the Cambrian explosion had a fairly long fuse
In the lowest Cambrian, the stromatolites were decimated. This allowed animals to begin colonization of warm-water pools with carbonate sedimentation. At first, it was s and (the fossilized grasping spines of ) fossils. Such mineral skeletons as shells, sclerites, thorns, and plates appeared in uppermost Nemakit-Daldynian; they were the earliest species of , , and other rare organisms. The beginning of the has historically been understood to mark an explosive increase of the number and variety of fossils of molluscs, s, and s, along with a rich complex of skeletal elements of unknown animals, the first s, s, s, and others. This sudden increase is partially an artefact of missing strata at the Tommotian type section, and most of this fauna in fact began to diversify in a series of pulses through the Nemakit-Daldynian and into the Tommotian.
What is true of the Cambrian explosion
To add a bit more, I think Meyers could be so much more compelling to examine some wider data than just what Doug Axe says. I do not know Doug and have nothing against him. Furthermore, I could not care less if the Darwinian paradigm falls apart on the Cambrian explosion. But there is what is known as the Ig superfamily of proteins which contain, as the name suggests, the Ig fold. Members of the Ig superfamily are involved in homotypic adhesion (the foundation for making tissues), receptors, signaling proteins (tyrosine kinases) and of course antibodies and T cell receptors. Now here are two points that are interesting. First, one fold is used for many different and relevant functions, and one in particular that lies at the heart of the Cambrian explosion – mulicellularity – which involves homotypic adhesion. Secondly, what is the sequence variability of the Ig fold in members of the superfamily. If it is as constrained as Meyer portends, then we should see it in the sequence data.
It can be helpful at this juncture to grasp the cumulative impact of , inventing , inventing , inventing that made possible, and inventing . Pound-for-pound, the complex organisms that began to dominate Earth’s ecosphere during the Cambrian Period consumed energy about 100,000 times as fast as the Sun produced it. Life on Earth is an incredibly energy-intensive phenomenon, powered by sunlight. In the end, only so much sunlight reaches Earth, and it has always been life’s primary limiting variable. Photosynthesis became more efficient, aerobic respiration was an order-of-magnitude leap in energy efficiency, the oxygenation of the atmosphere and oceans allowed animals to colonize land and ocean sediments and even fly, and life’s colonization of land allowed for a . Life could exploit new niches and even help create them, but the key innovations and pioneering were achieved long ago. If humanity attains the , new niches will arise, even of the , but all other creatures living on Earth have constraints, primarily energy constraints, which produce very real limits. Life on Earth has largely been a for several hundred million years, but the Cambrian Explosion was one of those halcyonic times when animal life had its greatest expansion, not built on the bones of a mass extinction so much as blazing new trails.
The long fuse of mammalian diversity - Gene Expression
Molecular studies have the potential to shed light on the origin of the animal phyla by providing independent estimates of the divergence times, but have been criticized for failing to account adequately for variation in rate of evolution. A method of dating divergence times from molecular data addresses the criticisms of earlier studies and provides more realistic, but wider, confidence intervals. The data are not compatible with the Cambrian explosion hypothesis as an explanation for the origin of metazoan phyla, and provide additional support for an extended period of Precambrian metazoan diversification.
The long fuse of mammalian diversity
The early history of the Metazoa, whether originating as part of a Cambrian “explosion” or with an extended, Precambrian “phylogenetic fuse,” remains controversial (–). The Cambrian explosion hypothesis—that the phyla and even classes of the animal kingdom originated in a rapid evolutionary radiation at the base of the Cambrian at 545 million yr ago (Ma) or 10–15 Ma before this date—rests on the sudden appearance of a diverse range of animals in the fossil record. Although recent discoveries of Ediacaran metazoans have extended the record of sponges and bilateral animals to 570 Ma (, ), the biological affinities of many Ediacaran organisms remain controversial, and the earliest palaeontological evidence of metazoan life is no more than 600 Ma (). However, the absence of earlier metazoan fossils could be caused by systematic biases in preservation that left the Precambrian history of recognized phyla unrecorded (). Molecular data have the potential to provide an independent test of gaps in the fossil record by providing a continuous historical record of all extant taxa, which can be used to infer the history of lineages that have low fossilization potential, or the presence of lineages over periods for which the fossil record is poor.
This blog is about evolution, ..
The CAMBRIAN EXPLOSION or CAMBRIAN RADIATION was the relativelyshort span event, occurring approximately 541 million years ago inthe period , during which most major animal phyla appeared,as indicated by the fossil record. Lasting for about the next 20 –25 million years, it resulted in the divergence of most modernmetazoan phyla. Additionally, the event was accompanied by majordiversification of other organisms. Prior to the explosion, most organisms were simple, composed of individual cells occasionallyorganized into colonies . Over the following 70 to 80 million years,the rate of diversification accelerated by an order of magnitude andthe diversity of life began to resemble that of today. Almost allpresent animal phyla appeared during this period. There is strongevidence for species of and existing in the and possible members of even before that duringthe . Bryozoans don't appear in the fossil record untilafter the Cambrian, in the Lower .