Bonitasaura
Encyclopedia
Bonitasaura is a titanosaurian dinosaur
hailing from uppermost layers of the Late Cretaceous
Bajo de la Carpa Formation
, Neuquen Group
, located in Río Negro Province
, Northwestern Patagonia
, Argentina
. The remains, consisting of a partial sub-adult skeleton jumbled in a small area of fluvial
sandstone
, including lower jaw with teeth, partial vertebrae series and limb bones, were described by Apesteguía in a short communication in mid-2004.
The genus name Bonitasaura refers to the fossil quarry’s name, “La Bonita”, while the name of the type species
, B. salgadoi, pays homage to Leonardo Salgado, a renowned Argentine palaeontologist.
Bonitasaura measured 9 meters (30 feet) in length, and had a skull similar to another group of sauropods, the diplodocid
s. The lower jaw had a distinctive, sharp ridge immediately behind a reduced set of teeth. This ridge supported in life a sharp, beak-like keratin
sheath that probably paired with a similar structure in the upper jaw. The keratin sheath worked much like a guillotine
to crop vegetation raked into the mouth by the peg-like front teeth. This animal also had a rather short neck and robust projections of the back vertebrae for muscle attachment, indicating that the neck was use in vigorous exertions, probably during feeding.
B. salgadoi is further evidence that, after a purported extinction of diplodocid sauropods, some lines of titanosaurian evolution converged with them, exhibiting low long skulls without the characteristic nasal arches of other macronaria
ns (such as Brachiosaurus
or Argentinosaurus
) and lower jaws that were squared off and contained comb-like teeth, reversed limb proportions (the front limbs shorter than the hind limbs, unlike the condition in most other macronarians) and rudimentary whiplash tails. This find also sheds light on some problematic aspects of the related dinosaur Antarctosaurus
, sometimes viewed as a chimera
made up of a titanosaurian skull and body and a diplodocid jaw.
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...
hailing from uppermost layers 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...
Bajo de la Carpa Formation
Bajo de la Carpa Formation
The Bajo de la Carpa Formation is a geologic formation that outcrops in Patagonia, in the provinces of Río Negro and Neuquén, Argentina. It is the first of two formations belonging to the Río Colorado Subgroup within the Neuquén Group...
, Neuquen Group
Neuquén Group
The Neuquén Group is a group of geologic formations found in Argentina. Rocks in the Neuquén Group fall within the Cenomanian to early Campanian stages of the Late Cretaceous Period, about 100 million to 80 million years in age...
, located in Río Negro Province
Río Negro Province
Río Negro is a province of Argentina, located at the northern edge of Patagonia. Neighboring provinces are from the south clockwise Chubut, Neuquén, Mendoza, La Pampa and Buenos Aires. To the east lies the Atlantic Ocean.Its capital is Viedma...
, Northwestern Patagonia
Patagonia
Patagonia is a region located in Argentina and Chile, integrating the southernmost section of the Andes mountains to the southwest towards the Pacific ocean and from the east of the cordillera to the valleys it follows south through Colorado River towards Carmen de Patagones in the Atlantic Ocean...
, 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...
. The remains, consisting of a partial sub-adult skeleton jumbled in a small area of fluvial
Fluvial
Fluvial is used in geography and Earth science to refer to the processes associated with rivers and streams and the deposits and landforms created by them...
sandstone
Sandstone
Sandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains.Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any colour, but the most common colours are tan, brown, yellow,...
, including lower jaw with teeth, partial vertebrae series and limb bones, were described by Apesteguía in a short communication in mid-2004.
The genus name Bonitasaura refers to the fossil quarry’s name, “La Bonita”, while the name of the type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
, B. salgadoi, pays homage to Leonardo Salgado, a renowned Argentine palaeontologist.
Bonitasaura measured 9 meters (30 feet) in length, and had a skull similar to another group of sauropods, the diplodocid
Diplodocid
Diplodocids, or members of the family Diplodocidae , are a group of sauropod dinosaurs. The family includes some of the longest creatures ever to walk the earth, including Diplodocus and Supersaurus, which may have reached lengths of up to .-Description:While still massive, when compared to the...
s. The lower jaw had a distinctive, sharp ridge immediately behind a reduced set of teeth. This ridge supported in life a sharp, beak-like keratin
Keratin
Keratin refers to a family of fibrous structural proteins. Keratin is the key of structural material making up the outer layer of human skin. It is also the key structural component of hair and nails...
sheath that probably paired with a similar structure in the upper jaw. The keratin sheath worked much like a guillotine
Guillotine
The guillotine is a device used for carrying out :executions by decapitation. It consists of a tall upright frame from which an angled blade is suspended. This blade is raised with a rope and then allowed to drop, severing the head from the body...
to crop vegetation raked into the mouth by the peg-like front teeth. This animal also had a rather short neck and robust projections of the back vertebrae for muscle attachment, indicating that the neck was use in vigorous exertions, probably during feeding.
B. salgadoi is further evidence that, after a purported extinction of diplodocid sauropods, some lines of titanosaurian evolution converged with them, exhibiting low long skulls without the characteristic nasal arches of other macronaria
Macronaria
Macronaria is a clade of sauropod dinosaurs from the Middle Jurassic to Late Cretaceous Periods of what are now North America, South America, Europe, Asia and Africa. The name means 'large nostrils' , in reference to the large nasal openings high on the head that probably supported fleshy...
ns (such as Brachiosaurus
Brachiosaurus
Brachiosaurus is a genus of sauropod dinosaur from the Jurassic Morrison Formation of North America. It was first described by Elmer S. Riggs in 1903 from fossils found in the Grand River Canyon of western Colorado, in the United States. Riggs named the dinosaur Brachiosaurus altithorax,...
or Argentinosaurus
Argentinosaurus
Argentinosaurus is a genus of titanosaur sauropod dinosaur first discovered by Guillermo Heredia in Argentina. The generic name refers to the country in which it was discovered...
) and lower jaws that were squared off and contained comb-like teeth, reversed limb proportions (the front limbs shorter than the hind limbs, unlike the condition in most other macronarians) and rudimentary whiplash tails. This find also sheds light on some problematic aspects of the related dinosaur Antarctosaurus
Antarctosaurus
Antarctosaurus is a genus of titanosaurian sauropod dinosaur from the Late Cretaceous Period of what is now South America. The type species, A. wichmannianus, was described by prolific German paleontologist Friedrich von Huene in 1929, who also described a second species in 1929. Three additional...
, sometimes viewed as a chimera
Chimera (paleontology)
In paleontology, a chimera is a fossil which was reconstructed with elements coming from more than a single species of animal. A now classic example of chimera is Protoavis.-List of paleontological chimeras:*Brontosaurus*Lametasaurus...
made up of a titanosaurian skull and body and a diplodocid jaw.