University of Michigan paleontologist Philip Gingerich and colleagues from the University of New Hampshire, Colorado College, and the California Institute of Technology presented new research at the Nov. 1, 2013, session of the annual meeting of the Society of Vertebrate Paleontology in San Francisco, California that indicates present climate change may result in dwarfism in mammals based on a rigorous study of the fossil past.
The researchers examined fossil evidence of decreasing size in mammals from the Paleocene-Eocene Thermal Maximum that occurred 55 million years ago and the Second Eocene Thermal Maximum that occurred about 53 million years ago.
The researchers used mammal tooth size as a direct comparative example of animal size that correlated with temperature changes during the two events. Teeth from fossils are some of the most enduring evidence of animal size.
Average mammal size decreased about 30 percent during the Paleocene-Eocene Thermal Maximum with an accompanying rise in temperature of nine to 14 degrees Fahrenheit. Average mammal size decreased by 19 percent during the Second Eocene Thermal Maximum with accompanying temperature increases of five degrees Fahrenheit.
Primates, horses, and large mammals all demonstrated the same reaction to increasing temperatures. The most probable cause in the reduction in mammal size was lack of food sources and lack of water.
The researchers note that similar mammal dwarfism may occur as the result of present climate change.