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Oct 27, 2021 · The most prominent animal phylum missing from the Cambrian record until now has been the Bryozoa, a group of aquatic animals that exist as individual organisms connected by tissue to form...
- Andrej Ernst, Mark A. Wilson
- 2021
Following Hickman et al. (2012), we therefore considered cephalization to be absent in all diploblastic phyla, that is, Cnidaria, Ctenophora, Placozoa, and Porifera. However, we also considered cephalization to be absent in Acoela and Echinodermata.
- Tereza Jezkova, John J. Wiens
- 10.1086/690194
- 2017
- 2017/03
- Introduction
- Cambrian Fossils and Systematics
- Preservation Problems
- Dating The Cambrian
- Conclusions
The “Cambrian explosion” is a poorly-defined term that refers to a period of time some 600–500 years ago (“Geon 5” [Hofmann, 1990]) during which the biosphere, as reflected in the eukaryotic fossil record, underwent a great expansion. Most popularly, the appearance in the fossil record of the first undoubted animals has, especially since the critic...
In 1979, the Systematics Association published an important volume summarising the fossil evidence for the origins of various major invertebrate groups (House, 1979). It is notable for its juxtaposition of two papers, one Whittington's summary of the phanerozoic fossil record of arthropods (Whittington, 1979; Fig. 1 herein), and the other Jefferies...
Whilst the difficulties inherent in interpretation of Cambrian fossils are dealt with elsewhere (Butterfield, 2003), the temporal aspects of exceptional preservation are also worth remarking on. Almost all of our detailed knowledge of the macro-fossil record of the Cambrian explosion comes from the exceptionally preserved biotas, of which the Burge...
The age of the Cambrian has been difficult to constrain on both biostratigraphic (Palmer, 1998; Geyer, 2001) and absolute radiometric grounds (Bowring et al., 1993; Tucker and McKerrow, 1995). These problems in fact reach back to the middle years of the 19th century, when Adam Sedgwick and Rodney Murchison clashed over its upper boundary (see e.g.,...
The combination of important refinements in the treatment of the systematics of Cambrian fossils, and in our understanding of Cambrian stratigraphy is leading to a more precise view of the Cambrian explosion. Phyla do not appear in a sudden jumble, implying an appearance in the fossil record induced by some external influence (e.g., a rise in atmos...
- Graham E. Budd
- 2003
Feb 1, 2003 · However, the description of late Precambrian body fossils and traces from around the world, from which members of diverse Cambrian phyla such as arthropods are conspicuously absent, has made arguments for a missing history less convincing.
May 11, 2015 · The lack of body fossils of unmineralized bryozoan fossils in the Cambrian fossil record seems surprising given the increasing number of Lagerstätten available. It is worth noting, however, that soft-bodied bryozoans are also conspicuously absent from the Lagerstätten within the known stratigraphical range of the phylum.
- Paul D. Taylor, Andrea Waeschenbach
- 2015
Oct 5, 2015 · Most significant is the accurate and, for the most part, unchallenged grouping of species into phyla, such as chordates, molluscs, annelid worms or arthropods, whatever the subsequent discussion of between-phylum and within-phylum relationships.
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Sep 25, 2008 · Did animal phyla suddenly appear in the Cambrian Explosion? Paleontologists have discovered that new animal forms almost always appear abruptly--not gradually--in the fossil record, without any obvious connections to the animals that came before.
