Fósseis, moléculas e embriões: novas perspectivas sobre a Explosão Cambriana
Development. 1999
Feb;126(5):851-9.
Fossils, molecules and
embryos: new perspectives on the Cambrian explosion.
Valentine JW, Jablonski
D, Erwin DH.
Collaborators (1)
Source
Department of Integrative
Biology and Museum of Paleontology, University of California, Berkeley,
CA 94720, USA. jwv@ucmp1.berkeley.edu
Abstract
The Cambrian explosion is named for the geologically sudden
appearance of numerous metazoan body plans (many of living phyla)
between about 530 and 520 million years ago, only 1.7% of the duration
of the fossil record of animals. Earlier indications of
metazoans are found in the Neoproterozic; minute trails suggesting
bilaterian activity date from about 600 million years ago. Larger and
more elaborate fossil burrows appear near 543 million years ago, the
beginning of the Cambrian Period. Evidence of metazoan activity in both
trace and body fossils then increased during the 13 million years
leading to the explosion. All living
phyla may have originated by the end of the explosion. Molecular
divergences among lineages leading to phyla record speciation events
that have been earlier than the origins of the new body plans, which can
arise many tens of millions of years after an initial branching. Various attempts to date those branchings by using
molecular clocks have disagreed widely. While the timing
of the evolution of the developmental systems of living metazoan body
plans is still uncertain, the distribution of Hox and other
developmental control genes among metazoans indicates that an extensive
patterning system was in place prior to the Cambrian. However, it is likely that much genomic repatterning
occurred during the Early Cambrian, involving both key control genes
and regulators within their downstream cascades, as novel body plans
evolved.
PMID: 9927587 [PubMed -
indexed for MEDLINE]
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NOTAS DESTE BLOGGER: http://pos-darwinista.blogspot.com.br/2012/12/fosseis-moleculas-e-embrioes-novas.html
O dilema de Darwin - ele
sabia que o Cambriano era uma dificuldade tremenda para a sua teoria da
evolução (mais particularmente a hipótese de descendência comum com
modificação) continua sem resposta no contexto de justificação teórica
(os darwinistas ortodoxos, fundamentalistas pós-modernos, chiques e
perfumados a la Dawkins, odeiam o contexto de justificação teórica!!!).
O artigo de 1999 de
Valentine, Jablonski e Erwin sugere que provavelmente
teve de ocorrer muita repadronização genômica envolvendo os genes controladores
e os reguladores à medida em que novos planos corporais evoluíam. O
nome disso é MILAGRE!!!
http://pos-darwinista.blogspot.com.br/2012/12/fosseis-moleculas-e-embrioes-novas.html
http://pos-darwinista.blogspot.com.br/2012/12/fosseis-moleculas-e-embrioes-novas.html
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