Ulnar articular surface 3-D landmarks and ecomorphology of small mammals: A case of study in two Early Miocene typotheres (Notoungulata) from Patagonia

MUÑOZ, NAHUEL ANTÚ; CASSINI, GUILLERMO HERNÁN; CANDELA, ADRIANA MAGDALENA; VIZCAÍNO, SERGIO FABIÁN

EARTH AND ENVIRONMENTAL SCIENCE TRANSACTIONS OF THE ROYAL SOCIETY OF EDINBURGH

ROYAL SOC EDINBURGH

Lugar: Edinburgo; Año: 2017 vol. 106 p. 315 - 323

1755-6910

Articular surfaces reflect the relative movements betweenadjacent bones, and the ones involved in the elbow joint provide informationabout forelimb movements and may be useful for making inferences about thesubstrate use. The proximal articular surface of the ulna was examined through3-D geometric morphometrics, in order to assess its usefulness as a proxy forpaleoecological interpretations; particularly for two small mammals from theEarly Miocene of Patagonia. The sample was composed of 22 extant small mammals(rodents, carnivorans and primates) and two extinct typotheres: Hegetotherium mirabile (Hegetotheriidae) and Interatheriumrobustum (Interatheriidae).Forty-five landmarks were taken and principal component analysis (PCA) was usedto explore the morphospace structure. The results of PCA for the whole surface wereinconclusive; therefore, successive analyses were made, subdividing the surfaceinto sub-units. The PCA for the proximal part of the trochlear notch was themost informative, allowing the recognition of morphospaces with functionalvalue: one for digging rodents and another for most climbers. Neither typotherewould have had a specialisation for climbing or digging in the featuresanalysed. This study allows morphological patterns on different parts of ajoint to be detected; interpreted, at least partially, as differentialresponses to different kinds of mechanical stress.