A Silurian Soft-Bodied Biota

Mikulic, Donald G.; Briggs, Derek E. G.; Kluessendorf, Joanne

doi:10.1126/science.228.4700.715

Cited by 98 publications

(64 citation statements)

References 14 publications

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“…Laminated argillaceous dolomite within the lower half of the Brandon Bridge Formation of Wisconsin bears a graptolite assemblage indicative of the spiralis Biozone (Mikulic, Briggs & Kluessendorf, 1985;pers. obs.).…”

Section: H1 Laurentiamentioning

confidence: 99%

Early Silurian sea-level changes

1998

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Of the various mechanisms suggested (Donovan & Jones, 1979), that most likely to be responsible for the eustatic sealevel changes in the early Silurian is variation in the amount of water incorporated in land-based ice-sheets. This conclusion is based first on the apparent rapidity of many of the sea-level changes (see, e.g. Loydell, 1994) and secondly on the direct evidence of glacial deposits present in the Silurian sequences of Brazil (Grahn & Caputo, 1992) and elsewhere in South America (see Hambrey, 1985).Obviously, the third (and possibly fourth) order cycles being discussed here are superimposed upon the longer term second order and first order cycles (Haq, Hardenbol & Vail, 1988) linked to global tectonic processes. It is likely, for example, that the particularly high sea-levels of the Telychian and early Sheinwoodian reflect the coincidence of interglacial 'greenhouse' conditions with an increase in the volume of oceanic ridges. Abstract -Global sea-level fluctuated markedly during the early Silurian, probably as a result of the waxing and waning of ice-sheets in the South American portion of Gondwana. The highest sea-levels of the Silurian are recorded by the Telychian upper crispus-lower griestoniensis and spiralis-lower lapworthi biozones. Other highstands occurred in the early Aeronian, during the convolutus Zone (mid Aeronian), guerichi Zone and late turriculatus Zone (early Telychian), and early Sheinwoodian. Low sea-levels characterized much of the argenteus and sedgwickii zones (Aeronian), the utilis Subzone (late guerichi-early turriculatus zones, early Telychian), the late Telychian (commencing in the mid lapworthi Zone) and, after a period of apparently only small amplitude sea-level fluctuations in the late Sheinwoodian and earliest Homerian, the mid-late Homerian, in particular the early nassa Zone. Facies (and faunal) changes in the Lower Silurian do not support the P and S model of Jeppsson and others, but are consistent with the sea-level changes proposed herein. Mid Telychian marine red beds appear to have been deposited during a minor sea-level fall immediately after a period of very high sea-levels, rather than during a transgressive episode as previously suggested. Comparison of the sea-level curve presented herein with those constructed in the past is hampered by the lack of precision currently possible in the correlation of early Silurian deep water (graptolitic) and shallow water (shelly) sequences. Improving the precision of this correlation should be a priority for future research.*

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Section: H1 Laurentiamentioning

confidence: 99%

Early Silurian sea-level changes

1998

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“…It is most similar to the slightly older (Llandovery) Waukesha Lagerstätte (Mikulic et al, 1985a(Mikulic et al, , 1985b, with which it shares exceptionally preserved arthropods, including branchiopod on June 11, 2015 geology.gsapubs.org Downloaded from or remipede-like forms (Fig. 2J), xiphosurans (Moore et al, 2005), phyllocarid crustaceans, and lobopodians (Wilson et al, 2004).…”

Section: Significance Of the Eramosa Lagerstättementioning

confidence: 95%

“…The several hundred skeletons recovered, comprising at least seven taxa, are the most abundant and diverse assemblage of articulated conodont skeletons known, quadrupling the number known from the Silurian. Conodonts preserving remains of soft tissues were previously limited to three genera from three localities (Briggs et al, 1983;Mikulic et al, 1985aMikulic et al, , 1985bAldridge et al, 1993;Aldridge and Theron, 1993;Gabbott et al, 1995). The Eramosa Lagerstätte adds two additional genera, with potential for more.…”

Section: Biotamentioning

confidence: 98%

“…Arthropods: phyllocarid and ostracode crustaceans, xiphosuran chelicerates, lobopodians, arthropods of uncertain affi nities (cf. branchiopods or remipedes of Mikulic et al, 1985aMikulic et al, , 1985b. Annelids: Myoscolex-like forms, polychaetes (including possible aphroditid-like forms with phosphatized muscle tissue), spirorbiform tubes and annulated worms of uncertain affi nity.…”

Section: Lmentioning

confidence: 99%

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Eramosa Lagerstätte—Exceptionally preserved soft-bodied biotas with shallow-marine shelly and bioturbating organisms (Silurian, Ontario, Canada)

Bitter

Purnell

Tetreault

et al. 2007

Geol

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The middle Silurian Eramosa Lagerstätte of Ontario, Canada, preserves taxonomically and taphonomically diverse biotas including articulated conodont skeletons and hetero stracan fi sh, annelids and arthropods with soft body parts, and a diverse marine fl ora. Soft tissues are preserved as calcium phosphate and carbon fi lms, the latter possibly stabilized by early diagenetic sulfurization. It is signifi cant that the biotas also include a decalcifi ed, autochthonous shelly marine fauna, and trace fossils. This association of exceptionally preserved and more typical fossils distinguishes the Eramosa from other Silurian shallow-marine Lagerstätten, such as the Waukesha Lagerstätte, and suggests that the Eramosa is not the product of exceptional preservation in an atypical environment, a bias claimed for many post-Cambrian Lagerstätten. The Eramosa Lagerstätte may provide a more reliable, balanced measure of what has been lost from the Silurian fossil record.

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“…Although there are some marine clitellate annelids, the evolution of this group included one or more major shifts from marine to freshwater, mire, and soil environments that probably occurred alongside the colonization of the land by plants in the early to mid-Palaeozoic (Sawyer, 1986;Humphreys, 2003). Putative body-fossil impressions have been reported sporadically in fossil-Lagerstätten as old as the Ordovician (Kozur, 1970; Conway Morris et al, 1982;Mikulic et al, 1985;Wills, 1993). However, convincing body fossil evidence of modern clitellate groups has only been forthcoming from Cenozoic strata (Conway Morris et al, 1982).…”

Section: The Fossil Record Of Clitellatamentioning

confidence: 99%

Fossil clitellate annelid cocoons and their microbiological inclusions from the Eocene of Seymour Island, Antarctica

McLoughlin

Bomfleur

Mörs

et al. 2016

Palaeontologia Electronica

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Clitellate annelids have a meagre body fossil record but they secrete proteinaceous cocoons for the protection of eggs that, after hardening, are readily fossilized and offer a largely untapped resource for assessing the evolutionary history of this group. We describe three species of clitellate cocoons (viz., Burejospermum seymourense sp. nov., B. punctatum sp. nov. and Pegmatothylakos manumii gen. et sp. nov.) from the lower Eocene La Meseta Formation, Seymour Island, Antarctica. The cocoons probably derive from continental settings and were transported to, and preserved within, nearshore marine to estuarine environments. The cocoons provide the first evidence of commensal or parasitic relationships in the Eocene continental ecosystems of Antarctica. Moreover, numerous micro-organisms and the oldest fossilized examples of animal spermatozoa are preserved as moulds within the consolidated walls of the cocoons. Fossil annelid cocoons offer potential for enhanced palaeoenvironmental interpretation of sediments, correlation between continental and shallowmarine strata, and improved understanding of the development of clitellate annelid reproductive traits and the evolutionary history of soft-bodied micro-organisms in general.

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A Silurian Soft-Bodied Biota

Cited by 98 publications

References 14 publications

Early Silurian sea-level changes

Early Silurian sea-level changes

Eramosa Lagerstätte—Exceptionally preserved soft-bodied biotas with shallow-marine shelly and bioturbating organisms (Silurian, Ontario, Canada)

Fossil clitellate annelid cocoons and their microbiological inclusions from the Eocene of Seymour Island, Antarctica

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