Creatures of Big Bend

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Want to know what types of creatures lived in what time periods? See below for a partial list.

Cretaceous Marine Environment

Giant clam (2-3 ft diameter) Even invertebrates can be impressive, as evidenced by Big Bend’s giant clams. In the warm, shallow seas of the Late Cretaceous, many invertebrates grew to large sizes. The clams of the Boquillas Formation can be 3 feet in diameter. Mosasaur skull (3-4 ft long) Mosasaurs were large swimming reptiles, with the largest specimens being over 50 feet long. They were fierce predators and became the dominant marine predator during the time period we are interpreting (Late Cretaceous). During this time at the end of the Age of Reptiles, mosasaurs dominated the oceans, dinosaurs lived on land, and pterosaurs ruled the sky. No mosasaur skulls have been found within the park, but a specimen was found near Lajitas, just outside of the park. Sea turtle (3-4 ft diameter) A potential specimen for display would be Terlinguachelys fischbecki, which is a species new to science that was discovered in the park and is unique to Big Bend. The specimen would require molding for a replica, which would increase the cost. Large ammonite Ammonites are shellfish with squid-like tentacles. Today, the chambered Nautilus is the best-known living relative of the ammonites. During the Cretaceous Period, ammonites were very common and diverse, but most of them went extinct along with the dinosaurs at the end of the Cretaceous. A large fossil specimen would be 1-2 ft in diameter, and we would probably use a real fossil for display. Large block of reef rock, containing numerous invertebrates This would provide a chance to interpret rudists. Rudists were oddly-shaped, asymmetrical bivalves that were major reef-builders of the Cretaceous Period but went extinct at the same time the dinosaurs went extinct. Shark teeth Shark teeth are small but would make an interesting part of the exhibit. Various invertebrates (snails, clams, oysters, sea urchins, ammonites) These help round out the display by showing the smaller, more numerous animals that shared the sea with bigger ones.  

Aguja Formation (Coastal Environment)

Deinosuchus crocodile skull (6-8 feet long), osteoderms (bony armor plates), teeth, etc. This spectacular fossil is the skull of a giant crocodile big enough to prey on dinosaurs. The entire animal would have been about 35 feet long. Researchers at the Texas Memorial Museum in Austin are preparing this specimen for reproduction. The park may be one of the first places to exhibit this specimen, which is appropriate since it was discovered in Big Bend National Park. Carnivorous dinosaur skull (2 ft x 18 in) and foot Carnivorous dinosaurs are great crowd-pleasers in museum exhibits. Teeth from numerous species of carnivorous dinosaurs have been found in BBNP, which documents the fact that members of the tyrannosaur family were present, including “new” species that were discovered at BBNP. Since no complete skulls have been found in the park, the display would probably use an Albertosaurus skull that can be purchased from a museum supply company. Foot bones have been recovered from the park, and these could be used to make a replica, if desired. Chasmosaurus horned dinosaur skull (7’ long x 46” across top of frill). Ceratopsians, or horned dinosaurs, were herding, grazing animals in the Cretaceous. This skull is one of the largest known skulls of a land animal, due to the extremely long frill behind the head. Kritosaurus duck-billed dinosaur skull (2’ x 2’ x 1’). Duck-billed dinosaurs were also grazing dinosaurs that gathered in herds. Turtle (about 3 ft diameter). This fresh-water turtle has partly-healed scratches and bite marks, suggesting that it was attacked by a crocodile, but it escaped. These scars on this specimen vividly demonstrate the stories that fossils can tell, and it would be interesting to have it in the same exhibit as the giant crocodile skull. The specimen would require molding to make a replica, increasing the cost of display. Petrified wood. Large pieces of petrified wood could be used in the exhibit.

Javelina Formation (Tropical Evergreen Rain Forest Environment)

Complete skeleton of giant pterosaur Quetzalcoatlus in standing position (15-18 ft tall). This world-famous fossil has a wingspan of 35 feet, making it the largest known flying creature of all time. It is displayed at many major museums, including the National Museum of Natural History (Smithsonian) in Washington, D.C. Most museums display the fossil in a flying pose, so the standing pose at the Fossil Bone Exhibit would be the only standing pose in the U.S. (it is also used by a museum in Korea). Alamosaurus dinosaur Perhaps the most common dinosaur fossil in BBNP is Alamosaurus, a member of the long-necked, plant-eating family of sauropods. The entire animal is about 90 feet long. Alamosaurus provides an interesting interpretive story. Prior to the appearance of Alamosaurus, sauropods had been extinct in North America for 35 million years, so early paleontologists were puzzled by the re-appearance of a sauropod in the fossil record after such a long gap. The mystery was not solved until the theory of plate tectonics explained how continents moved over geologic time. Alamosaurus apparently migrated into North America from South America following the connection of these two land masses in the Late Cretaceous. So, the earliest appearance of Alamosaurus in North America provides geologists with the date of the joining of the two continents. Petrified wood Petrified logs from this formation contain fossilized evidence of termites. Microfossils Although large fossils are impressive, the smaller fossils often provide the most important scientific information. We could include a display—similar to one the park is using at the Panther Junction Visitor Center—that contains a variety of fossils that were collected from a single site. The collection at the existing display includes dinosaur bones and teeth, crocodile teeth, fish bones, gar scales, turtle bones, oysters, and other fossils. This assortment of fossils from saltwater, freshwater, and brackish water animals shows that the ancient environment was an estuary, where the saltwater and freshwater environments intermingled. The term microfossil also includes tiny mammal bones and teeth—very important to scientists studying early mammals—that might be incorporated into a display.  

Tertiary Period (Savannah Grassland Environment)

Various mammals and other fauna Some of these specimens were found at the original Fossil Bone Exhibit, demonstrating that the exhibit is on a fossil site, reinforcing the display’s connection to the site. Interpretively, these specimens bring the display past the big extinction episode at the end of the Age of Reptiles and into the Age of Mammals. These fossils include Phenacodus, a sheep-sized plant-eater, one of the earliest hoofed mammals; Coryphodon, a hippo-like mammal that was 9 feet long, and Hyracotherium, a fox-sized mammal that is the earliest known ancestor of the modern horse (also called Eohippus, or the Dawn Horse).