This month, a team of international researchers led by the American Museum of Natural History and Stony Brook University determined in unprecedented detail what the earliest ancestor of placental mammals—the widely diverse group of animals ranging from whales to bats to humans—looked like.  The Museum is teaming up with WNYC’s Radiolab to sponsor a tournament to name this early ancestor. Want to enter? 

A small, furry-tailed, insect-eating creature was the earliest ancestor of placental mammals—a widely diverse group of animals ranging from bats to humans—according to a new study in the journal Science by a team of international scientists, including a core group of Museum researchers. 

To walk the fourth floor of the Museum — peering at the jagged “teeth” of armored fish Dunkleosteus, ducking under the 23-foot wingspan of the flying reptile Pteranodon, studying the long curved tusks of the elephant relative Mammuthus — is, in a sense, to walk the tree of life.

Each branching point represents the arrival of an evolutionary innovation — jaws, water-tight eggs, hooves, respectively — that unites one group of animals and distinguishes them from lineages that lack the feature. Known as synapomorphies, or shared traits derived from a common ancestor, these are the tracks of evolution.

Scientists have used trees to order life since before Charles Darwin first scribbled a spiky diagram in his notebook. In the 1950s, German biologist Willi Hennig formally proposed that trees of life should reflect evolutionary relationships among organisms, founding cladistics: a method for grouping organisms into ancestor-descendent clades, from the Greek word for “branch,” based on shared, derived features. But it took a Museum scientist, ichthyologist Gareth Nelson, to disseminate the idea among English-language biologists. Together with students and colleagues at the Museum — including another ichthyologist, Donn Rosen, paleontologists Eugene Gaffney and Niles Eldredge, ornithologist Joel Cracraft, and invertebrate specialists Norman Platnick and Randall T. Schuh – Nelson steadfastly argued the case for cladistics as the tool to test classification during academic talks, in research papers, and even on napkins over meals.