I’ve been piddling on this for a while. Honestly, I find the whole exercise extremely annoying. But I promised I would do this and I’ve been inspired to continue. Thanks to the Thoughts in a Haystack blog. I’m something of a narcissist (apparently) and if someone doesn’t tell me how awesome I am every few weeks, I go and get depressed.
Meyer’s next subtopic is The Cambrian Explosion and the Tree of Life.
Once again, in the opening sentence Meyer says that millions of years isn’t millions of years. He talks of the “abrupt appearance” and “not only millions of years, but the untold generations of ancestors”.
OK, yes, you’ve said this before and you still have no evidence to support these claims. The Cambrian Explosion (because I haven’t said this enough) lasted for a minimum of 20 million years and up to 50+ million years. Even assuming one generation a year, that’s 20-50 million generations of life.
Then Meyer talks about the fossil record and how one of Darwin’s opponents says that we should find not one ‘missing link’, but “innumerable links shading almost imperceptibly from alleged ancestors to presumed descendants”.
I can forgive Darwin’s opponent for this claim. The understanding of biology, geology, and the like were very primitive compared to our modern knowledge. But I can’t forgive Meyer for promoting this as truth, because it’s simply not true.
“Where are the fossilized remains?”
I’ll go ahead and cover the next section as well, since they are related. This next section is “Murchison, Sedgwick, and the Cambrian Fossils of Wales”.
Here, Meyer talks about Sedgwick finding what is now called the Cambrian and these fossils “appeared out of nowhere”. Meyer mentions (and it’s not clear if this is what Sedgwick thought or if this is Meyer himself) other “abrupt appearances” like the amphibians and turtles and dinosaurs.
“Where are the fossilized remains?”
At this point, again, I’m a little disgusted with Meyer. He appears to be poisoning the well. Preparing the reader for the “revelations” to come. An author that was truly examining the history of this scientific enterprise would, at several points, state, “But we know that this isn’t true now.” Because these claims are not true.
A brief discussion of fossilization follows. If you know this bit, then feel free to skip it.
Fossilization occurs in very, very rare circumstances. To become a fossil, an organism must die. That organism must remain undisturbed, preferably buried. in an environment where even bacteria can’t destroy it (totally). Then over millions of years, the hard parts of the body are slowly replaced by other minerals. Rarely, even for fossils, we get some soft part fossilized… at least to the point where we can identify them.
For soft parts (like feathers and skin), we occasionally get casts made. This is where the part is buried in very fine-grained mud or silt and when the soft part finally does decay, it leaves an impression in the rock. This is just like sticking a babies foot in plaster and getting an impression of the babies foot so good we can even see the footprint (analogous to fingerprint).
Then comes the really hard part (no pun intended). That piece of rock with the fossil in it has to survive for millions of years. In the case of Cambrian fossils, the rock has to survive for some one half billion years without being melted, metamorphosed, faulted, eroded, or any other process that would destroy the fossil. Then that rock has to be near the surface of Earth when we are ready to go looking for it.
These are not trivial problems. It is entirely possible that all the fossil evidence of the Cambrian explosion we could ever want exists… it just happens to be be buried under several thousand feet of lava flows… or the bottom of the Pacific… or underneath thousands of feet of ice in the Antarctic. We may never know.
The fact that we have any fossils at all of that time period is impressive. And we will talk about those sites and the unique circumstances that caused them in future installments.
I’d like to add that this chapter shows Meyer’s poor scholarship. When one makes a claim, one should investigate it and mention the material that contradicts one’s claim. Even if the claim is not 100% wrong, any verifiable material that puts doubt on it should be mentioned. I guess this is why Meyer writes casual books instead of peer-reviewed research.
I bring this up, because even a casual glance at the literature scores this paper from 2008. An ancestral turtle from the Late Triassic of southwestern China.
From the abstract
The origin of the turtle body plan remains one of the great mysteries of reptile evolution. The anatomy of turtles is highly derived, which renders it difficult to establish the relationships of turtles with other groups of reptiles. The oldest known turtle, Proganochelys from the Late Triassic period of Germany1, has a fully formed shell and offers no clue as to its origin. Here we describe a new 220-million-year-old turtle from China, somewhat older than Proganochelys, that documents an intermediate step in the evolution of the shell and associated structures. A ventral plastron is fully developed, but the dorsal carapace consists of neural plates only. The dorsal ribs are expanded, and osteoderms are absent. The new species shows that the plastron evolved before the carapace and that the first step of carapace formation is the ossification of the neural plates coupled with a broadening of the ribs. This corresponds to early embryonic stages of carapace formation in extant turtles, and shows that the turtle shell is not derived from a fusion of osteoderms. Phylogenetic analysis places the new species basal to all known turtles, fossil and extant. The marine deposits that yielded the fossils indicate that this primitive turtle inhabited marginal areas of the sea or river deltas.
Hey look at that. When science keeps looking, they continue to find evidence.
Finally, because it seems to keep coming up in creationist literature (and Meyer specifically), no one thinks that this individual creature is the ancestor of all turtles. That’s not how fossilization, populations, evolution, and science works. We don’t have to the exact ancestor of all turtles to say that turtles evolved.