Anyone remember the old creationist claim that dinosaur blood had been found freshly preserved?
Now, when I first heard about this claim, I referenced Mary Schweitzer's comments that this entire thing might simply be an odd "impression" of flesh rather than the actual thing (She did say that "the fossil record can mimic many things"). I also pointed out that plausible methods for fragments of biological tissue to survive were being investigated (See my original write up on this for more info). Others pointed out that this material was not found "still soft and stretchy" as creationists had claimed, but rather scientists had to painstakingly rehydrate this stuff to get it that way. Besides, the mammoth genome was being sequenced, and if this creature had lived at the same time as the dinosaurs, as creationists think, then we should be able to retrieve large chunks of dino DNA as well. But we haven't. So there was some inconsistency.
Now that I am done with my overly long intor, let's get down to it: Scientists now think that the alleged structures found in the bone have nothing to do with dinosaurs. They think that these structures are actually due to biofilms, or communities of bacteria which are enclosed in a polymer "film". Blogger Tara Smith sums this up:
"What they found provides an alternative hypothesis to the previous "dino blood" findings. The iron present (and thought to have come from blood cells) could be explained by the presence of iron-containing framboids: spheres commonly found in sediments. Blood vessel-like structures were found but also could be attributed to biofilm, and when compared by FT-IR to lab-grown biofilms, the chemical signature of the fossil structure more closely resembled modern biofilms than modern collagen. The authors argue that the biofilm hypothesis better explains the data, including the ubiquity of these structures in fractured fossils:
This investigation contends that iron-oxygen spheres are far too common in many formations to be the result of extraordinary preservation. Framboid morphology and elemental signature may superficially make them appear to be related to biological structures but they are, in fact, an inorganically produced mineral feature often found in association with organic matter."
Found via ScienceDaily:
[I]n a paper published July 30 in PloS ONE, a journal of the open-access Public Library of Science, Kaye and his co-authors contend that what was really inside the T. rex bone was slimy biofilm created by bacteria that coated the voids once occupied by blood vessels and cells.
He likens the phenomenon to what would happen if you left a pail of rainwater sitting in your backyard. After a couple of weeks you would be able to feel the slime that had formed on the inner walls of the bucket.
"If you could dissolve the bucket away, you'd find soft, squishy material in the shape of the bucket, and that's the slime," Kaye said. "The same is true for dinosaur bones. If you dissolve away the bone, what's left is biofilm in the shape of vascular canals."