Discovery of carbonaceous compressions and their multicellular tissues from the Changzhougou Formation (1 800 Ma) in the Yanshan range, North China

In 1997 and 1998, hundreds of specimens of megascopic carbonaceous compress ions or algal fossils were found from similar to 1800-million-year old Chan gzhougou Formation, which is the lowermost unit of the latest Palaeoprotero zoic Changcheng Group (similar to 1 600-1 800 Ma) in the Xinglong-Kuancheng areas at the middle Yanshan Riinge, North China. They are discoid, ellipso id and sausage-like, namely shaped like Chuaria Shouhsiennia (Ellipsophyta) and Tawuia. 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 com pressions, hamely Chuaria- and Shouhsienia-like forms, in addition to their morphology, The following three types of multicellular tissues have been f ound in the fragments of them: colony-like, pseudoparenchyma-like and paren chyma-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 metap hytes originated at least 1 800 million years ago.