamed giant velociraptorine is known only from isolated teeth found on the Isle of Wight, England. The teeth belong to an animal the size of dromaeosaurines of the genus Utahraptor, but they appear to belong to a velociraptorine, judging by the shape of the teeth and the anatomy of their serrations.

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