Interpreting the tracks of dinosaurs

By Alice Alesia

Jim Farlow's fascination with dinosaurs started when he was a child and saw the dinosaur sequence from Fantasia on the Mickey Mouse Club. Since then, Farlow has been intrigued by the size of dinosaurs and their similarities and differences from large land mammals.

Jim Farlow

For almost 17 years, Farlow, associate professor of geosciences, has been teaching geology at IPFW and studying dinosaurs. His research interests include the functional significance of the shape of meat-eating dinosaur teeth, theoretical attempts to reconstruct dinosaur ecology and behavior, and dinosaur footprints. He is particularly interested in matching dinosaurs with tracks left behind.

In March, Farlow was featured on Discover Magazine in a show entitled "The New Dinosaurs." The segment discussed two sets of dinosaur tracks uncovered in 1938 by Roland T. Bird in the Paluxy Riverway in central Texas. The two sets of tracks line the dry, barren landscape there. Bird believed one set of tracks belongs to a four-legged herbivore, Pleurocoelus, and the other to a two-legged carnivore, Arcocanthosaurus. According to Bird's track charts, the meat-eater's tracks run parallel to the tracks of the plant-eater. But the tracks also show that at one point, the meat-eater's tracks take a strange skipping stride or hop, leaving two consecutive right footprints in the mud.

Some paleontologists, like Bird, believe these two sets of prints with a peculiar hop in the middle represent the moment the smaller carnivore attacked the herbivore. Farlow, however, doesn't believe the tracks are evidence enough to come to that conclusion. "I see no unambiguous evidence that the carnivore attacked the herbivore in the trackway interval accessible to us," he said. "If the attack had occurred where and how R.T. Bird thought it did, I would expect to see distortion of the carnivore's print where it landed after the 'hop,' and there isn't any. However, I do think the carnivore was following the herbivore, presumably to attack it at some point."

Farlow's favorite research project is always the one on which he's working. Currently, he's studying other dinosaur footprints, in addition to those at Paluxy.

"My main project concerns determining the accuracy or precision with which the makers of three-toed footprints of bipedal dinosaurs can be identified," said Farlow. "Is it possible to identify trackmakers to the species level, or can we only make identifications at a higher taxonomic level?

"To answer this question, I have studied the shapes of dinosaur foot skeletons, and foot and footprint variability within and across species in ground birds, crocodilians and lizards," Farlow added.

"The Paluxy Riverway prints are part of this project, in that the ultimate goal of my study is to describe the Texas footprints and interpret their makers as closely as possible."

In addition to studying dinosaurs, Farlow has also been writing about them for several years. One of his most recent works, The Complete Dinosaur, was published in 1998 by the IU Press.

"The Complete Dinosaur represents a collection of articles about all aspects of dinosaur study, written by experts on those particular topics," said Farlow. "Michael Brett-Surman of the Smithsonian and I put it together. The book has done very well, and a paperback edition will be coming out this spring."

The Complete Dinosaur sold so well that Farlow was asked to become a "consulting editor." He is now editing a series of books on paleontology for the IU Press. Several authors are now under contract for the series, which covers different aspects of paleontology, such as dinosaur reproduction, fossil snakes, the first land vertebrates, an extinct giant lizard from Australia and huge flightless birds from New Zealand.

In addition to his editing duties, Farlow will also be featured on another Discovery Channel show in the fall. Currently in post-production, the show is an hour-long documentary about the Paluxy River dinosaur-chase footprints entitled "Dinosaur Attack." Farlow and fellow paleontologist Dave Thomas were interviewed on site in Texas to argue the pros and cons of Bird's attack scenario.

In the meantime, Farlow will continue his dinosaur research, delving into anything he can find on the Tyrannosaurus, his favorite dinosaur.

Why the Tyrannosaurus? "Beats me why," said Farlow, "except that I like carnivores."