Bonitasaura is a genus of 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 a Mandible with teeth, a 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 paleontologist.[Gallina, P. A. (2011). Notes on the axial skeleton of the titanosaur Bonitasaura salgadoi (Dinosauria-Sauropoda). Anais da Academia Brasileira de Ciências, 83(1), 235-246.]
Description
Bonitasaura measured in length, and had a skull similar to another group of
, the
. 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 also shows that some lines of titanosaurian evolution converged with diplodocids, namely low long skulls without the characteristic nasal arches of other
(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 made the suggestion that the titanosaur
Antarctosaurus is a chimera 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.
[Jacobs, L., Winkler, D. A., Downs, W. R., & Gomani, E. M. (1993). New material of an Early Cretaceous titanosaurid saurepod dinosaur from Malawi. Palaeontology, 36, 523-523.][McIntosh, J. S. (1990). Species determination in sauropod dinosaurs with tentative suggestions for their classification. In Dinosaur systematics symposium (pp. 53-69).][Apesteguía, S. (2004). Bonitasaura salgadoi gen. et sp. nov.: a beaked sauropod from the Late Cretaceous of Patagonia. Naturwissenschaften, 91(10), 493-497.][Upchurch, P. (1999). The phylogenetic relationships of the Nemegtosauridae (Saurischia, Sauropoda). Journal of Vertebrate Paleontology, 19(1), 106-125.]
Palaeopathologies
Multiple palaeopathologies have been identified from the holotype of
B. salgadoi. These include a
Femur osteoblastic tumour, an
enthesophyte on metatarsal III, and abnormal tissue in a caudal
prezygapophysis caused by an infection.
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
Aeolosaurini.
[Gallina & Apesteguí, 2015][Carballido, J. L., Pol, D., Otero, A., Cerda, I. A., Salgado, L., Garrido, A. C., ... & Krause, J. M. (2017). A new giant titanosaur sheds light on body mass evolution among sauropod dinosaurs. Proceedings of the Royal Society B: Biological Sciences, 284(1860), 20171219.] In the description of
Chucarosaurus in 2023, Agnolin
et al. recovered
Bonitasaura as a
colossosaurian member of the Titanosauria, as the
sister taxon to a clade formed by
Chucarosaurus,
Notocolossus and the
Lognkosauria. The results of their phylogenetic analyses are shown in the
cladogram below:
