Biomechanical performance in terror birds´ (Aves, Cariamiformes) jaw

DEGRANGE, F.J.; WROE, S.; TAMBUSSI, C.P.; WITMER, L.

Diamante

Congreso; 9th International Meeting of the Society of Avian Paleontology and Evolution; 2016

Society of Avian Paleontology and Evolution

The predominantly South American Phorusrhacidaecomprise a range of small to gigantic extinct terrestrial bird predators forwhich there are no close functional analogues, making reconstruction of theirfeeding behavior particularly interesting. In the present study, finite elementanalyses (FEA) were performed on the jaw of three Phorusrhacidae (Andalgalornis, Andrewsornis and Llallawavis)and one Cariamidae (Chunga) to assessthe cranial performance during trophic item capture. Models of the jaw weregenerated from CT scans and the analysis was performed using publishedhomogeneous bone properties for birds (Young´s modulus: 27GPa; Poisson ratio:0.4; Bone density: 2.19085 T/mm3). Antero-posterior, dorso-ventraland latero-medial forces were simulated applying published bite forces. Thearticular area was constrained in space. In all the cases, the jaw shows higherstress under dorso-ventral and latero-medial loadings than underantero-posterior (=`pullback´) simulations. However, dorso-ventral simulationproduces higher stresses values, which is highly contrasting with publishedrecords on the skull. Larger terror birds (Andalgalornis,Andrewsornis) have sturdier jaws,which results in lower stresses when compared with Llallawavis. Prolonged prey subjection using maximum bite force mayimpose risky stress. In concordance with previously skull analysis and based onthe present results, terror birds´ prey handling based on catching rapidly thetrophic item and tearing it apart through caudally directed movements of thehead would not pose risk to the jaw.