These fossils revealed a mystery: like other Cambrian fauna, these strange soft-bodied fossils appeared in the fossil record abruptly, without evolutionary precursors.How is this remotely a problem? What does Luskin think that Collins means when he says "groups?" In the previous sentence Collins refers to chordates as a group. That's some group! The phylum Chordata consists of all animals that have either a true vertebral column or a notochord. In the Cambrian you see the first few examples of chordates. Today, chordates number over 44 000 species and consist of cephalochords, urochords and vertebrates, none of which had diversified by this point. Within the vertebrates alone are Reptilia, Mammalia, the sub-class Aves (recall that Aves has been subsumed within Reptilia because of the shared ancestry of birds with dinosaurs, crocodiles and alligators) and a host of other classes. Absolutely none of the animals that make up the later fossil record show up in the Cambrian. Animals like bears and whales date to the last fifty million years.Darwin himself was aware of this problem in his own day, writing that the lack of fossil evidence for the evolution of Cambrian trilobites "must at present remain inexplicable; and may be truely urged as a valid argument against the views here entertained." Nearly 150 years after Darwin penned those words, biology textbooks are still observing things like, "Most of the animal phyla that are represented in the fossil record first appear, 'fully formed,' in the Cambrian." Indeed, the striking appearance of animals in the Cambrian explosion is captured in a recent article in Nature article commemorating the 100th anniversary of Wolcott's discovery, stating that "virtually all animal groups alive today were present in Cambrian seas."
The Cambrian "explosion" took place over the course of some 60-70 million years and included the appearance of the first hard-shelled organisms. Before the Cambrian, all the way back to the Archean, there is evidence of animal tracks. Luskin and other creationists continue to peddle this nonsense about how life in all of its grandeur simply appeared out of thin air in the Cambrian. I am no longer sure whether is it because they are ignorant or mendacious.
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Mendacious...good word. Perhaps it is a combination of both ignorance and mendacity.
ReplyDeleteMy default in the 'malice/ignorance' question with respect to creationists used to be ignorance. Over the last 10 years it has shifted to malice.
ReplyDeleteI am afraid that my position is shifting as well, which presents a problem because I have lots of friends who, through lack of education (not meant as a slight) in biology and palaeontology are buying the arguments of the creationists. It is no fun to tell them that the arguments they are adhering to are being perpetrated by people who know better. If you read Prothero's book carefully, you get the sense he feels the same way. One reviewer remarked that he liked the book but that Prothero was very hard on creationists. Ya know, after years of dealing with what comes out of those "institutes," I understand why.
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