One or Three Cambrian Radiations?

@article{Balavoine1998OneOT,
  title={One or Three Cambrian Radiations?},
  author={Guillaume Balavoine and Andr{\'e} Adoutte},
  journal={Science},
  year={1998},
  volume={280},
  pages={397 - 398}
}
The Cambrian explosion was a time of great evolutionary change, especially in the appearance of organisms with bilateral symmetry. In their Research Commentary, Balavoine and Adoutte discuss recent findings that may allow a reinterpretation of animal phylogeny and may have a profound bearing on understanding of the Cambrian explosion. 
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  • 1999
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Evo-Devo Course 2001 References
flatworms: Earliest extant bilaterian metazoans, not members of platyhelminthes.
...
1
2
3
4
5
...

References

SHOWING 1-10 OF 16 REFERENCES
The Cambrian radiation of shelly fossils.
  • A. Rozanov
  • Biology, Medicine
  • Trends in ecology & evolution
  • 1992
TLDR
One of the most significant events in the history of the organic world was the acquisition by animals of the ability to build a skeleton during a very short period (five to seven million years), early in the Cambrian. Expand
A possible Early Cambrian chordate
TLDR
The first chordate recorded from the Early Cambrian is the ceph-alochordate Yunnanozoon lividum from the 525 million-year-old Chengjiang fauna and predicts that other chordate clades (tunicates and craniates) had evolved by the Late Atdabanian, in the main burst of the Cambrian Explosion. Expand
The cambrian evolutionary ‘explosion’ recalibrated
TLDR
A new paradigm suggests that the ‘explosion’ in the record may have been decoupled from the evolutionary innovation, and the apparent paradox between the sudden appearance of recognisable metazoans and their extended evolutionary history might be explained by a sudden Cambrian increase in body size, which was accompanied by skeletisation. Expand
Molecular Evidence for Deep Precambrian Divergences Among Metazoan Phyla
TLDR
It is suggested that invertebrates diverged from chordates about a billion years ago, about twice as long ago as the Cambrian, which suggests a prolonged radiation of animal phyla. Expand
Proterozoic and early Cambrian protists: evidence for accelerating evolutionary tempo.
  • A. Knoll
  • Medicine, Biology
  • Proceedings of the National Academy of Sciences of the United States of America
  • 1994
TLDR
Evidently, the Cambrian diversification of animals strongly influenced evolutionary rates, within clades already present in marine communities, implying an important role for ecology in fueling a Cambrian explosion that extends across kingdoms. Expand
Origin of the metazoan phyla: molecular clocks confirm paleontological estimates.
TLDR
This work has analyzed 18 protein-coding gene loci and estimated that protostomes (arthropods, annelids, and mollusks) diverged from deuterostomes about 670 million years ago, and chordates from echinoderms about 600 million years old, consistent with paleontological estimates. Expand
The Late Precambrian fossil Kimberella is a mollusc-like bilaterian organism
TLDR
This work reconstructs Kimberella as a bilaterally symmetrical, benthic animal with a non-mineralized, univalved shell, resembling a mollusc in many respects, important evidence for the existence of large triploblastic metazoans in the Precambrian and indicates that the origin of the higher groups of protostomes lies well back in the precambrian. Expand
The early emergence of platyhelminths is contradicted by the agreement between 18S rRNA and Hox genes data.
  • G. Balavoine
  • Biology, Medicine
  • Comptes rendus de l'Academie des sciences. Serie III, Sciences de la vie
  • 1997
TLDR
New evidence from the sequences of Hox genes suggests that the duplicated genes Ultrabithorax/abdominal-A constitute a genetic synapomorphy of the whole protostome clade, compatible with the old idea that flatworms are derived from a coelomate ancestor. Expand
Three-dimensional preservation of algae and animal embryos in a Neoproterozoic phosphorite
TLDR
Embryos preserved in early cleavage stages indicate that the divergence of lineages leading to bilaterians may have occurred well before their macroscopic traces or body fossils appear in the geological record. Expand
Evidence from 18S ribosomal DNA that the lophophorates are protostome animals
TLDR
Sequence analyses show that lophophorates are protostomes closely related to mollusks and annelids, which deviates from the commonly held view of deuterostome affinity. Expand
...
1
2
...