Namacalathus-Cloudina assemblage in Neoproterozoic Miette Group (Byng Formation), British Columbia: Canada's oldest shelly fossils

Hofmann, Hans; Mountjoy, Eric W.

doi:10.1130/0091-7613(2001)029<1091:ncainm>2.0.co;2

Cited by 96 publications

(50 citation statements)

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“…The affinities of many of these Ediacaran fossils remain controversial (see Fedonkin, 2003;Seilacher et al, 2003). The earliest unambiguous representatives of most living bilaterian metazoan phyla do not become conspicuous in the fossil record until the Cambrian period (542 Mya) with the evolution of hard parts, although biomineralized metazoans from the Pro-*Corresponding Author terozoic/Phanerozoic transition have been described recently (e.g., Grotzinger et al, 2000;Hofmann and Mountjoy, 2001;Wood et al, 2002). Putative bilaterian fossils also have been described from 40-55 million years before the Cambrian (Chen et al, 2004), and there are reports of metazoan trace fossils from as far back as 1200 Mya (Brasier and McIlroy, 1998;Rasmussen et al, 2002), although the earliest trace fossils that are attributed confidently to stem-group bilaterians are about 555 million years old (Droser et al, 2002).…”

Section: Introductionmentioning

confidence: 98%

Decay and Mineralization of Invertebrate Eggs

Martin

Briggs

Parkes

2005

PALAIOS

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Both the timing and nature of early Metazoan evolution remain controversial, with complementary, and sometimes conflicting, evidence from molecular data and fossil occurrences. Exceptionally preserved embryos from the Neoproterozoic and early Phanerozoic remain an important source of direct evidence: fossil embryos of complex organisms at a relatively advanced stage of development provide a test of hypotheses based on comparative embryology and the evolutionary development of living forms. Understanding how these fossils are preserved, and what morphological changes are induced by decay, is essential to interpreting the evidence that they provide for early metazoan evolution. A range of decay experiments was performed on eggs of living arthropods to explore the controls on their mineralization and likely fossilization. Surface mineralization occurred within one month, mainly in calcium carbonate or in a combination of calcium carbonate and calcium phosphate. There was no enhancement of mineralization with increased phosphate or calcium concentrations, or with changing oxic/anoxic conditions, and mineralization occurred both in the absence and presence of an associated carcass. The eggs showed remarkable resistance to decay, indicating that an extended time-period (more than a year) would be available for mineralization and fossilization in some settings. Where sediment was available, it could become attached to the egg surface, replicating the morphology in a fashion analogous to mineralization. The interior of the eggs was not mineralized in the experiments. The degree of mineralization was very variable, reflecting conditions both in the natural environment and in the fossil record.

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Section: Introductionmentioning

confidence: 98%

Decay and Mineralization of Invertebrate Eggs

Martin

Briggs

Parkes

2005

PALAIOS

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“…plus Namacalathus , with or without biomineralized metazoan Namapoikia and possible calcareous algae, in microbial build‐ups (stromatolites, thrombolites) in Namibia (Nama Group; Germs, 1972; Grant, 1990; Wood et al. , 2002), Canada (Miette Group; Hofmann and Mountjoy, 2001), and Oman (Huqf Supergroup; Conway‐Morris et al. , 1990; Grotzinger et al.…”

Section: Introductionmentioning

confidence: 99%

Corumbella and in situ Cloudina in association with thrombolites in the Ediacaran Itapucumi Group, Paraguay

Warren

Fairchild

Gaucher³

et al. 2011

Terra Nova

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Terra Nova, 23, 382–389, 2011 Abstract An in situ assemblage of Cloudina, thrombolites and an ichnofossil (cf. Archaeonassa), together with fragments of Corumbella werneri, is reported here, from a tidally influenced, shallow, lagoonal setting on a carbonate ramp within the Itapucumi Group, Paraguay. The association of Cloudina with thrombolites is comparable to other terminal Neoproterozoic occurrences, but the coexistence of shelly fossils in situ with trace fossils and microbially induced sedimentary structures is apparently unique. This discovery extends the record of Cloudina and Corumbella in South America and further elucidates the diversity, distribution and palaeoecology of shelled organisms in late Ediacaran time.

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“…Unfortunately, this has not been applied in practice (e.g. Hofmann & Mountjoy 2001;Pyle et al 2004;Droser et al 2006). …”

Section: Taxonomy Of Discoidal Fossilsmentioning

confidence: 97%