[F] Two Medicine Formation - Montana - US - Alberta - Canada
Montana - US - Alberta - Canada
The Two Medicine Fm. is exposed in the high plains to the east of Glacier National Park in northwestern Montana. A variety of sedimentary rocks comprise the formation, and the outcropbelt of these ancient sediments consists of widespread badland exposures that are ideal both for paleontological prospecting and for geological investigations. deposition of the Two Medicine Formation commenced with the regression of the Colorado Sea and continued until maximum transgression of the Bearpaw Sea. (Gill and Cobban, 1973)
Correlation with marine ammonite zones suggests that the formation is probably Campanian in age (using Campanian Stage boundaries of Harland et al., 1990). Radioisotopic dating of volcanic ash horizons (bentonites) interbedded whitin the formation also yields a Campanian age (Rogers et al., 1993). On the basis of 40Ar/39Ar analyses, deposition of the Two Medicine Formation commenced approximately 83 million years ago and continued until approximately 74 million years ago.
The Two Medicine Formation consists of approximately 560m of terrestrial sediments, rare sandstones beds deposited in shallow marine environments occur low in the section. The formation as an whole is dominated by grey green claystone and siltstone, with lesser amounts of fine to medium-grained grey sandstone.
Achelousaurus horneri - Montana - Ceratopidae Pachyrhinosaurinae - Cretaceous Late Campanian
Acristavus gagslarsoni - Montana - Hadrosaurinae Brachylophosaurini - Cretaceous Late Campanian
Aublysodon mirandus - Montana - Tyrannosauria Tyrannosauridae - Cretaceous Late Campanian Maastrichtian
Avisaurus gloriae ~/~ - Montana - Ornithothoraces Enantiornithes - Cretaceous Late Campanian
Bambiraptor feinbergorum - Montana - Coelurosauria Dromaeosauridae - Cretaceous Late Maastrichtian
Brachyceratops montanensis - Montana - Centrosaurinae Nomina Dubia - Cretaceous Late Campanian Maastrichtian
Caenagnathus sternbergi - Montana - Oviraptorosauria Caenagnathidae - Cretaceous Late Campanian
Cerasinops hodgskissi - Montana - Ceratopia Neoceratopia - Cretaceous Late Campanian
Edmontonia rugosidens - Montana - Ankylosauria Nodosauridae - Cretaceous Late Campanian
Einiosaurus procurvicornis - Montana - Ceratopidae Pachyrhinosaurinae - Cretaceous Late Campanian
Euoplocephalus tutus - Montana - Ankylosauria Ankylosauridae - Cretaceous Late Campanian Maastrichtian
Glishades ericksoni - Montana - Hadrosauridae [Hadrosauroidae] - Cretaceous Late Campanian
Hypacrosaurus stebingeri - Montana - Hadrosauridae Lambeosaurinae - Cretaceous Late Maastrichtian
Maiasaura peeblesorum - Montana - Maiasaurini [Brachylophosaurs] - Cretaceous Late Campanian
NN (3) Saurolophini - Montana - Hadrosaurinae Saurolophini - Cretaceous Late Campanian
NN (4) Lambeosaurinae - Montana - Hadrosauridae Lambeosaurinae - Cretaceous Late Campanian
NN (5) Gryposaurini - Montana - Hadrosaurinae Gryposaurini - Cretaceous Late Santonian
Oohkotokia horneri - Ankylosauria Ankylosauridae - Two Medicine Formation, Montana
Orodromeus makelai - Montana - Ornithopoda Hypsilophodontidae - Cretaceous Late Campanian
Palaeoscincus rugosidens - Montana - Ankylosauria Nodosauridae - Cretaceous Late Campanian
Prenoceratops pieganensis - Montana - Ceratopia Neoceratopia - Cretaceous Late Campanian
Prosaurolophus blackfeetenis - Montana - Gryposaurini Saurolophini - Cretaceous Late Campanian Maastrichtian
Rubeosaurus ovatus - Montana - Ceratopidae Centrosaurinae - Cretaceous Late Campanian
Styracosaurus ovatus - Montana - Ceratopidae Centrosaurinae - Cretaceous Late Campanian
Velociraptor sp. - Montana
Dinosaur eggshell - Montana - Dinosauria - Cretaceous Late Santonian Campanian
Dromaeosaurid indet. - Montana - Theropoda - Cretaceous Late Santonian Campanian
Hadrosaurid indet. - Montana - Ornithopoda Hadrosauridae - Cretaceous Late Santonian Campanian
Theropoda indet. - Montana - Theropoda - Cretaceous Late Santonian Campanian
Undescribed ceratopid - Montana - Ceratopia - Cretaceous Late Santonian Campanian
Undescribed hadrosaurine - Montana - Ornithopoda Hadrosauridae - Cretaceous Late Santonian Campanian
Undescribed protoceratopsid - Montana - Ceratopia - Cretaceous Late Santonian Campanian
Albertosaurus sp. - Alberta - Theropoda Tyrannosauridae - Cretaceous Late Campanian
Dromaeosaurus sp. - Alberta - Theropoda Dromaeosauridae - Cretaceous Late Campanian
Edmontonia sp. - Alberta - Ankylosauria Nodosauridae - Cretaceous Late Campanian
Hypsilophodontid indet. - Alberta - Ornithopoda Hypsilophodontidae - Cretaceous Late Campanian
Saurornitholestes sp. - Alberta - Theropoda Dromaeosauridae - Cretaceous Late Campanian
Troodon sp. - Alberta - Theropoda Troodontidae - Cretaceous Late Campanian
?Centrosaurus sp. - Montana - Ceratopia - Cretaceous Late Campanian
Chasmosaurus sp. - Montana - Ceratopidae - Cretaceous Late Campanian
Proceratopsid indet. (= ? Leptoceratops sp.) - Montana - Ceratopia - Cretaceous Late Campanian
Troodon sp. - Montana - Theropoda Troodontidae - Cretaceous Late Campanian
Undescribed hadrosaurine - Montana - Ornithopoda Hadrosauridae - Cretaceous Late Campanian
Undescribed hypsilophodontid - Montana - Ornithopoda Hypsilophodontidae - Cretaceous Late Campanian
Undescribed lambeosaurine - Montana - Ornithopoda Hadrosauridae - Cretaceous Late Campanian