Probing dinosaur bones

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Probing dinosaur bones

Juvenile bone of a 150 million year old dinosaur (Dryosaurus from the Tendaguru beds of Tanzania) showing rapidly forming bone tissue. Large spaces are channels through which blood vessels traversed. Durban-born Anusuya Chinsamy-Turan is a University of Cape Town scientist whose passion lies not so much in rescuing humanity as in understanding the entire history of life on earth - in which case humanity is a wee bit of an afterthought.

The sari-clad professor is a palaeobiologist, one of the world's few experts in the rarified world of bone microstructure. But the limited perspective of self-obsessed humanity perplexes the mother of two. She wants to learn from life’s successes – and humans haven’t been around long enough to qualify as a success.

"Understanding our biodiversity means not just an understanding of today’s animals and plants," she points out. "For 160 million years dinosaurs lived on earth, and were one of the most successful vertebrates ever. Humans and their close relatives have been around for - at most - six million years."

She reaches out not to shake hands, but to demonstrate. If her entire arm up to the shoulder represents the 4.5 billion years since the planet formed, then crude early life forms only begin halfway between the arm and the elbow. Creatures with spines - vertebrates - come just below the wrist. Dinosaurs are on the palm of her hand. Mere humans only show up at the tips of her fingers and modern life is a sliver on the fingernails.

In other words, humans have just been put in their place.

Dinosaur detective work

But what a place South Africa is for dinosaur detective work. “To be surrounded by this extremely rich fossil heritage, it is such a shame that people don’t understand that literally on our doorstep there are hundreds of fossils!" she says with emotion. "We have some of the best in the world, our heritage is so phenomenal, it is a shame that we don’t have enough people to research them.”

I think her work is like throwing the bones to communicate with the ancestors. Chinsamy-Turan, ever the scientist, prefers to call it “reading the bones.” The fragile flesh and blood that makes up both Pteryodactyls and pop stars is intimately associated in life with the bone mineral. After death, collagen, muscle and blood soon decompose. But the microscopic patterns that they imposed on the bone, even the channels through which the blood flowed, are preserved for millions of years.

The academic's technique was scandalous at first. The bones have survived in their earthen tombs for endless hours, and dug out with sweat and sunburn. And what does she do? She cuts them up!

“It was very difficult to get material,” she recalls. “I had to beg collection managers to give me bits of fossil bone because thin sectioning is a destructive process. Later people realised that you can derive so much of information from fossil bone microstructure that the sacrifice is worth it.”

Dinosaur bones tell a story

Using diamond-encrusted blades she slices into the beautiful bones. Embedded in resin for protection, the bone is polished, re-cut, mounted on a slide and shaved again using a grinding wheel and a kind of sandpaper until it is thinner than prosciutto, a mere 30 microns thick. Practically transparent.

A petrographic microscope with filters allows light to go through the bone at different angles, like stained glass. The effect is beautiful - patterns of pink, yellow and blue. Stripes and ridges. The bubbles on the skin of a dinosaur embryo. I could be at a gallery offering modern art. She's searching the bones for clues.

The multi-coloured slides, those are from fast-growing animals. Uniform colours, that's a slowly-growing creature. Different colours indicate the orientation of the collagen that was once present in the bone. Signals recorded in the bone can explain if it was affected by changing seasons or suffered an illness such as cancer. Sliced sideways, the growth rings in the bones of some common dinosaur species show their age, like the concentric circles of trees. But not always. Nobody knows why.

Chinsamy-Turan was fortunate to work on enough bones that she could compare dinosaurs of the same species at different ages: some hatchlings, some juvenile, some adult. Eventually she was able to do this painstaking work with two local species - a two-footed dinosaur, a four-footed dinosaur, both 190 million years old - and another species series from Tanzania. Her studies, some of the first published, led Chinsamy-Turan to the conclusion that small dinosaurs (small like the three-metre-long syntarsus from Zimbabwe) grew up in about eight to ten years. That's slower than mammals of a similar size but still close to the "Live fast, die young" mantra.

Massive, four-footed, long necked dinosaurs took a less hasty approach. "Very large dinosaurs like the diplodocus found in the Algoa Basin took about three decades to reach adulthood."

In this quiet way, Chinsamy-Turan takes long journeys without ever leaving the zoology building on the upper campus . She rarely goes on digs. The fossils come to her cushioned in bubblewrap inside in plain brown boxes, couriered from colleagues around the world who recognise her expertise. She no longer needs to beg.

Not bad going for someone who never intended to be a palaeontologist. Her biology training, before she was sidetracked into dinosaur work, allows her a fresh take on the sometimes brutal subject matter. (The fate of some once-abundant, early four-legged mammals from Mongolia is briskly summed up with “out-competed.”)

“You can’t use fossils if you don’t understand modern bones,” is how she explains work with crocodiles and turtles. “You cross-reference.”

Mesozoic Birds

Birds – the feathered descendants of the dinosaurs – fascinate her. In the increasingly specialised world of science Professor Chinsamy-Turan is the one to turn to when puzzled by the remains of Mesozoic birds which flocked across the planet starting 245 million years ago. Nobody’s found a single such fossil on the African continent. But in a globalised world, she’s the one whose papers on these ancient birds get published in world-class journals such as Nature. Maybe dinosaurs aren't really extinct after all. It's just that Tyranosaurus Rex has downsized into something else.

Much of South Africa’s dinosaur work consists of rushing around the countryside rescuing fossils exposed by erosion and floods before they dissolve forever. Many bones then languish in climate-controlled storage, on steel slabs like mortuaries, waiting once again.

Professor Anusuya Chinsamy-Turan will power up her blades and cut them open. And in doing so, she gives them new life. Others agree. At the end of May she won a research grant worth R50,000 from the National Research Foundation in a new category, the best black female researcher in the decade since democracy began.

More information:

www.nstf.org.za

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