Researchers reconstruct ancient fish lizard

Geologists at Lund University in Sweden have mapped 300 years of research on the prehistoric marine reptiles known as ichthyosaurs. Using a uniquely well-preserved fossil, the team has also created the scientifically most up-to-date reconstruction of an ichthyosaur currently available.

Historical ichthyosaur reconstructions made during the 19th and early 20th centuries. A. Duria Antiquior (1830) by Henry De la Beche. B. “The Ichthyosaur and the Plesiosaur (period of the Lias)” in Earth before the Deluge (1863) by Louis Figuier. C. Photograph of a Tremnodontosaurus model in Crystal Palace Park made by Benjamin Waterhouse Hawkins. D. “Mosasaur and Ichthyosaurs” in Die Wunder der Urwelt (1912) by Heinrich Harder. E. Painting of a pod of ichthyosaurs by Heinrich Harder as part of a collector card series from Tiere der Urwelt (1916). Except for the photograph in C, which was taken by RDG, all reproductions are freely available online, as their copyright have long since expired.

Fish lizards, or ichthyosaurs, were a very successful group of animals that, much like today’s whales, migrated from land to the oceans where they thrived for about 160 million years. These dolphin-like reptiles lived from the Early Triassic to the Late Cretaceous, about the same time as dinosaurs ruled the Earth.

The fish lizards, who sustained themselves on a diet of turtles and octopuses, among other things, have left behind a rich fossil record. This consists mostly of bones and teeth, but recently the discovery of soft tissues – such as skin, muscles, fat and pigment – has opened up new opportunities for understanding the biology and ecology of these animals.

In a new study published in Earth-Science Reviews, a group of geologists at Lund University has analyzed existing fish lizard research – something that will benefit future paleontologists.

Photographs showing examples of ichthyosaur soft-tissue anatomy discussed in the text. A. A nearly complete juvenile Stenopterygius with a soft-tissue envelope. The specimen resides at the Goldfuβ-Museum in Bonn, Germany (see also Sander, 2000). B. Soft-tissue outline of the tail of another immature Stenopterygius. Note the downward bend of the vertebral column and overall semi-lunate shape of the tail fin. The specimen is on display at Urweltmuseum Hauff, Germany. C. Outline of the dorsal fin from the same specimen. D. Pectoral flipper from a Stenopterygius specimen residing at the Paleontologiska Museet, Uppsala, Sweden, with extended soft-tissue margins. E. Dark-colored gut contents inside the abdominal cavity of an adult Stenopterygius, likely from cephalopods as indicated by hooklets and probably also containing melanized ink sac remains. The specimen is showcased at Urweltmuseum Hauff, Germany. Scale bars (rough estimates); A, B. 10 cm, C–E. 2 cm.

“This research history spans 300 years. It is worth noting that the term ichthyosaur was coined in 1814, i.e. almost 30 years before the term dinosaur”, says Mats E. Eriksson, professor of paleontology at Lund University.

Based on the world’s collective knowledge of these primordial animals, as well as hard and soft fossil parts, the researchers enlisted the help of the Danish sculpture company 10 Tons, to create a scientifically correct life size reconstruction.

“Our reference point was a fish lizard that was found in Holzmaden, Germany. This fossil has previously been the subject of an extensive study on the biology and coloration of fish lizards, which I did together with Mats and several other colleagues, and was published in Nature”, explains Johan Lindgren, geology researcher at Lund University.

A variety of techniques, including clay sculpturing and 3D printing, were used in the work, something that took just over a year. The sculpture initiative, which could be carried out with support from the Crafoord Foundation, aims to reflect the current state of research. The sculpture is now on public display at the Department of Geology in Lund.

Photographs showing the finishing touches of the paint job and the resulting final sculpture of Stenopterygius. A. Esben Horn working on the lower jaw. B. Horn airbrushing the external right lateral side. Note that the lower jaw has still to be attached to the head. C. The final sculpture seen from the front. D. The final sculpture seen in oblique, right lateral view; note the distinctive predation wound (revealing the blubber), smaller scratches, and the minute teeth visible in the lower jaw. Also note that the boundary between the darker back and lighter belly is more gradual than in the earlier stage (A, B), and in concert with what could be deduced from the fossil specimen MH 432. For scale, the whole sculpture measures 1.6 m in length, and Horn is 1.85 m tall.

“Our reconstruction is the scientifically most modern, and hopefully correct, interpretation of what these animals looked like. It will be valuable for students and researchers who want to learn more about the iconic fish lizard”, concludes Mats E. Eriksson. (Newswise)