HGMS Dinosaur Tracks Field Trip STOPS

Dinosaur Valley State Park and nearby areas
Glen Rose, Texas, August 6, 2005

Glen J. Kuban

STOP 0, Interpretive Center at Park Entrance

The exhibits here make up the initial phase of a planned full scale museum, for which the park is raising funds (please consider donating; a box for this is near the display room entrance). Current exhibits focus on the history, geology and paleontology of the area, especially its world-renown dinosaur tracks. The tracks are exposed in several areas of the Paluxy Riverbed, whose limestone floors and shelves are part of the Lower Cretaceous Glen Rose formation (approx. 110 million years old).

The centerpiece of the display room is a cast reproduction of a section of the famous trackways excavated in the early 1940ís by paleontologist Roland T. Bird of the American Museum of Natural History. The casts include several distinct theropod tracks, probably made by the theropod (bipedal meat-eating dinosaur) Acrocanthosaurus atokensis, and a trail of deep sauropod tracks, made by a four-legged, long-necked "brontosaur" type dinosaur, possibly Pleurocoelus. Acrocanthosaurus somewhat resembled Tyrannosaurus rex, and was almost as large (perhaps over 30 feet from nose to tail tip when full grown), 12-15 feet or more tall, and 2-3 tons, although many of the tracks in the park evidently were made by sub-adult or adolescent individuals. Itís three-toed tracks resemble those of large birds, with three long toes ending in sharp claws. Pleurocoelus was a brachiosaur sauropod possibly over 50 feet long and weighing over 20 - 30 tons. Itís rear or pes tracks somewhat resemble large bear tracks, with five claws (three large, sharp ones, and two smaller, blunter claws). Itís front or manus tracks are somewhat circular and elephant-like when well preserved, but are often reduced to crescents or obliterated altogether when the rear prints overlap them or push mud into the front prints.

Although the theropod tracks in and near Glen Rose were discovered and identified around 1908, it was not until the 1930ís that the sauropod tracks were first found by local residents, who initially mistook them for mammoth tracks. A few years later they were officially identified by Roland Bird, who wrote several popular articles on the trackways. Although theropod tracks are known from scores of localities throughout the world, the Acrocanthosaurus tracks in Glen Rose are among the best for this species, and the sauropod tracks are arguably the most distinct and best preserved in the world.

Because its often difficult to firmly associate a track with a trackmaker, tracks or "ichnites" are given names separate from the trackmaker animals. The theropod tracks in Glen Rose have been named Eubrontes glenrosensis (or more recently, Irenesauripus glenrosensis by Wann Langston, 1974). in 1986 the sauropod tracks were officially named Brontopodus birdi by James Farlow, in honor of Dr. Bird.

Outside the interpretive center is another casting (in cement) from the R. T. Bird excavation. The trails actually show only a few different prints, but were alternated to create the appearance of trackways. The striding patterns and claws are much more apparent when viewed in the same direction in which the animals were walking.