Published 08/2019 updated 09/16/2026
Dinosaur Soft Tissue Discovered
In 2000, a team from the Museum of the Rockies discovered the remains of a Tyrannosaurus rex in the Hell Creek Formation of eastern Montana. The specimen, designated MOR 1125, became known as “B. rex,” named after Bob Harmon, who discovered it. According to the conventional geological timescale, the dinosaur had been buried for approximately 68 million years.
Paleontologist Dr. Mary Schweitzer and her colleagues later examined portions of the fossilized bones. In 2005, they reported a remarkable discovery: after mineral material was removed from portions of the T. rex femur, they recovered transparent, flexible, hollow vessel-like structures, fibrous material, and cell-like microstructures from within the fossilized bone.¹
The surprises did not end there. Further examination revealed medullary bone, a specialized reproductive tissue associated with egg production in female birds. This provided strong evidence that B. rex was female and reproductively active when the specimen died.²
How Was the Soft Tissue Discovered?
The discovery of soft, flexible structures within B. rex came about largely by accident.
The excavation site was extremely remote, requiring the fossils to be removed by helicopter. One plaster-jacketed section containing the massive T. rex femur proved too heavy for the helicopter to lift. The package therefore had to be divided, breaking the femur and providing access to material from deep inside the bone.³
That accident provided Schweitzer with an unusual opportunity to examine material that normally would have remained inaccessible within an intact fossil.
When portions of the bone were later demineralized, the mineral component dissolved away, but everything did not disappear. Schweitzer and her colleagues reported that some remaining structures were flexible, elastic, and resilient. They also recovered hollow, branching vessel-like structures containing small round microstructures.¹
There had already been clues that dinosaur fossils might contain more original biological material than scientists expected. While working with T. rex material from the Hell Creek Formation, Schweitzer noticed something particularly unusual: the fossil had a distinctly organic odor.
She later recalled:
“It smelled just like one of the cadavers we had in the lab who had been treated with chemotherapy before he died,” she says. Given the conventional wisdom that such fossils were made up entirely of minerals, Schweitzer was anxious when mentioning this to Horner. “But he said, ‘Oh, yeah, all Hell Creek bones smell,'” she says. To most old-line paleontologists, the smell of death didn’t even register. To Schweitzer, it meant that traces of life might still cling to those bones. Schweitzer’s Dangerous Discovery; http://discovermagazine.com/2006/apr/dinosaur-dna Yeoman, Barry (2006). “It smelled just like one of the cadavers we had in the lab who had been treated with chemotherapy before he died.”⁴
When Schweitzer mentioned the smell to paleontologist Jack Horner, he told her that Hell Creek bones commonly smelled that way. But to Schweitzer, the odor raised an intriguing question: Could traces of the original animal still remain within these dinosaur bones?
Schweitzer recalled encountering the microscopic structures within T. rex bone that appeared similar to red blood cells for the first time. She recalled getting “goose bumps” when a pathologist pointed them out because, according to conventional expectations, such structures should not remain recognizable for millions of years.⁴
Were Previous Expectations About Fossilization Wrong?
All the textbooks had been wrong? Before these discoveries, paleontologists generally did not expect recognizable, flexible biological structures or remnants of original proteins to survive within dinosaur bones for tens of millions of years. Soft tissues normally decay rapidly after death, while harder materials such as bones and teeth have a much greater potential for fossilization.
Yet when portions of B. rex bone were demineralized, Schweitzer and her colleagues recovered structures described in their peer-reviewed research as transparent, hollow, pliable blood vessels, flexible fibrous matrix, and cell-like microstructures.¹ ⁵
Subsequent research provided molecular evidence consistent with the preservation of original dinosaur protein, including collagen I, the primary organic component of bone. Mass spectrometry independently supported the collagen identification.⁶
These discoveries raised an obvious question:
How could remnants of original biological material and flexible structures survive for so long?
Under the conventional geological timescale, B. rex presents an extraordinary preservation problem requiring mechanisms capable of protecting biological material over approximately 68 million years.
But for those of us who question that timescale, the discovery raises a very different question:
Could such remarkably preserved biological material instead be evidence that these dinosaur remains are far younger than commonly believed?
Dinosaur “Shocker”
What initially appeared to be an extraordinary exception soon became even more interesting.
As Schweitzer and other researchers examined additional fossils, similar structures were recovered from other specimens. Schweitzer and her colleagues concluded that soft-tissue elements might be more commonly preserved in fossil bone than previously thought.⁵
Schweitzer later said that her team had found soft-tissue structures in approximately half of the fossil specimens they examined, including specimens extending back into the Jurassic Period.⁷
If remnants of original biological material and flexible structures occur repeatedly in fossils conventionally dated to tens or even hundreds of millions of years, an important question remains:
Are these discoveries evidence of extraordinary preservation over millions of years, or evidence that the fossils themselves are much younger than assumed?
Why Had Paleontologists Not Routinely Looked for Them?
If these structures could be recovered from numerous fossils, another obvious question followed: Why hadn’t paleontologists routinely looked for them before?
University of Maryland paleontologist Thomas Holtz Jr. offered an illuminating explanation:
“The reason it hasn’t been discovered before is no right-thinking paleontologist would do what Mary did with her specimens.”³
Holtz explained what he meant. Paleontologists spend enormous amounts of time recovering valuable fossils and normally do not want to destroy portions of them in acid. Also, no scientist believed any biological material might still be inside fossils tens of millions of years old.
Schweitzer herself later explained:
“The problem is, for 300 years, we thought, ‘Well, the organics are all gone, so why should we look for something that’s not going to be there?’”⁷
Schweitzer did look.
Instead of everything disappearing when portions of dinosaur bone were chemically demineralized, flexible structures remained.
This illustrates an important principle in science: existing models inevitably influence the questions scientists ask, the experiments they perform, and sometimes even the evidence they think is worth searching for.
Once researchers began looking, they discovered that extraordinary preservation was not necessarily limited to a single T. rex.
The Proposed Solution: Iron?
Scientists understandably began searching for a mechanism that could explain how such biological material might survive for immense periods of time.
In 2013, Schweitzer and her colleagues proposed an important possibility: Iron.
Iron is abundant in blood, primarily within the hemoglobin contained in red blood cells. After death, chemical reactions involving heme, iron, and oxygen can generate highly reactive free radicals. Schweitzer and her colleagues proposed that these reactions could promote cross-linking of proteins and other biological molecules, helping stabilize tissues against degradation.⁸
In effect, the chemistry might function somewhat like a natural tissue fixative.
The researchers tested this hypothesis experimentally using modern ostrich blood vessels. Some vessels were exposed to concentrated red blood cell lysate rich in hemoglobin, while controls were placed in water or buffered solution.
The results were dramatic because untreated controls showed extensive degradation in approximately three days, while hemoglobin-treated vessels remained intact for more than two years at room temperature, approximately 25°C. The researchers calculated that hemoglobin increased tissue stability by more than 200-fold.⁸
The experiment demonstrated something important: Hemoglobin and iron chemistry can substantially slow tissue degradation.
This provided a plausible preservation mechanism that had previously been overlooked but it also raised another important question: could it explain more than 68 million years?
Does Iron Explain 68 Million Years?
The results of Schweitzer’s experiment are impressive. Increasing tissue stability from approximately three days to more than two years demonstrates that hemoglobin can have powerful preservative effects.
But there remains an enormous difference between two years and 68 million years.
The ostrich vessels were maintained under controlled laboratory conditions at approximately 25°C. A dinosaur buried in nature would potentially encounter changing groundwater chemistry, microbial activity, temperature, pressure, mineral interactions, and other geological processes over its proposed history.
Most importantly, the experiment directly demonstrated preservation for more than two years. It did not experimentally demonstrate preservation for one million years, ten million years, or 68 million years.
That distinction is crucial.
The experiment demonstrated that a preservation mechanism exists. Extending that mechanism from years to tens of millions of years requires an extrapolation far beyond the duration actually observed.
Furthermore, Schweitzer and her colleagues did not claim that iron was necessarily the only process involved in fossil preservation. Their research discusses multiple chemical processes, including cross-linking, mineralization, oxygen chemistry, and environmental conditions that may work together to stabilize biological material.⁵ ⁸
Iron may therefore be an important part of the preservation story.
But demonstrating that iron can dramatically retard decomposition is not the same thing as experimentally demonstrating that flexible biological structures can survive for 68 million years.
What Does Dinosaur Soft Tissue Tell Us About Age?
The discovery of flexible structures and remnants of original biological material within dinosaur fossils does not, by itself, provide a numerical age for those fossils.
But neither should the presumed age of a fossil determine beforehand what biological material we expect to find within it.
Flexible and resilient structures were recovered from dinosaur bone.¹
Transparent, hollow, pliable vessel-like structures were identified.¹ ⁵
Cell-like microstructures were observed.¹ ⁵
Evidence consistent with original dinosaur collagen was detected.⁶
Similar soft-tissue structures have subsequently been identified in additional fossil specimens.⁵
Iron and hemoglobin chemistry can dramatically slow tissue degradation.⁸
Those are observations.
The disagreement concerns what those observations mean for the age of the fossils.
Under the conventional geological interpretation, these discoveries demonstrate that remnants of original biological material can survive for tens of millions of years when extraordinary preservation mechanisms operate.
Under a young-earth interpretation, the persistence of original biological material and flexible structures is exactly the kind of evidence we would expect if dinosaur fossils are thousands, rather than tens of millions, of years old.
The iron-preservation hypothesis provides an important potential mechanism for slowing degradation, however, claiming it demonstrates preservation for more than two years does not experimentally demonstrate preservation for 68 million years. This is a massive assumption and deduction well outside any empirical evidence.
The soft tissue is observable. The proposed millions of years are an interpretation placed upon that evidence.
For me, the extraordinary preservation of dinosaur soft tissue is not evidence that biological material has survived for 68 million years. Rather, it provides compelling reason to question whether 68 million years have actually passed.
Mary Schweitzer stated in a 2014 interview considering the magnitude of what the evidence implied. She said, “In the end, it left two alternatives for interpretation: either dinosaur aren’t as old as we think they are, or maybe we don’t know exactly how these things are preserved.” -2
Sources
1. Schweitzer, M. H., Wittmeyer, J. L., Horner, J. R., & Toporski, J. K. (2005). “Soft-Tissue Vessels and Cellular Preservation in Tyrannosaurus rex.” Science, 307(5717), 1952–1955. DOI: 10.1126/science.1108397.
https://pubmed.ncbi.nlm.nih.gov/15790853/
2. Schweitzer, M. H., Wittmeyer, J. L., & Horner, J. R. (2005). “Gender-Specific Reproductive Tissue in Ratites and Tyrannosaurus rex.” Science, 308(5727), 1456–1460. DOI: 10.1126/science.1112158.
https://pubmed.ncbi.nlm.nih.gov/15933198/
3. Fields, H. (2006). “Dinosaur Shocker.” Smithsonian Magazine.
https://www.smithsonianmag.com/science-nature/dinosaur-shocker-115306469/
4. Yeoman, B. (2006). “Schweitzer’s Dangerous Discovery.” Discover.
https://barryyeoman.com/2006/04/schweitzers-dangerous-discovery/
5. Schweitzer, M. H., Wittmeyer, J. L., & Horner, J. R. (2007). “Soft Tissue and Cellular Preservation in Vertebrate Skeletal Elements from the Cretaceous to the Present.” Proceedings of the Royal Society B, 274(1607), 183–197. DOI: 10.1098/rspb.2006.3705.
https://pmc.ncbi.nlm.nih.gov/articles/PMC1685849/
6. Schweitzer, M. H., Suo, Z., Avci, R., Asara, J. M., Allen, M. A., Arce, F. T., & Horner, J. R. (2007). “Analyses of Soft Tissue from Tyrannosaurus rex Suggest the Presence of Protein.” Science, 316(5822), 277–280. DOI: 10.1126/science.1138709.
https://pubmed.ncbi.nlm.nih.gov/17431179/
7. Pappas, S. (2013). “Controversial T. Rex Soft Tissue Find Finally Explained.” Live Science. Includes Schweitzer’s comments concerning the frequency with which her team encountered soft-tissue structures and why researchers had not previously searched routinely for them.
https://www.livescience.com/41537-t-rex-soft-tissue.html
8. Schweitzer, M. H., Zheng, W., Cleland, T. P., Goodwin, M. B., Boatman, E., Theil, E., Marcus, M. A., & Fakra, S. C. (2014). “A Role for Iron and Oxygen Chemistry in Preserving Soft Tissues, Cells and Molecules from Deep Time.” Proceedings of the Royal Society B, 281(1775), 20132741. DOI: 10.1098/rspb.2013.2741.
https://pmc.ncbi.nlm.nih.gov/articles/PMC3866414/
