Precambrian Sponges with Cellular Structures

Li, Chia-Wei; Chen, Jun-Yuan; Hua, Tzu-En

doi:10.1126/science.279.5352.879

Cited by 452 publications

(268 citation statements)

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“…Monaxonous thin-walled and hollow spicules of possible hexactinellids derive from Alaska (Allison & Awramik, 1989;Debrenne & Reitner, 2001), from beds inferred by chemostratigraphy to be Neoproterozoic, most likely pre-Varangerian (Kaufman, Knoll & Awramik, 1992). Skeletal remains of sponges found in thin-sections from the Doushantuo Formation on the South China Platform are interpreted as demosponges, because they consist exclusively of siliceous monaxonal spicules (Li, Chen & Hua, 1998). Their maximum age is c. 580 Ma (Condon et al 2005).…”

Section: A1 Demosponges and Hexactinellidsmentioning

confidence: 99%

Chronology of early Cambrian biomineralization

et al. 2011

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-Data on the first appearances of major animal groups with mineralized skeletons on the Siberian Platform and worldwide are revised and summarized herein with references to an improved carbon isotope stratigraphy and radiometric dating in order to reconstruct the Cambrian radiation (popularly known as the 'Cambrian explosion') with a higher precision and provide a basis for the definition of Cambrian Stages 2 to 4. The Lophotrochozoa and, probably, Chaetognatha were first among protostomians to achieve biomineralization during the Terreneuvian Epoch, mainly the Fortunian Age. Fast evolutionary radiation within the Lophotrochozoa was followed by radiation of the sclerotized and biomineralized Ecdysozoa during Stage 3. The first mineralized skeletons of the Deuterostomia, represented by echinoderms, appeared in the middle of Cambrian Stage 3. The fossil record of sponges and cnidarians suggests that they acquired biomineralized skeletons in the late Neoproterozoic, but diversification of both definite sponges and cnidarians was in parallel to that of bilaterians. The distribution of calcium carbonate skeletal mineralogies from the upper Ediacaran to lower Cambrian reflects fluctuations in the global ocean chemistry and shows that the Cambrian radiation occurred mainly during a time of aragonite and high-magnesium calcite seas.

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Section: A1 Demosponges and Hexactinellidsmentioning

confidence: 99%

Chronology of early Cambrian biomineralization

et al. 2011

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“…In contrast, fossil evidence of sponges dates to Ϸ580 Mya and reveals that their simple body plan predates the Cambrian and has since remained relatively unchanged (1,2). Although extrinsic environmental factors have received much attention as the driving force behind the Cambrian explosion (3), the disparate outcomes in lineages leading to modern sponges and eumetazoans point to intrinsic genetic differences.…”

mentioning

confidence: 99%

“…The fossil record of sponges predates that of all other animal groups (2), and phylogenetic analyses support sponges as an outgroup of all eumetazoan phyla (4). Indeed, recent studies indicate that sponges are paraphyletic (5)(6)(7)(8)(9) and that eumetazoans evolved from a sponge-like ancestor (9).…”

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confidence: 99%

Early evolution of animal cell signaling and adhesion genes

Nichols

Dirks²,

Pearse³

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

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In stark contrast to the rapid morphological radiation of eumetazoans during the Cambrian explosion, the simple body plan of sponges (Phylum Porifera) emerged from the Cambrian relatively unchanged. Although the genetic and developmental underpinnings of these disparate evolutionary outcomes are unknown, comparisons between modern sponges and eumetazoans promise to reveal the extent to which critical genetic factors were present in their common ancestors. Two particularly interesting classes of genes in this respect are those involved in cell signaling and adhesion. These genes help guide development and morphogenesis in modern eumetazoans, but the timing and sequence of their origins is unknown. Here, we demonstrate that the sponge Oscarella carmela, one of the earliest branching animals, expresses core components of the Wnt, transforming growth factor ␤, receptor tyrosine kinase, Notch, Hedgehog, and Jak͞Stat signaling pathways. Furthermore, we identify sponge homologs of nearly every major eumetazoan cell-adhesion gene family, including those that encode cell-surface receptors, cytoplasmic linkers, and extracellular-matrix proteins. From these data, we infer that key signaling and adhesion genes were in place early in animal evolution, before the divergence of sponge and eumetazoan lineages.eumetazoa ͉ porifera ͉ Cambrian explosion ͉ homoscleromorpha ͉ Oscarella T he fossil record from Ϸ540 Mya documents the abrupt appearance of fully diversified eumetazoan body plans during the ''Cambrian explosion.'' In contrast, fossil evidence of sponges dates to Ϸ580 Mya and reveals that their simple body plan predates the Cambrian and has since remained relatively unchanged (1, 2). Although extrinsic environmental factors have received much attention as the driving force behind the Cambrian explosion (3), the disparate outcomes in lineages leading to modern sponges and eumetazoans point to intrinsic genetic differences. Intrinsic factors that potentially contributed to the selective morphological diversification of eumetazoans include the evolution of developmentally important gene families, signaling pathways, or regulatory elements and linkages in their ancestors. A key to illuminating how intrinsic factors contributed to the Cambrian explosion will be to reconstruct the evolutionary sequence of origination, elaboration, and assembly of developmentally important gene families into interacting pathways and networks.Modern sponges promise to offer critical insights into the earliest events in animal genome evolution. The fossil record of sponges predates that of all other animal groups (2), and phylogenetic analyses support sponges as an outgroup of all eumetazoan phyla (4). Indeed, recent studies indicate that sponges are paraphyletic (5-9) and that eumetazoans evolved from a sponge-like ancestor (9). Among the major sponge groups, the homoscleromorphs (Fig. 1b) have particular relevance to the study of eumetazoan origins and evolution. Although of uncertain phylogenetic position (10, 11), homoscleromorphs are thought ...

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“…Among these, embryos at an advanced stage of development with complex organization are uncommon (4)(5)(6)(7)(8)(9)(10)(11). Although some are advanced with up to 2,600 cells, these advanced stage embryos remain simple, exhibiting no evidence of patterning organization, or even cell differentiation (4) (Fig.…”

mentioning

confidence: 99%

Complex embryos displaying bilaterian characters from Precambrian Doushantuo phosphate deposits, Weng'an, Guizhou, China

Chen

Bottjer

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

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Three-dimensionally preserved embryos from the Precambrian Ediacaran Doushantuo Formation, Weng'an, Guizhou, southern China, have attracted great attention as the oldest fossil evidence yet found for multicellular animal life on Earth. Many embryos are early cleavage embryos and most of them yield a limited phylogenetic signal. Here we report the discovery of two Doushantuo embryos that are three-dimensionally preserved and complex. Imaging techniques using propagation phase-contrast based synchrotron radiation microtomography (PPC-SR-CT) reveal that the organization of cells demonstrates several bilaterian features, including the formation of anterior-posterior, dorso-ventral, and right-left polarities, and cell differentiation. Unexpectedly, our observations show a noticeable difference in organization patterns between the embryos, suggesting that they represent two distinct taxa. These embryos provide further evidence for the presence of bilaterian animals in the Doushantuo biota. Furthermore, these bilaterians had already diverged into distantly related groups at least 40 million years before the Cambrian radiation, indicating that the last common ancestor of the bilaterians lived much earlier than is usually thought.early animal evolution ͉ early metazoan evolution ͉ nondestructive 3-D reconstruction ͉ precambrian ediacaran embryos ͉ Weng'an biota

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Precambrian Sponges with Cellular Structures

Cited by 452 publications

References 22 publications

Chronology of early Cambrian biomineralization

Chronology of early Cambrian biomineralization

Early evolution of animal cell signaling and adhesion genes

Complex embryos displaying bilaterian characters from Precambrian Doushantuo phosphate deposits, Weng'an, Guizhou, China

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