Mary Schweitzer and the mysterious dinosaur soft tissue

Science has an overview of Schweitzer’s work. You may recall that she published descriptions of cells and soft tissue imbedded deep in fossilized dinosaur bone. That work is much beloved by creationists (it means those bones must be young, they say), but despite starting out as a creationist, she does not support that claim of a young age. She’s a theistic evolutionist.

She went back to school at Montana State University in Bozeman for an education degree, planning to become a high school science teacher. But then she sat in on a dinosaur lecture given by Jack Horner, now retired from the university, who was the model for the paleontologist in the original Jurassic Park movie. After the talk, Schweitzer went up to Horner to ask whether she could audit his class.

“Hi Jack, I’m Mary,” Schweitzer recalls telling him. “I’m a young Earth creationist. I’m going to show you that you are wrong about evolution.”

“Hi Mary, I’m Jack. I’m an atheist,” he told her. Then he agreed to let her sit in on the course.

Over the next 6 months, Horner opened Schweitzer’s eyes to the overwhelming evidence supporting evolution and Earth’s antiquity. “He didn’t try to convince me,” Schweitzer says. “He just laid out the evidence.”

She rejected many fundamentalist views, a painful conversion. “It cost me a lot: my friends, my church, my husband.” But it didn’t destroy her faith. She felt that she saw God’s handiwork in setting evolution in motion. “It made God bigger,” she says.

I’ve read her papers, and they’re real head-scratchers. She seems to do good work; she documents everything carefully; she interprets the results cautiously. They don’t jibe well with expectations — chemistry ought to show more decay — but heck, data is data, if there are sound observations we’ve got to conform the theory to the evidence, not the other way around. She is reporting stuff that seems colossally unlikely, though.

Schweitzer’s most explosive claim came 2 years later in two papers in Science. In samples from their 68-million-year-old T. rex, Schweitzer and colleagues spotted microstructures commonly seen in modern collagen, such as periodic bands every 65 nanometers, which reflect how the fibers assemble. In another line of evidence, the team found that anticollagen antibodies bound to those purported fibers. Finally, they analyzed those same regions with Harvard University mass spectrometry specialist John Asara, who got the weights of six collagen fragments, and so worked out their amino acid sequences. The sequences resembled those of today’s birds, supporting the wealth of fossil evidence that birds descend from extinct dinosaurs.

It’s difficult to believe, but then there’s another dilemma: we expect extraordinarily strong evidence before it should be accepted, but how strong does it have to be? Is this too nitpicky?

She needs more fossils to quiet a continuing drumbeat of criticism. In addition to raising the specter of contamination, Buckley and others have argued that antibodies often bind nonspecifically and yield false-positive results. Critics also noted that one of the six amino acid sequences reported in the 2007 paper was misassigned and is likely incorrect. Asara later agreed and retracted that particular sequence.

“That’s worrying,” says Maria McNamara, a paleontologist at University College Cork in Ireland. “If you are going to make claims for preservation, you really need to have tight arguments. At this point I don’t think we are quite there.”

The biggest problem, though, is this one: all these results come from one and only one lab.

But no one except Schweitzer and her collaborators has been able to replicate their work. Although the study of ancient proteins, or paleoproteomics, is taking off, with provocative new results announced every few weeks, most findings come from samples thousands or hundreds of thousands of years old—orders of magnitude younger than Schweitzer’s dinosaurs.

“I want them to be right,” says Matthew Collins, a leading paleoproteomics researcher at the University of York in the United Kingdom. “It’s great work. I just can’t replicate it.”

That’s something I wish the creationists who bring up her work could understand: we want her to be right. I want to be able to go to a databank and download protein sequences from T. rex. I want to see a molecular phylogenetics comparison of Stegosaurus and Hadrosaurus osteocyte proteins. I think it would be awesome to compare sequences from different ceratopsians and assemble a family tree.

What I want and what we’ve got are two different things, though, and if only Schweitzer has the magic hands to extract this information, I’m not going to trust it. I don’t reject it out of hand, but damn,
it really needs more replication. At this point I don’t want to see another paper from her — I want to see it coming from another, unaffiliated lab. That would be better confirmation.


  1. devnll says

    “if only Schweitzer has the magic hands to extract this information, I’m not going to trust it. I don’t reject it out of hand, but damn, it really needs more replication. ”

    Could not possibly agree with you more. The question that leaps to my mind is: “Is anyone trying and failing to replicate it?” A “no” answer would not in any way detract from the “needs more replication” argument, but a bunch of people trying and failing would have to throw some serious doubt on the original research, requiring an order of magnitude more explanation.

  2. chrislawson says

    My skepticism flag also goes up at the concept of working out amino acid sequences from mass spectrometry of collagen fibres that have survived mineralisation from fossilisation plus 68 million years of natural degradation. I’m not saying it can’t possibly be true, but it seems a long shot. And why did they go for T. rexes when it would have been smarter to start with more recent fossils, say from the Miocene, to establish the validity of the method? I suspect they went for T. rexes because they’re “sexier” in media terms, but it’s not good science to start there.

  3. whywhywhy says

    #1 devnll

    Generally, studies that show ‘negative’ findings tend not to be published. However, this seems a hot enough topic that negative findings would be easily published. So hopefully we will see response from other labs in the literature (supporting or not) in the near future.

  4. Crip Dyke, Right Reverend Feminist FuckToy of Death & Her Handmaiden says

    I’ve always been only vaguely skeptical of Schweitzer’s claims. Although many people have said that such and such protein can’t possibly last that long, that’s P-Chem territory, a notoriously difficult class and one that I’ve never even taken. I have no good understanding of why one molecule lasts longer than another (save the bare minimum understanding that some inter-atomic bonds represent a very low-energy state and thus would require more energy, on average, to sever). I get it that if a tissue type has a high initial-decay rate (a decay rate I can observe over a few hours or days*1 for food in my kitchen/refrigerator) then almost certainly lots of molecules that make up that tissue are likely decaying and that without major environmental change that rate will continue to be largely steady. Thus some tissues simply won’t make it to fossilization.

    But some tissues do make it to fossilization. Once there, I simply can’t say anything about whether that process is capable of proceeding in such a way that molecules trapped within fossilizing tissue will or won’t decay at a slower rate than they did before the fossilization process started.

    Unable to be expert in everything (or, really, anything) I simply accept the success of these papers in navigating the peer review process as good evidence that the results (and at least some of the conclusions) can reasonably accepted as provisionally true. I’ll go on acting like I have more reason to believe the results and most conclusions are true than I have to believe that they are false right up until the moment that my understanding of P-Chem and taphonomy rules out Mega-year preserved proteins or until a better supported explanation arises (well-documented evidence of fraud, for instance*2).

    Not having reviewed the literature to see how many people are following this up with replication or attempted replication, I didn’t know that her lab’s research is as yet unconfirmed. That raises some red flags for me, but I’m not going to change my assessment yet.

    *1: :ahem: Or weeks.
    *2: Not saying I think Schweitzer’s lab is any more likely to be engaging in fraud than any other research lab in the world, just saying that if fraud related to samples or their analyses was sufficiently documented then that would change my evaluation of these results as provisionally true.

  5. bryanfeir says

    @Crip Dyke:
    It wouldn’t even need to be deliberate fraud. Wishful thinking and insufficient sterilization could be enough.

    That said, agree with the general assessment that this would be great if true, but needs better follow-up.

  6. kalilchernov says

    I was a student under her at NCSU. I have an extremely low opinion of her research technique and her personality – she was habitually cruel and condescending towards her grad students, and as far as her lab techniques go… You’re spot on in wanting to see some independent verification.
    There was a bit of a mini-scandal while I was there, where she took some false-color images of iron ooids and shopped them around to a bunch of cellular biologists, asking “what do these look like?” The cell bio folks, when shown a round red thing, all said “Oh, it’s a blood cell!”, which made for some really great grant proposals until someone thought to ask for the opinion of someone who had actually looked at rock under a microscope before…
    She was always uncomfortable with the adulation of the creationists, but she was /very/ happy with the adulation of the press and the administration.

  7. kalilchernov says

    @bryanfeir , I think you’re spot on re: “wishful thinking and insufficient sterilization”. While I was at NCSU, she fired a very competent lab technician. When I asked my mentor what had happened, he rolled his eyes and said “She wasn’t contaminating the specimens enough.”

  8. raven says

    Sciencenewsforstudents. org
    More dinosaur bones yield traces of blood, soft tissue
    Discovery gives scientists more places to search for clues to when warm-bloodedness emerged
    JUN 24, 2015 — 7:00 AM EST
    A scanning electron micrograph of a sliver of theropod claw reveals oval-like structures. These resemble red blood cells in living birds. Less dense, carbon-based material appears red. Denser mineralized material appears green.
    A scanning electron micrograph of a sliver of theropod claw reveals oval-like structures. These resemble red blood cells in living birds. Less dense, carbon-based material appears red. Denser mineralized material appears green.
    Scientists studying dinosaur evolution are finding many more bones to pick.

    Researchers from London have found hints of blood and fibrous tissue in a hodgepodge of 75-million-year-old dinosaur bones. These fossils had been poorly preserved. That now suggests residues of soft tissues may be more common in dino bones than scientists had thought. Details appeared June 9 in Nature Communications.
    The team used a scanning electron microscope to study the bones. This special microscope can highlight features that are just a few billionths of a meter across. The dinosaur bone images revealed what appeared to be red blood cells. A second type of powerful microscope probed the structure of some bone features. These images showed bands similar to patterns formed by collagen in animal bones today. Collagen is a fibrous protein. It is found not only in bones, but also in cartilage, tendons and other connective tissues.

    Some of what Schweitzer has seen has been replicated.
    I just picked this up on a 5 second Google search.

  9. raven says

    I don’t find it too hard to believe that trace macromolecules could survive in dinosaur bones.
    Other original tissues have survived that long including shell and chitin.

    Preservation of Chitin in 25-Million-Year-Old Fossils | Science
    science. sciencemag. org/content/276/5318/1541
    by BA Stankiewicz – ‎1997 – ‎Cited by 160 – ‎Related articles
    Preservation of Chitin in 25-Million-Year-Old Fossils. B. Artur Stankiewicz,; Derek E. G. Briggs,; Richard P. Evershed,; Matthew B. Flannery,; Michael Wuttke.

    As a kid, I dug some Baculite (shelled cephalopods) fossils out of limestone in South Dakota. They were greater than 65 nillion years old.
    What was eerie was that the original shells were still intact and still obviously shells.

    Baculites (“walking stick rock”) is an extinct genus of cephalopods with a nearly straight shell, included in the heteromorph ammonites. The genus, which lived worldwide throughout most of the Late Cretaceous,

  10. raven says

    Discovery of 505-million-year old chitin in the basal demosponge Vauxia gracilenta
    H. Ehrlich, J. Keith Rigby, J. P. Botting, M. V. Tsurkan, C. Werner, P. Schwille, Z. Petrášek, A. Pisera, P. Simon, V. N. Sivkov, D. V. Vyalikh, S. L. Molodtsov, D. Kurek, M. Kammer, S. Hunoldt, R. Born, D. Stawski, A. Steinhof, V. V. Bazhenov & T. Geisler
    Scientific Reports 3, Article number: 3497 (2013)
    29 November 2013
    Published online:
    13 December 2013
    Sponges are probably the earliest branching animals, and their fossil record dates back to the Precambrian. Identifying their skeletal structure and composition is thus a crucial step in improving our understanding of the early evolution of metazoans. Here, we present the discovery of 505–million-year-old chitin, found in exceptionally well preserved Vauxia gracilenta sponges from the Middle Cambrian Burgess Shale. Our new findings indicate that, given the right fossilization conditions, chitin is stable for much longer than previously suspected. The preservation of chitin in these fossils opens new avenues for research into other ancient fossil groups.

    One more.
    This is from the Burgess shale, 505 million years old.

  11. emergence says

    See, this feels like an actual scientific controversy. I really don’t know what to personally think about Schweitzer’s work, or other work similar to it. I do think more research on this stuff and attempts to replicate it are necessary.

    That’s the problem with stuff like creationism or AGW denial. They distract from actual disagreements in the scientific community.

  12. Owlmirror says

    Neither the review article, nor the OP, nor the comments, mention Schweitzer’s hypothesis that iron could have had a role in stabilizing some of the organic molecules by causing molecular cross-linking.

    Looking at the paper from Jan 2017 (DOI: 10.1021/acs.jproteome.6b00873), I see a paragraph that mentions more hypotheses than that:

    Multiple mechanisms have been proposed or experimentally demonstrated that may result in early stabilization of protein molecules, potentially resulting in preservation over geological time. These have included: (1) a role for iron/oxygen chemistry; [38] (2) association with bone mineral that may either provide protection from enzymatic activity [39−42] or prevent molecular swelling that exposes reactive sites; [43,44] or (3) preferential preservation of specific collagen I peptides identified in T. rex and B. canadensis because of their physically shielded location within the collagen fibril. [45]

    (Those references are:

    (38) Schweitzer, M. H.; Zheng, W.; Cleland, T. P.; Goodwin, M. B.; Boatman, E.; Theil, E.; Marcus, M. A.; Fakra, S. C. A role for iron and oxygen chemistry in preserving soft tissues, cells and molecules from deep time. Proc. R. Soc. London, Ser. B 2014, 281 (1775), 20132741.
    (39) Trueman, C. N. G.; Martill, D. M. The long-term survival of bone: the role of bioerosion. Archaeometry 2002, 44 (3), 371−382.
    (40) Butterfield, N. Exceptional Fossil Preservation and the Cambrian Explosion. Integr. Comp. Biol. 2003, 43, 166−177.
    (41) Butterfield, N. Organic preservation of non-mineralizing organisms and the taphonomy of the Burgess Shale. Paleobiology 1990, 16 (3), 272−286.
    (42) Turner-Walker, G. The Chemical and Microbial Degradation of Bones and Teeth. Wiley: New York, 2008; p 389.
    (43) Schweitzer, M. H. Soft tissue preservation in terrestrial Mesozoic vertebrates. Annu. Rev. Earth Planet. Sci. 2011, 39, 187−216.
    (44) Collins, M. J.; Nielsen-Marsh, C. M.; Hiller, J.; Smith, C. I.; Roberts, J. P.; Prigodich, R. V.; Wess, T. J.; Csapo, J.; Millard, A. R.; Turner-Walker, G. The survival of organic matter in bone. Archaeometry 2002, 44 (3), 383−394.
    (45) San Antonio, J. D.; Schweitzer, M. H.; Jensen, S. T.; Kalluri, R.; Buckley, M.; Orgel, J. P. R. O. Dinosaur Peptides Suggest Mechanisms of Protein Survival. PLoS One 2011, 6 (6), e20381.


  13. Owlmirror says

    raven @10&11: I don’t think there’s as much of a problem accepting that tough biologically-produced structures, like chitin, keratin, or shell (calcium carbonate, mostly), could last indefinitely in a stable preservational environment. The controversy and skepticism have arisen precisely because the structures and molecules Schweitzer (et al.) are claiming to have observed are known to not be particularly stable in typical conditions. Some additional chemical transformation to stabilize the structures is a reasonable hypothesis.

  14. rietpluim says

    “It made God bigger,” she says.

    I’ve never been a fan of theistic evolutionism, but this I don’t understand: how evolution would devaluate Gods greatness or the value of human life. Evolution is impressive, at least much more impressive than “let there be man” and there was man.

    Now if I were God, I wouldn’t have chosen evolution because of all the suffering that comes with it, but in a world that is full of suffering anyway, evolution is the way to go.

  15. chrislawson says

    raven@11: I find the idea of recovering chitin reasonably plausible, and I’m willing to entertain the possibility for collagen (which is the matrix that makes up bone), but I find the idea of finding blood cells and preserved haemoglobin extremely unlikely.

    Unlike chitin and bone, which have evolved to be tough, red blood cells have an average life expectancy of 120 days in the living humans they have evolved to circulate inside. If you take a blood sample from a living organism, it is not uncommon for the red blood cells to rupture merely from the flow pressure of sucking them out with a needle. Red blood cells are so sensitive to osmotic pressure that they will explode when dropped into plain water. When lab scientists make electron microscope scans of red blood cells, it requires precise preparation. For instance, in the early days of electron microscopy, one 1975 paper described it thus: “The best method, so far obtained to preserve 99% of normal erythrocytes as biconcave discocytes, was that of venous blood without anticoagulants or acid-citrate-dextrose, washed with physiological saline at 37 degrees C, fixed in 0.75% glutaraldehyde in 0.1 M phosphate buffer, pH 7.3 (318 mosmol), postfixed in 1% osmium tetroxide, dehydrated with graded ethanol and amyl acetate, dried with critical point drying method, and coated with carbon and gold.”

    Do I believe we could find fossils with iron stains from blood? Absolutely — iron is an incredibly stable element. No plausibility problem at all. But when a researcher says they saw red blood cells under electron microscopy of fossils as old as 80 My, I’m sure you can see why I expect some very robust evidence to accept it. (And I can’t help it, this also colours my willingness to accept the same researcher’s other findings on more robust cellular structures.)

  16. ctech says

    @kalilchernov: So, you had a research professor that was an a-hole? Welcome to the party pal. I have no problem with a person being an ass and your only other knocks against her are mini-scandal and hearsay. I do know that Horner gave a TedTalk which seems to indicate that his lab would likely make discoveries on fossils that other labs could not or dare not replicate… because he allowed his fossils to be destroyed. I am just saying it makes sense that it would be difficult because most fossils are in museums and those curators have cleaned and polished the bone and stored it and don’t allow anyone to mess with it much less cut it open. It also makes sense because of the given indoctrination that there should be zero soft tissue that these discoveries were never even looked for.

  17. Owlmirror says

    @Walter Solomon:

    Has the argument that the soft tissue is really a bacterial biofilm been debunked?

    Just last year, Schweitzer published Testing the Hypothesis of Biofilm as a Source for Soft Tissue and Cell-Like Structures Preserved in Dinosaur Bone.

    Key Paragraph:

    Finally, we show that antibodies raised against eukaryotic proteins not present in microbes bind to dinosaur vessels, but do not bind to biofilms grown in bone. Conversely, antibodies raised against microbial peptidoglycan do bind to the biofilm grown in bone, but do not bind to dinosaur vessels. These data, together with those put forth in previous publications (e.g. [1–3,6,7,41–43] refute the hypothesis that the vessels, osteocytes, and fibrous matrices derived from dinosaur and other fossil bone tissues are solely derived from microbial invasion. Furthermore, sequence data from chemically extracted dinosaur bone [3,41,42] and isolated dinosaur vessels [50] refutes a microbial source.

    I don’t think there’s been any further counter, as far as I can tell.