New species, local faunas, and paleoenvironmental data for the middle Miocene Quebrada Honda Fauna, Bolivia

CROFT, DARIN; ANAYA, FEDERICO; CATENA, A. M.; CIANCIO, MARTÍN R.; ENGELMAN, R. K.

Congreso; 73rd Meeting Of The Society Of Vertebrate Paleontology; 2013

The late middle Miocene site of Quebrada Honda, Bolivia is one of the few sites inthe South American tropics that has produced abundant fossil mammal remains. Ourteam?s ongoing field research in the area has cataloged more than 700 specimens fromboth traditional collecting areas (Quebrada Honda, Río Rosario) and newly discoveredsites. New sites are located north of Río Rosario (closer to Papachacra), 5 km northeast ofQuebrada Honda, and near Huayllajara (5 km south of Quebrada Honda). We report thefirst ichnofossils from the area, including Pallichnus and Coprinisphaera (dung beetlebrood balls) and Celliforma and Cellicalichnus (ground-dwelling bee/wasp nests),suggesting an open or wooded grassland habitat for Quebrada Honda. We also report thefirst birds from Quebrada Honda, a phorusrhacid and at least two other species.Sparassodonts are represented by a new very small species and a partial skeleton ofAcyon that supports previous assertions that this species is the largest hathliacynid.Paucituberculatan remains likely pertain to three species and include the first mandibularremains of Acdestis maddeni. Xenarthran specimens include two new dasypodids (oneeutatin, one euphractin), at least three glyptodonts (a lomaphorin, a hoplophorin, and aplohophorin), and at least four sloths (a new megatheriine, a nothrotheriid, anindeterminate megatherioid, and a mylodontid). The xenarthrans show high endemicityand appear to be most closely related species from the middle to late Miocene of low andmiddle latitude Argentina, Chile, and Bolivia. The first remains of chinchillinechinchillids from Quebrada Honda provide a new biogeographic link between this site,Chucal, Chile (late early Miocene), and Nazareno, Bolivia (early middle Miocene?), butchinchillines are much rarer at Quebrada Honda than at either of these other sites. Themost abundant rodents at Quebrada Honda are the lagostomine chinchillidProlagostomus, the caviid Guiomys, and the octodontoid Acarechimys. Among ungulates,no additional remains of the interatheriid Miocochilius and only two fragmentaryspecimens of the mesotheriid Plesiotypotherium have been recovered, highlighting therarity of these taxa in the fauna. Partial macraucheniid litoptern skeletons reinforce thesmall size of the Quebrada Honda species relative to Santacrucian Theosodon. Additionalongoing research focuses on temporal correlations between localities in the QuebradaHonda area and the geological and environmental contexts in which these fossil remainswere preserved.