{"id":35748,"date":"2018-12-05T13:00:11","date_gmt":"2018-12-05T18:00:11","guid":{"rendered":"http:\/\/naturalsciences.org\/calendar\/?post_type=news&p=35748"},"modified":"2018-12-05T13:13:28","modified_gmt":"2018-12-05T18:13:28","slug":"soft-tissue-shows-jurassic-ichthyosaur-was-warm-blooded-had-blubber-and-camouflage-coloration","status":"publish","type":"news","link":"https:\/\/naturalsciences.org\/calendar\/news\/soft-tissue-shows-jurassic-ichthyosaur-was-warm-blooded-had-blubber-and-camouflage-coloration\/","title":{"rendered":"Soft Tissue Shows Jurassic Ichthyosaur Was Warm-Blooded, Had Blubber and Camouflage Coloration"},"content":{"rendered":"

\"Cells,<\/a> Figure 1: Spectacular soft-tissue fossil (MH 432; Urweltmuseum Hauff, Holzmaden, Germany). Cells, cellular organelles and original biomolecules have been discovered in preserved soft parts of an approximately 180-million-year-old ichthyosaur (literally \u2018fish-lizard\u2019). Photographic (top) and diagrammatic (bottom) representation of the 85-cm-long fossil (which corresponds to roughly half of the original length of the animal).<\/p>\n

An ancient, dolphin-like marine reptile resembles its distant relative in more than appearance, according to an international team of researchers that includes scientists from North Carolina State University and Sweden\u2019s Lund University. Molecular and microstructural analysis of a Stenopterygius<\/em> ichthyosaur from the Jurassic (180 million years ago) reveals that these animals were most likely warm-blooded, had insulating blubber and used their coloration as camouflage from predators.<\/p>\n

\u201cIchthyosaurs are interesting because they have many traits in common with dolphins, but are not at all closely related to those sea-dwelling mammals,\u201d says research co-author Mary Schweitzer, professor of biological sciences at NC State with a joint appointment at the North Carolina Museum of Natural Sciences and visiting professor at Lund University. \u201cWe aren\u2019t exactly sure of their biology either. They have many features in common with living marine reptiles like sea turtles, but we know from the fossil record that they gave live birth, which is associated with warm-bloodedness. This study reveals some of those biological mysteries.\u201d<\/p>\n

Johan Lindgren, associate professor at Sweden\u2019s Lund University and lead author of a paper describing the work, put together an international team to analyze an approximately 180-million-year-old Stenopterygius<\/em> fossil from the Holzmaden quarry in Germany.<\/p>\n

\u201cBoth the body outline and remnants of internal organs are clearly visible,\u201d says Lindgren. \u201cRemarkably, the fossil is so well-preserved that it is possible to observe individual cellular layers within its skin.\u201d<\/p>\n

\"One<\/a> Figure 2: One hundred and eighty-million-year-old pigment cells (melanophores). To the left, light micrograph of the branched melanophores. In the center, synchrotron-radiation X-ray tomographic microscopy (SRXTM) rendering of a melanophore with long dendritic processes. To the right, transmission electron microscopy (TEM) image of a melanophore that contains melanosome organelles.<\/p>\n

Researchers identified cell-like microstructures that held pigment organelles within the fossil\u2019s skin, as well as traces of an internal organ thought to be the liver. They also observed material chemically consistent with vertebrate blubber, which is only found in animals capable of maintaining body temperatures independent of ambient conditions.<\/p>\n

Lindgren sent samples from the fossil to international colleagues, including Schweitzer. The team conducted a variety of high-resolution analytical techniques, including time-of-flight secondary ion mass spectrometry (ToF SIMS), nanoscale secondary ion mass spectrometry (NanoSIMS), pyrolysis-gas chromatography\/mass spectrometry, as well as immunohistological analysis and various microscopic techniques.<\/p>\n

Schweitzer and NC State research assistant Wenxia Zheng extracted soft tissues from the samples and performed multiple, high-resolution immunohistochemical analyses. \u201cWe developed a panel of antibodies that we applied to all of the samples, and saw differential binding, meaning the antibodies for a particular protein \u2013 like keratin or hemoglobin \u2013 only bound to particular areas,\u201d Schweitzer says. \u201cThis demonstrates the specificity of these antibodies and is strong evidence that different proteins persist in different tissues. You wouldn\u2019t expect to find keratin in the liver, for example, but you would expect hemoglobin. And that\u2019s what we saw in the responses of these samples to different antibodies and other chemical tools.\u201d<\/p>\n

\"Figure<\/a> Figure 3: Comparison between artificially matured modern porpoise integument and fossil ichthyosaur blubber. To the left, cross-section through porpoise skin and blubber before decay experiments. In the center, side (top) and internal (bottom) views of heat- and pressure-treated porpoise integument (note severe reduction of the blubber layer). To the right, side (top) and internal (bottom) views of fossilized ichthyosaur skin and blubber.<\/p>\n

Lindgren\u2019s lab also found chemical evidence for subcutaneous blubber. \u201cThis is the first direct, chemical evidence for warm-bloodedness in an ichthyosaur, because blubber is a feature of warm-blooded animals,\u201d Schweitzer says.<\/p>\n

Taken together, the researchers\u2019 findings indicate that the Stenopterygius <\/em>had skin similar to that of a whale, and coloration similar to many living marine animals \u2013 dark on top and lighter on the bottom \u2013 which would provide camouflage from predators, like pterosaurs from above, or pliosaurs from below.<\/p>\n

\u201cBoth morphologically and chemically, we found that although Stenopterygius<\/em> would be loosely considered \u2018reptiles,\u2019 they lost the scaly skin associated with these animals \u2013 just as the modern leatherback sea turtle has,\u201d Schweitzer says. \u201cLosing the scales reduces drag and increases maneuverability underwater.<\/p>\n

\"Fossilized<\/a> Figure 4: Fossilized skin with post mortem rippling.<\/p>\n

\u201cThis animal\u2019s preservation is unusual, especially for a marine environment \u2013 but then, the Holzmaden formation is known for its exceptional preservation. This specimen has given us more evidence that these tissues and molecules can preserve for extremely long periods, and that soft tissue analysis can shed light on evolutionary patterns, relationships, and how ancient animals functioned in their environment.<\/p>\n

\u201cOur results were repeatable and consistent across labs. This work really shows what we\u2019re capable of discovering when we perform a multidisciplinary, multi-institutional study of an exceptional specimen.\u201d<\/p>\n

The work appears in Nature<\/em>, and was supported in part by the National Science Foundation (INSPIRE grant EAR-1344198) and the Packard Foundation.<\/p>\n

\n

Note to editors<\/strong>: An abstract follows.<\/p>\n

\u201cSoft tissue evidence for homeothermy and crypsis in a Jurassic ichthyosaur\u201d<\/strong><\/p>\n

DOI: 10.1038\/s41586-018-0775-x<\/strong><\/p>\n

Authors:<\/strong> Johan Lindgren, Carl Alwmark, Mats E. Eriksson, Martin Jarenmark, Anders Engdahl, Ola Gustafsson, Irene Rodr\u00edguez-Meizoso, Per Uvdal, Lund University; Peter Sj\u00f6vall, Research Institutes of Sweden; Volker Thiel, University of Gottingen; Shosuke Ito, Kazumasa Wakamatsu, Fujita Health University; Rolf Hauff, Urweltmuseum Hauff; Benjamin Kear, Per E. Ahlberg, Uppsala University; Sven Sachs, Naturkunde-Museum Bielefeld; Federica Marone, Paul Scherrer Institute; Takeo Kuriyama, University of Hyogo; Per Malmberg, Chalmers University of Technology; Aur\u00e9lien Thomen, University of Gothenburg;\u00a0 Makoto Ojika, Nagoya University; Mary Schweitzer, North Carolina State University and the NC Museum of Natural Sciences; Wenxia Zheng, North Carolina State University
\n<\/strong><\/p>\n

Published:<\/strong> Nature<\/em><\/p>\n

Abstract:
\n<\/strong>Ichthyosaurs are extinct marine reptiles that display a remarkable external similarity to modern toothed whales. Here we show that this resemblance is more than skin deep. We apply a novel multidisciplinary experimental approach to characterise the cellular and molecular composition of integumental tissues in an exceptionally preserved specimen of the Early Jurassic ichthyosaur Stenopterygius<\/em>. Our analyses recovered still flexible remnants of the original scaleless skin, comprising 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. Ichthyosaur convergence with extant marine amniotes thus extends to ultrastructural and molecular levels, reflecting the omnipresent constraints for their shared adaptation to pelagic life.<\/p>\n","protected":false},"author":2,"featured_media":35774,"menu_order":0,"template":"","format":"standard","meta":{"_links_to":"","_links_to_target":""},"acf":[],"_links":{"self":[{"href":"https:\/\/naturalsciences.org\/calendar\/wp-json\/wp\/v2\/news\/35748"}],"collection":[{"href":"https:\/\/naturalsciences.org\/calendar\/wp-json\/wp\/v2\/news"}],"about":[{"href":"https:\/\/naturalsciences.org\/calendar\/wp-json\/wp\/v2\/types\/news"}],"author":[{"embeddable":true,"href":"https:\/\/naturalsciences.org\/calendar\/wp-json\/wp\/v2\/users\/2"}],"version-history":[{"count":0,"href":"https:\/\/naturalsciences.org\/calendar\/wp-json\/wp\/v2\/news\/35748\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/naturalsciences.org\/calendar\/wp-json\/wp\/v2\/media\/35774"}],"wp:attachment":[{"href":"https:\/\/naturalsciences.org\/calendar\/wp-json\/wp\/v2\/media?parent=35748"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}