The landscape in Flagstaff today is dominated by ponderosa pine trees, but 270 million years ago, it was all under water.
Even more surprising, it was swarming with sharks, boasting perhaps more sharks than any other place in the world at the time.
Covering the city was a vast inland body of water called the Kaibab Sea that stretched all the way north to present-day Canada. Surrounding it was a barren and sandy desert similar to modern conditions in eastern Africa. In deeper waters to the west, there was a string of islands.
There were few lifeforms on land, but beneath the water, life was teeming and sharks had diversified to fill many of the niches that modern bony fish now fill.
“A lot of stuff we’re finding here is new to science,” says John-Paul Hodnett, a former Northern Arizona University postdoctoral student. “You never know because when you’re walking around out in the woods in Flagstaff, you could be walking on an ancient marine bed on top of sharks.”
EARLY LEOPARD SHARK?
The most recent example is Diablodontus, the “Devil Tooth” shark, which was discovered in the Kaibab Limestone formation near Kachina Village.
The lead author on a paper announcing the new species, Hodnett says the shark was about 3 1/2 feet long and fed on small fish and soft-bodied marine creatures like snails. It likely looked similar to the modern leopard shark.
Its body and head likely had spines and horns, with spikes just in front of the dorsal fin.
Diablodontus was just one species of shark that Hodnett and his NAU geology adviser David Elliott have published in recent years.
They also found a massive predator, the Kaibabvenator swiftae, which was similar to a great white shark. Another massive shark, called Mega T, was discovered north of Grand Canyon in the 1940s and was similar in size to an orca.
Hodnett, who started out as an undergraduate at NAU, says his interest wasn’t always in sharks. One day on the way back from a statistics course on campus, he came a across a shark tooth in the limestone. The discovery was to change his eventual research field.
Together with Elliott, the pair realized the potential of Flagstaff as a hotbed for marine research because of the extensive limestone formations.
TEETH ARE KEY
The rocks were formed from the shells of ancient marine creatures frozen into the huge bodies of sand. Fish and shark teeth, as well as many other animals from the time, can still be seen fossilized in the formations around that time.
They started looking through the shark teeth that had been found by coauthor Tom Olson back in the 1990s and cataloguing them. Among the teeth were five from Kachina Village that stood out because of their notable spikes. The find was to be Diablodontus.
They would eventually find even more Diablodontus teeth in the same Kachina Village area, leading them to believe the species is widespread.
They were able to reconstruct what the shark looked like based on related species of shark for which paleontologists have already discovered entire fossils. They also compare it to modern relatives.
“Unfortunately the composition of the Kaibab is not suited to preserving whole species of shark,” Hodnett said.
But the shark’s heyday was to eventually subside. The massive Permian-Triassic Extinction killed off much of the life in the ocean. And while Diablodontus was a survivor, many other sharks weren’t so lucky.
“Bony fish started to take off in diversity after the PT-event,” he said. “Before that, sharks filled in a lot of those niches.”
Eric Betz can be reached at firstname.lastname@example.org or 556-2250.