Eurypterids, commonly known as sea scorpions, are an extinct group of predatory arthropods that lived during the Palaeozoic. Some of them grew to enormous size and the largest known was estimated as being 2.5m long. National Museums Scotland has a very important collection of eurypterids, mostly from Silurian, Devonian and Carboniferous rocks of Scotland, and several can be seen on display. The collection includes type specimens, those that were given new species names by scientists. Many of these were named in the 19th century.
Recently Dr James Lamsdell, Associate Professor of Geology at West Virginia University, visited the National Museums Collection Centre to study hibbertopteroid eurypterids. Hibbertopteroids were a group that lived during the Carboniferous Period and, unlike earlier forms, lived in freshwater and may even have been amphibious to enable them to move from pool to pool and lay their eggs on land. We have a large collection, mainly collected in the 1980s and 1990s by Stan Wood and former staff but not adequately studied and with some specimens still wrapped in newspaper from the time. Dr Lamsdell’s visit provided a great opportunity to sort out this material.
Dr James Lamsdell with a Hibbertopterus head-shield that he found in the collection.
Many of the hibbertopteroid specimens are fragmentary, consisting of pieces of head-shield, body segments and limbs, and they are ornamented with distinctive scales of various shapes and sizes. This has led to a problem taxonomically as in the past different names have been used for different parts. Are these different parts of the same species or are there several species present? That is what Dr Lamsdell is hoping to work out, as well as looking at how they changed as they grew.
In the Beginnings gallery there are two specimens on display, a Cyrtoctenus feeding arm and a small individual consisting of a head-shield and body in two parts.
A type specimen of Hibbertopterus scouleri on display in Beginnings. NMS G.1891.92.478.
Little was known about the small individual although it’s registration number, G.1891.92.478, indicated it had been in the museum for some time. However, examination of the original hand-written register entry revealed that the head-shield and body were figured in Henry Woodward’s monograph on British Fossil Merostomata in 1872. Woodward indicated they were first figured by Samuel Hibbert in 1836. Hibbert figured several specimens and named them Eurypterus scouleri, so they are type specimens (now called Hibbertopterus scouleri). The NMS specimens are in Hibbert’s figures 1 (top view) and 2 (bottom view) and clearly show that the head-shield and two body parts belong to one individual, just as it is shown on display.
The original plate from Hibbert’s paper of 1836 showing the specimen on display in figs 1 & 2.
The database entry has now been updated so that the importance of this sea scorpion will not be forgotten again.