RT Journal Article
SR Electronic
T1 Fossilized Metazoan Embryos from the Earliest Cambrian
JF Science
JO Science
FD American Association for the Advancement of Science
SP 1645
OP 1648
DO 10.1126/science.277.5332.1645
VO 277
IS 5332
A1 Bengtson, Stefan
A1 Zhao, Yue
YR 1997
UL http://science.sciencemag.org/content/277/5332/1645.abstract
AB Small globular fossils known as Olivooides andMarkuelia from basal Cambrian rocks in China and Siberia, respectively, contain directly developing embryos of metazoans. Fossilization is due to early diagenetic phosphatization. A nearly full developmental sequence of Olivooides can be observed, from late embryonic stages still within an egg membrane, to hatched specimens belonging to several ontogenetic stages. Earlier cleavage stages also occur, but cannot be identified to taxon.Olivooides shows similarities to coronate scyphozoans and to their probable Paleozoic representatives, the conulariids.Markuelia eggs contain looped embryos of a segmented worm with short, conical processes covering the body.