Protungulatum ('first ungulate') is an extinct genus of within extinct family Protungulatidae,[Z. Kielan-Jaworowska, R. L. Cifelli and Z. X. Luo (2004.) "Mammals from the age of dinosaurs: Origins, evolution, and structure." Columbia University Press, New York 1-630][Maeva Orliac (2016.) "The inner ear of Protungulatum (Pan-Euungulata, Mammalia)" Journal of Mammalian Evolution 23(4)]
Fossils of this genus were first found in the Bug Creek Anthills in northeastern Montana. The Bug Creek Anthills were initially believed to be Late Cretaceous (latest Maastrichtian) because of the presence of the remains of non-avian and common Cretaceous mammals,[Z. Kielan-Jaworowska, T. M. Bown and J. A. Lillegraven (1979.) "Eutheria." In J. A. Lillegraven, Z. Kielan-Jaworowska, W. A. Clemens (eds.), "Mesozoic mammals: the first two-thirds of mammalian history" 221-258] but these were later shown to have been Reworked fossil from Late Cretaceous strata, and consequently the Bug Creek Anthills are currently believed to be Early Paleocene (Puercan) in age.[D. L. Lofgren (1995.) "The Bug Creek problem and the Cretaceous-Tertiary transition at McGuire Creek, Montana." University of California Publications in Geological Sciences 140:1-185] Remains from the Ravenscrag Formation of Saskatchewan, Canada have been assigned to Protungulatum donnae. These remains may also be Cretaceous in age, but the age of the Ravenscrag Formation is not entirely certain. In 2011, a new species Protungulatum coombsi was named based on fossil material discovered from the strata within the Hell Creek Formation specifically dated to at least 300,000 years before the K-Pg extinction, suggested that Protungulatum was present in both the latest Cretaceous and the early Paleocene. P. coombsi was estimated to be 20% larger than the next largest Paleocene species.[
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Studies differ on the placement of Protungulatum. This genus was initially assigned to the family Arctocyonidae,[R. Tabuce, J. Clavel and M. T. Antunes (2011.) "A structural intermediate between triisodontids and mesonychians (Mammalia, Acreodi) from the earliest Eocene of Portugal." Naturwissenschaften 98:145-155] in order Condylarthra,[Malcolm C. McKenna, Susan K. Bell: Classification of Mammals: Above the Species Level in Columbia University Press, New York (1997), 631 Seiten. ][J. D. Archibald (1998.) "Archaic ungulates ("Condylarthra")." In C. M. Janis, K. M. Scott, and L. L. Jacobs (eds.), "Evolution of Tertiary Mammals of North America" 1:292-331] (a group of archaic "ungulates", that is now known to be polyphyletic). Some found that it is not a true placental mammal and it is found to be close to Placentalia.[Averianov, A. O. & Lopatin, A. V. (2014.) "High-level systematics of placental mammals: Current status of the problem." Biology Bulletin, 41(9), 801–816.][ Conference abstract (p. 99) . Explanation and conclusions: .]
Phylogeny
The phylogenetic relationships of genus Protungulatum are shown in the following cladogram.
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