Soft-tissue evidence for homeothermy and crypsis in a Jurassic ichthyosaur
Journal article, 2018

Ichthyosaurs are extinct marine reptiles that display a notable external similarity to modern toothed whales. Here we show that this resemblance is more than skin deep. We apply a multidisciplinary experimental approach to characterize the cellular and molecular composition of integumental tissues in an exceptionally preserved specimen of the Early Jurassic ichthyosaur Stenopterygius. Our analyses recovered still-flexible remnants of the original scaleless skin, which comprises morphologically distinct epidermal and dermal layers. These are underlain by insulating blubber that would have augmented streamlining, buoyancy and homeothermy. Additionally, we identify endogenous proteinaceous and lipid constituents, together with keratinocytes and branched melanophores that contain eumelanin pigment. Distributional variation of melanophores across the body suggests countershading, possibly enhanced by physiological adjustments of colour to enable photoprotection, concealment and/or thermoregulation. Convergence of ichthyosaurs with extant marine amniotes thus extends to the ultrastructural and molecular levels, reflecting the omnipresent constraints of their shared adaptation to pelagic life.


Johan Lindgren

Lund University

Peter Sjövall

RISE Research Institutes of Sweden

Volker Thiel

University of Göttingen

Wenxia Zheng

North Carolina State University

Shosuke Ito

Fujita Health University

Kazumasa Wakamatsu

Fujita Health University

Rolf Hauff

Urwelt-Museum Hauff

Benjamin P. Kear

Uppsala University

Anders Engdahl

Lund University

Carl Alwmark

Lund University

Mats E. Eriksson

Lund University

M. Jarenmark

Lund University

Sven Sachs

Naturkundemuseum Bielefeld

Per E. Ahlberg

Uppsala University

Federica Marone

Paul Scherrer Institut

Takeo Kuriyama

Wildlife Management Research Center

University of Hyogo

Ola Gustafsson

Lund University

Per Malmberg

Chalmers, Chemistry and Chemical Engineering, Chemistry and Biochemistry

Aurélien Thomen

University of Gothenburg

Irene Rodríguez-Meizoso

Lund University

P. Uvdal

Lund University

Makoto Ojika

Nagoya University

Mary H. Schweitzer

Lund University

North Carolina State University

North Carolina Museum of Natural Sciences


0028-0836 (ISSN) 1476-4687 (eISSN)

Vol. 564 7736 359-365

Subject Categories

Evolutionary Biology

Other Earth and Related Environmental Sciences



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