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University of Wyoming

LIFE WASN'T EASY FOR "BIG AL" 145 MILLION YEARS AGO

(NOTE: This is the fourth in a series of articles about "Big Al," an Allosaurus that roamed Wyoming 145 million years ago. The first display skeletal cast of "Big Al" is on exhibit at the University of Wyoming Geological Museum.)

Jan. 29, 1996 -- Life wasn't easy for one of the most dreaded dinosaurs of its time, "Big Al," a 25-foot long Allosaurus who lived 145 million years ago.

JURASSIC ENCOUNTER"Big Al," now on display at the University of Wyoming Geological Museum, was named by the paleontologists who uncovered its fossil remains on Bureau of Land Management property in 1991. Scientists at Montana State University's Museum of the Rockies and at the UW Geological Museum are studying "Big Al's" bones to determine how this young adult carnosaur lived and died.

During its life, the Allosaurus sustained broken ribs and injuries or infections to its feet, claws and hips.

Were "Big Al's" ribs broken when it was hit by the tail of a larger plant-eating dinosaur warding off an attack? Was it wounded while contesting for a female with another Allosaurus in a violent mating ritual? Was it suffering from a disease when it died?

"There is a lot we can speculate about, but we do know Big Al had a hard life," says Brent Breithaupt, UW Geological Museum director. "Even for a fierce predator of its size, its injuries were painful and troublesome."

"Big Al" is the most complete Allosaurus specimen ever discovered and it is providing paleontologists with exciting investigative opportunities, including a paleopathological study. The completeness of the skeleton allows for the first study of this type on an individual Allosaurus. Scientists believe that "Big Al" is a young adult because it is smaller than a 40-foot long full-grown dinosaur and because some of its bones aren't completely fused together. This information is useful in making comparisons to other Allosaurus specimens.

"Big Al" may help scientists chart the life span and growth rate of Allosaurus, information that is very difficult to determine from most dinosaur specimens previously discovered.

Other questions "Big Al" might help answer include whether such carnosaurs actually hunted their prey or were scavengers as some paleontologists speculate; if Allosaurus hunted alone or in packs; and how they were affected by the environment.

Wyoming during the Jurassic Period was a lowland floodplain. The region's climate and landscape were similar to that found today in Africa's Serengeti Plain, with comparable wet and dry seasons. Scientists theorize that herds of plant-eating sauropods such as Apatosaurs were constantly on the move in search of food to satisfy their large appetites. Predators such as the Allosaurus followed these herds, preying on the young and weak.

"Big Al's" skeleton was found in an ancient stream bed. It may have been trailing a sauropod herd when it died. Scientists are examining nearby fossil deposits for clues about its death.

Many theories of how dinosaurs lived are based on observations of modern animals. It is assumed that Allosaurus may have hunted in packs because it is unlikely that a single carnosaur could take down an Apatosaurus or other large herbivore several times its size. Today's "King of Beasts," the African lion, hunts in groups to bring down larger animals such as buffalo.

"If we've learned anything from the past century and more of dinosaur digging, it is that we're learning something new everyday," Breithaupt cautions. "We make assumptions about dinosaurs based on animal behavior today, and we don't know everything about modern animal behavior."

Scientists do know is that Wyoming and the region has many more secrets and surprises about the Earth's prehistoric past awaiting discovery.

The only display skeletal cast of "Big Al" is on exhibit at the UW Geological Museum. For more information, call (307) 766-2646.

THE STORY OF "'BIG AL' 

On Display at the UW Geological Museum

BBC Dinosaur page featuring Big Al