Thursday, January 15, 2015

[Paleontology • 2015] Dearcmhara shawcrossi • Ichthyosaurs from the Jurassic of Skye, Scotland

Dearcmhara shawcrossi
 Illustration: Todd Marshall

Fossils of Mesozoic vertebrates are rare in Scotland, particularly specimens of marine reptiles such as plesiosaurs and ichthyosaurs. We describe a suite of ichthyosaur fossils from the Early to Middle Jurassic of Skye, which to our knowledge are the first ichthyosaurs from Scotland to be described and figured in detail. These fossils span approximately 30 million years, from the Sinemurian to the Bathonian, and indicate that ichthyosaurs were a major component of Scottish marine faunas during this time. The specimens include isolated teeth that could represent the most northerly known occurrences of the widespread Sinemurian species Ichthyosaurus communis, a characteristic component of the famous Lyme Regis faunas of England, suggesting that such faunas were also present in Scotland during the Early Jurassic. An associated humerus and vertebrae from Toarcian–Bajocian-aged deposits are named as a new genus and species of basal neoichthyosaurian, Dearcmhara shawcrossi. The taxonomic affinities of this taxon, which comes from a critical but poorly sampled interval in the fossil record, suggest that non-ophthalmosaurid neoichthyosaurians dominated European assemblages around the Early–Middle Jurassic boundary, and were later replaced by ophthalmosaurids, whose radiation likely took place outside Europe. Many of these specimens were collected by amateurs and donated to museum collections, a co-operative relationship essential to the preservation of Scotland’s fossil heritage.

Dearcmhara shawcrossi gen. et sp. nov. 
Etymology. Dearcmhara, Scottish Gaelic for ‘marine lizard’; shawcrossi, in honour of Brian Shawcross, who collected the specimens and magnanimously donated them to a museum collection instead of retaining them in private hands. In English phonology Dearcmhara is pronounced as ‘jark vara’ (IPA for Scottish English Phonology: d͡ʒɐrk vɐrɐ). Note that in other English phonologies the open vowel (i.e. ‘a’) can be pronounced differently, and the alveolar trill (‘rolled r’) is the alveolar approximant (ɹ).

Stephen L. Brusatte, Mark T. Young, Thomas J. Challands, Neil D. L. Clark, Valentin Fischer, Nicholas C. Fraser, Jeff J. Liston, Colin C. J. MacFadyen, Dugald A. Ross, Stig Walsh and Mark Wilkinson. 2015. Ichthyosaurs from the Jurassic of Skye, Scotland. Scottish Journal of Geology.
First published online January 11, 2015, doi: 10.1144/sjg2014-018

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