Article: Reinterpretation of the Silurian scorpion Proscorpius osborni (Whitfield): integrating data from Palaeozoic and recent scorpions

The morphology of the Late Silurian (Pridoli) scorpion Proscorpius osborni (Whitfield, 1885a) (Arachnida: Scorpiones), from the Phelps Member of the Fiddlers Green Formation of New York, the ‘Bertie Waterlime’ of earlier stratigraphic schemes, is revised based on studies of new and existing material (a total of 32 specimens). Previous reports of four cheliceral articles, gnathobasic coxae, a labium and gill slits in P. osborni can be dismissed. However, we confirm the presence of both median and compound lateral eyes, a pair of tarsal claws, albeit on a more digitigrade foot compared to that of modern scorpions, more than five ventral mesosomal sclerites and a fairly modern pattern of metasomal (i.e. tail) carinae. The co-occurring Archaeophonus eurypteroides Kjellesvig-Waering, 1966 and Stoermeroscorpio delicatus Kjellesvig-Waering, 1986 are regarded as junior synonyms of P. osborni. Fossil scorpion higher systematics is plagued by a plethora of unnecessary and largely monotypic higher taxa and we draw on the results of Jeram’s cladistic analysis from 1998 to synonymize formally a series of families and superfamilies with Proscorpiidae Scudder, 1885.