中国科学院南京地质古生物研究所机构知识库

Saint Jacques is a classic Oligocene fossil locality in China, which was first investigated by P. Teilhard de Chardin and E. Licent in 1923. All the fossil mammals previously reported from the area are Oligocene in age. Here we report some new material of the hyracodontid Ard)nia from two lower horizons in the Saint Jacques area. These new specimens represent two species: Ardynia praeco,k Matthew and Granger. 1923 and A. ordosensis n. sp. A right lower jaw of Ardynia praecox with complete il-c shows that i2 is the largest. The new species, Ardynia ordosensis, is characterized by a moderately hypsodont Ml with a pillar-like "crista" and the metaloph connecting the ectoloph distal to the metacone, characters that are more similar to those of A. altidentata than to any other species in Ardynia. The stratum bearing Ergilian Ardynia extends the deposits at Saint Jacques down to the upper Eocene. In combination with early Oligocene microfossils from the strata overlying the upper Eocene Ardynia-bearing layers, it is reasonable to conclude that the Saint Jacques section may bracket, or likely document, the Eocene-Oligocene transition. (C) 2017 Elsevier Ireland Ltd Elsevier B.V. and Nanjing Institute of Geology and Palaeontology, CAS. Published by Elsevier B.V. All rights reserved.