In their quest to understand what kind of hunter the extinct marsupial thylacine was, two paleobiologists built a dataset of forelimb bone measurements that predict the predation style of a wide variety of carnivorous mammals. They describe the data in a study posted online in the Journal of Morphology.
PROVIDENCE, R.I. [Brown University] — At the start of their research, paleobiologists Christine Janis and Borja Figueirido simply wanted to determine the hunting style of an extinct marsupial called thylacine (also known as the “marsupial wolf” or the “Tasmanian tiger”). In the end, the Australian relic, which has a very dog-like head but both cat- and dog-like features in the skeleton, proved to be uniquely unspecialized, but what emerged from the effort is a new classification system that can capably predict the hunting behaviors of mammals from measurements of just a few forelimb bones. (more…)
In a new paper in the Proceedings of the Royal Society B, scientists propose that the bony structures in the skin of many early four-legged creatures might have been there to relieve acid buildup in bodily fluids. Analysis of their anatomy suggests that as they ventured out of water, the animals would have had trouble getting rid of enough CO2 to prevent acid buildup.
PROVIDENCE, R.I. [Brown University] — Here’s an anatomical packing list for making that historic trip from water to land circa 370 million years ago: Lungs? Check. Legs? Check. Patches of highly vascular bone in the skin? In a new paper, scientists propose why many of the earliest four-legged creatures that dared breathe on land carried bony skin features. (more…)
*Climate changes profoundly influenced the rise and fall of six distinct, successive waves of mammal species diversity in North America over the last 65 million years, shows a novel statistical analysis led by Brown University evolutionary biologists. Warming and cooling periods, in two cases confounded by species migrations, marked the transition from one dominant grouping to the next.*
PROVIDENCE, R.I. [Brown University] — History often seems to happen in waves — fashion and musical tastes turn over every decade and empires give way to new ones over centuries. A similar pattern characterizes the last 65 million years of natural history in North America, where a novel quantitative analysis has identified six distinct, consecutive waves of mammal species diversity or “evolutionary faunas.” What force of history determined the destiny of these groupings? The numbers say it was typically climate change.
“Although we’ve always known in a general way that mammals respond to climatic change over time, there has been controversy as to whether this can be demonstrated in a quantitative fashion,” said Christine Janis, professor of evolutionary biology at Brown University. “We show that the rise and fall of these faunas is indeed correlated with climatic change — the rise or fall of global paleotemperatures — and also influenced by other more local perturbations such as immigration events.” (more…)
