Cladotheria
| Cladotheres Temporal range: Early Jurassic–Holocene,
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| Fossil of the basal cladotherian Henkelotherium guimarotae | |
Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Clade: | Trechnotheria |
| Clade: | Cladotheria McKenna, 1975 |
| Subgroups | |
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Cladotheria is a clade (sometimes ranked as a legion)[2] of mammals. It contains modern therian mammals (marsupials and placentals) and several extinct groups, such as the dryolestoids, amphitheriids and peramurids. The clade was named in 1975 by Malcolm McKenna. In 2002, it was defined as a node-based taxon containing "the common ancestor of dryolestids and living therians, plus all its descendants".[1] A different, stem-based definition was given in 2013, in which Cladotheria contains all taxa that are closer to Mus musculus (the house mouse) than to the "symmetrodont" Spalacotherium tricuspidens.[3]
Description
Early cladotherians can be distinguished from other mammals by a number of derived traits (apomorphies). Their teeth differed from those of the "symmetrodonts" by the evolution of a talonid shelf (hypoflexid) on the lower molars, which occluded with the paracone of the corresponding upper molars. A true talonid basin, allowing for the crushing and grinding of food, was however absent in early-diverging groups like the dryolestoids, amphitheriids and peramurids. Cladotherians are also distinguished by a backwards-pointing angular process at the rear end of the dentary bone, below the jaw joint. The shape of this process indicates that early cladotherians had a more transverse (side-to-side) chewing motion than more basal mammal groups. The connection of the middle ear bones to the dentary through an ossified Meckel's cartilage appears to have been lost in cladotherians, but a cartilaginous connection may have been retained in early-diverging groups.[4]
Phylogeny
The cladogram below is simplified after a 2022 phylogenetic analysis by Lasseron and colleagues:[5]
| Cladotheria | |
References
- ^ a b c Luo, Z.-X.; Kielan-Jaworowska, Z.; Cifelli, R. L. (2002). "In quest for a phylogeny of Mesozoic mammals" (PDF). Acta Palaeontologica Polonica. 47 (1): 1–78.
- ^ McKenna, M. C.; Bell, S. K. (1997). Classification of Mammals Above the Species Level. Columbia University Press. pp. 9–10. ISBN 978-0-231-11012-9. Retrieved 16 March 2015.
- ^ Averianov, A. O.; Martin, T.; Lopatin, A. V. (2013). "A new phylogeny for basal Trechnotheria and Cladotheria and affinities of South American endemic Late Cretaceous mammals". Naturwissenschaften. 100 (4): 311–326. doi:10.1007/s00114-013-1028-3.
- ^ Grossnickle, D. M. (2017). "The evolutionary origin of jaw yaw in mammals". Scientific Reports. 7 (1): 45094. doi:10.1038/srep45094.
- ^ Lasseron, M.; Martin, T.; Allain, R.; Haddoumi, H.; Jalil, N.-E.; Zouhri, S.; Gheerbrant, E. (2022). "An African Radiation of 'Dryolestoidea' (Donodontidae, Cladotheria) and its Significance for Mammalian Evolution". Journal of Mammalian Evolution. doi:10.1007/s10914-022-09613-9.
External links
- MESOZOIC MAMMALS; Stem zatherians, zatherians & Peramuridae, an internet directory
- Palaeos Vertebrates 430_500 Mammalia Spalacotheroidea & Cladotheria
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