more than double the canal’s capacity, allowing ships up to 1,200 feet long and 160 feet wide to make the transit. It will also allow ships to pass each other, even at the tightest spots, ending the alternating one-way system now employed. While the expanded canal is expected to be a boon to Panama and international trade, it is the construction that most interests MacFadden and his colleagues. The contractors are doing all the heavy lifting for the paleontologists, excavating more than 150 million cubic meters of soil. “This expansion is providing a oncein-a-century opportunity to access new rock outcrops rich in fossil diversity,” MacFadden says. “But within a year after the excavations are finished, all the outcrops will be covered by grass and no longer accessible to our team, so we’re racing against the clock for the next couple of years, trying to discover everything we possibly can.” And there’s a lot to discover in Panama, because millions of years ago Panama was the place where North met South. “Where we are right now was the southernmost tip of North America,” MacFadden says. “Just to the south, between here and Colombia, there was a very deep seaway called the Central American Seaway that was a barrier to animals dispersing into South America and animals coming from South America into North America.” Then, about 4.5 million years ago the two continents came together with the formation of the Isthmus of Panama, which served as a bridge for animals to cross in both directions in what’s called the Great American Biotic Interchange. “We’re interested in the kinds of animals that lived in this area before the formation of the bridge, about 19 to 21 million years ago, during the time period geologists call the Miocene,” MacFadden says. “That’s the age of the
18 Spring 2014
“THIS EXPANSION IS PROVIDING A ONCE-IN-ACENTURY OPPORTUNITY TO ACCESS NEW ROCK OUTCROPS RICH IN FOSSIL DIVERSITY.” — BRUCE MACFADDEN