TY - JOUR
T1 - Phase contrast synchrotron X-ray microtomography of Ediacaran (Doushantuo) metazoan microfossils
T2 - Phylogenetic diversity and evolutionary implications
AU - Chen, Jun Yuan
AU - Bottjer, David J.
AU - Davidson, Eric H.
AU - Li, Gang
AU - Gao, Feng
AU - Cameron, R. Andrew
AU - Hadfield, Michael G.
AU - Xian, Ding Chang
AU - Tafforeau, Paul
AU - Jia, Quan Jie
AU - Sugiyama, H.
AU - Tang, Rui
PY - 2009/9
Y1 - 2009/9
N2 - Microfossils from the Ediacaran Weng'an Phosphate Member of the Doushantuo Formation (Guizhou Province, southern China) have received widespread attention. The Doushantuo, which overlies the glacial deposits of the Nantuo Formation, was deposited following the Marinoan glaciation, the last extensive glaciation of Snowball Earth. Radiometric age dating indicates that the Doushantuo is older than 580 my, and hence that these microfossils are older than the Ediacara Biota. However, the diversity represented by these fossils has yet to be fully documented. A recent technological approach that has increasingly been used to image fossils, propagation phase contrast synchrotron X-ray microtomography, has allowed non-destructive study of both exterior and interior features of a variety of Doushantuo microfossils from the gray facies of the Weng'an Phosphate Member, cropping out along the axis of the Mt. Beidou anticline. Studies of Doushantuo embryos demonstrate the existence of a large suite of modern embryonic features, including macromeres and micromeres, cell lineage, polar lobes, compacted epithelia, equal and unequal cleavage, blastulation and gastrulation, and chorionic protection. Because embryos such as those here studied provide only a limited amount of phylogenetic information, and because adult metazoans of the types that produced these embryos have yet to be discovered in Doushantuo-age rocks, these fossilized embryonic forms can at present be assigned only to the various superclades represented amongst living Metazoa. The diversity of the embryos here studied suggests that the metazoan fauna of the Doushantuo may well have included animals of poriferan, cnidarian, and both protostomial (representatives possibly of basal protostome lineages) and deuterostomial affinity. If this interpretation is correct, it would then follow that the last common ancestor of the bilaterian metazoan lineage, as well as the last common ancestor of sponges, cnidarians and bilaterians, pre-dated deposition of the Doushantuo strata.
AB - Microfossils from the Ediacaran Weng'an Phosphate Member of the Doushantuo Formation (Guizhou Province, southern China) have received widespread attention. The Doushantuo, which overlies the glacial deposits of the Nantuo Formation, was deposited following the Marinoan glaciation, the last extensive glaciation of Snowball Earth. Radiometric age dating indicates that the Doushantuo is older than 580 my, and hence that these microfossils are older than the Ediacara Biota. However, the diversity represented by these fossils has yet to be fully documented. A recent technological approach that has increasingly been used to image fossils, propagation phase contrast synchrotron X-ray microtomography, has allowed non-destructive study of both exterior and interior features of a variety of Doushantuo microfossils from the gray facies of the Weng'an Phosphate Member, cropping out along the axis of the Mt. Beidou anticline. Studies of Doushantuo embryos demonstrate the existence of a large suite of modern embryonic features, including macromeres and micromeres, cell lineage, polar lobes, compacted epithelia, equal and unequal cleavage, blastulation and gastrulation, and chorionic protection. Because embryos such as those here studied provide only a limited amount of phylogenetic information, and because adult metazoans of the types that produced these embryos have yet to be discovered in Doushantuo-age rocks, these fossilized embryonic forms can at present be assigned only to the various superclades represented amongst living Metazoa. The diversity of the embryos here studied suggests that the metazoan fauna of the Doushantuo may well have included animals of poriferan, cnidarian, and both protostomial (representatives possibly of basal protostome lineages) and deuterostomial affinity. If this interpretation is correct, it would then follow that the last common ancestor of the bilaterian metazoan lineage, as well as the last common ancestor of sponges, cnidarians and bilaterians, pre-dated deposition of the Doushantuo strata.
KW - Animal evolution
KW - Doushantuo
KW - Early animal diversification
KW - Precambrian embryos
KW - Weng'an biota
UR - http://www.scopus.com/inward/record.url?scp=67651017558&partnerID=8YFLogxK
U2 - 10.1016/j.precamres.2009.04.004
DO - 10.1016/j.precamres.2009.04.004
M3 - Article
AN - SCOPUS:67651017558
SN - 0301-9268
VL - 173
SP - 191
EP - 200
JO - Precambrian Research
JF - Precambrian Research
IS - 1-4
ER -