The Björn Kurtén Club is hosting a guest lecture
Mammals from the Age of Dinosaurs by
Steinmann-Institut für Geologie, Mineralogie und Paläontologie, Universität Bonn, Nussallee 8, 53115 Bonn, Germany
Mammals are the dominant vertebrates on land, having colonized almost all kinds of environments. The great mammalian radiation began after the extinction of the dinosaurs about 65 million years ago, and subsequently the modern diversity arose. However, the history of mammals started much earlier, some 200 million years ago in the Late Triassic, meaning two thirds of mammalian evolutionary history occurred in the Mesozoic, alongside the dinosaurs. The Jurassic is particularly important for mammalian evolution, with important key characters of modern mammals having evolved. Mammals are characterized by two highly complex sets of features which can be studied in both living and fossil species; tribosphenic molar teeth, with a grinding function in addition to the primitive piercing and cutting; and the inner ear, with a coiled cochlea and three middle ear bones. Recent work and new fossils have thrown up surprises in the evolution of both these features.
For a long time, Mesozoic mammals were regarded as small insectivorous animals without any particular specializations. Spectacularly preserved new fossil discoveries of basal/primitive mammals in the Jurassic have revealed striking body plans and lifestyles that were inconceivable a decade ago for early mammals. Castorocauda from Mongolia reveals the oldest fossilised fur and was perfectly adapted for swimming with a beaver-like, flattened tail covered by small horny scales and webbed hind feet. Volaticotherium was a climber with a gliding membrane like the modern sugar glider. Fruitafossor, from the U.S.A., was a burrower and had enamel-less peglike teeth, like those of living armadillos that feed on ants/termites. These highly specialized Jurassic mammals lived and became extinct during the Mesozoic. In contrast the direct ancestors of modern mammals, such as Henkelotherium from the Jurassic of Portugal, were more generalized. They survived extinction at the end of the Cretaceous and evolved into the spaces left by the dinosaurs.
Professor Thomas Martin’s lecture will explore this fascinating Jurassic mammalian world, weaving these new fossil discoveries with his work on the body plans and lifestyles, teeth, and inner ears of Jurassic mammals, and stories from his fieldwork across the globe. The exciting new fossils may be just a glimpse of what is to come, demonstrating that we stand at the threshold of a dramatic change in the picture of early mammalian evolutionary history.
Time and location:
8.2.2012 (Wed.), 16.00, E204, Physicum, Kumpula Campus