Skip to Main Content
GEOREF RECORD

Phosphatized animal embryos from the Neoproterozoic Doushantuo Formation at Weng'an, Guizhou, South China

Shuhai Xiao and Andrew H. Knoll
Phosphatized animal embryos from the Neoproterozoic Doushantuo Formation at Weng'an, Guizhou, South China
Journal of Paleontology (September 2000) 74 (5): 767-788

Abstract

Phosphorites of the uppermost Neoproterozoic Doushantuo Formation (ca. 570+ or -20 Ma) exposed at Weng'an, South China, contain globular microfossils characterized by distinctively sculpted outer coverings and precise patterns of cell division. Forms assigned to the genera Megasphaera and Parapandorina were originally interpreted as problematica and volvocacean green algae, respectively, but newly discovered populations support their reinterpretation as the eggs and embryos of early animals. The fossils' large size (about half a millimeter in diameter), persistent enveloping membrane, precise cleavage pattern, and inferred physiology are fundamentally different from those of volvocaceans or other algae, but are expected features of animal embryos preserved in early stages of cleavage. In this light, Megasphaera is interpreted as an egg enveloped within its egg case, and Parapandorina represents equally and totally cleaving stereoblastulas. Despite their exquisite preservation, the phylogenetic placement of Megasphaera and Parapandorina cannot be resolved with confidence, due largely to the absence of recognizable adult morphologies to which they might be linked. Individual characters of Megasphaera and Parapandorina can be found in eggs and embryos of extant sponges, cnidarians, and bilaterians. Three other distinctive globular forms, Megaclonophycus onustus, Caveasphaera costata n. gen. and sp., and Spiralicellula? bulbifera? occur in the same deposit. Interpretations of these fossils are more problematic, although they may also be animal embryos.


ISSN: 0022-3360
EISSN: 1937-2337
Coden: JPALAZ
Serial Title: Journal of Paleontology
Serial Volume: 74
Serial Issue: 5
Title: Phosphatized animal embryos from the Neoproterozoic Doushantuo Formation at Weng'an, Guizhou, South China
Affiliation: Harvard University, Botanical Museum, Cambridge, MA, United States
Pages: 767-788
Published: 200009
Text Language: English
Publisher: Paleontological Society, Lawrence, KS, United States
References: 161
Accession Number: 2001-052589
Categories: Invertebrate paleontology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. strat. cols., sketch map
N24°40'00" - N29°19'60", E103°00'00" - E109°30'00"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute.
Update Code: 200117
Close Modal
This Feature Is Available To Subscribers Only

Sign In or Create an Account

Close Modal
Close Modal