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NCEAS welcomes members of the press and media to get in touch, to learn more about our research related to pressing environmental problems.

Mammalian dispersal at the Paleocene/Eocene boundary

A profound faunal reorganization occurred near the Paleocene/Eocene boundary, when several groups of mammals abruptly appeared on the Holarctic continents. To test the hypothesis that this event featured the dispersal of groups from Asia to North America and Europe, we used isotope stratigraphy, magnetostratigraphy, and quantitative biochronology to constrain the relative age of important Asian faunas.

Sea-level variations and the quality of the continental fossil record

Origination and extinction through the Phanerozoic: A new approach

Temporal patterns of origination and extinction are essential components of many paleontological studies, but it has been difficult to obtain accurate rate estimates because the observed record of first and last appearances is distorted by the incompleteness of the fossil record. Here I analyze observed first and last appearances of marine animal and microfossil genera in a way that explicitly takes incompleteness and its variation into consideration. This approach allows estimates of true rates of origination and extinction throughout the Phanerozoic.

Global databases will yield reliable measures of global biodiversity

On the importance of global diversity trends and the viability of existing paleontological data

Cenozoic bolide impacts and biotic change in North American mammals

Taxonomic inflation and body mass distributions in North American fossil mammals

Lack of community saturation at the beginning of the Paleozoic plateau: The dominance of regional over local processes

Long-term diversity equilibria, ecological incumbency, and widespread recurrent fossil assemblages have each been cited as evidence that local processes, such as competition, played an important role in structuring communities over geologic time. We analyze the relationship between local and regional diversity in tropical marine communities spanning approximately 13 Myr of the Late Ordovician to test for the role of local processes in structuring local communities.

A unified mathematical framework for the measurement of richness and evenness within and among multiple communities