Wonderful strife: systematics, stem groups, and the phylogenetic signal of the Cambrian radiation

@inproceedings{Briggs2005WonderfulSS,
  title={Wonderful strife: systematics, stem groups, and the phylogenetic signal of the Cambrian radiation},
  author={Derek E. G. Briggs and Richard A. Fortey},
  booktitle={Paleobiology},
  year={2005}
}
Abstract Gould's Wonderful Life (1989) was a landmark in the investigation of the Cambrian radiation. Gould argued that a number of experimental body plans (“problematica”) had evolved only to become extinct, and that the Cambrian was a time of special fecundity in animal design. He focused attention on the meaning and significance of morphological disparity versus diversity, and provoked attempts to quantify disparity as an evolutionary metric. He used the Burgess Shale as a springboard to… 

Wonderful Life Revisited: Chance and contingency in the Ediacaran-Cambrian radiation

In his 1989 book Wonderful Life Stephen Jay Gould employed the fossils of the middle Cambrian Burgess Shale to argue for a pervasive role of contingency in the history of life. But Gould wrote at the

From weird wonders to stem lineages: the second reclassification of the Burgess Shale fauna.

  • Keynyn Brysse
  • Environmental Science
    Studies in history and philosophy of biological and biomedical sciences
  • 2008

Extraordinary fossils reveal the nature of Cambrian life: a commentary on Whittington (1975) ‘The enigmatic animal Opabinia regalis, Middle Cambrian, Burgess Shale, British Columbia’

  • D. Briggs
  • Geography
    Philosophical Transactions of the Royal Society B: Biological Sciences
  • 2015
TLDR
Although Opabinia initially defied assignment to any group of modern animals, it is now interpreted as lying below anomalocaridids on the stem leading to the living arthropods, and significantly augmented the information available on this critical interval in the history of life.

THE SYSTEMATICS AND PHYLOGENETIC RELATIONSHIPS OF VETULICOLIANS

TLDR
It is not possible on current evidence to reach an unequivocal conclusion regarding the phylogenetic position of the vetulicolians, but one possibility is that they are a sister group of arthropods that lost limbs but gained gill structures analogous to those of deuterostomes, but several features remain unexplained by this model.

On the Phylum Vetulicolia

TLDR
Since all vetulicolians share similar characters in their anterior section (pharynx), and on the basis of differences in their posterior section, a new classification system is proposed, with a new class, the Heteromorphida erected.

Macroevolutionary patterns of body plan canalization in euarthropods

TLDR
Overall ordination patterns between the main morphogroups are consistent with another, independently coded, extant-only dataset providing molecular and morphological rates of evolution, which would support the view that the swiftness of the Cambrian explosion was mostly associated with the buildup of genetic regulatory networks.

Darwin's dilemma: the realities of the Cambrian ‘explosion’

  • S. Conway Morris
  • Geology, Geography
    Philosophical Transactions of the Royal Society B: Biological Sciences
  • 2006
TLDR
It is proposed that despite its step-like function this evolutionary event is the inevitable consequence of Earth and biospheric change.

Amiskwia is a large Cambrian gnathiferan with complex gnathostomulid-like jaws

TLDR
It is shown that the rare soft-bodied animal Amiskwia from the Cambrian of Canada and China, which has variously been considered a chaetognath, a nemertine, allied to molluscs, or a problematica, is related to gnathiferans, thereby resolving its ambiguous phylogeny.

Darwin's dilemma: the realities of the Cambrian 'explosion'

TLDR
It is proposed that despite its step-like function this evolutionary event is the inevitable consequence of Earth and biospheric change.
...

References

SHOWING 1-10 OF 157 REFERENCES

The Early Radiation and Relationships of the Major Arthropod Groups

TLDR
Cladistic analysis of characters of Cambrian and living representatives (excluding Uniramia) shows that trilobites and chelicerates are relatively advanced compared with "crustaceans," and there are doubts whether the latter constitute a national group.

Cambrian and Recent disparity: the picture from priapulids

Abstract An understanding of several macroevolutionary trends has been greatly advanced in recent years by a focus on disparity (morphological variety) rather than taxic diversity. A seminal issue

The disparity of the Burgess Shale arthropod fauna and the limits of cladistic analysis: why we must strive to quantify morphospace

TLDR
Although the three arguments against the claim for greater early disparity cannot be confidently established until the authors develop quantitative techniques for the characterization of morphospace and its differential filling through time, it is shown that these arguments are either false or illogical.

A critical reappraisal of the fossil record of the bilaterian phyla.

TLDR
It is shown that the prospect of lineage diversification occurring early in the Proterozoic can be seen to be unlikely on grounds of both parsimony and functional morphology, and this analysis points to the requirement for a careful application of systematic methodology before explanations are sought for alleged patterns of constraint and flexibility.

A critical reappraisal of the fossil record of the bilaterian phyla

  • G. BuddS. Jensen
  • Biology
    Biological reviews of the Cambridge Philosophical Society
  • 2000
TLDR
It is shown that the prospect of lineage diversification occurring early in the Proterozoic can be seen to be unlikely on grounds of both parsimony and functional morphology, and this analysis points to the requirement for a careful application of systematic methodology before explanations are sought for alleged patterns of constraint and flexibility.

The Cambrian "explosion" of metazoans and molecular biology: would Darwin be satisfied?

TLDR
The origins of metazoan bodyplans and the extent to which they are coincident with the Cambrian "explosion" are both areas of continuing debate and molecular and developmental biology offer other unique insights, but may be problematic in terms of conflicting phylogenetic signals and questions.

The “evolution” of Anomalocaris and its classification in the arthropod class Dinocarida (nov.) and order Radiodonta (nov.)

  • D. Collins
  • Environmental Science
    Journal of Paleontology
  • 1996
The remarkable “evolution” of the reconstructions of Anomalocaris, the extraordinary predator from the 515 million year old Middle Cambrian Burgess Shale of British Columbia, reflects the dramatic

A Pikaia-like chordate from the Lower Cambrian of China

TLDR
A single specimen of a Lower Cambrian chordate, Cathaymyrus diadexus, new genus and species, that is similar to Pikaia but predates it by about 10 million years (Myr).

Cambrian and recent morphological disparity.

TLDR
B Briggs et al. conclude that modem disparity of arthropods is about equal to that in the Cambrian, thus controverting a widely held premise that maximal disparity occurred early in the history of metazoan life and that disparity has subsequently decreased.

The Cambrian evolutionary ‘explosion’: decoupling cladogenesis from morphological disparity

TLDR
Evidence is presented that the important events in the generation of clades were earlier than the Cambrian ‘explosion’, at which time the groups become manifest in the fossil record.
...