The imagery on this page is featured in a paper entitled Tribosphenic mammals from the Lower Cretaceous Cloverly Formation of Montana and Wyoming by R.L. Cifelli and B.M. Davis (2015, Journal of Vertebrate Paleontology, e920848). The abstract is as follows:
We report a diverse assemblage of tribosphenidan mammals from several localities in the Cloverly Formation
(Lower Cretaceous, Albian) of Montana and Wyoming. This unit is of historical significance for yielding well-known dinosaurs (e.g., Deinonychus antirrhopus, Tenontosaurus tilletti) and early mammals (e.g., Gobiconodon ostromi, Montanalestes keeblerorum). We provisionally identify 13 taxa (five of which are formally recognized), including Pappotherium pattersoni, a new species of the deltatheroidan Oklatheridium (O. wiblei, sp. nov.), a eutherian (Montanalestes, previously named), and two new basal tribosphenidans (Argaliatherium robustum, gen. et sp. nov., and Carinalestes murensis, gen. et sp. nov.). An unnamed taxon, represented by associated but almost edentulous dentaries, is interpreted to have had four incisors, a single-rooted canine, three premolars, and four molars, indicating that the metatherian tooth formula was established by the Albian. In addition, an indeterminate lower molar fragment preserving twinned talonid cusps and a buccal postcingulid provides the earliest evidence for Marsupialiformes. We also provide a more detailed description of the associated dentaries (holotype) of Montanalestes keeblerorum. The mammalian fauna from the Cloverly Formation shares several taxa with the roughly contemporaneous Trinity Group of Oklahoma and Texas, an observation that also applies to the dinosaur fauna, suggesting some degree of latitudinal homogeneity among described terrestrial vertebrates in this part of the North American Early Cretaceous.
About the Species
This specimen, the holotype, was collected from lower unit VII of the Cloverly Formation (Lower Cretaceous, Albian), Carbon County, Montana. It was made available to the University of Texas High-Resolution X-ray CT Facility for scanning by Richard Cifelli of the University of Oklahoma. Funding was provided by Dr. Cifelli.
About this Specimen
The specimen was scanned by Matthew Colbert and Richard Ketcham on 29 November 1999 along the sagittal axis for a total of 33 slices. Each slice is 0.10 mm thick, with an interslice spacing of 0.10 mm and a field of reconstruction of 16 mm.
Click here to download the original CT scan data.
Cifelli, R.L. 1999. Tribosphenic mammal from the North American Early Cretaceous. Nature, 401, 363–366.
Cifelli, R.L., and Davis, B.M. 2015. Tribosphenic mammals from the Lower Cretaceous Cloverly Formation of Montana and Wyoming. Journal of Vertebrate Paleontology, e920848.