by Lenny Flank
(c) copyright 2006
The creationists liked this argument because it not only allowed them to criticize evolution, but also allowed them to claim that this part of the fossil record supported their own ideas about the sudden creation of all life.
The Cambrian was a period of life that began about 540 million years ago, and lasted until about 480 million years ago. For over 3 billion years previous to the Cambrian, life existed almost exclusively as single-celled organisms. At the time of the Cambrian period, however, multicellular life appeared, and rapidly diversified to produce organisms as different as sponges, trilobites, and strange animals that resembled nothing alive today. (The process was "rapid" when view in geological terms -- the actual process required at least 10 or 15 million years). The Cambrian organisms are best known from the Burgess Shale fossils, which were described by Stephen Jay Gould in his best-selling book Wonderful Life.
The creationist argument is that since all the major groups of life appeared suddenly in the Cambrian, and there were no life forms prior to that, and evolution can't explain where they came from, then this must represent the time when all the major "kinds" of life were first created:
"Creationists have long pointed out the problem for evolution theory, namely that all the major groups (phyla) of life which we know today appear in the Cambrian with no evolutionary ancestors. This is why evolutionists refer to it as an ‘explosion’ of evolution. There are no groups which have been identified as ancestral to any of the phyla, and geologically these phyla ‘seem to have appeared suddenly and simultaneously’." (Carl Weiland, AIG, Creation Magazine, March 1994)
"Neither is there any clue as to how the one-celled organisms of the primordial world could have evolved into the vast array of complex multi-celled invertebrates of the Cambrian period." (Henry Morris, ICR Impact #330, Dec 2000)
"In the supposedly 600-million-year-old layers of rock designated as Cambrian (the first appearance of multicelled life), sponges, clams, trilobites, sea urchins, starfish, etc., etc., are found with no evolutionary ancestors. Evolutionists don't even have any possible ancestors to propose." (John Morris, Dr John's Q&A, June 1, 1989)
Indeed, this argument was so commonly heard that Stephen Jay Gould was asked about it when he testified during the Arkansas trial in 1981:
Q: Professor Gould, are you familiar with the creation science argument that there are unexplained gaps between pre-Cambrian and Cambrian life?
A: Yes, indeed. The pre-Cambrian fossil record was pretty much nonexistent until twenty or thirty years ago. Creationists used to like to make a big point of that. They argued, `Look, for most of earth's history until you get rocks that you say are six hundred million years old, there were no fossils at all.
Starting about 30 years ago, we began to develop a very extensive and impressive fossil record of pre-Cambrian creatures. They are, indeed, only single-celled creatures. And the reason we haven't found them before is because we were looking for larger fossils in different kinds of rocks.
So creation scientists had to acknowledge that, and they then shifted the argument and said that, "All right, these are only single-celled creatures and they are not ancestors to the more complicated forms that arise in the Cambrian, but there are no fossils of multi-cellular animals before the Cambrian strata." But we've known now for about twenty years that that, too, is false. There is one rather well known fauna called the Ediacaran fauna, after a place in Australia where it was first found, but now, in fact, found on almost every continent of the earth.
These fossils are pre-Cambrian. They are not very ancient pre-Cambrian fossils. They occur in rocks pretty much just before the Cambrian. They are caught all over the world invariably in strata below the first appearance of still invertebrate fossils.
And the creation scientists, as far as I can see, for the most part, just simply ignore the existence of the Ediacaran fauna. (Gould testimony, McLean v Arkansas transcript, 1982)
The creationist assertion that "all the major groups of life" appear suddenly in the Cambrian period without any ancestors, is simply wrong. There are, for instance, no plants at all anywhere in the Cambrian. Reptiles, fish, birds and mammals didn't exist then -- the only vertebrate that existed at the time was Pikaia, a tiny creature that looked something like the modern amphioxus. No terrestrial organisms of any sort existed -- the Cambrian fauna were entirely aquatic.
The argument that these organisms didn't have any known fossil ancestors is also wrong. As Gould noted in his testimony, the creationists simply ignored the earlier pre-Cambrian Ediacaran fossils, known from Australia and China, which present fossilized ancestors for worms, arthropods and even chordates (the group to which all vertebrates belong). Even earlier than the Edicaracan fauna are fossilized bacterial colonies known as stromatolites, which can be found in desposits dating back almost 3.5 billion years. Fossilized single-celled bacteria have been found in deposits almost 3.8 billion years old.