Past Time

Whales are spectacularly specialized mammals that seem perfectly adapted to their marine habitat. Plenty of other mammals have gone back to the water, but whales take it to a whole new level. No back legs, weird ear bones, noses on top of the head. What could the land-based ancestor of whales possibly looked like? Is there a fossil record of walking whales? In this episode we discover whales belong to the hooved animal group called Artiodactlys and their closest relatives, according to molecular comparisons, are hippos! But hippos and extinct fossil whales don't look very much alike. How did paleontologists, like our guest Dr. Marueen O'Leary, figure out the origins of whales, and how will they figure out the origins of hippos? As always, there are always more questions to answer when we start digging into the fossil record!

Mammals were scrambling around during the Age of Dinosaurs and they're usually seen as small, shrew-like animals waiting for their chance to become diverse. But recent research, including three new fossils discovered in 160 million-year-old rocks from China, show our mammalian cousins were ecologically specialized creatures. Arboroharamiya was climbing through the trees while Megaconus scrambled along the ground, and Rugosodon lead the way for the diverse radiation of mammals called Multituberculates. In this episode, Matt tries to show Adam why these new, tiny mammals are so interesting and where they fit into the mammalian tree of life.

The fossil record is pretty patchy. Most discoveries are tooth fragments, chunks of shell, or isolated slivers of bone and paleontologists are trained to eke out as much information from these precious fragments as they can. But some fossil deposits preserve more than just bones and teeth. Called "Lagerstätte" some rare deposites preserve traces of difficult-to-fossilized soft-tissues like feathers and fur. Some even preserve an animal's last meal before it entered the fossil record. In this episode of Past Time, Matt and Adam discuss Messel, a German fossil site that is one of the best examples of the biological and ecological knowledge preserved in these rare Lagerstätten deposits. Early bats, mini horses, and galloping crocodiles once roamed this extinct jungle in the heart of Europe. The exquisite preservation at Messel lets paleontologists travel back to this exotic ecosystem to tease out connections between the beginning of the Age of Mammals and modern tropical environments.

Humans are weird animals. We walk around on two legs, we have big brains...and we like to throw things at each other. Did all this happen in a gradual march to Homo sapiens? In this episode of Past Time, Adam and Matt talk to Dr. Susan Larson, an expert on the anatomy of living and extinct apes. Dr. Larson and Matt will try to convince Adam that mammalian and primate evolution is actually pretty interesting stuff. Dr. Larson's research introduced new wrinkles to the smoth transition from a chimp-like ancestor to us. Her work shows our close bipedal ancestors - like "Lucy" the Australopithecus and "Turkana Boy" the Homo erectus/Homo ergaster - had very different shoulder blades than ours that limited their ability to rotate their arms. This arrangement would have made throwing difficult for Homo erectus and you would have left him on the bench for the playoffs. The evolution of pitching in recent human ancestors shaped our modern anatomy and is part of what makes us human!

Meet Ocepechlon, one of the strangest turtles to ever paddle the open ocean in our first Past Time Quick Bite! This new species was announced a few weeks ago based on a lone, beautifully preserved skull from the Late Cretaceous (end of the Age of Dinosaurs) of Morocco. The gigantic animal had a long, tubular snout that the discoverers have interpreted as an adaptation to suction feeding, a specialized feeding method used by lots of aquatic animals including some types of whales. But this would be the first known suction-feeding sea turtle. Ocepechelon also has its nasal opening placed high on its head, between its widely spaced eyes, just like the spout of a whale. Based on the researcher’s analysis, its closest relatives include the gigantic leatherback sea turtle, a huge, beautiful animal that is critically endangered. In case you were cruising for a new favorite, bizarre sea turtle, look no farther than Ocepechelon! Images and comparisons are up at www.pasttime.org