What does it mean to be a 21st-century American naturalist? On Tuesday, April 9, join moderator Tom Brokaw and panelists Douglas Brinkley, a Roosevelt biographer; Lisa Graumlich, scientist and dean at the University of Washington's College of the Environment; Michael Novacek, senior vice president and provost of science at the Museum; and Rick Ridgeway, vice president for environmental initiatives at Patagonia, for Conservation, Wilderness, and the American Dream, a special event about the close links between American identity and natural heritage, as well as the role today's naturalists can play in conservation.

It's down to just a final, furry 4 potential nicknames for our hypothetical placental ancestor! Vote for the two finalists now.

Okay, just 8 possible nicknames left. Does our hypothetical common placental ancestor look more like a Placentor or a Mancestor? Nova or Hypotheshrew? Make your vote today for a final, furry 4!

Watch the 2013 Isaac Asimov Memorial Debate, moderated by Hayden Planetarium Director Neil deGrasse Tyson at the American Museum of Natural History, on Wednesday, March 20, at 7:30 pm EDT on amnh.org/live. 

Nearly 3,000 people cast their vote during our first round of March Mammal Madness, narrowing the possible names for our hypothetical common placental ancestor down to 16. Help us narrow down the choices even further by voting for your favorites below. You have until 5 pm EDT on Tuesday, March 19, to make your selections.