Big Fossil 'Raptor' Tracks Show Group Behavior

But until now, there was no direct evidence of either of these things. Now, an international team of Chinese, British, American and Japanese paleontologists reported fossilized footprints made by two different kinds of “raptors” from 120 million year old rocks in Shandong Province, China.

The discovery, published recently in the European journal Naturwissenschaften, is remarkable because tracks made by these kinds of carnivorous dinosaurs, which are correctly called deinonychosaurs, are very rare. The only previous reports have been very dubious or poorly preserved. The new tracks are preserved with much more detail, and some are preserved in trackways made by a group of animals walking together.

“In one spot, there are parallel trackways we named Dromaeopodus shandongensis (DROH-mee- oh-POH-dus SHAN-dong-EN-sis) made by at least six individuals, and none of them overlap,” said Dr. Martin Lockley of the Dinosaur Tracks Museum, University of Colorado at Denver, an author of the study. “The nature of the sediments in which the tracks are preserved tells us that there cannot have been much time between the tracks being made and being buried. All together, this strongly indicates that the track makers were there at the same time – moving as a group.”

The trackways were discovered in 2005 by geologists Dr. Rihui Li of the Qingdao Institute of Marine Geology and Mingwei Liu of the Fourth Geological and Mineral Resources Survey of Shandong. Lockley, Li, Liu, and Dr. Masaki Matsukawa of Gakugei University, Tokyo studied the tracks beginning in 2005.

“The Dromaeopodus tracks are unusual for two other reasons,” said Dr. Peter Makovicky of the Field Museum in Chicago, a specialist in deinonychosaurs and an author on the paper. “First, they show that deinonychosaurs, like the much younger Velociraptor, really did walk with the huge second toe claw held off the ground, perhaps to keep it from being worn down by constant contact with the ground; previously, we suspected this based on some fossil feet, but had no direct evidence on the life position of this toe. Second, they show that very large deinonychosaurs, around 4 feet (1.2 meters) tall at the hip, lived in Asia at a time when the only skeletons known are from chicken- to turkey-size, feather-covered species. It is probable that the large deinonychosaurs that lived in North America around the same time, like Deinonychus and Utahraptor, descended from immigrants that evolved in China.”

Although the tracks show that the big deinonychosaurs were moving in a group, they do not prove that they were capable of the kind of cooperative hunting that many living mammalian predators, like lions and wolves, use. “But it is very suggestive,” said Dr. Jerry Harris of Dixie State College of Utah, an author on the paper. “Animals that live in groups almost always have relatively sophisticated behaviors that often involve cooperation in some activities, so even though it’s impossible to say whether the makers of the Dromaeopodus tracks were hunting when they made the tracks, it certainly suggests that such behavior really was possible.”

 The tracks were found in the same place that produced tracks called Shandongornipes muxiai that were made by a roadrunner-like bird reported earlier this year. Other rare and unusual tracks are also preserved at the site and are being studied by Lockley, Li, Liu, and Matsukawa. “This is one of the most important fossil track localities in all of Asia,” said Lockley. “We’re getting all kinds of new and valuable information from the tracks preserved there.”