May 2, 2011 | David F. Coppedge

Original Soft Tissue Found in Mosasaur Fossil

Original collagen has been found in a mosasaur fossil.  Mosasaurs are marine reptiles that lived in the age of dinosaurs.  This one, found in chalk layers in Belgium, is alleged to be 70 million years old.
    The press release on PhysOrg said, “the discovery demonstrates that the preservation of primary soft tissues and endogenous biomolecules is not limited to large-sized bones buried in fluvial sandstone environments, but also occurs in relatively small-sized skeletal elements deposited in marine sediments.
    The paper announcing the discovery of “Cretaceous bone proteins” is in PLoS One.1  For more on mosasaurs, see 08/13/2010 and 11/16/2005.

The fossil record is capable of exceptional preservation and occasionally labile and decay-prone tissues, such as skin and melanosomes (color-bearing organelles), are preserved as phosphatized remains or organic residues with a high degree of morphological fidelity.  Yet, whether multimillion-year-old fossils harbor original organic components remains controversial, and, if they do, a positive identification of these biomolecules is required.

Using infrared spectroscopy in connection with OM, SEM, TEM, amino acid, antibody and histochemical analysis, the researchers from Lund University found a good match in the collagen spectrum from the mosasaur and from a modern lizard; thus they feel confident the material is primordial.
    The authors postulated some mechanisms by which the proteins might have survived (entombment in crystals, high levels of phosphate and carbonate, small cavities within bone protected from microorganisms, etc.).  They described the fossil as “exceptionally well preserved”.  This was the first “direct spectroscopic characterization of isolated fibrous bone tissues, a crucial test of hypotheses of biomolecular preservation over deep time,” they said.

1.  Lindgren et al, ”Microspectroscopic Evidence of Cretaceous Bone Proteins,” PLoS One, e19445. doi:10.1371/journal.pone.0019445.

Marine fossils are buried in marine sediments – wet, and full of microbes.  Seventy million years is a long time!  Is it plausible that there was no decay for that long?  Would not bioturbation have occurred, and degradation by microbes, long before the strata was uplifted into dry chalk inland in Belgium?
    Imagine that these bones are only a few thousand years old, buried rapidly under a load of sediment.  Wouldn’t that assumption fit the data perfectly?  Why must we be forced to fit the bones into millions of years?  We cannot test a modern bone for millions of years, but surely some taphonomic experiments (testing fossilization processes) should be able to measure steady-state decay rates for collagen to give some degree of empirical evidence for the plausibility of preservation of soft tissue for millions of years.
    Scientists: don’t just tell us it’s millions of years old.  Prove it.  Otherwise, it sounds like adjusting your web of belief (07/25/2008) to evade falsifiability.

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Categories: Fossils, Marine Biology

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