For the love of bones

From mere fragments, Gina Sorrentino seeks larger stories

Paleontologists don't tend to find a fully-formed skeleton just waiting for them. They uncover a piece of an animal's tail here, a shoulder fragment from its prey over there. Excavations yield a challenge: reconstruct an individual story, and perhaps more, from incomplete evidence.

But the meagerness of the findings doesn't lead to despair. Instead, in the words of Gina Sorrentino '02, paleontologists "geek out" over the fragments they discover.

Sorrentino, who is pursuing a Ph.D. in anatomical sciences at Stony Brook University Health Sciences Center, part of the State University of New York, knows how to make the most of fragments. From a bit of bone, she can extrapolate the age, sex, and pathology of an animal.

And she may intuit small dramas. A dinosaur tail with a healed nodule in the place of a missing tip, for example, raises questions, and may suggest answers, about the predator who got the tip as well as about the healing process. "Throwing a baseball or riding a horse--these are things you do in everyday life that affect the physical part of you," Sorrentino notes. Daily life leaves its marks on the bones.

But when Sorrentino says that she's after "an image of the whole," she's talking about something larger than the individual animal. The picture she's seeking may, in fact, embrace an entire era.

Sorrentino spent last summer in the Mahajanga Basin of northwestern Madagascar, digging for fossils as part of a project that combined paleontological research with humanitarian work. Her colleagues from Stony Brook's medical school (where she teaches anatomy) provided dental care and medical aid to local villagers. Sorrentino and her fellow researchers, meanwhile, under the guidance of lead scientist David Krause, looked for Late Cretaceous fossils, with an ultimate goal of sketching a new vision of the ancient earth.

In brief, the research challenges scientists' earlier notions about the plate tectonic breakup of the Cretaceous supercontinent known as Gondwana, which encompassed present-day Antarctica, South America, Africa, Australia, India, and Madagascar. It was generally thought that Africa, Madagascar, India, and South America broke off at the same time.

One of Krause's earlier expeditions uncovered fossils in Madagascar that scientists then compared to fossils of the same age in South America and Africa. They found that the Madagascar fossils more closely resembled those of South America. According to Sorrentino, the finding suggests that Africa broke off first, leaving Madagascar and South America connected via Antarctica for one to five million years. It is a small discovery that may reshape the way we envision the earth's distant past.

Sorrentino traces her "love of bones" to Kenyon, specifically to a course in human osteology with anthropologist J. Kenneth Smail and a geology course with Eric Holdener of the physics faculty. Holdener remembers her as "someone who loved the subject thoroughly and unabashedly." A biology major, Sorrentino wrote a senior exercise in paleobiology. Her advisor, biologist Christopher Gillen, says she had "that spark, a real inquisitiveness about looking into all of the questions" relating to her topic.

Sorrentino's career path after graduation took her from a conservation project in New Mexico, to a dig in Pompeii, to a biochemistry lab in Minnesota, all in the space of four years. Before starting at Stony Brook in 2006, she also worked as a researcher on a dinosaur dig in Montana sponsored by the Museum of the Rockies.

Her current doctoral research focuses on the relationship between individual development and evolution in several species--she wants to know why certain traits evolved and how change occurred on multiple levels, from gross morphological traits like fins and wings down to finer details involving the regulation of gene expression. The work takes place both in the lab and among fossil collections.

"So many scientists describe what they see, often in an extremely detailed way," says Sorrentino. "But there's so much to be done after that."

-- Lauren C. Ostberg '07

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