Deinosuchus riograndensis skull cast

By Jenny Cobb, Associate Curator of Exhibitions

Besides offering views of sweeping sunsets, plants, and wildlife, Big Bend National Park has been the site of paleontological and geological excavations for decades.

The fossilized remains of Deinosuchus, the largest crocodile ever known, were originally discovered in the Aguja Formation in the south-central part of the Park in 1940. With lengths of 40–50 feet and jaws studded with 6-inch teeth, Deinosuchus riograndensis was equipped to feed upon a variety of dinosaurs 80 to 75 million years ago. Just like modern day crocodiles, Deinosuchus most likely ambushed prey while lying submerged near shore, seizing large dinosaurs as they foraged amid the vegetation of Big Bend’s ancient swamps. In 2013, Dr. Wann Langston, Jr., director of the Vertebrate Paleontology Laboratory at The University of Texas from 1969 to 1986, reconstructed the 6-foot long skull of Deinosuchus based on specimens recovered from Big Bend.

Fossils can be extremely fragile, and all are subject to damage by vibration and changes in temperature and humidity. Historically important fossils are irreplaceable so exact replicas, like the Deinosuchus skull, are often made for teaching and display, or to fill in gaps for a skeleton structure that might be missing bones. One of the most common ways of making a replica is the mold and cast method. A mold is formed around a fossil and once removed, filled with a resin or plastic to create an exact replica of the original. Once the cast hardens and the outer shell of the mold is broken away, artists dye or paint the casting to match the original fossil. Because a mold can only be used once, and producing a new mold can cause damage to the original specimen, scientists typically make only a few from a fossil, so the casts are often seen as important as the original.

The 6-foot-long skull cast of Deinosuchus and approximately 30 additional artifacts are part of a new exhibition, Journey Into Big Bend, on view April 22—September 18 on the Museum’s third floor.