For fossils as old as dinosaurs (over 65 million years), the conventional wisdom has been that no original organic material could remain. If the delicate structure of soft body parts is discernable, that is only because these parts were converted to some type of inorganic mineral in the fossilization process. However, over the past two decades, paleontologist Mary Schweitzer has rocked our world by presenting visual evidence of soft tissues recovered from the interior of dinosaur bones, and biochemical evidence indicating that these are in fact the remnants of the original cells and structures from within the dinosaur bone pores. For instance, here is a network of blood vessels, containing little round red things that look like red blood cells:Young earth creationists have widely cited these findings as evidence that dinosaur fossils cannot really be millions of years old, and so the rock layers (radioactively dated to more than 65 million years of age) cannot really be millions of years old – – and so the whole old-earth dating edifice collapses. There have been some responses to these young earth claims by mainstream scientists, but many of these responses are sketchy or outdated. I read through most of Schweitzer’s papers on this topic, and reviewed the key findings from them in a 25-page article, which I posted as “Dinosaur Soft Tissue”, along with other long essays at the top of this blog window. If you want lots of facts and literature references, that is the place to go. For those who do not want to wade through all that information, here are some key takeaways:
TISSUES AND PROTEINS IDENTIFIED IN DINOSAUR BONES
These remarks pertain mainly to thighbones from two dinosaur specimens, a T. rex (approx. 68 million years old) and a duckbill hadrosaur (approx. 80 million years old). In both cases, the fossils had been buried in sandstone (which may help wick away destructive enzymes from the corpse) and the fossils were analyzed within a relatively short time after excavation, which minimized degradation from sudden exposure to a new set of environmental conditions.
After dissolving away the mineral portion of the bone with weak acid, various types of flexible structures have been recovered. They conform to the microscopic pores of the bone in which they had resided, so they are mainly viewed under a microscope. These structures include transparent, branching hollow vessels corresponding to the blood vessels found in modern animals (e.g. ostriches), and also what look like modern osteocyte cells. Various biochemical tests have indicated that these structures are composed of animal protein, showing that they derive from the original dinosaur tissue, as opposed to being merely biofilms produced by microbes which invaded the bone pores.
An electron microscopy study by Thomas Kaye indicated that what looks like red blood cells in the dinosaur blood vessels are not cells at all. They are little clusters of iron oxide.
The proteins which have been identified include collagen, actin, and tubulin. These are known to have structures which are resistant to degradation, especially when they are crosslinked. Tests indicate that these proteins from the dinosaur bones are indeed highly crosslinked, which appears to be a key aspect of their longevity.
Iron from blood hemoglobin can be highly effective in promoting this crosslinking and in general passivating the reactive groups on the proteins. Schweitzer’s group performed a dramatic experiment to demonstrate this effect, using modern ostrich blood vessels: the blood vessels which were incubated in a solution of hemoglobin (extracted from the red blood cells of chicken and ostrich) showed no signs of degradation for more than two years. In contrast, the ostrich vessels in plain water showed significant degradation within three days, which is more than 240 times faster degradation than with the hemoglobin. The osteocyte cell remnants from dinosaur fossils are essentially coated with iron-rich nanoparticles.
Beside the effect of iron, being in contact with the mineral walls of the pores, and being sealed in tiny pores, away from the enzymes and other body chemicals, can act to preserve remnants of the original proteins. Also, if soft tissue is initially dried out before it decays, it undergoes changes that make it more stable even if it is later rehydrated. Thus, several plausible mechanisms are known to help explain the preservation of these flexible tissues, and there are likely other factors yet to be discovered.
WIDE VARIATIONS IN TISSUE DECAY RATES
There are plenty of other examples of wide difference in the rates of tissue degradation, besides the ostrich blood vessels cited above. For instance, raw meat may spoil in a few days at room temperature, but will keep for weeks in a refrigerator, and for years if it is frozen or (in the case of country hams) if it is treated with salt and smoke. All the flesh can decay off a human face within a month if a body is left outside. However, this chap found in a Danish peat bog looks pretty fresh after more than 2200 years, demonstrating a difference of more than 25,000 (1 month versus 2200 years) in decay rates:
Thus, protein and soft tissue decomposition rates vary enormously, depending on the conditions. Some academics have done lab studies of protein degradation using accelerated conditions of high temperature and high acidity, but it is not valid to extrapolate those results to proteins locked in the pores of dinosaur bones. The reality is that we don’t know, with any precision, how fast proteins degrade under the conditions found in dinosaur fossil bones. So it is incorrect to claim that we know that it is impossible for soft tissue to survive in any form for 80 million years. And so the whole young earth case here falls apart.
In contrast, the rates of nuclear decomposition of elements have been measured over and over again, and found to be essentially invariant. As discussed in the main article there are a few conditions where nuclear decay can be accelerated, but these conditions are known and predictable, and do not apply to the rock layers in Montana where these dinosaur fossils were found.
Thus, it is absurd and insupportable to set aside the radioactive dating of these rock layers because some partly degraded soft tissue has been found in dinosaur fossils from those layers. That is probably the key conclusion from that long article on soft tissue in dinosaur fossils.
Some other topics covered there include the dinosaur-bird connection, the significance of trace indications of DNA, and Mary Schweitzer’s views on this controversy. She happens to be a devout evangelical Christian, who weathers defamatory emails from her young-earth brethren. She seems to handle that with grace, and finds that her view of the Creator has been enriched, not diminished, as she learns more about the complexities of the natural world.
The main driver for folks to hold to a young earth perspective is that they have been taught that this is the only faithful way to handle the Bible creation story. However, that is not the case: the Reasons to Believe site here lists about 40 well-known, impeccably conservative Christian leaders and writers that endorse or are at least open to an old-earth perspective. These include names like Gleason Archer, Michael Behe, Chuck Colson, Norman Geisler, Hank Hannegraff, C. S. Lewis, Francis Schaeffer, C. I. Schofield, Lee Stroble, and B. B. Warfield. Billy Graham wrote, “I believe that God did create the universe. I believe that God created man, and whether it came by an evolutionary process and at a certain point He took this person or being and made him a living soul or not, does not change the fact that God did create man. … whichever way God did it makes no difference as to what man is and man’s relationship to God.” A hermeneutical case for an old earth interpretation of Genesis is made by Reasons to Believe, and by the Christian geologists at Old Earth Ministries.