Metric analysis of ungulate mammals in the early Middle Pleistocene of Britain, in relation to taxonomy and biostratigraphy

Rhinoceroses (Stephanorhinus) and large bovids (Bison, Bos) from the early Middle Pleistocene of Britain are analysed with regard to their taxonomy, biometric variation, and possible biochronological significance. The localities considered are West Runton (type Cromerian), Pakefield, Westbury-sub-Mendip, and Boxgrove. The samples include important, previously undescribed material. Among the rhinos, in addition to the common Stephanorhinus hundsheimensis, upper dentitions from Pakefield and West Runton provide hints of undescribed taxa with affinity to, but distinct from, S. etruscus and S. hundsheimensis. At Boxgrove, a further rhino cf. S. megarhinus occurs, corroborating the chronological extension of this 'Pliocene' species into the Middle Pleistocene. A small bison referable to B. schoetensacki occurs at all sites, but in the Westbury Yellow Breccia (upper interglacial level) it is accompanied by a larger bison which may be B. priscus. Dental material from Pakefield provides evidence of additional, smaller bovid species, with features recalling Leptobos and Bubalus, but their identity is unclear; there is also larger material probably representing Bos, which if confirmed would be the oldest record of aurochs in the British Isles.