DALLAS, TX.- A 2,100 pound Triceratops Prorsus skull — 80 percent complete and roughly 66 million years old — may sell for $200,000+ in Heritage Auctions’ Sept. 28 Nature & Science Signature Auction in Dallas. The massive skull was discovered on private land in Montana and is one of five stunning dinosaur skulls in the auction, in addition to the only known complete skeleton of a prehistoric swordfish (est. $110,000+).

"The skull speaks to the inner child in all of us who love Dinosaurs,” said Craig Kissick, Associate Director for Nature & Science at Heritage Auctions. "This incredible skull from the popular Late Cretaceous herbivore is superlative for its size, completeness and aesthetic appeal.”

Measuring an impressive 7 x 6 x 5 feet, the rare Triceratops skull fossil retains much of the original fossil material and includes the first two fused vertebrae attached to the brain case (occipital condyle). The Triceratops (Greek for "three-horn face”) was a massive herbivore that roamed North America at the same time as the fearsome Tyrannosaurus.

Additional Montana dinosaur skulls include a downward curving-horned Einiosaurus skull from an adult specimen dating to the Upper Cretaceous era (est. $75,000+), and a juvenile Einiosaur skull ($50,000+). A rare a desirable Maiasaur with a rare ‘brain’ cast, also from Montana, includes both the upper and lower sections (est. $150,000+).

Another rare discovery from America’s heartland is a fossilized Protosphyraena nitida (est. $110,000+), an extinct species of swordfish, from the Cretaceous era. It was found entombed in rock in Kansas’ Smoky Hill Chalk of the Niobrara Formation. It is the first complete skeletal presentation of this cartilaginous fish and the first accurate representation of a prehistoric swordfish. The fragments of the creature were first discovered by man more than 150 years ago in Europe.

Measuring roughly 8 feet long from tip of sword to tip of upper tail fin, the skull alone measures an immense 29 inches long. "This specimen is the only full skeletal rendition of the 85 million year old bill-fish, and it will look beautiful over some lucky fisherman’s fireplace,” Kissick said.

Leading a selection of decorative petrified wood is an intact slab, approximately 7-feet in diameter from Arizona (est. $50,000+), which has been reinforced to be used as a table or hung on a wall. From Burma, come four distinct lots of Agatized Petrified Wood, the largest of which stands more than three feet high ($20,000+). The logs are discovered buried 100 feet deep and painstakingly hand-polished to present stunning translucent green, blue and burgundy minerals against a milky white ground.

The auction also includes a selection of extinct mammals and more familiar creatures, such as a Fossil Pig (Archaeotherium mortoni) in Matrix (est. $8,000+); a large Fossil Turtle Shell with a High Dome (est. $3,000+); a Fossil Turtle Shell with Skull (est. $4,000+) and a humerus bone from a Titanothere, one prehistory’s largest mammals to roam North America 30 million years ago (est. $1,500+).

Additional highlights include, but are not limited to:

• A stunning Canadian Gem Ammonite in Matrix, (est. $60,000) is one of two such examples, the second being a Gem Ammonite on a Stand (est. $40,000+).

• A rare Elephant Bird Egg (est. $50,000+).

• A fossil crinoid, a marine animal, which — although presented on a plate of matrix — still appears to undulate in a primordial sea (est. $50,000+).