Jurassic Plesiosaurs and Ichthyosaurs of Svalbard
Plesiosaurs and ichthyosaurs are two groups of marine reptiles that inhabited the Earth's oceans in the Mesozoic - the plesiosaurs being most diverse in the Jurassic and Early Cretaceous, while the ichthyosaurs dominated the Triassic and diminished throughout the Jurassic and Cretaceous. Like today's whales and seals, plesiosaurs and ichthyosaurs descended from land-living animals that adapted to a life in water. The evolutionary path to this life is reflected in the anatomy of the body. Both groups had four flippers of which, in plesiosaurs, all four were used for locomotion, whereas in the dolphin-like ichthyosaurs the hind flippers were reduced and a fish-like tail propelled the animal forward, while the fore flippers were used for steering.
On Svalbard the first remains of these animals are of Triassic ichthyosaurs found over a century ago. The first Jurassic fossil - a plesiosaur - was found in 1913 on Spitsbergen near the mountain Janusfjellet. In 1931 the postcranial remains of another plesiosaur was found by an American group of medical doctors studying the spread of the common cold in Longyearbyen. This material was later described and named Tricleidus svalbardensis . With the exception of one isolated plesiosaur limb, no new material from Jurassic rocks were recorded until 2001 when an excursion of Norwegian scientists and students came across the remains of a marine reptile weathering out of the black shale in the Slottsmøya Member of the Agardhfjellet Formation (Tithonian, Upper Jurassic). The find was reported to Dr. Jørn Harald Hurum at the Natural History Museum in Oslo , who in 2004 led a team into the field to collect the specimen, which turned out to be a partial plesiosaur skeleton. While in the field, Dr. Hurum's team found an astounding nine additional occurrences including a large complete ichthyosaur skull (which was also collected and is being prepared).
Based on the exceptional number and quality of specimens collected in 2004, Dr. Hurum and Dr. Hans Arne Nakrem, planned a larger expedition for the summer of 2006. The purpose of this return trip to Spitsbergen was to locate and map other marine vertebrate skeletons occurring in the Slottsmøya Member. During this 11-day expedition parts of additional 28 specimens were discovered, including six ichthyosaurs, 20 long-necked plesiosaurs, and two remarkable short-necked plesiosaurs (commonly known as pliosaurs). One of these pliosaurs along with one long-necked plesiosaur and one ichthyosaur were collected during a 3 week expedition led by Dr. Hurum the following year. Back in Oslo the material was prepared and is now part of the Ph.D. study of Espen M. Knutsen at the Natural History Museum, University of Oslo.
In the summer of 2008 the same team led by Dr. Hurum collected the last pliosaur and two more long-necked plesiosaurs.
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Jørn H. Hurum preparing a plesiosaur scull, Janusfjellet, 2004
A plesiosaur scull from Janusfjellet. Now on display in Svalbard Museum, Longyearbyen
Hurum, Druckenmiller & Knutsen demonstrating the powerful wind at Knorringfjellet, 2008
May-Liss Knudsen preparing the ichthyosaur skull, Natural History Museum, Oslo