After trilobites, the most characteristic fossils of the Palaeozoic are known as graptolites. Whereas trilobites lasted throughout that era, the graptolites have been documented (until now) from the Middle Cambrian to the Lower Devonian. They are described as colonial hemichordates, with both benthic and planktonic forms. Although graptolites as a class are extinct, a related group within the phylum hemichordata are extant, with fossil ancestors also going back to the Cambrian Explosion. These animals belong to the class Pterobranchia, and can be described as living fossils. There are about 30 species alive today. Newly published is a report of the earliest and largest hemichordate zooid ever found. It is a pterobranch with the name Galeaplumosus abilus and it is preserved in exquisite detail.
"The 525-million-year-old fossil belongs to a group of tentacle-bearing creatures which lived inside hard tubes. Previously only the tubes have been seen in detail but this new specimen clearly shows the soft parts of the body including tentacles for feeding."
Galeaplumosus abilus (source here)
A modern-day pterobranch genus is Rhabdopleura. An informative description is provided here. Comparing the new fossil and Rhabdopleura leads to the exclamation: "You don't look a day over 500 million years. You and Rhabdopleura could be sisters". The detail has led to comments such as this from co-author Professor David Siveter: "Amazingly, it has exceptionally preserved soft tissues -- including arms and tentacles used for feeding -- giving unrivalled insight into the ancient biology of the group." The significant finding is that the earliest fossil hemichordate zooid looks remarkably similar to Rhabdopleura.
"Galeaplumosus abilus demonstrates stasis in pterobranch morphology, mode of coenecium construction, and probable feeding mechanism over 525 million years."
The phenomenon of stasis is something Darwinists and neo-Darwinists have struggled with. Their theory predicts gradualism, but gradualism is not what the fossil record delivers. Darwinists have sought to evade the evidence by appealing to an impoverished fossil record, but we have reached the stage where this retort must be interpreted as a form of denialism. Stephen Jay Gould declared in 1991 that "Stasis is data" and any theory of Earth history that fails to face up to this data must be abandoned. The conclusion was apparent several decades ago - the following quotations are taken from this source.
Eldredge and Tattersall (1982) wrote: "Darwin's prediction of rampant, albeit gradual, change affecting all lineages through time is refuted. The record is there, and the record speaks for tremendous anatomical conservatism. Change in the manner Darwin expected is just not found in the fossil record."
Gould (1993) wrote: "[S]tasis, or nonchange, of most fossil species during their lengthy geological lifespans was tacitly acknowledged by all paleontologists, but almost never studied explicitly because prevailing theory treated stasis as uninteresting nonevidence for nonevolution. [T]he overwhelming prevalence of stasis became an embarrassing feature of the fossil record, best left ignored as a manifestation of nothing (that is, nonevolution)."
Having said this, it should be pointed out that stasis does not mean absolute fixity. Organisms vary as alleles are shuffled, as was demonstrated by Mendel. More recent work has documented significant epigenetic variability and other causal factors that may or may not be generic. Most examples of "living fossils" are not at the species level, but more often at the genus level of classification. Most, if not all, living fossils can be understood in terms of Mendelian genetics and epigenetics. But Darwinists have approached "stasis" in defensive mode, as though the honour of their hero is at stake. It would appear that the only scientists who can think clearly about the implications of stasis are scientists with reservations about Darwinism! A recent example is Lynn Margulis, the author of the theory of endosymbiosis (some discussion is here). Margulis has been speaking about some of her radical views and the interview appears in Discover for April 2011. This is what she says about Mendelian genetics:
"In the first half of the 20th century, neo-Darwinism became the name for the people who reconciled the type of gradual evolutionary change described by Charles Darwin with Gregor Mendel's rules of heredity (which first gained widespread recognition around 1900), in which fixed traits are passed from one generation to the next. The problem was that the laws of genetics showed stasis, not change. If you have pure breeding red flowers and pure breeding white flowers, like carnations, you cross them and you get pink flowers. You back-cross them to the red parent and you could get three-quarters red, one-quarter white. Mendel showed that the grandparent flowers and the offspring flowers could be identical to each other. There was no change through time. There's no doubt that Mendel was correct."
The changes that we find in the fossil record reveal that something other than Darwinian gradualism is involved. This is what turned Margulis against neo-Darwinism:
"What you'd like to see is a good case for gradual change from one species to another in the field, in the laboratory, or in the fossil record - and preferably in all three. Darwin's big mystery was why there was no record at all before a specific point [dated to 542 million years ago by modern researchers], and then all of the sudden in the fossil record you get nearly all the major types of animals. The paleontologists Niles Eldredge and Stephen Jay Gould studied lakes in East Africa and on Caribbean islands looking for Darwin's gradual change from one species of trilobite or snail to another. What they found was lots of back-and-forth variation in the population and then - whoop - a whole new species. There is no gradualism in the fossil record."
Back to Galeaplumosus abilus which is a Lower Cambrian life form. The research paper declares that it "demonstrates stasis in pterobranch morphology, mode of coenecium construction, and probable feeding mechanism over 525 million years." This organism is found among the pioneers of the Cambrian Explosion. As soon as seawater became calcitic, they could thrive. Although there has been diversification, this has not contributed new biological information, for ancient forms are recognisably the same as their modern counterparts. For more on the Cambrian Explosion, go here.
There are major implications here for education and the importance of doing justice to evidence. Those who want to conceal the problems facing Darwinism must face the charge that they are acting more to defend their adopted paradigm than they are prepared to follow the evidence wherever it leads.
An Early Cambrian Hemichordate Zooid
Xian-guang Hou, Richard J. Aldridge, David J. Siveter, Derek J. Siveter, Mark Williams, Jan Zalasiewicz, Xiao-ya Ma
Current Biology, Volume 21, Issue 7, 612-616, 24 March 2011 | 10.1016/j.cub.2011.03.005
Summary: Hemichordates are known as fossils from at least the earliest mid-Cambrian Period (ca. 510 Ma) and are well represented in the fossil record by the graptolithinid pterobranchs ("graptolites"), which include the most abundantly preserved component of Paleozoic macroplankton. However, records of the soft tissues of fossil hemichordates are exceedingly rare and lack clear anatomical details. Galeaplumosus abilus gen. et sp. nov. from the lower Cambrian of China, an exceptionally preserved fossil with soft parts, represents by far the best-preserved, the earliest, and the largest hemichordate zooid from the fossil record; it provides new insight into the evolution of the group. The fossil is assigned to the pterobranch hemichordates on the basis of its morphological similarity to extant representatives. It has a zooidal tube (coenecium) with banding throughout comparable to that in the extant pterobranchs and a zooid with paired annulated arms bearing paired rows of annulated tentacles; it also displays a putative contractile stalk. G. abilus demonstrates stasis in pterobranch morphology, mode of coenecium construction, and probable feeding mechanism over 525 million years.
Remarkable Fossil Sea Creature - 525 Million Years Old - Shows Soft Parts of Body Including Tentacles, ScienceDaily (Mar. 28, 2011)
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