Tracking the Hadrosaurs
March 10, 2011|Academics
In retrospect, it’s clear that a backyard in Chicago’s western suburbs may not have been the best place in the world to dig for dinosaur bones. Merrilee Guenther knows this now. But to be fair, she was just seven years old when she started to dig behind her family’s house in Itasca. She had just decided on a career in paleontology–the study of fossil remains from distant geological periods–and was eager to get started.
Today, Guenther is an assistant professor in Elmhurst’s biology department, and her research on the anatomy of dinosaurs takes her further afield. She’s interested in the development of hadrosaurs, sometimes called the “duck-billed dinosaurs” for their distinctively flattened snouts.
“They were the cows of the Cretaceous,” she explained last week in her office on the first floor of the Schaible Science Center, where a vintage Sinclair gas station sign, with its trademark silhouetted green dinosaur, hangs above her desk. (The Cretaceous period extended from about 135 million to 65 million years ago and marked the end of the age of reptiles and the emergence of flowering plants and modern insects.) “They were bulky herbivores and they moved in giant herds.” In some sites on the western North American plains, researchers have found what they call “death assemblages” of as many as ten thousand hadrosaurs. For paleontologists like Guenther, that means a plentiful supply of hadrosaur specimens to study. “Alberta is like hadrosaur heaven,” she said.
The sheer number and variety of hadrosaur specimens available, and the attention-grabbing shape of their skulls, makes them a popular research subject. But Guenther’s investigations take her down one of the less heavily traveled avenues of hadrosaur research. Where others focus on hadrosaur skulls, she’s interested in the “postcranial skeleton”—that is, everything but the skull. She said that analyzing and comparing diverse samples of hadrosaur bones—from adults and juveniles, males and females—helps answer questions about how they grew and how they moved.
“The skulls are so cool that everyone else ignores the other stuff. They get distracted by the awesome skulls,” she said. “So looking at how their limbs grew is really unmined territory. There are maybe three of four of us in the world doing it.”
Guenther’s ongoing hunt for hadrosaur bones has taken her to the fossil beds of Alberta and the Dakotas, but she also mines the large collection at Chicago’s Field Museum. In the lab adjacent to her office, she pulled from a long wooden carrying case a set of the calipers she uses to measure hadrosaur bones. The data she gathers about their size—and just as importantly, their shape and arrangement—could help confirm the premise that hadrosaurs were not sluggish and cold-blooded like modern reptiles, but rather fast-growing and warm-blooded like modern birds. Settling such questions would add some crucial pieces to the evolutionary puzzle.
Guenther wants to enlist her Elmhurst students in the search for answers. She has applied for a grant to take students to Utah to dig for the remains of sauropods, the group of long-necked plant-eaters that included some of the largest animals ever to walk the earth.
Students are already working with her on another project involving a more modern, and considerably smaller, species. With Venkatesh Gopal, an assistant professor in the physics department, Guenther is investigating how rats’ skulls are shaped, and their whiskers arrayed, to maximize their ability to sense.
Rats depend on a precise and reliable sense of smell to alert them to predators and help them find food. “So if a better sensing capability helps animals thrive, we’re looking at how they have evolved to maximize success.” Guenther said. “ Do their physical parameters, the size of the nasal cavity, the arrangement of their whiskers, affect their ability to sense?” (See this Quick Studies story on Gopal’s research into the sensory processes of animals.)
Just as in her dinosaur studies, Guenther works with specimens from the Field Museum’s collection. And just as with dinosaurs, the data she gathers about rat morphology—their form and structure—can be analyzed for clues to their development. Guenther wants to use data about the form of an animal—whether it’s a rat or a hadrosaur—to learn important things about the animal’s function.
“I’m an anatomist,” she said. “It’s just that I tend to study the anatomy of some things that have been dead a very long time.”
