New allotherian specimens from the Middle Jurassic Woodeaton Quarry (Oxfordshire) and implications for haramiyidan diversity and phylogeny

Abstract

We report new allotherian tooth specimens from the Middle Jurassic White Limestone Formation at Woodeaton Quarry (Oxfordshire), United Kingdom. Two teeth are assigned to Kermackodon (=Eleutherodon) oxfordensis, a taxon whose original generic name (Eleutherodon) was preoccupied and is here assigned to Kermackodon to form a new binomial combination for the species name. Butlerodon quadratus gen. et sp. nov. (family Kermackodontidae), based on 13 cheek teeth and incisors, shows dental features intermediate between K. oxfordensis and the Late Triassic “haramiyidans” (Haramiyavia and Thomasia). Woodeatonia parva gen. et sp. nov. (family indeterminate), based on three teeth, is characterized by its small size. A second upper molar from a multituberculate is identified as Hahnotherium cf. H. antiquum, which possesses characters typical for multituberculates but distinctive from “haramiyidans”. The allotherian teeth from the Forest Marble Formation, previously assigned to the haramiyidans “Eleutherodon”, “Millsodon” and “Kirtlingtonia”, and the multituberculate Kermackodon, are reinterpreted as teeth from different upper or lower dental loci of the same haramiyidan species K. oxfordensis, which result in significant taxonomical modification of these allotherians (“haramiyidans” and multituberculates). Given that Kermackodon has been regarded as a transitional form between multituberculates and “haramiyidans”, these taxonomical modifications would affect interpretation of early evolution of allotherians. In a comparison of molars in known “haramiyidans”, we delve into their occlusal patterns and cusp homologies that have been controversial but pivotal for understanding evolution of allotherians. We further conduct the first phylogenetic analysis of haramiyidan species. The European Late Triassic species form the stem-ward taxa of “haramiyidans” and the Jurassic species from the United Kingdom are grouped with arboroharamiyids from the Yanliao Biota, China, and nested in “haramiyidans”. http://zoobank.org/urn:lsid:zoobank.org:pub:38F1FB5A-17A2-498F-B1FD-38D975548201 http://zoobank.org/urn:lsid:zoobank.org:act:FF5ADA10-C044-4541-ADA6-54448F17C673 http://zoobank.org/urn:lsid:zoobank.org:act:6E59071A-56DF-43D2-A140-2860465BFECA http://zoobank.org/urn:lsid:zoobank.org:act:CA2EE3CF-951C-450A-879D-2AE438F6BB2A http://zoobank.org/urn:lsid:zoobank.org:act:6B26D9C3-9FC3-4517-A1EF-51822067F970