REVIEW OF THE BRITISH HARAMIYIDAE (MAMMALIA, ALLOTHERIA), THEIR MOLAROCCLUSION AND RELATIONSHIPS

Haramiyid teeth from the Rhaeto-Lias of Holwell Quarry, England, which had been previously described, were re-examined in the light of the l arge sample from Saint-Nicolas-de-Port. Haramiya and Thomasia are inte rpreted as upper and lower teeth, respectively. Differences within eac h 'genus' are ascribed largely to position within the dentition (anter ior 'molars', posterior 'molars', 'premolars'). There is much individu al variation within each of these tooth groups, but at Holwell, as wel l as Saint-Nicolas-de-Port, it is possible to distinguish a larger (Th omasia moorei) and a smaller species (T. antiqua, including T. anglica , H. butleri, and probably H. fissurae). Upper molars, but not lower m olars, appear to be more advanced at Holwell than at Saint-Nicolas-de- Port. It is inferred from tooth wear that the upper and lower molars w ere reversed buccolingually and anteroposteriorly, and the effective c hewing stroke was longitudinal and backwards (palinal), but with an or thal component at the beginning of the stroke, giving a crushing-grind ing action. The chewing movement resembled in principle that of the tr aversodontid Scalaenodon. Opposition between the teeth has probably ev olved by the development of a second row of cusps from the lingual cin gulum in both jaws. However, the transformation of a triconodont into a haramiyid would involve a major change from unilateral, transverse c hewing to presumably bilateral, longitudinal chewing. Possible relatio nships of haramiyids to multituberculates and to broad-toothed cynodon ts are discussed, with their implications for early mammalian phylogen y. Support is given for ordinal separation from the Multituberculata, as Haramiyida. A new interpretation is proposed of the cusp pattern of Theroteinidae, as haramiyid relatives.