Today we’re wrapping up our tour of the Michigan State University Museum’s Hall of Evolution with a stroll through the Cenozoic Era (65.5 million years ago to present). Divided into three time periods (Paleogene, Neogene, and Quaternary), the Cenozoic begins, like its predecessor, with the fallout left behind by another brutal extinction. The great dinosaurs along with almost half of the species on earth were wiped out. A massive 65 million-year-old crater on the Yucatan Peninsula in Mexico lends credence to the theory that an asteroid was responsible this time around.
During the Cenozoic Era, temperatures cooled, the continents settled into their current locations, and sea levels receded. The earth continued to make a herky jerky path around the sun, causing dramatic shifts in climate. Life on the planet endured not one, but twelve glaciations (think subzero temperatures, mountains of snow and glaciers miles thick with ice). Land bridges temporarily formed between the continents and like a Midwestern retiree, species migrated in the hopes of finding warmer climes.
When the earth wasn’t covered in ice, life on the planet flourished. The interior seaways–our good friend, Xiphinactinus’s cruising grounds—drained away. Fish and whales dominated the ocean, avian dinosaurs (aka birds) filled the sky, smaller reptiles (crocodiles, turtles, snakes) slithered about, and mammals thrived and diversified.
One such mammal is the Australopithecus afarensis (3.85 to 2.95 million years ago). Discovered in 1974, by Donald Johanson and Tom Gray, this hobbit-sized (3 ½ feet tall) hominid was a historic addition to our evolutionary tree. Nicknamed Lucy, this darling of the paleontology world possessed both ape (flat nose, large lower jaw, small brain, and chimp-like, tree climbing feet) and human characteristics (stands upright and walks on two legs).
Here was an ape-brained little creature with a pelvis and leg bones almost identical in function with those of modern humans. ~Donald Johanson, Lucy: The Beginnings of Humankind (1981)
Despite their ape-brains and munchkin size, the Australopithecus afarensis were robust and adaptable, qualities vital to survival during the Cenozoic Era (remember all that snow and ice?). Adapting to life on the ground and in the trees, Lucy and her kind roamed the earth for 900,000 years—four times longer than humans—and they did it without smart phones and the internet 😉
This concludes our prehistoric trip through time. Next week we’ll fast forward to the Renaissance and that ultimate man about town, Leonardo da Vinci.
Fun Lucy Facts: After Donald Johanson and graduate student, Tom Gray discovered Lucy’s bones, they returned to camp, kicked back and celebrated the find with the rest of their team.
While we were talking, Sgt. Pepper’s Lonely Hearts Club Band was playing on a small Sony tape deck. When “Lucy in the Sky with Diamonds” came on, my girlfriend Pamela Alderman, who had come to spend some time in the field with me said, “Why don’t you call her Lucy?” ~ Donald Johanson, Lucy’s Legacy: The Quest for Human Origins (2010).
And the rest, as they say, is history. Take a listen to Lucy in the Sky with Diamonds
Fun Family Facts: The earliest homo sapiens first lived 200,000 years ago in Africa. They are characterized by their large brains and slighter frames in comparison to other hominids. You may be surprised to learn modern humans (homo sapiens) did not evolve along one straight line of ancestry. To learn more, check out the Smithsonian Institute’s Human Family Tree.
Sources:
Johanson & Edey (1981), Lucy: The Beginnings of Humankind
Johanson & Wong (2010), Lucy’s Legacy: The Quest for Human Origins
Michigan State University Museum
Smithsonian Institute Human Family Tree
Museum Bites 