It’s time to return to the ICR, at last. Monday’s article, by Brian Thomas, is called Evidence Doesn’t Fade from Colorful Fossils – it’s about preserved evidence of coloured tissue in 340 million year old fossil crinoids.
Some crinoid fossils are supposed to be quite colourful – I say “supposed” because while this claim would appear to be true based on what the paper says and cites, none of the pictures I’ve seen are particularly impressive (the picture above is of a living specimen, if you were confused). The paper offers an explanation for how the “biomarker molecules” were preserved, but Thomas doesn’t like it:
Generations of onlookers have appreciated the long-lasting luster of “Egyptian blue,” an ancient dye still brilliant thousands of years after it was painted onto various murals and artifacts. But a new study found colors that apparently blow Egypt’s puny pigment longevity out of the water. Researchers discovered colorful organic chemicals embedded in fossils supposedly 340 million years old. Did the stories they concocted to explain this anomaly depart from scientific sense?
Tl;dr: no. But if you’re prepared to stick around, there are three aspects to the explanation in the paper. First:
The remarkable stability of these compounds results from the physiology of echinoderms. We recognize three factors as primarily responsible for the preservation of taxon-specific organic molecules from Mississippian and Jurassic crinoids. First, as mentioned above, these crinoids were buried rapidly in fine-grained sediments that preserved the fossils well and isolated them from significant exposure to fluids moving through the enclosing rocks that could leach or otherwise alter the organic and inorganic composition of these fossils.
Normally, Brian would be seizing on any claim that a fossil was “buried rapidly,” but today it doesn’t suit him. Instead he says:
First, they asserted that these fossils must have remained dry since they were initially deposited. Nearby water flow would have dissolved, washed away, or reacted with the pigments. But how feasible is this story when considering 300 million years’ worth of crustal plate collisions, catastrophic impacts, floods, earthquakes and constant weathering and erosion?
Importantly, all of those listed disasters would have been able to destroy the entire fossil just as easily as the biomarkers. The chances of one fossil surviving everything the planet can throw at it for millions of years may be slim, but there are just so many of them. And in a sense this fossil did ‘lose’ the struggle, in that it did end up getting weathered out of the hillside – it was simply lucky enough to be picked up and preserved, rather than being destroyed.
Many of the same catastrophes that would have taken place over the millennia are also featured in the young Earth creationist narrative as well: even if these were potential problems, Thomas cannot say that his own ideas are immune. What’s more the fact that water would need to have been excluded after burial could be problematic for a flood-based explanation, as they tend to invoke damp rocks as an explanation for rock-folding.
The second point is not mentioned by Thomas at all:
Second, the microstructure and crystallinity of crinoids and other echinoderms are unique. The crinoid skeleton is formed within mesodermal tissue. When alive, individual crinoid ossicles are a single crystal of the mineral calcite, with ∼50% of the volume composed of calcite, and the porosity of the plate is filled with various soft tissues. After death, during early diagenesis, the porosity of individual plates is occluded rapidly by syntaxial calcite cement that retains the crystallinity of the original ossicle. In so doing, some of the organic molecules from the organism may become trapped within the newly precipitated calcite and preserved (Thomas and Blumer, 1964). Thus, organic molecules from the living organism may be trapped inside a single, relatively large calcite crystal that is geochemically stable over geologic time, unless altered through diagenesis or metamorphism. Dickson (2001) referred to echinoderm ossicles as “crystal caskets”, and the trapped organic molecules within a crystal casket are resistant to normal diagenetic change and leaching.
(Emphasis added.) The other two points really boil down to ensuring that this crystal wouldn’t be disturbed. Thomas skips to the last:
Maybe the fossils could be protected from natural disasters and erosion if they were buried deep beneath earth’s crust. But the study authors wrote that the crinoid-containing Mississippian beds from Indiana “have never been buried deeply,” and therefore were not exposed to the temperatures and pressures that would metamorphose rocks and would have certainly fried the crinoid’s quinones. In other words, the biomolecules’ colors were doomed to fade if buried too deep, but doomed to spoil if held closer to the surface. The study authors did not address this dilemma.
The relevant quote is:
The third factor is that the lower Mississippian rocks studied from Indiana have never been exposed to any metamorphism, and they have never been buried deeply, as indicated by a conodont alteration index of 1.5 or less for the deposit under study.
Conodont alteration is a system used to determine the maximum temperature that a rock has been subjected to, which can then be used to infer rough depth. According to wikipedia an index of one can encompass temperatures anywhere up to about 80 degrees Celsius while a value of two ranges from 60 to 140 degrees. The rock could thus easily have been buried a more than a kilometre down, well safe from erosion and water damage, without exceeding the permissable temperature range. “Deep” in this context means very deep by normal human standards – there is no “dilemma” to address.
So far, a better explanation for original chemistry remaining in these colorful fossils is that their rock layers were deposited thousands, not millions, of years ago.
Once again, Brian makes a flawed attack on the standard explanation, claims victory, and then uses that to assert that his own position must be better without first subjecting it to the same criticism. Nothing then has changed in my absence.