|Behold, the Once Ferocious Gorgon|
While searching a site in South Africa's Karoo region for fossils, Roger Smith of the South African Museum and UW Professor Peter Ward noticed a small bone fragment jutting from the earth. Excavating the site, they found the first complete skeleton of a gorgonopsid--a ferocious predator that became extinct 250 million years ago. Museum scientists rate the discovery as one of the most important paleontological finds in South Africa during this century.
What makes this discovery so noteworthy? In more than 150 years of collecting in the Karoo, one of the richest fossil beds on earth, this is the first complete gorgonopsid--or gorgon skeleton--found. Gorgon fossils also have been found in China and Russia, but none are complete.
"Skulls are the most common gorgon fossil discovery," says Ward, professor of geological sciences. "Torso bones typically have been scattered, perhaps by scavengers after the animal's death."
Not this time. This gorgon skeleton excavated by a five-person team including Ward was so intact that "it's like it just died and fell over," says Ward. The skeleton was prone, head curled to the right and all four limbs tucked beneath the body, with the lower parts of the skeleton extended into underlying rock.
Scientists believe that this discovery will provide new insights into the anatomy of a gorgon's torso and limbs. What is already known: gorgons were the largest predators of the late Paleozoic era (the era just before dinosaurs), growing as large as ten feet long, with both reptilian and mammalian characteristics. "Think of the biggest, most ferocious lion you can imagine, but with lizard skin," Ward told the Seattle Post-Intelligencer.
Gorgons' heads appeared somewhat dog-like, with large saber-tooth upper canine teeth up to four inches long. Though they had a somewhat mammalian appearance, their eyes were set at the sides of the head like those of a lizard, and the body was probably covered with scales rather than hair. It has been unclear whether the creatures held their legs beneath them like mammals or splayed from the body like reptiles. Study of the complete skeleton should resolve that debate.
Gorgons' mix of mammalian and reptilian features makes sense, given their lineage. Members of the Therapsida, one of the major groups of vertebrates, they shared a common descendant with reptiles but were on a line that gave rise to mammals rather than dinosaurs, lizards, turtles, or birds. They were wiped out in the world's most severe extinction--the Permo-Triassic mass extinction--250 million years ago, which killed 80 to 90 percent of all species on Earth. The fossil was found in sediment beds lying immediately below those marking the mass extinction.
"This specimen should yield valuable clues about the extinction and provide a better understanding of how the extinction took place," says Ward. "The biggest question is about the rapidity of that extinction."
The specimen, measuring nearly 9.75 feet with a 30-inch skull, will be plastered and removed from the site with jackhammers and large rock-moving equipment. It will then be studied by vertebrate anatomists and mounted for display in the South African Museum in Cape Town.