Article: A Lower Carboniferous conodont fauna from Chillaton, southwest Devonshire
S. C. Matthews, P. M. Sadler and E. B. Selwood
Siliceous shale in the Lower Carboniferous at Chillaton, Devonshire, has abundant moulds of conodonts. The relatively rare genus Dollymae is represented by the species D. hassi, which has previously been found only in the upper part of the German anehoralis-Zone. The presence of this form might seem to give a precise indication of the age of the Chillaton fauna. However, the three primary indices recommended for the anchoralis-Zoae by Voges are missing. It is therefore necessary to take account of information from Texas and Belgium, where Dollymae species (although, so far, not D. hassi) are known to occur before the first appearance of Scaliognathus anchoralis. It emerges that the new fauna from Devonshire has much in common with what has been found in Texas, but rather less in common with what has been reported from Belgium. The Chillaton fauna is regarded, for the present, as being approximately of anchoralis-Zone age.The systematic section deals principally with Dollymae and Gnathodus. Present information on the genus Dollymae is reviewed. Mass' and Voges' information is included, with a corrected rendering of assumptions on the orientation of this conodont. In Gnathodus, a wide variety of form is referred to G. punctatus. It is suggested that particular variants of G. punctatus might have been the sources from which particular species of Dollymae were derived.