Bonitasaura

Description

Bonitasaura measured 10 m 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 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 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.

Palaeopathologies

Multiple palaeopathologies have been identified from the holotype of B. salgadoi. These include a femoral 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 Rinconsauria. 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: |{{clade

References

References

1. Gallina, P. A. (2011). [https://www.scielo.br/pdf/aabc/v83n1/aop0111.pdf Notes on the axial skeleton of the titanosaur Bonitasaura salgadoi (Dinosauria-Sauropoda).] ''Anais da Academia Brasileira de Ciências'', ''83''(1), 235-246.
2. 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.
3. McIntosh, J. S. (1990). Species determination in sauropod dinosaurs with tentative suggestions for their classification. In ''Dinosaur systematics symposium'' (pp. 53-69).
4. Apesteguía, S. (2004). Bonitasaura salgadoi gen. et sp. nov.: a beaked sauropod from the Late Cretaceous of Patagonia. ''Naturwissenschaften'', ''91''(10), 493-497.
5. Upchurch, P. (1999). The phylogenetic relationships of the Nemegtosauridae (Saurischia, Sauropoda). ''Journal of Vertebrate Paleontology'', ''19''(1), 106-125.
6. (November 2017). "Multiple paleopathologies in the dinosaur Bonitasaura salgadoi (Sauropoda: Titanosauria) from the Upper Cretaceous of Patagonia, Argentina". [[Cretaceous Research]].
7. Gallina & Apesteguí, 2015
8. 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.
9. (2023-02-02). "A new giant titanosaur (Dinosauria, Sauropoda) from the Upper Cretaceous of Northwestern Patagonia, Argentina". Cretaceous Research.