6 November 2015

“Making North America,” episode 2: Life

Posted by Callan Bentley

The PBS series NOVA has a new three-part series called “Making North America” that premiered last week. Hosted by the director of the Smithsonian Institution’s National Museum of Natural History, Kirk Johnson, the series will explore the tectonic assembly of terranes that resulted in the bedrock of the continent, the panoply of diverse creatures that have dwelled here in the past, and the human prehistory of our continent. I was given press access to review the episodes in advance. I’m covering them one by one.

Episode 2 is about paleontology, and the extraordinary natural heritage of our continent’s fossils. This is a topic near and dear to the host, a paleobotanist who tweets as @leafdoctor.

The episode begins on the Kaiparowits Plateau in Utah, where Kirk begins with the general public’s favorite fossils, dinosaurs. He points out North America’s rich dinosaur heritage, and asks why it might be so diverse. That guiding question takes viewers to the Bahamas, where Kirk scuba dives to examine stromatolites in the tidal current-scoured channels where they persist despite the attempts of corals and seaweed to colonize their exteriors. I appreciated the program referring to the microbes that built up the stromatolites as bacteria rather than “algae,” as is often the case in public-interest programs like this. In a related segment, Kirk and a local expert wade into a shallow lake to examine in situ microbial mats, which they examine in hand and say resembles “nasty black lasagna.”

The stromatolites of course pumped out a bunch of waste gas, and that totally transformed the world (sound familiar, Industrialized humans?). That sets the stage for the future evolution of animals. So then we go to Kansas, and visit Monument Rocks, a place I visited with Ron Schott when he made the GigaPan that’s one of many featured in the new “Explore North America” virtual experience on the NOVA website. (I have one that’s included in the collection, too!) There, the paleogeography of North America during the Cretaceous is explored, though the word “Cretaceous” only slips in once by my count. Then, the Western Interior Seaway divided the continent into two isolated landmasses, each with its own unique dinosaur evolutionary trajectory.

In the badlands of North Dakota, Kirk examines the K/Pg boundary by digging up the boundary layer, and showing in the field with a small microscope the little impact spherules (tektites) that rained down in North Dakota due to the Chicxulub impact. This was pretty cool – I’ve seen that layer in that same formation (the Hell Creek Fm.) but hadn’t seen the spherules.

There’s a nice graphic where Kirk and colleague look at a cliff where the Z Coal (base of the Hell Creek) is exposed, and below it, the magic of computer animation draws in dinosaurs, and above it, other animals, but no dinos (other than a duck). It’s a nice composition – combining stratigraphy with a cartoon sketch.

The extinction of the dinosaurs leads to the rise of mammals, and footage of Kirk in a lemur sanctuary feeds into an examination of why there are so few native primates on North America before people: ancient climate change led to ecological turnover and a drier, grassland dominated ecosystem, which was rough on the arboreal primates. That changed when people invaded, and that sets the stage for Episode 3 of the series.

In all, it was a grand sweep, and I felt the narrative arc was more fully expressed than in Episode 1.

The gender balance wasn’t as balanced in this episode, though: of the named experts, five were men and two were women.

Episode 2 airs on November 11. Check your local PBS station for times.