title: Freshwater Fossil Pearls from the Nihewan Basin, Early Early Pleistocene.
abstract: Fossil blister pearls attached to the shells of an Anodonta mollusk from China, early Early Pleistocene, are reported here for the first time. The pearls were investigated in detail using a variety of methods. Micro-CT scanning of the fossil pearls was carried out to discover the inner structure and the pearl nucleus. Using CTAn software, changes in the gray levels of the biggest pearl, which reflect the changing density of the material, were investigated. The results provide us with some clues on how these pearls were formed. Sand grains, shell debris or material with a similar density could have stimulated the development of these pearls. X-ray diffraction analysis of one fossil pearl and the shell to which it was attached reveals that only aragonite exists in both samples. The internal structures of our fossil shells and pearls were investigated using a Scanning Electron Microscope. These investigations throw some light on pearl development in the past.
authors.affiliation: Institute of Geology, Chinese Academy of Geological Sciences, Beijing, P. R. China.|Key Laboratory of Stratigraphy and Paleontology, Ministry of Land and Resources of China, Beijing, P. R. China.
authors.forename: Su-Ping
authors.initials: SP
authors.lastname: Li
authors.affiliation: Institute of Geology, Chinese Academy of Geological Sciences, Beijing, P. R. China.
authors.forename: Pei-Yi
authors.initials: PY
authors.lastname: Yao
authors.affiliation: State Key Laboratory of Systematics and Evolution, Institute of Botany, Chinese Academy of Sciences, Beijing, P. R. China.
authors.forename: Jin-Feng
authors.initials: JF
authors.lastname: Li
authors.affiliation: University of Vienna, Institute of Palaeontology, Vienna, Austria.
authors.forename: David Kay
authors.initials: DK
authors.lastname: Ferguson
authors.affiliation: Institute of Geology, Chinese Academy of Geological Sciences, Beijing, P. R. China.
authors.forename: Long-Rui
authors.initials: LR
authors.lastname: Min
authors.affiliation: Institute of Geology, Chinese Academy of Geological Sciences, Beijing, P. R. China.
authors.forename: Zhen-Qing
authors.initials: ZQ
authors.lastname: Chi
authors.affiliation: Institute of Geology, Chinese Academy of Geological Sciences, Beijing, P. R. China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Institute of Geology, Chinese Academy of Geological Sciences, Beijing, P. R. China.|Key Laboratory of Stratigraphy and Paleontology, Ministry of Land and Resources of China, Beijing, P. R. China.
authors.forename: Jian-Xin
authors.initials: JX
authors.lastname: Yao
authors.affiliation: Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing, P. R. China.
authors.forename: Jin-Geng
authors.initials: JG
authors.lastname: Sha
mesh_terms: D000818:Animals; D005580:Fossils; D005618:Fresh Water; D055593:Geological Phenomena; D008974:Mollusca