Constraining the timing of basal metazoan radiation using molecular biomarkers and U-Pb isotope dating

Love, Gordon D.; Fike, David A.; Grosjean, Emmanuelle; Stalvies, Charlotte; Grotzinger, J. P.; Bradley, Alexander S.; Bowring, Samuel A.; Condon, Daniel J.; Summons, Roger E.

doi:10.1016/j.gca.2006.06.748

Cited by 35 publications

(12 citation statements)

References 8 publications

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“…Our studies indicate that M. brevicollis does not produce a candidate isopropyl sterol precursor for the 24-isopropylcholestanes. Such a conclusion is consistent with the hypothesis that 24-isopropyl steranes in pre-Ediacaran sedimentary rocks are molecular proxies for demosponges (17), although it will be necessary to analyze a greater diversity of choanoflagellates to provide more definitive support. Exploration of biosynthetic pathways although comparative genomics provides an approach to investigating the uniqueness and utility of lipid biomarkers.…”

Section: Evolution Of Sterol Biosynthesis In Choanoflagellatessupporting

confidence: 76%

Sterols in a unicellular relative of the metazoans

Kodner

Summons

Pearson

et al. 2008

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

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Molecular clocks suggest that animals originated well before they first appear as macroscopic fossils, but geologic tests of these hypotheses have been elusive. A rare steroid hydrocarbon, 24-isopropylcholestane, has been hypothesized to be a biomarker for sponges or their immediate ancestors because of its relatively high abundance in pre-Ediacaran to Early Cambrian sedimentary rocks and oils. Biolipid precursors of this sterane have been reported to be prominent in several demosponges. Whether 24-isopropylcholestane can be interpreted as a sponge (and, hence, animal) biomarker, and so provide clues about early metazoan history, depends on an understanding of the distribution of sterol biosynthesis among animals and their protistan relatives. Accordingly, we characterized the sterol profile of the choanoflagellate Monosiga brevicollis, a representative of the unicellular sister group of animals. M. brevicollis does not produce a candidate sterol precursor for 24-isopropylcholestane under our experimental growth conditions. It does, however, produce a number of other sterols, and comparative genomics confirms its biosynthetic potential to produce the full suite of compounds recovered. Consistent with the phylogenetic position of choanoflagellates, the sterol profile and biosynthetic pathway of M. brevicollis display characteristics of both fungal and poriferan sterol biosynthesis. This is an example in which genomic and biochemical information have been used together to investigate the taxonomic specificity of a fossil biomarker.choanoflagellates ͉ molecular fossils ͉ origin of metazoans ͉ Monosiga brevicollis S terols constitute a diverse class of triterpenoid lipids having wide ranging importance in biology. All eukaryotes require sterols; they serve important functions because membrane lipids play roles as developmental regulators and precursors to steroid hormones in multicellular organisms. Recently, sterols have emerged as an important investigative tool for paleontologists (1-4) because steranes, the hydrocarbon skeletons of sterols, resist microbial attack and remain stable over long periods of time. Thus, they are well represented as molecular fossils in sedimentary rocks. The discovery of diverse steranes in the geologic record has fueled a search for unique precursor sterols in many branches of the eukaryotic tree, because for a molecular fossil to be useful as a biomarker, it must have significant taxonomic and/or physiological specificity.One candidate for a paleobiologically useful biomarker is 24-isopropylcholestane, the geologically stable derivative of the C 30 sterol 24-isopropylcholesterol. Although much of eukaryotic sterol diversity is manifested in double bonds and functional groups that do not preserve in fossil hydrocarbon skeletons, the isopropyl moiety in the side chain of 24-isopropylcholesterol and related sterols results in a structure that is both unique and preservable. Particularly abundant as a molecular fossil in rocks deposited during the Ediacaran and Cambrian periods (3, 5) i...

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Section: Evolution Of Sterol Biosynthesis In Choanoflagellatessupporting

confidence: 76%

Sterols in a unicellular relative of the metazoans

Kodner

Summons

Pearson

et al. 2008

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

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“…One of the earliest lines of evidence for sponges comes from well-preserved molecular biomarkers of demosponges from strata of the Neoproterozoic Huqf Supergroup of the South Oman Salt Basin pre-dating the termination of the Marinoan glaciation and having a minimum age of c. 635 Ma (McCaffrey et al 1994;Love et al 2006Love et al , 2009. Fossils interpreted as sponge-grade metazoans are also found in the pre-Marinoan Trezona Formation of South Australia with a maximum age of 659.7 ± 5.3 Ma (Maloof et al 2010c).…”

Section: A Sponges and Spongiomorphsmentioning

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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“…Fourth, the maximum for the origin of GastropodaCBivalvia, is the first appearance of skeletons in the fossil record, ca 542 Myr ago (Bengtson 1994;Amthor et al 2003). Fifth, the maximum for the origin of crown-group demosponges, is the first appearance of demosponge-specific biomarkers (McCaffrey et al 1994;Love et al 2006;see Peterson et al 2007 for discussion), sometime after the Sturtian, ca 657 Myr ago (Kendall et al 2006). Finally, the maximum for the origin of crown-group Eumetazoa, which was only used in the BEAST analyses, is argued to be 635 Myr ago based on palaeoecological observations (Peterson & Butterfield 2005).…”

Section: Introductionmentioning

confidence: 99%

The Ediacaran emergence of bilaterians: congruence between the genetic and the geological fossil records

Peterson

Cotton

Gehlîng

et al. 2008

Phil. Trans. R. Soc. B

282

152

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Unravelling the timing of the metazoan radiation is crucial for elucidating the macroevolutionary processes associated with the Cambrian explosion. Because estimates of metazoan divergence times derived from molecular clocks range from quite shallow (Ediacaran) to very deep (Mesoproterozoic), it has been difficult to ascertain whether there is concordance or quite dramatic discordance between the genetic and geological fossil records. Here, we show using a range of molecular clock methods that the major pulse of metazoan divergence times was during the Ediacaran, which is consistent with a synoptic reading of the Ediacaran macrobiota. These estimates are robust to changes in priors, and are returned with or without the inclusion of a palaeontologically derived maximal calibration point. Therefore, the two historical records of life both suggest that although the cradle of Metazoa lies in the Cryogenian, and despite the explosion of ecology that occurs in the Cambrian, it is the emergence of bilaterian taxa in the Ediacaran that sets the tempo and mode of macroevolution for the remainder of geological time.

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Constraining the timing of basal metazoan radiation using molecular biomarkers and U-Pb isotope dating

Cited by 35 publications

References 8 publications

Sterols in a unicellular relative of the metazoans

Sterols in a unicellular relative of the metazoans

Chronology of early Cambrian biomineralization

The Ediacaran emergence of bilaterians: congruence between the genetic and the geological fossil records

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