INFERRING THE LOCOMOTOR AND PREDATORY HABITS OF UNENLAGIINES (THEROPODA, PARAVES) BASED ON MORPHOMETRIC STUDIES AND COMPARISONS WITH LAURASIAN DROMAEOSAURIDS

FEDERICO A. GIANECHINI; MARCOS D. ERCOLI; IGNACIO DÍAZ-MARTÍNEZ

Puerto Madryn

Congreso; Reunión de Comunicaciones de la Asociación Paleontológica Argentina; 2018

Asociación Paleontológica Argentina y CENPAT

Unenlagiinae is generally considered as a subfamily within Dromaeosauridae. Dromaeosaurids share a modified pedal digit II, which is typicallyrelated to predation. However, differences between unenlagiines and derived Laurasian dromaeosaurids (eudromaeosaurs), including a more robustdigit II and a shorter metatarsus in eudromaeosaurs and a subarctometatarsus in unenlagiines, possibly reflect different locomotor and predatoryhabits. To evaluate this it was conducted a morphometric study analyzing the lengths of femur (FL), tibia (TL), metatarsus (MtL), non-ungual pedalphalanges (PhL), and the width of metatarsus (ML) of several theropod taxa. Two PCAs were performed, one of them using the measurements FL,TL, MtL and ML and the other using PhL. The first analysis showed the unenlagiines close to taxa with high TL and MtL and low ML. Thesefeatures are considered to provide high cursorial capacities. Instead, eudromaeosaurs are between taxa with low TL and MtL and high ML, whichcan be considered with low cursorial capacities. In the second analysis the position of dromaeosaurids, including unenlagiines, in the morphospacewas mainly influenced by a long digit IV. Thus, phalanges proportions do not differ significantly, although the other discrepancies could suggestgreater cursorial capacities and different predatory strategies in unenlagiines. Eudromaeosaurs, with more robust feet, had the potential of huntinglarge preys, tearing flesh with their serrated teeth. Instead, unenlagiines such as Buitreraptor, with slender feet and tiny non-serrated teeth,possibly foraged on the ground and hunted smaller preys. Thus, these results could indicate different life habits between unenlagiines andeudromaeosaurs.