Triceratops skull (Originally published in: Marsh, O.C. "The dinosaurs of North America." Sixteenth Annual Report of the United States Geological Survey, pp. 133-244. Washington: Government Printing Office, 1896. Sometimes Wikipedia is just really cool.)

OK, so the odds are that this guy wasn’t actually the very last dinosaur on the planet before the mass extinction, but it makes for a good headline. (Isn’t it wonderful how facts can be misconstrued so succinctly?)

But I didn’t link to the article just to make a point about its headline.

The prevailing dinosaur extinction theory at the moment is the impact theory (dinosaurs became extinct after a meteor struck the earth, kicking up a massive dust cloud that killed off the plants, then the plant-eaters, then the meat-eaters, while the flying dinosaurs and small mammals somehow survived). This lovely theory has a flaw, referred to in the field as the “3 meter gap.”

Basically, until recently paleontologists hadn’t found any fossils within 10 feet (3 meters) of the K-T boundary (the layer of rock created around the time of the impact). This gap in the fossil record led some to speculate that perhaps dinosaurs had already begun to die out by the time the meteor hit.

A recent find in the Hell Creek Formation in Montana (which loyal readers will know is my daughter’s top tourist destination) has changed that. A team from Yale University found a fossilized horn, most likely from a Triceratops, just 5 inches below the boundary. The find provides evidence that some dinosaurs at least were doing just fine a few thousand years before the meteor hit, thank you.

The find is also leading some to question whether the 3 meter gap ever really existed. The K-T boundary is notoriously hard to spot in the field, making it possible that fossils found in the past were much closer to the boundary than they appeared. For example, when the team from Yale found this Triceratops horn in the field, they estimated it to be some 3 feet below the boundary based on a visual analysis of the rock surrounding it. A soil analysis performed after they brought the fossil home, however, proved that it actually lay a mere 5 inches below the boundary.

Darn you advancing technology!

I suppose there isn’t much paleontologists can do about the fossils found in the past, but as this more sophisticated soil analysis technique is used on future finds, the 3 meter gap may go the way of the upright T-Rex and underwater sauropods.

(And yes, I know, it’s not Science Friday yet, but my daughter and I are too excited about this to wait.)