Discovery of carbonaceous compressions and their multicellular tissues from the Changzhougou formation (1800 Ma) in the Yanshan range, North China

In 1997 and 1998, hundreds of specimens of megascopic carbonaceous compressions or algal fossils were found from ∼ 1800-million-year old Changzhougou Formation, which is the lowermost unit of the latest Palaeoproterozoic Changcheng Group (∼1 600–1 800 Ma) in the Xinglong-Kuancheng areas at the middle Yanshan Range, North China. They are discoid, ellipsoid and sausage-like, namely shaped likeChuaria Shouhsiennia (Ellipsophyta) andTawuia. By adopting HF acid-resistant maceration coupled with scanning electron microscope and petrologic section, the authors made a preliminary research on the histology for some circular and ellipsoid carbonaceous compressions, namelyChuaria- andShouhsienia-like forms, in addition to their morphology. The following three types of multicellular tissues have been found in the fragments of them: colony-like, pseudoparenchyma-like and parenchyma-like. All of the new data about multicelluar tissues not only supply a very important basis in histology to determine the biological affinity of multicellular algal remains for the Changzhougou carbonaceous compressions newly found, but also provide reliable fossil evidence to prove that metaphytes originated at least 1 800 million years ago.