I am interested
in the evolution of mammalian dental and jaw morphology during the
Mesozoic. In particular, my research focuses on the origin(s) of
tribosphenic mammals from more primitive groups during the Jurassic, and the evolution of terrestrial ecosystems through the Jurassic and into the Cretaceous.
The earliest members of modern mammal lineages (marsupials and
placentals) are generally thought to have appeared at the very beginning
of the Cretaceous. However, discoveries of Middle Jurassic fossils
displaying a surprising combination of advanced dentition and primitive
jaws have led some to rethink the early history of modern groups.
use of computed tomography (CT) has enabled investigation of novel
features of some of the first Mesozoic mammal specimens ever collected,
providing new data and allowing thorough redescription of important
species. Some questions that are central to my research
| Late Cretaceous sediments of the Kaiparowits Plateau, Utah
Are there transitional mammalian faunas in North America to fill the temporal and morphological gap between the Upper Jurassic Morrison Formation and units of Aptian-Cenomanian age (e.g., Cloverly, Antlers, and Cedar Mountain formations)?
Cifelli, R. L., Davis, B. M., and Sames, B. in press. Earliest Cretaceous mammals from the western United States. Acta Palaeontologica Polonica.
Earliest Cretaceous dryolestid from the Lakota Fm., South Dakota
dentally advanced Middle Jurassic species and their relatives
(the Australosphenida) functionally tribosphenic, and if so, is this
acquisition homology or homoplasy?
Davis, B. M. 2011. Evolution of the tribosphenic molar pattern in early mammals, with comments on the "dual-origin" hypothesis. Journal of Mammalian Evolution 18: 227-244. (PDF)
| Early Cretaceous australosphenidan Ausktribosphenos
the morphology of the sister group to traditional tribosphenic mammals
(the Peramura) tell us about dental homologies across the tribosphenic
Davis, B. M. 2012. Micro-computed tomography reveals a diversity of peramuran mammals from the Purbeck Group (Berriasian) of England. Palaeontology 55: 789-817. (PDF)
| Early Cretaceous pretribosphenic mammal Peramus
phylogenetic patterns be gleaned from the diversity of early, somewhat
generalized tribosphenic mammals (such as the Early Cretaceous Trinity
therians), and do they have any bearing on the early history of
marsupials or placentals?
Fig. to R from: Davis, B. M. 2011. A novel interpretation of the tribosphenidan mammal
Slaughteria eruptens from the Early Cretaceous Trinity Group, and
implications for dental formula in early mammals. Journal of Vertebrate Paleontology 31: 676-683. (PDF)
Davis, B. M.,
Cifelli, R. L. and Kielan-Jaworowska, Z. 2008. Earliest evidence of
Deltatheroida (Mammalia: Metatheria) from the Early Cretaceous of North
America. In: Sargis, E. J. and Dagosto, M. (eds.), Mammalian Evolutionary Morphology: A Tribute to Frederick S. Szalay, 3-24. Springer, Dordrecht. (PDF)
Premolar replacement from CT data, Early Cretaceous therian Slaughteria
I also revised
the systematics of a large, diverse family of Late Cretaceous, North
American marsupials for my Masters thesis. The Pediomyidae were among
the most numerically dominant mammals in many faunas towards the end of
the Cretaceous. The principal genus, Pediomys, contained nine
very diverse species, which I redistributed across a total of four
genera. The highly distinctive molar morphology which characterizes
pediomyids may reflect a relationship with other taxa with purported
ties to a South American faunal exchange.
See: Davis, B. M. 2007. A revision of “pediomyid” marsupials from the Late Cretaceous of North America. Acta Palaeontologica Polonica 52: 217-256. (PDF)
| Late Cretaceous pediomyid marsupial Pediomys
| || |