| Bonitasaura | |
|---|---|
 | |
| Right dentary | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | †Sauropodomorpha |
| Clade: | †Sauropoda |
| Clade: | †Macronaria |
| Clade: | †Titanosauria |
| Clade: | †Colossosauria |
| Genus: | †Bonitasaura Apesteguía, 2004 |
| Type species | |
| †Bonitasaura salgadoi Apesteguía, 2004 | |
Bonitasaura is agenus oftitanosauriandinosaur hailing from uppermost layers of theLate Cretaceous (Santonian)Bajo de la Carpa Formation,Neuquén Group of the easternNeuquén Basin, located inRío Negro Province, NorthwesternPatagonia,Argentina. The remains, consisting of a partial sub-adult skeleton jumbled in a small area offluvialsandstone, including alower jaw with teeth, a partial vertebrae series, and limb bones, were described by Sebastian Apesteguía in 2004.[1]
The genus nameBonitasaura refers to thefossil quarry's name, "La Bonita", while the name of thetype species,B. salgadoi, pays homage to Leonardo Salgado, a renowned Argentinepaleontologist.[2]
Bonitasaura measured 10 metres (33 ft) in length, and had a skull similar to another group ofsauropods, thediplodocids. The lower jaw had a distinctive, sharp ridge immediately behind a reduced set of teeth. This ridge supported in life a sharp, beak-likekeratin sheath that probably paired with a similar structure in the upper jaw. The keratin sheath worked much like aguillotine 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 also shows that some lines of titanosaurian evolution converged with diplodocids, namely low long skulls without the characteristic nasal arches of othermacronarians (such asBrachiosaurus orCamarasaurus) and lower jaws that were squared off and contained comb-like teeth (as inRebbachisauridae), reversed limb proportions (the front limbs shorter than the hind limbs, unlike the condition in most other macronarians) and rudimentary whiplash tails. It also made the suggestion that the titanosaurAntarctosaurus is achimera made up of a titanosaurian skull and body and a diplodocoid jaw, as proposed by some authors (McIntosh 1990; Jacobs et al. 1993; Upchurch 1999) less likely.[3][4][1][5]
Multiplepalaeopathologies have been identified from the holotype ofB. salgadoi. These include afemoral osteoblastic tumour, anenthesophyte on metatarsal III, and abnormal tissue in a caudalprezygapophysis caused by an infection.[6]
Bonitasaura was originally classified as a member ofNemegtosauridae in the original description, but subsequent cladistic analyses and description found it to be nested among the titanosaur clade that includesLognkosauria andRinconsauria.[7][8] In the description ofChucarosaurus in 2023, Agnolinet al. recoveredBonitasaura as acolossosaurian member of the Titanosauria, as thesister taxon to a clade formed byChucarosaurus,Notocolossus and theLognkosauria. The results of theirphylogenetic analyses are shown in thecladogram below:[9]
