Protungulatum ('first ungulate') is an extinct genus of eutherian mammals within extinct family Protungulatidae,Jacqueline S. Silviria (2025.) "Direct inference of ontogenetic pathway networks in PhyG: a viable alternative to ‘cladistic’ Relative Maturity Assessment and ‘reticulistic’ Ontogenetic Sequence Analysis?", in "The Society of Vertebrate Paleontology 85th annual meeting" and is possibly one of the earliest known placental mammals in the fossil record, that lived in North America from the Late Cretaceous to early Paleocene.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 1-630Maeva Orliac (2016.) "The inner ear of Protungulatum (Pan-Euungulata, Mammalia)" Journal of Mammalian Evolution 23(4)
Discovery
Fossils of this genus were first found in the Bug Creek Anthills, a site in northeastern Montana from the uppermost Hell Creek Formation. The Bug Creek Anthills were initially believed to be Late Cretaceous (latest Maastrichtian) because of the presence of the remains of non-avian dinosaurs 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 These fossils were later shown to have been reworked 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 slightly older strata within the Hell Creek Formation, specifically dated to at least 300,000 years before the K-Pg extinction. It suggests 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.
Classification 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, rather a eutherian close to Placentalia. However, a number of studies consider to support it as a placental mammal and relative to true ungulates in the clade Pan-Euungulata.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: . Its inner ear anatomy was one avenue supporting a relationship to ungulates.
Kharmerungulatum, a mammal from the Late Cretaceous Intertrappean Beds of India, may be a close relative of Protungulatum.
The phylogenetic relationships of genus Protungulatum are shown in the following cladogram.
Notes
References