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Paleontology

Above, a photo of Turkana taken from a single engine plane shows the Koobi Fora spit and Lake Turkana alongside a time map. Photo from Bob Raynolds

By Daniel Dunaief

In a wide-ranging interview, Louise Leakey, Director of Public Education and Outreach for the Turkana Basin Institute and a Research Professor in the Department of Anthropology at Stony Brook University shared her thoughts on numerous topics in the field of paleontology.

Louise Leakey at the Richard Leakey Memorial Conference on June 5. Photo by John Griffin/SBU

Leakey, who earned her PhD at the University College London, suggested that the process of finding fossils hasn’t changed that much, although other options beyond scouring a landscape for fragments of the world’s former occupants may be forthcoming.

“It may very well change if we can implement machine learning with high resolution imagery, using drones,” she said. “That’s one of the things we’re looking at the moment.”

What’s really changed, however, is the accuracy field scientists have in marking where, and, importantly, when new discoveries originated, she said.

Geologists like Bob Raynolds, Research Associate at the Denver Museum of Nature & Science, have created time maps that indicate the approximate age of sediments around a fossil in some select areas of the Turkana Basin.

These maps “can be uploaded onto an iPad app for use in the field that shows you in real time where you are on the geological map,” Leakey explained. “This is a game changer for field work in the basin.”

A time map created by Bob Raynolds in collaboration with Geologic Data Systems, a Littleton, Colorado company.

The maps represent the work of many people, Raynolds explained.  Originally, teams of Master’s students used air photographs, tracing paper and ink to make a map. These students spent many weeks walking systematically on the ground and tracing the patterns on the photos.

The rugged and isolated nature of the ground in Northern Kenya makes the work done on foot difficult, Raynolds explained.

The original maps, which were made in the 1970’s, took months to make and were presented as paper copies in unpublished Master’s theses. After numerous enhancements, Raynolds, working with companies including Geologic Data Systems in Littleton, Colorado, created time maps.

The internal GPS on an iPhone enables a blue dot to indicate a person’s location on the map.

“I have worked on the maps to make a new set of derived products that are maps of the age of the rocks,” said Raynolds who created these time maps earlier this year. “The resolution of the time maps is 100,000 years” which is an “astonishingly detailed resolution for us who are accustomed to million year packages of time.”

The maps cover the entire Turkana Basin at various scales, Raynolds added.

More broadly, Bernard Wood, University Professor of Human Origins in the Center for the Advanced Study of Human Paleontology at George Washington University and the first speaker at a recent Stony Brook University conference to honor Richard Leakey, explained that dating fossils has become increasingly accurate.

The first dates of fossils in the KBS Tuff, which is an ash layer in the Koobi Fora Formation east of Lake Turkana, was estimated within 260,000 years of a specific date. Using improved methods, a study published this year has reduced that range to 600 years.

Publishing pace

In the meantime, the pace of publishing has slowed considerably.

“There’s so much more material” that can serve as a frame of reference for new discoveries, Leakey said. “The rate of publication is frustratingly slow for some of these specimens.” This contrasts dramatically with the experience of Leakey’s father Richard.

When the elder Leakey submitted his letters or paper to the prestigious journal Nature, the late editor John Maddox never sent them out for review. “[Maddox] explained that he couldn’t see the point, because they concerned fossils so recently discovered” that few had seen them, Wood explained in his presentation.

Louise Leakey also differed from Richard in earning her bachelor’s degree and PhD, while her father dropped out of high school and never received any additional formal education.

Wood suggested that, next to marrying Meave, the elder Leakey described leaving school as one of the best decisions he’d ever made.

For his daughter, though, Leakey “encouraged me to go and do that,” Louise Leakey said. The education helped “in terms of being able to be [principal investigator] on grant applications,” she said.

Leakey suggested it was a “real privilege to be able to spend time” earning her PhD. She also found that the educational experience gave her the opportunity to “stand on my own two feet” in her research.

Like her father, Louise Leakey is concerned about conservation and declining biodiversity. When she was younger, she saw areas that were teeming with wildlife. On a recent three-hour drive, she only saw a golden jackal and a dik-dik, which is a type of small antelope, compared with the much wider variety of creatures she would have seen decades ago, such as Grévy’s zebra, Burchell zebra, lesser kudu, ostriches, warthogs, topi, gerenuk, oryx and, possibly lions and cheetah. 

She attributes this decline to hunting as some have exterminated these species as result of competition for grazing areas and hunting the animals for meat. Record droughts are also threatening their survival.

Leakey is working with the next generation to get “kids to care about nature” so they can “think about what they’re doing and the real impact it has.”

In addition to preserving biodiversity, Leakey remains passionate about studying the past, which could help the current and future generations tackle climate change. “We might be able to learn lessons” from those who survived during such challenging conditions, she said.

Leakey is able to maintain her involvement and commitment to numerous efforts by working with talented collaborators.

“If you don’t have teams to really hold it together, you can’t do any of it,” she said.

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By Elof Carlson

Fossils are relatively rare because most of the animals and plants that have died in nature have been eaten or decomposed. Fossils are often found in sedimentary rocks, and those dead organisms were buried after drowning, caught by volcanic ash, buried in a mudslide or sucked down by quicksand or some other event less likely than falling on a field or in the underbrush of a forest, or left as scattered bones by hungry predators. Only in the past few ten thousand years have humans buried their dead, improving the chances that their remains will someday be unearthed and studied by paleontologists.

DNAUntil the last half of the twentieth century, the only way to use human fossils to work out a historical association was through comparative anatomy and a variety of chemical and physical tools to determine the age of the sediments in which they were unearthed. The idea of a paleogenetics arose in 1963, with the use of that term by Linus Pauling and his colleagues, who studied the amino acid sequences in hemoglobin molecules of numerous organisms, from sipunculoid worms to humans, that use hemoglobin to carry oxygen to body tissues.

In 1964, the first sequence of fragments of the DNA of an extinct quagga were worked out using the skin of an extinct specimen in a museum. The quagga was an animal that looked like a chimera of giraffe and a zebra.

Once DNA sequencing was worked out, especially by Fred Sanger and his colleagues, viruses, bacteria, single-celled organisms, and then more complex worms and flies were sequenced. By 2000, the human genome was being worked out. Svante Pääbo and his colleagues are leaders in the working out of fossil human DNA.

This is what has been found so far. Four contenders for species status lived about 40,000 years ago. Three populations of humans arose after an initial origin in Africa. Of these three, the Neandertals (Homo neanderthalis) left Africa earlier than our own Homo sapiens. The Neandertals were named for the Neander river valley where they found in Germany. We were named by Linnaeus as Man (Homo) the Thinker (sapiens).

Two additional populations were found, one in western Siberia and the other in Indonesia. The Siberian humans are called Denisovans (Homo denisova). They were named for the Denis cave in which they were found and they also had an exit from Africa. The Indonesian humans are called Homo floresiensis and are named for the island Flores in Indonesia where they were found. Where they came from is not yet known. They are unusual for their small size, a Hobbit-like three- and-a-half feet tall.

The DNAs of three forms of humanity have been sequenced. The complete sequence of DNA of an organism’s cell is called a genome. The Indonesian form went extinct about 12,000 years ago, but no DNA has been extracted from their remains. Neandertals and Denisovans went extinct about 40,000 years ago.

Analysis of the three available genomes shows that most Europeans have about 4 percent Neandertal DNA. Living people in Melanesia and Australian aborigines have about 4 percent H. denisova DNA. About 17 percent of Denisovan DNA is from Neandertals. The human branch Homo bifurcated and one branch split into H. neanderthalis and H. denisova. The other branch from Homo produced us, H. sapiens. We are 99.7 percent alike for H. sapiens and H. neanderthalis.

Since we have 3 billion nucleotides to our genome, there remain 9 million mutations between us, most of it in our junk DNA. There are, nevertheless, hundreds of gene differences between our two species. It also means that where these populations came into contact, fertile matings occurred, and remain in our DNA from our ancestral “kissing cousins.”

Elof Axel Carlson is a distinguished teaching professor emeritus in the Department of Biochemistry and Cell Biology at Stony Brook University.

Studying parts of dinosaur bones that are smaller than the width of a human hair, Michael D’Emic specializes in sauropods, which includes the long necked Brontosaurus. Photo from SBU

They didn’t mark the wall in crayon or pencil with a date to monitor how they grew, the way parents do in suburban homes with their children. Millions of years ago, however, dinosaurs left clues in their bones about their annual growth.

Dinosaur bones have concentric rings, which are analogous to the ones trees have in their trunks.

A diagram represents the growth rings in dinosaur bones. Image from Michael D’Emic and Scott Hartman
A diagram represents the growth rings in dinosaur bones. Image from Michael D’Emic and Scott Hartman

Michael D’Emic, a paleontologist and Research Instructor in the Department of Anatomical Sciences at Stony Brook, studied these bones and the size of these rings and concluded that dinosaurs were warm-blooded.

In a paper published in the journal Science, D’Emic demonstrates how the growth rates of these bones indicate dinosaurs were much more like birds than reptiles in their metabolism.

“This supports the idea that dinosaurs were warm-blooded,” said Holly Woodward Ballard, an Assistant Professor of Anatomy in the Center for Health Sciences at Oklahoma State University.

D’Emic re-analyzed data that appeared in a 2014 Science article, in which other scientists had suggested dinosaurs were mesothermic, which is somewhere in between cold blooded organisms, like reptiles, and warm-blooded creatures, like birds, three-toed sloths, and humans.

D’Emic was on a dinosaur dig in Wyoming when the paper came out last June. When he returned to Stony Brook in July, he took a closer look at the results. “When I read the paper, I thought they hadn’t accounted for a couple of factors that would bias the results,” he said. “I was curious how changing some of those factors” would affect the conclusions.

D’Emic studies the smallest parts of bones. Indeed, for creatures that lived millions of years ago and weighed as much as 40 tons, he looked closely at cells that were a fraction of the width of a human hair.

In his approach to the data, D’Emic adjusted for seasonal growth patterns. Typically, dinosaurs grow only half the year. In the other half, when food is scarce or the temperature drops enough, the dinosaurs would have needed that energy to survive. When he accounted for this, he said the rate of growth doubled.

Comparing his estimated growth rate for dinosaurs with the rate for mammals and reptiles of similar size suggested the dinosaurs  “fell right in line with mammals,” he said.

Michael D’Emic enjoys a Lord of the Rings moment in Beartooth, Wyoming, near an excavation site in 2010. Photo from D’Emic.
Michael D’Emic enjoys a Lord of the Rings moment in Beartooth, Wyoming, near an excavation site in 2010. Photo from D’Emic.

A dinosaur’s metabolism could affect life histories including how the dinosaurs raised their young, as well as elements to their physiology, he said. “Such a fundamental aspect of an organism has implications for the kind of animals we expect them to be,” he said.

D’Emic recognizes that some paleontologists will question his conclusions about dinosaur metabolism. When looking at a broad group of paleontologists, he “still finds a pretty big spectrum of ideas” about metabolism and the “debate is probably still open.” After this recent work, D’Emic reached out to partners from around the world to explore bone growth in other groups of dinosaurs.

Ballard, who studies the growth and development of Maiasaura (duck-billed) dinosaurs from hatchling to adults primarily in Montana, supports D’Emic’s conclusions. She said his analysis will reinforce some of the hypotheses she had about dinosaur metabolism. Ballard said D’Emic was “well thought of” and has“definitely made an impact in the histological field.”

When he was in high school, D’Emic had the opportunity to join a dinosaur dig in New York, where he found a mastodon tusk. He was living in Manhattan at the time and went to Hyde Park with a summer class. After two weeks at the site with the class, he asked if he could come back, and wound up returning regularly for months, until school started.

“I didn’t want to go back to high school when September rolled around,” D’Emic recalled.

D’Emic, who recently left a dig in Utah and was on his way to join other Stony Brook researchers in Madagascar, said he still feels inspired by the opportunity to learn about dinosaurs. When he came to the University of Michigan in 2006 to start his PhD program, he planned to focus on Titanosaurs. By the time he left, the number of species of Titanosaurs scientists had discovered and categorized had doubled.

“It’s a cool time to be a paleontologist,” he said.