The Story of Stan T. rex

by Peter L. Larson

Stan T. rex's Skeleton

Stan's Skull/ "Stan's Teeth
The Black Hills Museum of Natural History Exhibit
Black Hills Institute of Geological Research, Inc (BHIGR)
Contest Results: "If Stan could talk, what might he say?"

The story of "STAN", the Tyrannosaurus rex, began 65 million years ago in the heart of what is known today as North America. By studying the earth, along with fossil bones and plants, scientists can piece together a picture of what life was like then - and how this largest carnivore to walk the Earth lived out his days.

After studying T. rex specimens found together, we believe that "Stan" lived his life in a family group. Hatching from an egg (like a modern bird), Stan would have been cared for by his parents, who taught him and his siblings to hunt. Eventually, Stan left the family group and found his own mate, a female 30% heavier than himself and with whom he probably spent the rest of his life.

Stan and his mate fought many battles during their lifetimes - some with other T. rex! For example, each attack to bring down a prey animal not only afforded the opportunity to dine, but also the possibility of injury, and competition. Stan's skeleton, along with those of other T. rex specimens, shows the scars of ancient battles. By studying these "pathologies" in the bones, we surmise that T. rex scuffled for territory, fought over food, and engaged in other behaviors similar to today's carnivores.


A Miniature Replica of Stan's Skull

Stan's pathologies include several broken and healed ribs, with one scar the same size and shape as a T. rex tooth. He also suffered a broken neck. In the process of healing, two vertebrae fused together and a third became immobilized by extra bone growth. (Apparently his spinal cord was not severed, or he would not have lived to heal.) His cheeks also show healed injuries, but probably the most chilling is a healed injury on the back of the brain case. Through the back of the skull, we found a circular hole more than an inch in diameter - into which a T. rex tooth fits nicely. The hole ends at a spot where a large chunk of bone (two by five inches) actually broke away! Amazingly, Stan lived through this incredible injury, because a thin layer of bone sealed the broken surface.

Whatever the immediate effect of these injuries, Stan lived through them to fight another day. We are not sure what finally killed him. Perhaps it was disease or old age. At any rate, his female companion finally had to leave Stan on the sandbar of a stream flowing southeastward to the sea. As Stan's carcass rotted in the sun, scavengers pulled apart much of the skeleton and skull. Spring floods eventually covered the bones, which remained buried for sixty-five million years.

Stan's Discovery and Name

In the spring of 1987, amateur paleontologist Stan Sacrison was exploring outcrops of the Hell Creek Formation near the town of Buffalo, South Dakota when he came across a large pelvis weathering out of a sandy cliff face 100 feet above the prairie. During that summer Stan spent his free time attempting to uncover what was obviously the skeleton of a large dinosaur. It wasn't until the spring of 1992 that Black Hills Institute workers began excavation of the dinosaur which was named after his discoverer. After more than thirty thousand hours of preparation, the speciman was ready for exhibit. "Stan", the largest and most complete (65% real bone) T. rex available to science, headlined the T. Rex World Exposition which opened its Japanese tour in Tokyo during July 1995. After the tours completion, Stan returned to be on permanent display at the Black Hills Museum of Natural History Exhibit in Hill City, South Dakota.

Stan's Ancestors

Tyrannosaurus lived first in Asia, where T. rex's smaller great-great-grandparent, Tyrannosaurus bataar, reigned. A half-million years before "STAN" was born T. bataar's descendants crossed over into this continent, evolved into T. rex - and grew. The area they saw looked completely different from our world today. Then, South Dakota closely resembled the Mississippi delta, with richly diverse subtropical plants and animals. (Now, the high plains are scorched during hot, dry summers and lie frozen during below-zero winters!) "STAN's" world included palm, ginkgo, and redwood trees, and many types of ferns, but no grasses. Crocodiles, flying reptiles, large lizards and small mammals lived there, along with a host of dinosaurs, including: Triceratops, Edmontosaurus (a duckbill) , Ankylosaurus, Pachycephalosaurus, and Thescelosaurus (all T. rex food); as well as the meat-eaters Nanotyrannus, Struthiomimus, Chirostenotes, and Dromaeosaurus.

©Peter L. Larson
Stan's Skull/ "Stan's Teeth
The Black Hills Museum of Natural History Exhibit
Black Hills Institute of Geological Research, Inc (BHIGR)
Contest Results: "If Stan could talk, what might he say?"
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