Aegialodon dawsoni, a new trituberculosectorial tooth from the Lower Wealden

摘要: This paper describes a new mammalian tooth from the Lower Wealden bone-bed at Cliff End, near Hastings. The is lower molar. It has trituberculate structure with well-developed talonid. nature of wear on this talonid shows that true protocone (a definite pointed cusp as against an enlarged lingual cingulum) must have been present in upper molars. Aegialodon first mammal which existence definitive can be inferred. A good morphological series traced back through Peramus (Upper Jurassic), Amphitherium (Middle Jurassic) to Upper Triassic Welsh pantotheres. illustrates increasing importance crushing shearing function molar teeth their evolution progresses. expression development enlargement and associated cingulum Finally, last member ( ) becomes protocone. From main line therian symmetrodonts then dryolestid pantotheres branched off by emphasizing reducing function. would adaptation exclusively insectivorous diet. derived Trinity Sands ‘ Theria ’ Endotherium further increase size continuation same process give rise marsupials placentals.