New Remains of Megathericulus patagonicus Ameghino, 1904 (Xenarthra, Tardigrada) from the Serravallian (Middle Miocene) of Bolivia; Chronological and Biogeographical Implications

BRANDONI, DIEGO; CARLINI, ALFREDO A; ANAYA, FEDERICO; GANS, PHIL; CROFT, DARIN A

JOURNAL OF MAMMALIAN EVOLUTION

SPRINGER

Lugar: Berlin; Año: 2018 vol. 25 p. 327 - 337

1064-7554

In this contribution, we describe new remains (skulland humeri) of the Megatheriinae Megathericuluspatagonicus Ameghino, 1904, recovered from the middleMiocene fossiliferous locality of Quebrada Honda, Bolivia.We also discuss the taxonomic, biogeographical, and chronologicalrelevance of this discovery. Referral of the new specimensdescribed here to Megathericulus patagonicus is basedon metric and morphological similarities with the holotypeand a humerus that has been referred to this species. Sharedfeatures include: 1) molariforms that are mesiodistally compressedand rectangular in outline; 2) a relatively less compressedM1 with labial and lingual margins that convergeslightly mesially; 3) a very long premolariform portion ofthe maxillae (rostrum); 4) anteriorly divergent lateral edgesof the maxillae; 5) a prominent, median V-shaped notch (apexposterior) between the articular surfaces of the maxillae andpremaxillae; and 6) a long, gracile humerus with a prominentanterolaterally positioned deltopectoral crest on the anteriorsurface and a clearly evident lateral musculo-spiralchannel. Precise geographic and stratigraphic data exist forthe described remains, which are closely associated with atuff dated at 12.2?12.5 Ma (Serravallian, middle Miocene),making it the first accurately dated specimen referred toMegathericulus Ameghino, 1904.On.line version: 04-2017Issue version: 09-2018