The Holotype of Maiocercus orbicularis

This is the fossil of a Trigonotarbid, a creature related to spiders, scorpions and mites. The head body and legs are missing, this is just the abdomen. It is 300 million years old and was found in rocks in Westhoughton around 1911 by E.Leonard Gill, curator of the Hancock Museum, Newcastle. It is the first and only example of the species, the one referred to when the species was named, and as such we call it the 'holotype'.

In 1996 a palaeontologist at Manchester University called Dr Jason Dunlop was writing his PhD on trigonotarbids, analysing the entire group, to bring together all known specimens and work out how they were related and how they lived.

A French geologist, Pierre Pruvost, had suggested in 1919 that Maiocercus orbicularis was actually the same as Maiocercus celticus, but this had never been resolved.

So Jason contacted Bolton, but with no specialist in place to identify it, and access to the collection difficult due to the material being mid-move, Bolton had to say they couldn’t find it at that time. As such, the specimen was recorded as 'missing' from the perspective of the scientific community. This doesn’t mean it was really missing, just that it was unavailable at the time of writing.

He agreed with Pruvost, but still the specimen had not been re-examined. He finished at Manchester soon after and started work at the Humboldt University Museum für Naturkunde in Berlin.

In September 2003 Bolton Museum hired David Craven to work on the geology collections. At a conference in Leicester just before Christmas, Jason and David were talking about the Bolton collections, including the 'missing' specimen.

When he got back to Bolton, David went looking for the specimen and soon found it.

So finally, 93 years after Gill’s paper, a new paper was written providing a proper description and images of Maiocercus orbicularis. In this paper Jason and David were finally able to confirm that it was the same as Maiocercus celticus.

In science, the first species named gets seniority. So since Maiocercus celticus was named in 1908, and Maiocercus orbicularis in 1911, Maiocercus celticus is the senior name. This makes Maiocercus orbicularis a 'junior synonym' of Maiocercus celticus.

Basically, if you go back 40 years or so, palaeontologists were keener to assign any specimen found to a new species on the basis of one or two minor differences. Today we can conduct much more detailed analysis of two specimens and this makes it easier to see where small differences are just differences between two individuals of the same species, whereas in the past they’d have been called two different species.

Despite Jason and David confirming Maiocercus orbicularis as a junior synonym of Maiocercus celticus, this specimen is still regarded as the holotype of Maiocercus orbicularis (just in case someone decides to disagree with their findings in another 100 years!)