Rosa Rubicondior: Refuting Creationism - 183-Million-Year-Old Fossilised Soft Tissue

Soft tissue from a 183 Million-Year-Old Jurassic Plesiosaur analysed | Lund University

Some palaeontology finds must seem like a god-send to creationist cult leaders looking for something to misrepresent to their dupes, but it has been a few years since Dr. Mary Higby Schweitzer's team reported finding 'soft' tissue in a fossilised dinosaur bone.

Creationists routinely misrepresent this discovery, particularly the discovery of soft-tissue structures in fossilised dinosaur bones. Schweitzer and her team found microscopic structures resembling blood vessels, cells, and proteins in well-preserved fossils, which creationists have seized upon as supposed evidence that dinosaurs lived only a few thousand years ago, rather than tens of millions. However, their claims are based on a fundamental misunderstanding—or deliberate misrepresentation—of both the science and Schweitzer’s own conclusions.

Far from supporting a young Earth, Schweitzer’s findings actually highlight the remarkable durability of biological molecules under specific conditions. Her research suggests that iron particles from haemoglobin help preserve proteins by acting as a natural fixative, similar to formaldehyde. This explains how soft-tissue structures can persist for millions of years without requiring the fossils to be "recent," as creationists falsely claim. Despite Schweitzer’s repeated clarifications that her discoveries do not challenge the vast timescales of evolutionary history, creationists continue to misquote her work to fit their pre-existing religious narratives.

This distortion is part of a broader pattern in which creationists cherry-pick scientific findings, strip them of context, and twist them to manufacture doubt about evolutionary theory. Rather than engaging with the scientific explanations provided by Schweitzer and other researchers, they rely on misleading rhetoric to persuade those unfamiliar with the complexities of molecular preservation. In doing so, they not only misrepresent the science but also the integrity of the scientists behind it. Some creationists even claim the tissue was carbon dated to just a few thousand years old. This is a lie since no such dating was performed because carbon dating is only accurate on specimens less than about 50,000 years old and is never used to date fossils because the original carbon from the living animal is lost in the mineralisation process.

And now we have something else for the frauds to fool their dupes with and win new ignorant simpletons into the creationist cult.

It comes in the form of a report by researchers at Lund University in Sweden which concerns 'soft' tissue found in a fossilised plesiosaur. However, and this is something that creationists will ignore in their eagerness to misrepresent the find - the fossilised tissue is fossilised hard parts of skin, such as scales. There is no question of the fossils being soft tissue. Creationists will also dismiss the fact that the fossil is 183 million years old and will claim the presence of soft tissue 'proves' the dating method is flawed because it must only be a few thousand years old.

Can you explain the basis and possible sources of error of Re-Os dating, please. Rhenium–Osmium (Re-Os) dating is a radiometric dating method that relies on the radioactive decay of rhenium-187 (\(^{187}\)Re) to osmium-187 (\(^{187}\)Os). This method is particularly useful for dating certain types of rocks and minerals, including sulphides (e.g., molybdenite), iron meteorites, and ancient organic-rich sedimentary rocks.

Basis of Re-Os Dating

Radioactive Decay

\(^{187}\)Re undergoes beta decay to \(^{187}\)Os with a long half-life of approximately 41.6 billion years.
The decay equation follows:
\[ ^{187}Os = ^{187}Os_0 + ^{187}Re \times (e^{\lambda t} - 1) \] where:

\(^{187}Os\) is the total measured osmium-187,
\(^{187}Os_0\) is the initial osmium-187,
\(^{187}Re\) is the amount of rhenium-187,
\(\lambda\) is the decay constant, and
\(t\) is the age of the sample.

Isochron Method

By analyzing multiple samples from the same rock or mineral suite, the Re/Os ratio is plotted against the \(^{187}Os/^{188}Os\) ratio on an isochron diagram.
The slope of the line provides the age of the rock, while the intercept gives the initial \(^{187}Os/^{188}Os\) ratio.

Applications

Dating sulphide minerals (e.g., molybdenite) in ore deposits.
Dating iron meteorites to study planetary formation.
Determining the age of organic-rich sedimentary rocks (e.g., black shales) for petroleum exploration.

Possible Sources of Error

Initial Osmium Composition Uncertainty

The accuracy of Re-Os dating depends on knowing the initial \(^{187}Os/^{188}Os\) ratio.
If the initial osmium content is not well constrained, it can introduce errors in age calculations.

Open-System Behaviour (Loss or Gain of Re or Os)

If the system has experienced post-formational alteration, rhenium or osmium may be added or lost, leading to incorrect ages.
This can occur due to hydrothermal fluids, metamorphism, or weathering.

Contamination from Extraneous Osmium

External sources of osmium (e.g., mantle-derived fluids, meteoritic contributions) can alter the isotopic ratios, affecting the age calculation.
This is particularly problematic in sedimentary rocks where osmium can be sourced from multiple origins.

Measurement Uncertainties

Precise measurement of Re and Os isotopes requires highly sensitive mass spectrometry techniques (e.g., ICP-MS or TIMS).
Small errors in isotope ratio determination can propagate into significant age uncertainties.

Isochron Scatter and Poor Correlation

If data points do not form a well-defined isochron, it suggests either heterogeneity in initial osmium composition or disturbance of the system, making the age unreliable.

Fractionation Effects During Sample Preparation

Isotopic fractionation during chemical extraction and analysis can introduce systematic errors.

Interference from Other Isotopes

Isotopic interference in mass spectrometric analysis, such as from tungsten (\(^{186}\)W affecting \(^{186}\)Os measurements), can require careful correction.

Summary
Re-Os dating is a powerful tool for geochronology, particularly in sulphide minerals, meteorites, and organic-rich sedimentary rocks. However, its reliability depends on maintaining a closed system, precise isotopic measurements, and careful consideration of initial osmium ratios. Potential errors arise from open-system behaviour, contamination, instrumental limitations, and uncertainties in the initial osmium composition.

Because the dating of the rock formation is based on Rhenium-Osmium (Re-Os) dating, the AI panel on the right explains this method:

The team’s findings are the subject of a paper in Current Biology and a news item from Lund University:

Soft tissue from a 183 Million-Year-Old Jurassic Plesiosaur analysed
Researchers at Lund University in Sweden have analysed the soft tissue from a fossilized plesiosaur for the first time. The results show that the long-necked marine reptile had both smooth and scaly skin. This was likely so it could both swim rapidly and move along rough seabeds.
Plesiosaurs lived in the world's oceans for much of the Mesozoic Era (203–66 million years ago). These reptiles, which could grow up to 12 meters long, fed on fish and moved much like sea turtles using four paddle-like flippers. Until now, little has been known about the external anatomy of plesiosaurs. However, in a new study published in the scientific journal Current Biology, a research team led by scientists from Lund University has managed to analyze soft tissue from a 183-million-year-old plesiosaur found near Holzmaden, Germany.

Fossilized soft tissue, such as skin and internal organs, is exceptionally rare. We used a broad range of techniques to identify smooth skin in the tail region as well as scales along the rear edge of the flippers. This provided us with unparalleled insights into the appearance and biology of these long-extinct reptiles.

Miguel Marx, First author
Department of Geology
Lund University, Lund, Sweden.

The results reveal an unusual combination of smooth and scaly skin on different parts of the body. The researchers believe this variation could be related to different functions. The plesiosaur needed to swim efficiently to catch fish and squid-like animals, a task made easier by its smooth and hydrodynamic skin. However, it also needed to move across rough seafloors, which the scaly flippers would have likely allowed it to do.
Our findings help us create more accurate life reconstructions of plesiosaurs, something that has been extremely difficult since they were first studied over 200 years ago. Also, the well-preserved German fossil really highlights the potential for soft tissue in providing valuable insights into the biology of these long-extinct animals.

Miguel Marx.

Skeleton of the new plesiosaur at the Urwelt-Museum Hauff in Holzmaden, Germany.

Image: Klaus Nilkens/Urwelt-Museum Hauff.

By reconstructing the appearance of ancient animals, researchers can enhance our understanding of macroevolution and the adaptations required to survive in specific environments. In recreating the past, we can also better understand Earth’s history and where we are headed.

Apart from the mosaic of smooth skin and scales, it was an incredible moment to visualize the cells in thin sections of the fossilized plesiosaur’s skin. I was shocked when I saw skin cells that had been preserved for 183 million years. It was almost like looking at modern skin.

Miguel Marx.

Highlights

The first in-depth study of plesiosaur soft tissues is reported
Some plesiosaurs had smooth skin on the body and small scales on the flippers
Scales likely enhanced swimming and/or grip on the substrate during feeding

Summary
Plesiosaurs are an iconic group of Mesozoic marine reptiles with an evolutionary history spanning over 140 million years (Ma).¹ Their skeletal remains have been discovered worldwide; however, accompanying fossilized soft tissues are exceptionally rare.² Here, we report a virtually complete plesiosaur from the Lower Jurassic (∼183 Ma)³ Posidonia Shale of Germany that preserves skin traces from around the tail and front flipper. The tail integument was apparently scale-less and retains identifiable melanosomes, keratinocytes with cell nuclei, and the stratum corneum, stratum spinosum, and stratum basale of the epidermis. Molecular analysis reveals aromatic and aliphatic hydrocarbons that likely denote degraded original organics. The flipper integument otherwise integrates small, sub-triangular structures reminiscent of modern reptilian scales. These may have influenced flipper hydrodynamics and/or provided traction on the substrate during benthic feeding. Similar to other sea-going reptiles,^{4,5,6,7,8,9,10} scalation covering at least part of the body therefore probably augmented the paleoecology of plesiosaurs.

Figure 1 Plesiosaur specimen (MH 7) with comparisons
(A) MH 7 in ventral view, showing soft tissue sampling sites (arrows) on the dorsal (1) and ventral side (2) of the tail and trailing edge (3) of the right front flipper. (B) Skin from the ventral side of the tail showing thick folds (white arrows) and an apparently torn surface (black arrow). (C) Skin from the dorsal side of the tail (white arrows). (D and E) (D) TLM image of skin from (B) with diagram (E), showing the differentiated stratum corneum (sc) and underlying stratum spinosum (ss), keratinocytes with cell nuclei (circular structures with black dots), melanosome aggregates (brown patches), voids (light gray patches), and indeterminate organics or minerals (dark gray patches). (F) Comparative thin-section through the eyelid epidermis of an extant Leatherback turtle, Dermochelys coriacea, indicating the similarly differentiated sc, pre-corneous layer (pl), ss, and keratinocytes (ker). (G) TLM image of a petrographic thin-section showing skin from the ventral side of the tail in MH 7. Inset: SEM image enlargement of ellipsoidal melanosome microbodies (red box). (H) TEM image of carapace skin from D. coriacea, showing differentiated sc and ss, including melanosomes (dark dots). (I and J) (I) TLM image with diagram (J) showing a petrographic thin-section of skin from the dorsal side of the tail in MH 7 incorporating the sc, ss with a remnant melanophore, and the stratum basale.

Figure 3 Plesiosaur flipper scales
(A) Scales from the trailing edge of the right flipper in MH 7 (see Figure 1A), showing their irregularly sub-triangular shape and light-colored midline sediment infill. (B) SEM image with inset EDX elemental map (orange dashed line: scale boundary). Colors: red, S; blue, P; yellow, Si. (C) SEM image of demineralized scale fragment from MH 7 showing a smooth surface. (D) Enlarged SEM image showing absence of melanosome microbodies on the scale surface of MH 7. (E) SEM image of the scale margin from MH 7 showing internal layering (white arrows). (F and G) (F) TLM image with diagram (G) of a petrographic thin-section through the scaly flipper skin from MH 7 showing ker (black arrows), cell nuclei (black dots), and the outermost dense corneocyte layer (brown fill) covered by mineral deposits (white fill). See also Figures S1 and S2.

Figure 2 Plesiosaur tail skin
(A) EDX elemental map of a petrographic thin-section through skin from the ventral side of the tail in MH 7, indicating the phosphorus (P)-rich sc and P/calcium (Ca)-rich ss. Colors: cyan, silicon (Si); purple, P; orange, sulfur (S); blue, Ca; yellow, fluorine/aluminum (F, Al). (B) EBSD map of (A). Color: blue, calcite (Cal). (C) EBSD map of skin from the dorsal side of the tail, showing the ss permeated with Cal. Colors: green, apatite (Ap); purple, Cal; red, quartz (Qtz). (D and E) (D) Light microscopy (LM) image of skin from the ventral side of the tail in MH 7 showing clusters of melanosome microbodies (dark dots) with TLM image of the same skin after demineralization (E). (F and G) (F) SEM image of demineralized skin from the ventral side of the tail in MH 7 with enlargement (G) of melanosome microbodies. (H and I) (H) Skin from the ventral side of the tail showing pitted ss with apparent folding (white arrow) and tearing (black arrows). Smooth areas of the ss (red arrow); (I) enlargement of possible torn skin from (H). See also Figures S3 and S4.

Figure 4 Plesiosaur soft tissues and gut contents
(A) UV image (cutoff at ∼365 nm) of soft tissues and glued edges (yellow arrows) from the trailing edge of the right flipper in Seeleyosaurus guilelmiimperatoris (MB.R.1992). White box indicates enlargement (B). (B) Enlargement from (A) showing skin traces with embedded 3D “fibrous structures”15,17,42,43 (white arrows) and surrounding glue (red arrows). (C) Left forelimb trailing edge (white arrows) of Microcleidus brachypterygius (GPIT-PV-30094). (D) UV image (cutoff at ∼365 nm) of the incomplete and partially restored19,47,48 (yellow arrows) tail fin from S. guilelmiimperatoris (MB.R.1992). (E) Enlargement from (D) showing fibrous structures.15,17,42,43 (F) Preserved gut contents from S. guilelmiimperatoris (MB.R.1992), comprising a coarse sediment mass with a gastropod shell (white arrow). (G) Possible belemnite phragmocone/guard (white arrow) and onychite (arm hook: cyan arrow) within the preserved gut contents from S. guilelmiimperatoris (MB.R.1992).

Marx, Miguel; Sjövall, Peter; Kear, Benjamin P.; Jarenmark, Martin; Eriksson, Mats E.; Sachs, Sven; Nilkens, Klaus; Op De Beeck, Michiel; Lindgren, Johan
Skin, scales, and cells in a Jurassic plesiosaur
Current Biology (2025), DOI: 10.1016/j.cub.2025.01.001

Copyright: © 2025 The authors.
Published by Elsevier Inc. Open access.
Reprinted under a Creative Commons Attribution 4.0 International license (CC BY 4.0)

It should be as obvious from this paper as it was in Dr. Mary Schweitzer’s that what is being reported is not wet, almost fresh tissue complete with almost fresh blood, as creationist frauds still claim, but the result of a fossilisation process many tens of millions of years ago.

So, rather than the scientific evidence of a young Earth that creationists crave, despite their general contempt for scientific evidence, this plesiosaur fossil is evidence of advanced life on Earth at least 183 million years before creationists think there was even a universe in which life could evolve on a planet within it.

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