Bonitasaura

Bonitasaura is a titanosaurian dinosaur hailing from uppermost layers of the Late Cretaceous (Santonian) Bajo de la Carpa Formation, Neuquén Group of the eastern Neuquén Basin, 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 Sebastian Apesteguía in 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.[1]

Bonitasaura
Temporal range: Santonian
~85 Ma
Bonitasaura
Right dentary
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Order: Saurischia
Suborder: Sauropodomorpha
Clade: Sauropoda
Clade: Titanosauria
Clade: Eutitanosauria
Genus: Bonitasaura
Apesteguía 2004
Type species
Bonitasaura salgadoi
Apesteguía 2004

Description

Bonitasaura head
Illustration of the head

Bonitasaura measured 10 metres (33 ft) in length, and had a skull similar to another group of sauropods, the diplodocids. 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 used in vigorous exertions, probably during feeding.

Bonitasaura Size Comparison by PaleoGeek
Scale chart of B. salgadoi

Bonitasaura also shows that some lines of titanosaurian evolution converged with diplodocids, namely low long skulls without the characteristic nasal arches of other macronarians (such as Brachiosaurus or Camarasaurus) and lower jaws that were squared off and contained comb-like teeth (as in Rebbachisauridae), reversed limb proportions (the front limbs shorter than the hind limbs, unlike the condition in most other macronarians) and rudimentary whiplash tails. It also threw a wrench into the suggestion by some authors (McIntosh 1990; Jacobs et al. 1993; Upchurch 1999) that the titanosaur Antarctosaurus is a chimera made up of a titanosaurian skull and body and a diplodocoid jaw.[2]

Classification

Bonitasaura was originally classified as a member of Nemegtosauridae in the original description, but subsequent cladistic analyses and description found it to be nested among the titanosaur clade that includes Lognkosauria and Rinconsauria.[3][4][5]

References

  1. ^ Gallina & Apesteguía, 2011, p.46
  2. ^ Apesteguía, 2004
  3. ^ Gallina & Apesteguía, 2011, p.54
  4. ^ Gallina & Apesteguí, 2015
  5. ^ Carballido et al., 2017

Bibliography

Antarctosaurus

Antarctosaurus (; meaning "southern lizard") is a genus of titanosaurian sauropod dinosaur from the Late Cretaceous Period of what is now South America. The type species, Antarctosaurus wichmannianus, and a second species, Antarctosaurus giganteus, were described by prolific German paleontologist Friedrich von Huene in 1929. Three additional species of Antarctosaurus have been named since then but later studies have considered them dubious or unlikely to pertain to the genus.

The type species, A. wichmannianus, is controversial because there is uncertainty as to whether all the described remains belong to the same individual or even genus. The second species, A. giganteus, is considered dubious, but the fragmentary remains represent one of the largest dinosaurs known.

Austroposeidon

Austroposeidon is an extinct genus of titanosaurian sauropod dinosaur from the Late Cretaceous Presidente Prudente Formation of Brazil. It contains one species, Austroposeidon magnificus.

Baalsaurus

Baalsaurus (named after the dinosaur fossil site Baal in Argentina, which in turn is named after the ancient Phoenician god Baal) is a genus of titanosaurian sauropod dinosaur from the Late Cretaceous of Neuquén Province, Patagonia, Argentina. The type and only known species is B. mansillai, with the specific name honoring the discoverer Juan Eduardo Mansilla, a museum technician at the Geology and Paleontology Museum of the National University of Comahue.

The holotype specimen, MUCPv-1460, is a mostly complete right dentary that was found in rocks of the upper Portezuelo Formation. The dentary is squared-off instead of curved when viewed from above or below, with the teeth crowded into the front of the jaw, making it similar to the jaw of Antarctosaurus, Brasilotitan, and to a lesser extent Bonitasaura. The specimen is currently held at the Geology and Paleontology Museum of the National University of Comahue, Parque Natural Geo-Paleontológico Proyecto Dino, Barreales Lake.

Brasilotitan

Brasilotitan is a genus of titanosaurian sauropod dinosaur from the Late Cretaceous (early Maastrichtian) Adamantina Formation of Brazil. The type species is Brasilotitan nemophagus.

Cetiosauridae

Cetiosauridae is a family of sauropod dinosaurs. While traditionally a wastebasket taxon containing various unrelated species, some recent studies have found that it may represent a natural clade. Additionally, at least one study has suggested that the mamenchisaurids may represent a sub-group of the cetiosaurids, which would be termed Mamenchisaurinae.

Clasmodosaurus

Clasmodosaurus was a genus of dinosaur, probably a sauropod. It lived during the Late Cretaceous in what is now Argentina. It is known only from three fossilized teeth, and is therefore a tooth taxon. It is a nomen dubium.The type species, Clasmodosaurus spatula, was described by Argentine paleontologist Florentino Ameghino in 1898. For a long time, these teeth were thought to belong to a theropod. The teeth of Clasmodosaurus spatula were polygonal in cross section rather than round, an unusual trait also found in the titanosaur Bonitasaura salgadoi.

Diplodocinae

Diplodocinae is an extinct subfamily of diplodocid sauropods that existed from the Late Jurassic to Early Cretaceous of North America, Europe and South America, about 161.2 to 136.4 million years ago. Genera within the subfamily include Tornieria, Supersaurus, Leinkupal, Galeamopus, Diplodocus, Kaatedocus and Barosaurus.Cladogram of the Diplodocidae after Tschopp, Mateus, and Benson (2015).

Ferganasaurus

Ferganasaurus was a genus of dinosaur first formally described in 2003 by Alifanov and Averianov. The type species is Ferganasaurus verzilini. It was a sauropod similar to Rhoetosaurus. The fossils were discovered in 1966 in Kyrgyzstan from the Balabansai Formation and date to the Callovian stage of the Middle Jurassic.

Gravisauria

Gravisauria is a clade of sauropod dinosaurs consisting of some genera, Vulcanodontidae and Eusauropoda.

Jiutaisaurus

Jiutaisaurus is a genus of sauropod dinosaur from the Quantou Formation of China. Jiutaisaurus was a sauropod which lived during the Cretaceous. The type species, Jiutaisaurus xidiensis, was described by Wu et al. in 2006, and is based on eighteen vertebrae.

Laplatasaurus

Laplatasaurus (meaning "La Plata lizard", named for La Plata, Argentina) is a genus of titanosaurian sauropod dinosaur that lived during the Late Cretaceous in South America.

The genus was named in 1927 by Friedrich von Huene, but without a description, so that it remained a nomen nudum. In 1929 the type species, Laplatasaurus araukanicus, was described by Huene. The generic name refers to La Plata. The specific name is derived from the Araucanos or Mapuche. By accident Huene in 1929 also mentioned a "Laplatasaurus wichmannianus" but that was a lapsus calami for Antarctosaurus wichmannianus. In 1933 however, he and Charles Alfred Matley renamed Titanosaurus madagascariensis to Laplatasaurus madagascariensis. This last species is today commonly referred to the original Titanosaurus.

Huene based Laplatasaurus on fragmentary material found in three locations in Argentina, in strata of the Allen Formation, dating from the Campanian faunal stage. It consisted of limb elements, some dorsal vertebrae and a series of caudal vertebrae. Part of the finds had earlier been referred by Richard Lydekker to Titanosaurus australis. Huene never assigned a holotype, but in 1979 José Fernando Bonaparte chose MLP 26-306 as the lectotype, a specimen consisting of a tibia and a fibula that perhaps originate from different individuals.

Huene assigned those fossils to Laplatasaurus that seemed to indicate a rather large yet at the same time elegantly built sauropod. The about eighteen metres (60 ft) long Laplatasaurus was perhaps similar to Saltasaurus. Osteoderms forming an armored plating on the back, have been referred to Laplatasaurus but the association is uncertain. These plates had much smaller ridges than those of Saltasaurus.

Huene placed Laplatasaurus in the Titanosauridae, which is still a common classification. In his 2003 review of South American titanosaurs, Jaime Eduardo Powell assigned Laplatasaurus to Titanosaurus, creating the new combination Titanosaurus aurakanicus. Others however, continued to treat Laplatasaurus as valid genus separate from Titanosaurus.A 2015 re-assessment of Laplatasaurus found it to be closely related to Bonitasaura, Futalognkosaurus, Mendozasaurus, and Uberabatitan. The genus was restricted to the lectotype, and the material from Rancho de Avila was assigned to cf. Bonitasaura sp.

Lognkosauria

Lognkosauria is a group of giant long-necked sauropod dinosaurs within the clade Titanosauria. It includes some of the largest and heaviest dinosaurs known.

Microcoelus

Microcoelus is a dubius genus of small Titanosaurian sauropod dinosaur native to Argentina. It is known from only a single dorsal vertebra. A left humerus was formerly referred to this species, but it is now considered to belong to Neuquensaurus. This species may be a synonym of the contemporary sauropod Neuquensaurus australis.It was described by British paleontologist Richard Lydekker in 1893.

Nemegtosauridae

Nemegtosauridae is a family of titanosaurian sauropod dinosaurs based originally on two late Cretaceous Mongolian species known only from their diplodocid-like skulls: Nemegtosaurus and Quaesitosaurus.

Nemegtosaurus

Nemegtosaurus (meaning 'Reptile from the Nemegt') was a sauropod dinosaur from Late Cretaceous Period of what is now Mongolia. Nemegtosaurus was named after the Nemegt Basin in the Gobi Desert, where the remains — a single skull — were found. The skull resembles diplodocoids in being long and low, with pencil-shaped teeth. However, recent work has shown that Nemegtosaurus is in fact a titanosaur, closely related to animals such as Saltasaurus, Alamosaurus and Rapetosaurus.

Pilmatueia

Pilmatueia is a diplodocoid sauropod belonging to the family Dicraeosauridae that lived in Argentina during the Early Cretaceous.

Tambatitanis

Tambatitanis is an extinct genus of titanosauriform dinosaur from the Early Cretaceous (probably early Albian) of Japan. It is known from a single type species, Tambatitanis amicitiae. It was probably around 14 meters long and its mass was estimated at some 4 tonnes. It was a basal titanosauriform and possibly belonged to the Euhelopodidae.

Titanosauria

Titanosaurs (members of the group Titanosauria) were a diverse group of sauropod dinosaurs which included Saltasaurus and Isisaurus of Africa, Asia, South America, Europe and Australia. The titanosaurs were the last surviving group of long-necked sauropods, with taxa still thriving at the time of the extinction event at the end of the Cretaceous. The group includes the largest land animals known to have existed, such as Patagotitan—estimated at 37 m (121 ft) long with a weight of 69 tonnes (76 tons)—and the comparably sized Argentinosaurus and Puertasaurus from the same region. The group's name alludes to the mythological Titans of Ancient Greece, via the type genus (now considered a nomen dubium) Titanosaurus. Together with the brachiosaurids and relatives, titanosaurs make up the larger clade Titanosauriformes.

Vulcanodontidae

The Early Jurassic sauropod dinosaurs Zizhongosaurus, Barapasaurus, Tazoudasaurus, and Vulcanodon may form a natural group of basal sauropods called the Vulcanodontidae. Basal vulcanodonts include some of the earliest known examples of sauropods. The family-level name Vulcanodontidae was erected by M.R. Cooper in 1984. In 1995 Hunt et al. published the opinion that the family is synonymous with the Barapasauridae. One of the key morphological features specific to the family is an unusually narrow sacrum.

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