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A Mammoth Mystery
For over a million years, huge mammoths roamed across every continent except South America and Antarctica. But the last of them became extinct about 10,000 years ago. Ross wanted to know why. Popular theories were that overhunting and climate change led to their extinction. But neither of these theories convinced Ross. Then he read about the Ebola virus, a human disease that suddenly appeared a few decades ago in Africa, probably because it 'jumped' from some other host and rapidly adapted to humans. He thought, "Why couldn't that happen to other mammals?" Ross proposed that many large mammals went extinct in the past 40,000 years because of diseases introduced by migrating humans. To test his idea, he traveled to Wrangel Island, Siberia—the last place on Earth mammoths survived. With a team of scientists, he recovered bones and teeth of extinct mammals like mammoths. Back in the lab, the team is studying genetic information from these bone samples. They hope to isolate the DNA of the "germ" that carried the disease.
Hometown: Edmonton, Alberta, Canada
Job: Curator, Division of Vertebrate Zoology
Education: PhD, University of Alberta, Canada
Focus of Work: extinction of mammals within the last 40,000 years
Research Locations: Antarctica, Siberian tundra, the Caribbean islands
Cool Fact: Ross can determine the age of a mammoth fossil by counting the rings of its tusk.
Ross has discovered fossils of large extinct mammals, like mammoths, giant sloths, and huge condor-like birds. A term for them is:
megaflora
microfauna
megafauna
Correct!
Mega means big and fauna means animals, so megafauna means big animals—specifically, mammals weighing more than 100 pounds. Ross researches why so many megafauna became extinct at the end of the last ice age.
Mammals like primates and sloths live in the Greater Antilles islands hundreds of kilometers from Florida. Ross hypothesizes that:
ancestors of these mammals swam from the mainland
these mammals evolved from birds that flew to the islands
the islands were once part of a land area connected with S. America
Correct!
Ross has found fossils that support the hypothesis that the islands were once part of a land area that connected with South America. He's interested in how many different mammal species have colonized these islands.
One of Ross' biggest finds was a fossil smaller than grain of rice.
Fact
In Antarctica, his team found a tiny tooth of an extinct mammal. It's similar to fossils found in Madagascar, Africa, and North America, sugg-esting the landmasses were once connected.
We don't have a time machine, so we can only make informed guesses about what the planet looked like millions of years ago from the fossils of extinct plants and animals.
Ross MacPhee,
Paleontologist
The best part of my job is fieldwork. I get to go to fascinating places, dig around in the dirt, and find interesting things.
Ross MacPhee,
Paleontologist