Researcher Paints New Dinosaur Portrait
Memo to Spielberg: Lose the lips.
Dinosaurs never had them, advises paleontologist Lawrence Witmer.
And while you’re at it, chop off the cheeks.
In Witmer’s view, it’s time for a makeover, and not just for dinosaurs that Hollywood illusionists such as Steven Spielberg have resurrected in “Jurassic Park” and other dino-thrillers.
Scientists too clutter their official models with mammalian characteristics that would make any planet-ruling reptile recoil.
Mammalian features such as fleshy lips and cheeks make the dinosaurs appear subtly familiar, or even cute or ferocious--depending on their expression.
But too often, Witmer complains, researchers, as well as dinosaur illustrators and model builders, add features without determining whether it would be anatomically possible for a hungry Tyrannosaurus rex to smirk as it prepares to kill, or for a triceratops to stuff a big chaw of grass in its cheek like a sheep.
Does it matter? Yes, if scientific accuracy counts in a billion-dollar dino industry; curators of museums and publishers of textbooks, as well as makers of films and toys, would have to recast the profiles of their most popular extinct stars.
“Subconsciously, when we see the fossils of a duckbilled dinosaur, many people can’t help but think of a moose. Or when we look at a triceratops, we think of a rhino,” says Witmer, who teaches comparative anatomy at Ohio University in Athens, Ohio.
“But I can find no scientific justification,” he says. “I know that we’re overturning some cherished notions about these creatures.”
No kidding. Even Witmer’s 5-year-old son, Sam, accuses Daddy of paleo-heresy.
“He asked me if all this means that he has to stop playing with his dinosaur toys,” Witmer says. “I’m more interested in the science. There is a more serious, disciplined way to determin1696595969how these animals looked.”
To Witmer, getting serious means reaching into his subject “up to the elbows.”
For comparisons with fossils, he dissects scores of animal carcasses supplied by government agencies, slaughterhouses and other authorized sources.
He strips and boils the flesh off the bones of modern mammals, great and small. He takes a band saw and slices their parts like salami to expose fine internal structures. Or he scans them with sophisticated X-ray technology that hospitals usually reserve for patients.
His laboratory, at times, contains a gruesome smorgasbord: horses’ heads, seal snouts, crocodile jaws rest in the refrigerator. A bison head simmers in a pot on a stove. Bones, new white and ancient brown, pile up awaiting closer inspection.
He concedes that this is “a shop of horrors.” Sometimes, the biomedical researchers down the hall complain about ghastly odors seeping from beneath his door.
But to Witmer, it’s all about soft tissues, and how they connect to bones to form a whole being.
Muscles, nerves, cartilage and organs are the most perishable and elusive of dinosaur leftovers. But they provide the evidence that researchers need to flesh out their bony models and settle long-standing controversies, such as whether dinosaurs were warm-blooded and if they were the ancestors of birds.
Last November, Oregon State University paleontologist John Ruben found a dinosaur fossil in China with superbly preserved organs. Its lungs, he asserted, could not have processed enough oxygen to sustain a warm-blooded creature.
And its diaphragm, he said, neatly separated the heart and lungs from other organs like a modern crocodile’s, and unlike a bird’s.
But such finds are rare. So to make comparisons, Witmer must resort to modern beasts that are the closest living relatives of the dinosaurs.
“You have to understand how these systems work in all their gory detail,” he says. “We actually look [at] how animals are put together and how they compare with dinosaurs.”
Much of paleontology so far has been related to geology, he adds, but now scientists are asking questions that are much more biological.
Take lips. Scientists endorsed the idea of dino lips because dinosaur jaws contain rows of holes called foramina. Blood vessels and nerves ran through such bone passages, supplying mammalian lips with extra blood and nerve impulses for enhanced sensation.
The problem, Witmer says, is that the dinosaurs’ foramina aren’t located in the same position as in mammal jaws. For help, he turned to the anatomy of other creatures that are thought to be biologically closer to dinosaurs.
Crocs, turtles, eagles and other beaked creatures have foramina too. But they don’t have lips that pucker up. Lizards don’t have lips at all. They have bands of overlapping bony scales concealing salivary glands.
So, Witmer concludes, no lips on dinosaurs. The whole subject is a novelty, he admits.
“Lips or no lips,” he says, “Tyrannosaurus rex was ferocious.”
But don’t lump dinosaur cheeks into the same cosmetic category. To biologists, cheeks represent significant evolutionary progress.
Mammals use muscular cheeks to control chewing and guide food while swallowing. Such cheeks allow cows to graze deliberately.
The jaws of dinosaurs such as triceratops and stegosaurs have long dents running along the sides. Researchers have assumed that the grooves provided attachments for cheek muscles, enabling the animals to graze.
In doing so, they believe, cheeks helped herbivores to thrive and perhaps pushed less efficient plant-eaters to extinction.
But Witmer has compared plant-eating dinosaur skulls with those of many large plant-eating mammals. Unlike mammals, the dinosaurs lack the bony attachments that enable mammals’ cheeks to work.
Instead, Witmer believes dinosaurs’ unusual jaw-line grooves are much larger versions of similar attachment points for the powerful, curved beaks on birds of prey and snapping turtles. An enormous beak attached to a pair of 5-foot jaws would act like giant yard clippers, allowing these tank-sized herbivores to snap and gulp entire leafy trees.
Now Witmer has turned his attention to dinosaur noses. Skulls of three groups of dinosaurs--triceratops, brontosaurs and duckbills--have nostrils up to two feet deep.
He’s examining a variety of seal that uses large nostrils to inflate a fleshy hood during courtship rituals.
