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Evolutionary radiation of the cheek teeth of Cretaceous placentals

100%

Butler P. M.

Acta Palaeontologica Polonica

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1977

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tom 22

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nr 3

Included is a comparative study of the molars and posterior premolars of the Cretaceous placentals. Particular attention is paid to occlusal relations. An attempt is made to identify primitive characters, and the advance of each genus from the primitve condition is analysed. It is found that nearly all known genera are on different lines of evolution, indicating that a major radiation of placentals was taking place during the Cretaceous.

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Review of the early allotherian mammals

100%

Butler P. M.

Acta Palaeontologica Polonica

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2000

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tom 45

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nr 4

Comparison of the early allotherian genera, Haramiyavia, Thomasia, Theroteinus, and Eleutherodon shows that their molariform teeth are variants of a common pattern, justifying the inclusion of these genera in a single order Haramiyida. Haramiyavia is made the type of a new family Haramiyaviidae. The order Haramiyida is divided into two suborders: (1) Theroteinida (only family Theroteinidae), and (2) Haramiyoidea (families Haramiyaviidae, Haramiyidae, Eleutherodontidae). Dental resemblances support the hypothesis that the Multituberculata originated within the Haramiyida, in which case the Haramiyida would be paraphyletic. Derivation of multituberculates from within the Mammaliaformes would involve a highly improbable transformation of the dentition. It is therefore postulated that allotherian (Haramiyida + Multituberculata) and non-allotherian mammaliaform clades separated before the Mammaliaformes developed a shearing dentition with unilateral occlusion and transverse jaw movements. This hypothesis implies that the two clades evolved to a large extent in parallel, to account for the apparent synapomorphies of multituberculates and therians.

3

New teeth of allotherian mammals from the English Bathonian, including the earliest multituberculates

63%

Butler P. M., Hooker J. J.

Acta Palaeontologica Polonica

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2005

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tom 50

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nr 2

Twenty one isolated multituberculate−like teeth are described from the Forest Marble (late Bathonian) of Oxfordshire and Dorset, England. Eighteen are additional to the teeth described as Eleutherodon oxfordensis by Kermack et al. (1998), and three of those are placed in new taxa. Six new molars of Eleutherodon provide further information on variation in size, proportion and root pattern. Millsodon superstes gen. et sp. nov. (family indeterminate), based on first and last lower molars and a referred upper molar, has resemblances to Haramiyidae and Theroteinidae. Kirtlingtonia catenata gen. et sp. nov. (family indeterminate), based on last upper molars and a probable upper premolar, has a slight resemblance to Eleutherodon, and also to M2 of some paulchoffatiid multituberculates. Kermackodon multicuspis gen. et sp. nov. (family Kermackodontidae nov.) and Hahnotherium antiquum gen. et sp. nov. (family Hahnotheriidae nov.) are based on second upper molars, recognised as multituberculate by their horizontal wear and inferred occlusal displacement with respect to m2. A lower molar referred to H. antiquum confirms this. A blade−like lower premolar and an upper premolar with conical cusps, referred to Kermackodon, are multituberculate−like, but distinctive. Divergence between the two Bathonian multituberculates indicates that the order originated much earlier, more probably from a haramiyid than from a morganucodontid source. Mojo is regarded as probably a haramiyid. The Hahnodontidae, which have basined wear, are removed from the Multituberculata to the “Haramiyida”.

Ograniczanie wyników

3 Acta Palaeontologica Polonica

3 Butler P. M.

1 Hooker J. J.

1 2005

1 2000

1 1977

Evolutionary radiation of the cheek teeth of Cretaceous placentals

Review of the early allotherian mammals

New teeth of allotherian mammals from the English Bathonian, including the earliest multituberculates