Sudden appearance of fossils in the Cambian strata

http://www.ncbi.nlm.nih.gov/pubmed/19557680

The sudden appearance of diverse animal body plansduring the Cambrian explosion.
Chen JY.
Author information
Abstract

Beautifully preserved organisms from the Lower Cambrian Maotianshan Shale in central Yunnan, southern China, document the sudden appearance of diverse metazoan body plans at phylum or subphylum levels, which were either short-lived or have continued to the present day. These 530 million year old fossil representatives of living animal groups provide us with unique insight into the foundations of living animal groups at their evolutionary roots. Among these diverse animal groups, many are conservative, changing very little since the Early Cambrian. Others, especially Panarthropoda (superphylum), however, evolved rapidly, with origination of novel body plans representing different evolutionary stages one after another in a very short geological period of Early Cambrian time. These nested body plans portray a novel big picture of pararthropod evolution as a progression of step-wise changes both in the head and the appendages. The evolution of the pararthropods displays how the head/trunk boundary progressively shifted to the posterior, and how the simple annulated soft uniramous appendages progressively changed into stalked eyes in the first head appendages, into whip-like sensorial and grasping organs in the second appendage, and into jointed and biramous bipartite limbs in the post-antennal appendages. Haikouella is one of most remarkable fossils representing the origin body plan of Cristozoa, or crest animals (procraniates+craniates). The anatomy of Early Cambrian crest animals, including Haikouella and Yunnanozoon, contributes to novel understanding and discussion for the origins of the vertebrate brain, neural crest cells, branchial system and vertebrae.

http://www.angelfire.com/pro/kairosfocus/resources/Info_design_and_science.htm

The Cambrian explosion represents a remarkable jump in the specified complexity or "complex specified information" (CSI) of the biological world. For over three billions years, the biological realm included little more than bacteria and algae (Brocks et al. 1999). Then, beginning about 570-565 million years ago (mya), the first complex multicellular organisms appeared in the rock strata, including sponges, cnidarians, and the peculiar Ediacaran biota (Grotzinger et al. 1995). Forty million years later, the Cambrian explosion occurred (Bowring et al. 1993) . . . One way to estimate the amount of new CSI that appeared with the Cambrian animals is to count the number of new cell types that emerged with them (Valentine 1995:91-93) . . . the more complex animals that appeared in the Cambrian (e.g., arthropods) would have required fifty or more cell types . . . New cell types require many new and specialized proteins. New proteins, in turn, require new genetic information. Thus an increase in the number of cell types implies (at a minimum) a considerable increase in the amount of specified genetic information. Molecular biologists have recently estimated that a minimally complex single-celled organism would require between 318 and 562 kilobase pairs of DNA to produce the proteins necessary to maintain life (Koonin 2000). More complex single cells might require upward of a million base pairs. Yet to build the proteins necessary to sustain a complex arthropod such as a trilobite would require orders of magnitude more coding instructions. The genome size of a modern arthropod, the fruitfly Drosophila melanogaster, is approximately 180 million base pairs (Gerhart & Kirschner 1997:121, Adams et al. 2000). Transitions from a single cell to colonies of cells to complex animals represent significant (and, in principle, measurable) increases in CSI . . .

http://www.icsintegrity.org/fossil-data.html

This is not the only such explosion in the fossil record. Paleontologists have observed a fish explosion, a plant explosion, a bird explosion, and even a mammal explosion. Abrupt explosions of mass biological diversity seem to be the rule, not the exception, for the fossil record. Transitions plausibly documented by fossils seem to be the rare exception. As evolutionary biologist, the late Ernst Mayr, wrote in 2001, “When we look at the living biota, whether at the level of the higher taxa or even at that of the species, discontinuities are overwhelmingly frequent. . . . The discontinuities are even more striking in the fossil record. New species usually appear in the fossil record suddenly, not connected with their ancestors by a series of intermediates.”85 This phenomenon exists not only at the species level but also among higher taxa, as one zoology textbook admits: “Many species remain virtually unchanged for millions of years, then suddenly disappear to be replaced by a quite different, but related, form. Moreover, most major groups of animals appear abruptly in the fossil record, fully formed, and with no fossils yet discovered that form a transition from their parent group.”86

http://ncu9nc.blogspot.com.br/2014/09/the-missing-ancestors-of-cambrian.html

About the missing precursors at the base of the tree of the animal phyla, Valentine notes:
...many of the branches, large as well as small, are cryptogenetic (cannot be traced into ancestors). Some of these gaps are surely caused by the incompleteness of the fossil record..., but that cannot be the sole explanation for the cryptogenetic nature of some families, many
invertebrate orders, all invertebrate classes, and all metazoan phyla.

Charles Marshall concurs:
While the fossil record of the well-skeletonized animal phyla is pretty good, we have virtually no fossils that are unambiguously assignable to the most basal stem groups [putative ancestors] of these phyla, those first branches that lie between the last common ancestor of all bilaterians and the last common ancestor of the living representatives of each of the phyla….their absence is striking. Where are they?