Modern distribution of Scolytus ratzeburgi Jan. and Tecmnochila coerulea Westw. with 17 degrees July mean isotherm. These species were recovered as fossils within the same context, in deposits of c. 4,000-3,000 B.P. on Thorne Moors; Scolytus ratzeburgi has also been found in fossil deposits on Hadfield Moors. The distribution illustrates some of the current problems in the interpretation of such data. For example, do these distributions reflect variation in oceanicity versus continentality in the late Holocene climate?
Note: actual species distribution is much more discontinuous. Question marks indicate a lack of information, rather than known absence of species.
This drawing has been published previously in Whitehouse et al., 1997. Drawing: Philip I. Buckland.