Brontoscorpio anglicus; A Gigantic Lower Paleozoic Scorpion from Central England
1972; Cambridge University Press; Volume: 46; Issue: 1 Linguagem: Inglês
ISSN
1937-2337
Autores Tópico(s)Venomous Animal Envenomation and Studies
ResumoBrontoscorpio anglicus, the largest scorpion ever recorded, is described from a free finger collected from the Siluro-Devonian, Downtonian sandstone beds of Trimpley, Worcestershire, England. The part preserved indicates a scorpion more than nine-tenths of a meter length from anterior of the carapace to the end of the telson. This is nearly twice as long as the largest fossil scorpion previously known, and about five times longer than the largest living scorpion. KNOWLEDGE of lower Paleozoic scorpions is meagre, although recently several important discoveries of Silurian and Lower Devonian scorpions have been made. These include those by Leif Stormer from the Lower Devonian of Germany, and by me of forms from the Silurian of New York and the Lower Devonian of Wyoming. In studying a collection of eurypterids, the writer noted an enormous free finger of a scorpion which had, quite understandably, been mistaken for the free finger of the chelicera of a pterygotid eurypterid. The fact that the specimen is preserved in the round, completely uncrushed, reveals clearly that the characteristic large teeth of the pterygotids are not present and that the inner edge shows distinct granules, characteristic of all scorpions except some fossil ones which are entirely cultrate or without granules or denticles. The counterpart is also preserved, and this shows that there is no possibility of pterygotid teeth being embedded the matrix. The curvature of the free finger is typical of the pedipalp of scorpions and not of the chelicera of pterygotids. Although usually preserved crushed, some pterygotid chelicerae are preserved sandstone and retain the original configuration. The free finger is always straight, not curved. The free finger of this gigantic scorpion can easily be identified as the one belonging to the right pedipalp. There is no possibility that the specimen represents a vertebrate, as the material definitely is not bone and the surrounding, enclosing tissue is chitin, although thin and mainly carbonized: therefore, an arthropod. The configuration and the inner granules, not greatly unlike those of the living scorpion Urodacus, confirm its scorpionid nature. From the Carboniferous, Stormer (1963) described the then largest known scorpion, Gigantoscorpio willsi, which was estimated to be 365 mm length (measured from anterior of carapace to the end of the aculeus). Vachon (in Stormer, 1963, p. 60), using the relationship of the length of the pectines to total length, arrived at a length estimate between 280-420 mm. This great variation estimates reveals the unreliability of using the pectines as length indicators, a fact easily proved by the great length of the pectines many Buthidae, as against the unusually short pectines of the Chaerilidae-nevertheless, both families are quite similar dorsal aspects and proportions. My calculations of the size of G. willsi differ some important respects from these authors. G. willsi has a free finger 51 mm length; furthermore it is of the type found many Buthidae, i.e., long slender fingers with a relatively short manus as most scorpions of the genera Buthus, Tityus, Centruroides, etc. Therefore, using the free finger as a reference for comparison with the length and using Tityus trinitatis Pocock, the fingers of which are much like those of Gigantoscorpio willsi, the latter my opinion would reach a length of 390 mm if a female and 440 mm if a male. Obviously, the free finger of Gigantoscorpio willsi is not of the type present most Scorpionida where the pedipalps are generally very broad and the fingers are unusually short; comparison with forms like those would give a wrong estimation. It is the same with the pectines. It should be noted, however, that it is a secondary sex character for the female to have comparatively shorter fingers than the male, regardless of whether the male is larger or smaller than the
Referência(s)