EVALUATING LOCOMOTION STRATEGIES IN ALVAREZSAURIA (DINOSAURIA, THEROPODA): TECHNICAL INTEGRATIONS FOR DETERMINING FUNCTIONAL IMPLICATIONS.

MESO, J.G.; PITTMAN, M.; QIN, Z.; SALGADO, L.

Villa El Chocón

Jornada; III Jornadas de Paleontología de la Cuenca Neuquina; 2021

Comisión Organizadora

Alvarezsauria is most well known for their forelimb and its tail evolution but less is known about the function of other parts of their bodies. Therefore, the morphology and dimensions of the pelvis and hindlimbs also are a proxy of the morphofunctional properties of this clade. Here we perform two analyses, namely, a quantitative analysis about different variables taken from hindlimb, and linear regression analysis about agility force, in order to delineate how different are the alvarezsaurs compared to other theropods and to understand locomotor aspects of this group. The analysis 1 involves two datasets of linear measurements of the hindlimb bones from several theropod taxa. The first dataset is based on the long-bone measurements of the hindlimb, whereas the second is based on the lengths of the pedal phalanges. The analysis 2 is focused on a linear regression performed in order to estimate agility force through the use of body mass, muscle force, and rotational inertia inferred. Our results show that for the first dataset, earliest-branching alvarezsaurians converge with the morphospace of oviraptorosaurians, while the Patagonian forms do so with some troodontids, dromaeosaurids, and accipitrid birds. Later-diverging forms converge with the falconiform and tinamiform bird morphospace. Regarding the second dataset, alvarezsaurians are close to the morphospace occupied by Struthioniformes and Ornithomimosauria. Furthermore, the second analysis shows that rotational inertia and ilium area indicate a major agility force that would have conferred more rapid turns compared to other theropods. The results reflect differences in locomotor and predatory habits along the Alvarezsauria clade.