Soft tissue preservation in a ‘Jurassic’ ichthyosaur
Posted on homepage: 20 January 2021 (GMT+10)
A stunningly preserved skin of a fossil ichthyosaur, Stenopterygius, has revealed a wealth of original soft tissue and proteins.1 However, this fossil, from Germany’s Holzmaden Posidona shale quarries, was found in Jurassic strata ‘dated’ to 180 million years old (Ma).
The researchers claim this is the most in-depth study of a soft-tissue fossil ever. There were still remnants of the original skin (apparently scaleless in this species, there is at least one other ichthyosaur type that appears smooth-skinned but apparently has microscopic scales)2.
The research team were even able to distinguish different cellular layers within the skin and subcutaneous tissues, including a layer of fossilized blubber that contained original chemical traces. The blubber has ignited further debate on whether ichthyosaurs were warm- or cold-blooded.
Close examination of the demineralized soft skin unveiled pigment cells called melanophores which contained eumelanin, a biological pigment. By studying their concentration, the researchers were able to identify that Stenopterygius was counter-shaded, i.e. dark on top, and light on the underside. The ‘countering’ is compared with illumination from above, which makes the top lighter and the underside shadowed. So this provides some camouflage, as well as likely providing protection against UV light when close to or at the surface (ichthyosaurs needed to come up intermittently to breathe air). It would have also helped regulate body temperature (darker areas absorb more sunlight).
The researchers were able to identify the liver, which when demineralized and treated revealed original pliable organic material. Analysis also confirmed the remains of proteins such as tropomyosin, hemoglobin, α-keratin, elastin, actin, and collagen.
Lead author of the study, Dr Johan Lindgren, admitted, “Soft tissues, such as skin, have hitherto been considered to be so labile (easily broken down) that the only way they can survive is via full replacement by minerals. However, as it turns out, when these minerals are removed, some of the original organics remain.”3 In order for these original biological substances to survive within the replacement minerals surrounding them, he said, “They were exceedingly rapidly-entombed [sic] in the minerals.”4
A press release by Lindgren’s own Lund University, Sweden, summed up: “Among other things, the study reveals that the soft parts have fossilised so quickly that both the original cells and their internal contents are preserved. … they also show how little we know about the fossilisation process and what can actually be preserved in the fossil record.”5
Dr Mary Schweitzer, of dinosaur-soft-tissue fame, was also part of the team. This discovery adds to the ever-growing list of original-soft-tissue finds in fossils claimed to be tens to hundreds of millions of years old. But as the list grows, so does the controversy in the evolutionary world over the exact mechanism for the exceedingly rapid and deep burial required to fossilize these animals, and how original organic material can last as long as claimed.
The Bible clearly describes the global Noahic Flood occurring about 4,500 years ago. With its massive erosion and redeposition of mineral-rich sediment, this provides a suitable mechanism for rapidly burying and fossilizing the specimens. And the presence of original biomaterial makes the biblical timescale much more credible than evolution’s ‘millions of years’.
References and notes
- Lindgren, J. and 22 others, Soft-tissue evidence for homeothermy and crypsis in a Jurassic ichthyosaur, Nature 564(7736): 359–365, 05 Dec 2018. Return to text.
- Bardet, N., & Fernandez, M., A new ichthyosaur from the upper Jurassic lithographic limestones of Bavaria, Journal of Paleontology 74(2):502–511, 2000. Editor’s note: this sentence was corrected in February 2021; the original said there were ‘many other’ types with scales. A reader graciously pointed out the error, and thea dditional reference has been added for the other ichyosaur with the microscopic scales. Return to text.
- Rincon, P., Fossil preserves ‘sea monster’ blubber and skin; bbc.co.uk, 5 Dec 2018. Return to text.
- Phorn, B., Remarkable fossil of 180-million-year-old ‘sea monster’ preserved its Jurassic-era blubber and skin; abcnews.go.com, 6 Dec 2018. Return to text.
- Lund University, Remarkably preserved fossil sea reptile reveals skin that is still soft; lunduniversity.lu.se, 6 Dec 2018. Return to text.