Evolutionary trends of Protypotherium (Interatheriidae, Notoungulata) lineage throughout the Miocene of South America

SCARANO, ALEJO; VERA, BÁRBARA; REGUERO, MARCELO

JOURNAL OF MAMMALIAN EVOLUTION

SPRINGER

Lugar: Berlin; Año: 2021 vol. 28 p. 885 - 895

1064-7554

Protypotherium (Mammalia, Notoungulata, lnteratheriinae) is a well-known and verydiverse genus of extinct native ungulates of South America, widely distributed fromsouthern to middle latitudes of Argentina, Chile, and Bolivia. This genus exhibitsdistinctive species throughout the Miocene to the beginning of the Pliocene that displayan interesting size pattern. The large sample of specimens studied during severalyears of research allow us to analyze the shape and size of upper and lower molars fornine species of Protypotherium , in order to test the hypothesis of reduction of sizeranges preserving a general tooth morphology as a response to climate deterioration,documented in South America by a markedly descend of temperature occurred duringMiocene times. Elliptic Fourier analyses were used to capture the shape of the occlusalmorphology and the centroid size was also retained for subsequent analyses. Ourresults demonstrate that: 1) a similar morphological tooth pattern is observed among allspecies; 2) tooth shape variation is not associated with a change in size; and 3) thereis a tendency to increase the size from the smallest species to the largest one, both inupper and lower molars and between small and large species. This striking patterncould be correlated with a global trend to lower temperatures, which indicates adeterioration of paleoenvironmental conditions. A conservative tooth pattern, togetherwith an increase of size and a reduction in number of species were the mainevolutionary and ecological tendencies accounted in Protypotherium from the early tolate Miocene-beginning of the Pliocene, which were accompanied by a latitudinaldisplacement from Patagonia to northern areas at the end of the Miocene.