Fall 2010

Three of Carnegie Museum of Natural History’s own rock stars (left to right), vertebrate paleontologists Chris Beard, Zhe-Xi Luo, and Matt Lamanna.

Photo: Joshua Franzos


Rock Stars

Today’s top vertebrate paleontologists—many of whom will meet in Pittsburgh this October for their professional society’s annual meeting—are constantly digging up new clues to the history of life. And the more they learn, the more they’ll admit they’re only scratching the surface.

By Reid R. Frazier


A highlight of Dinosaurs in Their Time, this Camarasaurus is one of the most complete skeletons of a sauropod ever found, and was unearthed during a Carnegie expedition in 1919-1920. Photo: Joshua Franzos

They walk softly and carry a big pick. Or a medium-sized one, depending on what they’re into. They really dig animals, specifically those with backbones that lived thousands, or even millions, of years ago. They’re VPs—vertebrate paleontologists— and they’re coming to Pittsburgh.

When the Society of Vertebrate Paleontology convenes this fall at the David L. Lawrence Convention Center for its 70th anniversary meeting, the field will, in a way, be coming home. The city holds an important place in this area of science, mainly because of Carnegie Museum of Natural History’s many contributions. Carnegie Museum researchers have made some of the biggest fossil finds in history, and the museum’s paleontological collection is chock full of important specimens.

David Berman, Carnegie Museum curator of vertebrate paleontology, and Amy Henrici, collection manager, matched fossilized tracks found in Germany to the reptile-like creatures that made them some 295  million years ago—Diadectes and Orobates—which were among the first four-legged plant eaters on land. Photo: Joshua Smith

For a science so fixated on the past, the 1,200 or so professional paleontologists, students, and amateur enthusiasts who will attend the conference represent a discipline with more and more to say about the present and future of life on Earth. Their field is undergoing a kind of technological revolution, as researchers have begun using tools traditionally associated with molecular biology to extract DNA from fossils of Ice Age mammals and to analyze proteins of dinosaurs more than 65 million years old.

Perhaps even more importantly, paleontology continues to fascinate the public in a way that few other sciences can.

“Paleontology is up there with astronomy and deep-sea exploration as sciences with really broad popular appeal,” says Matt Lamanna, the museum’s assistant curator of vertebrate paleontology and one of its resident dinosaur hunters. “For children, especially, fossils can be the spark that ignites an interest in science.”

In 2000, Matt Lamanna co-led an expedition in Egypt that
unearthed the sauropod Paralititan, one of the largest
dinosaurs ever found. Photo: Joshua Smith

A science for today

For a paleontologist, the planet’s most vexing problems are really quite familiar. Climate change? The Earth,  evidently, has been there. Mass extinction? Done that one, too.

Vertebrate paleontologists are scientists who study the fossil record to learn about prehistoric animals with a backbone, such as dinosaurs and mammals, including our own ancestors. As a result, they’re well equipped to tell how large-scale environmental changes can affect the survival of species.

“How changes in climate impact life on Earth is an issue we deal with all the time,” says Chris Beard, the museum’s Mary R. Dawson Chair of Vertebrate Paleontology and a world-renowned expert on early   primates. “Paleontology has a unique role to play in this area for the simple reason that we can’t approach this problem experimentally. We can’t heat up the planet, see what happens, then run another experiment and do it again. But we can ask what happened in the past. These are big questions that only paleontology can address.”

Five years later, Lamanna was part of a team that uncovered
this sauropod jackpot in Patagonia, Argentina. Photo: Kenneth Lacovara

If you want to know what life was like the last time the atmosphere contained as much carbon dioxide as it does today—15 million years ago by some estimates—go see a paleontologist.

How will the current rate of climate change affect biodiversity? One way to look at this question is to go back 11,000 years, to the end of the Pleistocene Epoch or Ice Age, says Ross MacPhee, vertebrate paleontologist and longtime curator of mammalogy at New York’s American Museum of Natural History. Back then, a large number of big mammals like the woolly mammoth and the North American horse went extinct.
Did humans overhunt these animals? Was climate change the cause of their demise? MacPhee and a team of collaborating scientists are looking for trace amounts of DNA from extinct mammals found in Alaskan permafrost (permanently frozen subsoil) to answer these questions. Their initial findings show that these animals co-existed with humans for thousands of years. “It surely was not as simple as the original overkill argument,” MacPhee says. “It’s not just people coming in and the fauna collapsing around them. What it seems is the nature of the collapse was much more long-term.”

The lesson for today? Look for complex answers,  not simple ones, MacPhee says. Human encroachment surely was a factor in species extinctions during the Pleistocene, but there were other causes as well. “The more you dive into it,” MacPhee says, “the question gets more complicated.”
One of Chris Beard’s major finds, the lower jaw of Pondaungia, a 40-million-year-old “dawn monkey” from Myanmar.
Photo: Kenneth Lacovara

Under a microscope

Until recently, paleontologists did much of their work with the naked eye. They looked at fossils and compared them to others. But in 1991, a veterinarian examining a piece of T. rex bone under a microscope—just by chance at a conference—made a shocking discovery. The vet saw what looked to be ancient blood cells. Soft-tissues weren’t supposed to survive more than 65 million years of slumber. At least, that was what scientists thought. When Mary Schweitzer, the paleontologist who was studying the fossil, told others about the find, it stunned the field.

More than a decade later, Schweitzer debuted more images of cells and blood vessels from a different T. rex fossil at a Society of Vertebrate Paleontology conference. Lamanna, who was at her talk, recalls the audience’s reaction while watching videos she had taken through   a microscope.

“The crowd was gasping in awe, because Mary was showing these things that she’d pulled out of a T. rex leg bone that looked like what you’d get out of a chicken bone today,” Lamanna says.

A microscopic piece of still-stretchy soft-tisue from inside a T. rex leg bone
suggests that this specimen had not completely decomposed.

The observations could shed new light on myriad aspects of dinosaur biology, such as how these animals evolved and how their muscles, cells, and blood vessels looked and worked. Since Schweitzer’s initial discovery, paleontologists have made oodles of other mind-boggling finds by working with molecular biologists and other “gene jocks.” They’ve extracted DNA from a mastodon tooth between 50,000 and 130,000 years old, and from pine trees and insects at least 450,000 years old. And they’ve detected the same biomolecule in microbes more than one million years old. Scientists have partially decoded Neanderthal DNA, and revealed that these close human relatives probably mated with early Homo sapiens before going extinct around 30,000 years ago.

No, scientists won’t be able to clone a dinosaur like in Jurassic Park (at least not in the near future). But   they will be able to tell us more about how prehistoric animals lived, and how they were related to each other and to today’s species.

In rare cases, molecular paleontologists can even tell what color an extinct animal was, based on studies of tiny cellular structures called melanosomes. Recently, a team of scientists determined that one species of bird-like dinosaur had a dark gray body, a crown of red feathers atop its head, and long feathers banded in black and white on its fore and hind limbs.

“This is our first glimpse of what these animals might actually have looked like when they were alive,” Lamanna says. “Instead of having to guess at colors based on modern species, we may be able to know with more certainty how a particular dinosaur looked.”

“The more you discover, the more you realize this huge evolutionary process is a grand experiment in history. Our job is to discover how it happened.”

- Zhe-Xi Luo, Carnegie Museum of Natural History curator of vertebrate paleontology and associate director of science

Digging dinosaurs

Lamanna spends much of the year in remote regions of the Southern Hemisphere, making discoveries the old-fashioned way—with a pick and shovel. Digging for fossils is still the lifeblood of paleontology, and a well-spring for many important new finds.

“People are still discovering dinosaurs that nobody expected,” says Lamanna. “Every year, someone finds a species that no one, not even those of us who study these animals for a living, saw coming.” Indeed, in recent years, at least 20 new dinosaur species have been named every year—roughly one every two weeks.

Lamanna spent a good part of the past two years in Argentine Patagonia, the Australian Outback, and, most recently, Antarctica, in search of new fossils. He focuses his research on the southern end of the world for a simple reason—the dinosaurs of these continents tend to  be much less known than their counterparts in North America, Europe, and Asia. Among his specialties are gigantic, long-necked creatures called titanosaurs, which, he is learning, were the dominant plant-eaters throughout much of the Southern Hemisphere during the Cretaceous (the third and final period of the Age of Dinosaurs). Lamanna has been part of teams that have formally named five new dinosaur species, with several more on the way.

Discovering a new dinosaur might best be likened to the birth of a child, Lamanna says. “You’ve uncovered an animal that no one has ever seen before. Nobody knew it existed.”

New fossil finds can change our understanding of even comparatively well-known dinosaurs, such as the ceratopsians—the group that includes the famous three-horned Triceratops. A pair of recent discoveries, one in Hungary and the other in China, have substantially altered the way paleontologists think these horned dinosaurs evolved and moved about the planet.
An artist's rendering of the sauropod Paralititan, the giant titanosaur that
Matt Lamanna and colleagues discovered in Egypt in 2000 and named in 2001.
Painting by Todd Marshall
“This is the dinosaur group that we thought we knew the most about,” says Lamanna. “Yet in the span of a    few days this past spring, a couple of discoveries totally blew the accepted story of ceratopsian evolution and dispersal apart.”

Probing the mammalian family tree

Evolving around the same time as dinosaurs, early mammals were small creatures with canine-like teeth. Mammals arose from land-dwelling reptiles that walked on all fours, but precisely how and why this came to be is an area of intense interest among paleontologists.

One way to find out is to look at their teeth, precisely the method chosen by Zhe-Xi Luo, Carnegie Museum of Natural History’s curator of vertebrate paleontology and associate director of science. Luo—whose fossil discoveries, including Hadrocodium wui, the oldest known close relative of living mammals, have literally altered science’s view of how mammals originated and diversified—studies how the mammalian jaw evolved from a complex structure comprised of many bones, like that of a reptile, to one composed of a single bone with precisely matched teeth. Vast improvements in the structure of their teeth, as well as their simple, strong jaws, made mammals the best chewers in the world, allowing them to rapidly adapt to very diverse diets.

“The vast majority of non-mammals aren’t able to chew,” Luo says. “If you look at a crocodile, they just swallow things whole or in large chunks. Crocodiles, T. rex, snakes, barracuda, sharks, you name it. This adaptation is one of the most fundamental features that allowed mammals to become predominant in evolutionary history.”

An ancient mammalian relative newly discovered in South America, called Brasilodon, may provide the best clue yet as to when this happened. The animal was the size of a mouse and lived 210 million years ago. Its jaw shows both reptilian and mammalian features. A milestone in mammalian history? Perhaps, says Luo.

Brasilodon is showing some precursory conditions of the great transition of mammals from their ancestors,” Luo notes. “It’s almost a halfway stop between a near-mammal and a real mammal.” The teeth and jaws of these tiny, mouse-sized critters could yield fresh clues as to how the group of warm-blooded, furry animals to which we humans belong came to walk the Earth.

Meet cousin Ardi

Some 200 million years after Brasilodon, ape-like primates came down from the trees and began walking on two feet. For decades, paleontologists have wondered how it was that our forebears came to shed their knuckle-walking ways and ultimately evolve into our species, Homo sapiens. This year’s Society of Vertebrate Paleontology meeting will spotlight a recent discovery of a possible human ancestor that has shaken the scientific world.

Keynote speaker Owen Lovejoy is the Kent State University paleontologist who was part of the team of scientists who discovered and studied “Ardi.” Ardi is the world’s most complete fossil of the primate species Ardipithecus ramidus, a hominid (the group of species that includes humans and their direct ancestors) that could walk upright but that also had several tree-climbing features, including a thumb-like big toe and a pelvis suited to climbing.

For years, scientists have wondered whether “Lucy,” the famed skeleton that belongs to the species Australopithecus afarensis, did in fact represent the transitional stage in our evolution from knuckle-walkers to striding bipeds. (Scientists generally avoid the term “missing link.”) Lucy is 3.2 million  years old. Ardi, who is 4.4 million years old, was likely an ancestor of Lucy, and Lovejoy believes Ardi to be the species that brought early human ancestors out of the trees and onto the ground for good. “It is now quite clear the true transitional form was Ardipithecus and not Australopithecus,” Lovejoy says.

Chris Beard, an expert on the origins of anthropoids, the group of primates that includes all monkeys, apes, and humans, says Ardipithecus is such a new and pivotal discovery that it is bound to be controversial. One reason why is Ardi’s opposable big toe—a toe that juts out nearly perpendicular to its other toes so that it can bend and grasp things like tree limbs. It’s a real head-scratcher, Beard notes. Virtually every primate has this feature except humans. So, is Ardi an ancestor of ours, or not?
According to Chris Beard, this new fossil primate, Ganlea megacanina,
supports his belief that early anthropoids originated in Asia rather than Africa.
Mark A. Klingler/Carnegie Museum of Natural History

Also in this issue:

Ordinary Madness  ·  A Nut on the Plane: Marilyn in Midflight  ·  Hubble Vision  ·  Director's Note  ·  NewsWorthy  ·  Face Time: Mike Hennessy  ·  Science & Nature: Winging It  ·  Artistic License: Opening the Book on André Kertész  ·  Field Trip: Warhol in Coffee Country  ·  The Big Picture