Fossils representing two, probably new, species of catarrhine primate were recovered in November 2009 from the lignite mine site of Yongle, located in the Zhaotong Basin of northeastern Yunnan Province, China. The fossils recovered include a complete cranium of a juvenile hominoid, and a nearly complete mandible of a colobine. Preliminary study of associated fauna suggests that the site is of late Miocene or early Pliocene age. This is an interval of known global climatic change that witnessed the extinction and origination of many terrestrial mammals due to increased seasonality and heterogeneity of environments. The new Yongle hominoid and colobine fossils thus appear to be, respectively, one of the geologically youngest of the Miocene apes and one of the geologically oldest of the Eurasian monkeys. The objectives of this project are to: (1) immediately complete the excavation of the primate-bearing locality due to duel threats of the impending monsoon season and potenetial vandalism, (2) conduct initial preparation, physical stabilization, and CT-scanning of the hominoid cranium and associated endocast, and (3) conduct preliminary paleomagnetic analysis on samples from the fossil-yielding section to help establish the geochronological framework of the site.
This project has important implications for studies of primate and mammalian evolution. It brings to light new species of fossil catarrhine primates that may represent early members of the gibbon and colobine lineages, and promotes a deeper understanding of the latest Miocene in East Asia, a poorly known period that played a crucial role in the evolution of modern faunal lineages due to the dramatic global and regional environmental changes during this time. The broader impacts of this project include the collaboration with Chinese scientists and institutions to increase our knowledge of mammalian and primate evolution in the late Tertiary of Asia.
Research on the late Tertiary mammalian faunas of Yunnan Province in southwestern China in the last 30 years has shown that Yunnan contains key fossil sites that are informative about the origins, radiations, and evolutionary fates of several primate lineages. Among them is the newly discovered site of Shuitangba (previously known as Yongle), located in the Zhaotong Basin of northeastern Yunnan Province, China. Fieldwork at Shuitangba has resulted in a rich collection of diverse mammalian and non-mammalian fauna, as well as plant remains that include wood, leaves, and seeds. Of note are specimens representing two new primate species – a complete cranium of a juvenile ape (Lufengpithecus sp. nov.) and a nearly complete mandible of a colobine monkey (Mesopithecus sp. nov.). Further excavation of the locality where these specimens found resulted in the recovery of additional primate specimens. Due to the delicate nature of ape cranium, CT-scans were taken for virtual reconstruction. CT imaging revealed that much of the internal morphology is preserved and provides us with information on previously known morphology of Lufengpithecus. Studies of the associated fauna and magnetostratigraphic correlation date the site to the latest Miocene, about 6 million years ago. This is an interval of known global climatic change that witnessed the extinction and origination of many terrestrial mammals due to increased seasonality and heterogeneity of environments. Because of the extraordinary preservation of faunal and floral remains at Shuitangba, this project has important implications for studies of primate and mammalian evolution. It brings to light new species of fossil catarrhine primates that represent early members of the Asian ape and colobine lineages and promotes a deeper understanding of the latest Miocene in eastern Asia, a poorly known period that played a crucial role in the evolution of modern faunal lineages due to the dramatic global and regional environmental changes during this time.
