Greetings.

Next Tuesday, Ian Corfe will give a talk about a paper that came out on Wednesday:

“Adaptive radiation of multituberculate mammals before the extinction of dinosaurs”

(Or as the Daily Mail in the UK entitled it:

“Revealed: the secret of the peaceful beaver-like mammals which lived alongside the
dinosaurs for 20 million years”)

Time & Location:
16.00, 20.3.2012, C108 Physicum

Welcome

—Anton

Gregory P. Wilson, Alistair R. Evans, Ian J. Corfe, Peter D. Smits, Mikael Fortelius &
Jukka Jernvall

Nature (2012) doi:10.1038/nature10880

The Cretaceous?Paleogene mass extinction approximately 66 million years ago is
conventionally thought to have been a turning point in mammalian evolution. Prior to that
event and for the first two-thirds of their evolutionary history, mammals were mostly
confined to roles as generalized, small-bodied, nocturnal insectivores, presumably under
selection pressures from dinosaurs. Release from these pressures, by extinction of
non-avian dinosaurs at the Cretaceous?Paleogene boundary, triggered ecological
diversification of mammals. Although recent individual fossil discoveries have shown that
some mammalian lineages diversified ecologically during the Mesozoic era5, comprehensive
ecological analyses of mammalian groups crossing the Cretaceous?Paleogene boundary are
lacking. Such analyses are needed because diversification analyses of living taxa allow
only indirect inferences of past ecosystems. Here we show that in arguably the most
evolutionarily successful clade of Mesozoic mammals, the Multituberculata, an adaptive
radiation began at least 20 million years before the extinction of non-avian dinosaurs
and continued across the Cretaceous?Paleogene boundary. Disparity in dental complexity,
which relates to the range of diets, rose sharply in step with generic richness and
disparity in body size. Moreover, maximum dental complexity and body size demonstrate an
adaptive shift towards increased herbivory. This dietary expansion tracked the ecological
rise of angiosperms and suggests that the resources that were available to
multituberculates were relatively unaffected by the Cretaceous?Paleogene mass extinction.
Taken together, our results indicate that mammals were able to take advantage of new
ecological opportunities in the Mesozoic and that at least some of these opportunities
persisted through the Cretaceous?Paleogene mass extinction. Similar broad-scale
ecomorphological inventories of other radiations may help to constrain the possible