Fossils of the Flaming Cliffs

[Quick series of archival photos, illustrations, and footage of various dinosaurs, paleontologists at work in the field, and museum visitors looking at exhibits.]

MICHAEL NOVACEK (Curator, Division of Paleontology): A lot of people think that when we say dinosaur extinction, we're talking about a global picture that we know really well. We do not.  

[An animated visualization of a large meteor hurtling toward the Earth, entering the atmosphere in flames, and then striking. Ash floats through a burned forest and the skeleton of a dinosaur looms in the foreground.]

NOVACEK: We know what happened to dinosaurs and other land animals in North America, 

[A hand points to a mollusk fossil. Various images of fossilized marine invertebrates and microscopic organisms.]

NOVACEK: …and the impact of the extinction on marine invertebrates and microorganisms in many places throughout the Earth. 

[Michael Novacek, a man with a light beard and a black sweater, speaks to camera in front of book-lined shelves.]

NOVACEK: But what happened elsewhere in the world? We really don't know. 

[Novacek unfolds a large map of the Gobi Desert on a table in his office.]

NOVACEK: Because we haven't precisely identified that extinction event in a lot of other places. So how global is this? 

[Museum visitors look at a dinosaur family tree. Various large fossil mammals are on display in a Museum hall.]

NOVACEK: Were all the dinosaurs that we know of all wiped out at the same time? Was it later? How fast was the diversification of mammals?

[Novacek zooms into a satellite image of the Gobi Desert on his desktop computer.]

NOVACEK: We want a global picture of what happened in this extraordinary slice of time in the history of life: 

[Footage from a drone swooping through the Hall of Saurischian Dinosaurs and around the Tyrannosaurus rex. A jerboa, a small rodent with incredibly large ears and an almost pig-like nose excavates a hole in the desert sand.]

NOVACEK: …the time between the sort of the Camelot of the dinosaur empire—to put it in a corny way— and the beginning of the age of mammals, the beginning of the modern era. 

[A small group of paleontologists excavate a fossil surrounded by the barren sands and hot sun of the Gobi Desert.]

NOVACEK: To have a better resolved and a more global picture of what happened here, is extraordinarily important. 

[Novacek stands in the Gobi Desert, looking out at a geologic formation. The AMNH logo animates out on top of the footage.]

NOVACEK: I'm Michael Novacek. I'm a curator at the American Museum of Natural History.

[Novacek and a fellow paleontologist walk in the Gobi in the present day. A montage of slides shows Novacek and his colleagues during their work in Mongolia in the 1990s.]

NOVACEK: I started working in the Gobi, with our team from the American Museum and Mongolian paleontologists more than 30 years ago. 

[Close-ups of various fossils found in the Gobi, including a pair of oviraptors, a dinosaur fossilized on top of its egg-filled nest, a small rodent-like mammal fossil, and pieces of an ancient lizard’s skull and jaws.]

NOVACEK: What keeps us coming back are these incredible fossils: dinosaurs, but also sites where the animals were actually preserved brooding on their nests, and lots of mammals, and lizards, and everything else.

[Two researchers confer at a fossil site in the Gobi.]

YI HONGYU (Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences): And this is not the croc that we used to find.

MAUREEN O’LEARY (Stony Brook University): That’s amazing.

HONGYU: So, it’s something new.

[Two geologists clamber around the top of a large red rock formation in the Gobi Desert, gathering samples.Novacek and O’Leary look out across the rock formations of the Gobi Desert landscape.]

NOVACEK: And also the rocks that contain those fossils. Because we're learning a lot more about what the rocks can tell us about life around 80 million years ago. 

[A paleontologist brushes dirt off a dinosaur fossil in the red sands of the Gobi.]

NOVACEK: Fossils do tell us in a general sense, what the age of beds can be, if we're trying to correlate different groups of animals from different parts of the world. 

[Archival diagram of complicated geological strata. The word “biostratigraphy” animates out along the illustrated formation’s contours.]

NOVACEK: But biostratigraphy… 

[Illustrations of various fossil shells, teeth, etc. animate on screen in quick succession.]

NOVACEK: …where certain assemblages of fossils indicate one slice of time… 

[The previous fossils disappear and a new set of different fossils pops in.]

NOVACEK: …and different kinds of species will represent another time, it has its limitations… 

[Dramatic rock formations make up a distant horizon, and in the foreground, delicate yellow flowers stand out against the desert sands.]

NOVACEK: …because it needs an independent calibration from something that's not biological. 

[Camera pans across a huge red rock formation.]

NOVACEK: So, rocks are very important as a clue.

[Novacek, O’Leary and two other scientists confer in a windy desert site.]

NOVACEK: We're working in the Western Gobi…

[A map of Mongolia animates out and quickly zooms into a region in the south of the country. Text labels it as the Nemegt Basin.]

NOVACEK: …in a vast valley called the Nemegt Basin. 

[Team members hike through starkly beautiful landscapes. Some of the formations are a deep red color, and others a light tan, or ashy grey.]

NOVACEK: There are about 4 or 5 different rock units that we call formations in that western section. They range all the way from the Late Cretaceous through the earliest stage of the age of mammals, the Paleogene. 

[Three geologists gather samples on the sharply sloping face of a rock formation. Two paleontologists closely examine a fossil as they brush away dirt. Novacek confers with colleagues in the windy desert landscape.]

NOVACEK: The last couple seasons, especially, we have the geologic team, the geologists, and then we have the paleontologists. And there’s kind of people like me who run back and forth between the two.

[Novacek speaks to camera in his office.]

NOVACEK: We found fossils that were supposed to be from younger beds in older beds. 

[A geologist examines a small specimen with a loupe. Team members hike through the desert and collect rock samples.] 

NOVACEK: So, it suggests there's more of a complex pattern in terms of age dating and certainly biostratigraphy than we thought before. It’s hard to over-express the excitement of working with this new geologic team. 

[Novacek speaks to camera in his office.]

NOVACEK: I've worked in these beds for over 30 years in these rocks and with these fossils, and to see it through their eyes is just a tremendous window that's been clarified.

[Two geologists look out across the desert landscape.]

ERIC ROBERTS (Colorado School of Mines): …because it’s irregular where it starts and ends.

WILLIAM WOLFE (PhD Student, Colorado School of Mines): Right, exactly.

[A geologist chips off a piece of rock and hands it to her colleague.]

SARAH SLOTZNIK (Dartmouth College): I’m not seeing anything here.

NOVACEK: So the geologic team is applying a number of different techniques. 

[Wolfe wearing sun-protective gear and a large backpack walks through the desert landscape.]

NOVACEK: Step one: just simply read the rocks. 

[Wolfe, Roberts, and Slotznick look out on rock formations and take notes.]

ROBERTS: The dip might be a little bit steeper.

NOVACEK: Measure the thickness of certain kinds of rocks. Record the faults in the cracks and whether there's discontinuities or breaks in the rock record there. 

[Roberts chips away at an exposed rock wall as Slotznick looks on. The rock formation displays clear bands of different-colored strata.]

NOVACEK: Stratigraphy is the framework. It's the scaffold from which we can build a history. That's our map. It's our map in time.  

[Roberts, Wolfe, and Slotznick hike down a steep, sandy slope, carrying their gear.]

NOVACEK: Step two is sampling. 

[Slotznick drills into a rock wall, collecting small core samples. She inserts a measurement device into a rock face.]

NOVACEK: And the sampling involves drilling for small cores that we hope will give us good measurements of what we call paleomagnetics. 

[An animated illustration of the Earth’s sphere, surrounded by magnetic field lines. Poles are labeled “N” and “S.” The two poles then switch places several times, N replacing S, and S replacing N.]

NOVACEK: The Earth is enclosed in a magnetic field and that field flip-flops, it reverses its pole from time to time. 

[As Novacek speaks to the camera in his office, an animated timeline appears alongside him. The left side of the diagram is a vertical scale marked from 0 to 5, representing time in millions of years ago. “0” at the top represents the present day. The center of the image features a vertical bar composed of alternating white and black horizontal bands. White bands represent periods of normal polarity, the magnetic field oriented as it is today, and black bands represent periods of reversed polarity, where the magnetic north and south poles were swapped.]

NOVACEK: That is miraculously recorded in the rocks. And we know enough about a chronology, about a calendar that’s based on a series of reversals, that we can get an estimate of how old those rocks are.  

[Roberts, Wolfe, and Slotznick take notes on the desert landscape under a glaring sun.]

NOVACEK: In the last few years, there have been a lot of new ways of looking at the rock record that we didn't have before. 

[Close-up of a research publication titled “U-Pb calcite age dating of fossil eggshell as an accurate deep time geochronometer.” The camera zooms in even further to highlight the phrases “fossil eggshell” and “deep time.”]

NOVACEK: We now have abilities and new techniques, like very recently a paper was published…

[Roberts and Hongyu examine samples of dinosaur eggshells in the Gobi Desert.]

NOVACEK: ...one of the authors is also a member of our team—that dinosaur eggshells can be dated using uranium and lead signals. 

[An expedition team member puts small pieces of fossil eggshell into a small white specimen bag. Close up on hands wrapping samples in a plastic bag on top of a field notebook labelled “2025 Geology Catalogue”.]

NOVACEK: We now have provided samples to that lab from our sites, so we’re anxious to see what the results are.

[Novacek speaks to camera in his office.]

NOVACEK: It’s basically forming a web of correlation that gives us stages and ages for those rocks. The overall goal for all of this is resolution. 

[A series of photographs transform from blurry pixellation into detailed, high-resolution images.]

NOVACEK: Just like a photograph, the greater the resolution, the greater the information. 

[Wolfe and Slotznick take measurements on a rock formation.]

NOVACEK: And so, we’re trying to maximize the resolution. 

[Novacek speaks to camera in his office.]

NOVACEK: Seventy-five plus or minus half a million years can make a big difference. 

[Museum visitors stand in front of the duck-billed Anatotitan dinosaur fossils in the Hall of Ornithischian Dinosaurs.]

NOVACEK: Certainly it did with the dinosaur extinction event. 

[An expedition team member closely examines a fossil with a loupe and then shows it to Hongyu Yi.]

NOVACEK: So, we’re getting closer to a much more resolved picture of what was actually happening over shorter spans of time. 

[Time lapse sequence of clouds skittering through a bold blue sky over a pyramidal rock formation in the Gobi. Novacek and O’Leary prospect for fossils in the stark landscape.]

NOVACEK: Once we have a much better picture of what’s happening in the Gobi Desert in terms of these chronologies, we can really apply that on a global scale. We’ll have an opportunity to match our results with these other places in the world. 

[Novacek examines a fossil under a microscope in his office.]

NOVACEK: There’s an extremely important relevance to the origin of the modern mammal groups, especially the placental mammals: 

[Close-ups of a treeshrew, a snow monkey, a whale’s tail, a bat, a small rodent poking its nose out of a hole, and a fossa—a cat-like carnivore—peering from a tree perch.]

NOVACEK: …the orders of mammals that include primates and whales and bats and rodents. 

[A group of camels in the Gobi sands.]

NOVACEK: They’re the dominant land animals on Earth for the last 66 million years or roughly that. 

[Novacek confers with his colleagues in the windy desert landscape.]

NOVACEK: So, you know, how did that happen? How fast? A more refined record could tell us more about that. There’s no question. And tell us more about that in a global sense. 

[Video credits.]