Cretaceous creatures make a comeback.

The camptosaurs have resurfaced. A large deposit of bones that belonged to these and other dinosaurs that lived more than 100 million years ago -- a period that has yielded few fossil remains -- has been uncovered about 75 miles southwest of Fort Worth, Tex. Scientists involved in the excavation says the find should provide new insights into plant and animal life at the time.

"In terms of both quality and abundance of fossils, this ranks among the paleontologist Louis Jacobs of Southern Methodist University (SMUe in Dallas, who supervised the dig with Phillip Murry of Tarleton State University in Stephenville, Tex., also a palentologist. "We've probably removed about a half dozen fairly complete dinosaur skeletons, and there are a number of partial skeletons," Jacobs told SCIENCE NEWS. "A lot more are still in the ground."

The skeletons appear to represent several previously unknown species, says Murry. "Certain skull bones are unlike any we've ever seen," he explains. Most of the uncovered dinosaurs were plant-eaters related to the camptosaurs, observe the scientists. These relatively small creatures walked on their hind legs most of the time. None of the skeletons is longer than about 10 feet. Murry notes that the new discoveries may flesh out the evolution of camptosaurs during the Cretaceous period, between 135 million and 65 million years ago.

Another skeleton at the site has the jaw and teeth of a meat-eater, he adds.

The dinosaur foosils were found in June by Tarleton State geology student Rusty Branch. He noticed bits of fossil bones exposed on the surface of ridges between gullies that had eroded near the shore of Proctor Lake in northern Texas. The team of scientists then removed the earth surrounding the fossils and encased each skeleton, or several partial skeletons, in a plaster cast for transport to laboratories at SMU.

Research associate Will Downs, director of the laboratory work, estimates it will take from six to eight months to remove each skeleton from its cast. After that, scientific analysis begins.

In addition, says Murry, there are an abundance of bones still to be excavated at the site. For now, however, the scientists will screen soil for bone fragments from other animals that existed in the early Cretaceous period of 100 million years ago.

"The layers of earth below the animal bed should have pollen for analysis," adds Murry. "At that time it was early in the history of flowering plants."

The age of the dinosaurs unearthed so far was estimated by the known dates of marine fossils embedded in limestone just above the layers of earth containing the skeletons.

Early Creataceous dinosaur fossils are scarce and have been found in only a few sites, points out Murry. Dinosaurs became extinct at the end of the Creatceous period. The oldest known dinosaur was recently discovered in Arizona's Petrified Forest National Park by University of California at Berkeley paleontologists; it lived about 225 million years ago (SN: 5/25/85, p. 325).

The great numer of offils at the Texas site, located on federal land managed by the U.S. Army Corps of Engineers, has discouraged further fieldwork. "we won't remove more than we can handle," says Jacobs. Closer study of wht has already been recovered, observes Murry, may reveal "'ow these fossils relate to their environment and how they fit into a geological time frame."