Article: The Upper Carboniferous tetrapod assemblage from Newsham, Northumberland
The Upper Carboniferous amphibians from Newsham in Northumberland constitute one of only five large, compact tetrapod assemblages known from the Westphalian of Europe and North America. The environment in which the Newsham tetrapods were preserved appears to have been a large and deep freshwater lake occupying a stretch of abandoned river channel. The lake was apparently surrounded by swamp-forest dominated by arborescent lycopods; sphenopsids, including Catamites, probably grew around its shoreline.A revised list of the (eight) Newsham tetrapods which are certainly determinate at least to family level is presented. Specimens probably representing three additional species, including a colosteid temnospondyl, are described. A census of tetrapod specimens from the site facilitates distinction of the abundant endemic species from those representing erratics from environments other than that in which they were preserved. The eogyrinid embolomere Eogyrinus attheyi Watson, the loxommatid Megalocephalus pachycephalus (Barkas) and the keraterpetontid nectridean Batrachiderpeton reticulatum (Hancock & Atthey) seem to have been endemic in life to the Newsham lake. The aistopod Ophiderpeton nanum Hancock and Atthey, a lysorophid and a urocordylid nectridean are each represented by only a single specimen and are regarded as possible erratics from water bodies smaller and shallower than the Newsham lake. The colosteid specimen is probably also derived from a shallow-water/swamp-lake environment, as may be the material representative of the medium-sized eogyrinid Pteroplax cornutus Hancock and Atthey. The only Newsham tetrapod which appears to represent an erratic from a terrestrial/marginal environment is the anthracosaurid embolomere Anthracosaurus russelli Huxley.The structure of the, fish-dominated, open-water/lacustrine community which includes the three endemic Newsham tetrapod species is briefly discussed. Finally, the Newsham assemblage is compared with the only other large, compact tetrapod assemblage of Westphalian B age known, that from Joggins in Nova Scotia. In direct contrast to those known from Newsham, the Joggins tetrapods appear to represent only the more terrestrial elements of the Westphalian B lowland tetrapod fauna of the southern margin of Laurasia. It is therefore suggested that, in view of their close contemparaneity, the assemblages from Newsham and Joggins may be regarded as complementary.