1 Nature 1950 Vol: 166(4225):696-697. DOI: 10.1038/166696a0

A Symmetrodont Tooth from the Rhaeto-Lias

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  1. KUHNE, WALTER G.Department of Zoology and Comparative Anatomy, University College, Gower Street, London, W.C.1. June 13.SINCE the discovery of the tooth Morganucodon uatsoni in a fissure at the Duchy Quarry near Bridgend, Glamorgan, which yields a Rhaeto-Liassic mammalian fauna, about fifty teeth or fragments of teeth have been found. With few exceptions the fauna consists of /`Triconodonts/', identical with those collected by Prof. B. Peyer from Upper Rhaetic bone-bed material at Hallau near Schaffhausen. The only members of the fauna which are adequate for comparison with other material are the /`Triconodonts/'. I wish to emphasize that all the known facts having a bearing on the geological age of the Morganucodon fissure are consistent with a Rhaeto-Liassic age.On Morganucodon a few new points may be given. If one looks upon this lower post-canine as a [ast]pre-pantothere', the changes needed to lead to the panto-theres would be the following: the anterior accessory cusp which in Morganucodon is very small would have to disappear, and the antero-internal cingulum cusp would have to increase in size to make the paraconid. The highest cingulum cusp, well separated in Morganucodon, would also have to increase in order to form the metaconid. The very substantial posterior accessory cusp in Morganucodon would have to disappear and the talonid to become basined. , .