Mesodma
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Mesodma is a genus of extinct mammal that lived during the upper Cretaceous and Paleocene periods of North America. It was a member of the extinct order Multituberculata within the suborder Cimolodonta, family Neoplagiaulacidae. This genus has been the subject of much revision, and has also been known as Cimexomys (partly); Cimolomys (partly); Halodon; Parectypodus (partly); Ptilodon (partly).
The species Mesodma hensleighi is found in the Hell Creek Formation in the US and in Saskatchewan, Canada. They lived during the Campanian (Upper Cretaceous). The holotypes for this species are in the collection of the University of Alberta. Individual members of this species weighed around 15 g.
Species: Mesodma ambigua Place: Mantua Lentil, Wyoming (USA) Age: Maastrichtian-Puercan, Upper Cretaceous - Paleocene This has been cited as a possible descendant of M. thompsoni. It weighed about as much as a couple of well-fed mice (about 55 g).
Species: Mesodma formosa is also known as Cimolomys formosus; Cimolomys gracilis; Halodon formosus; M. formosus; and Ptilodon formosus Place: Hell Creek and Frenchman Formation Country: USA & Canada Age: Maastrichtian-Puercan (Upper Cretaceous to the Paleocene). This species is possibly also known from Utah. Individuals weighed about 30 g.
Species: Mesodma garfieldensis Place: Puercan (Lower Paleocene) Hells Hollow of Montana. Individuals of this species probably weighed around 40 g.
Species: Mesodma primaeva Aka: Cimolomys primaevus; Parectypodus primaeva; Ptilodus primaevus Place: Campanian (Upper Cretaceous – Lower Paleocene) of Montana and Wyoming
Species: Mesodma pygmaea Place: Gidley Quarry, Montana, as well as Wyoming and Alberta, Canada Age: Torrejonian-Tiffanian (Middle Paleocene). This species was very small, with individuals weighing about 8 g.
Species: Mesodma senecta Age: Campanian (Upper Cretaceous) This species is in a further Alberta University holotype. Individuals of this species weighed about 50 g.
Species: Mesodma thompsoni Aka: Cimolodon nitidus; Cimolomys gracilis; Cimolomys nitidus Place: St Mary River Formation & Montana and Wyoming of the USA and Canada Age: Maastrichtian-Puercan, Upper Cretaceous - Paleocene Individual members of this species weighed about 55 g.
References
- Osborn (1891); "A review of the Cretaceous Mammalia". Proc. Acad. Nat. Sci. Phila. 124 - 135.
- Simpson (1929), "American Mesozoic Mammalia". Mem. Peabody Mus. Nat. Hist. iii (i): p.1-235.
- Clemens (1963), "Fossil mammals of the type Lance formation Wyoming. Part I. Introduction and Multituberculata". Univ. Calif. Pub;. Geol. Sci. 48, p.1-105. (According to Peabody Museum database.)
- Marsh (1889), "Discovery of Cretaceous Mammalia". Am. J. Sci. (3) xxxviii, p.177-180.
- Archibald (1982), A study of Mammalia and geology across the Cretaceous-Tertiary boundary in Garfield County, Montana. Univ. of Calif. Publ. Geol. Sci. 122xvi+, 286pp.
- Jepsen (1940), "Paleocene faunas of the Polecat Bench formation, Park County, Wyoming". Pro. Amer. Philos. Soc 83, p.217-341, 21 figs., 5 pls.
- Kielan-Jaworowska Z & Hurum JH (2001), "Phylogeny and Systematics of multituberculate mammals". Paleontology 44, p.389-429.
- [1] (http://home.arcor.de/ktdykes/ptilodon.htm) Mesozoic Mammals; Ptilodontoidea, an Internet directory.