When a Monsanto phosphate ore-mining crew member took a slice off the mountain of deposits in front of him Wednesday morning, he unearthed a reminder of Idaho’s world 250 million years ago.
It was a time when only creatures with gills survived.
The swirl-shaped array of fossilized teeth in front of the Monsanto worker belonged to one of those creatures — one that likely existed at the top of the food chain. The spiral teeth once rested inside the business end of a prehistoric shark called Helicoprion. Because the body was made of cartilage just like modern sharks, all that remains of this once giant fish are its teeth.
And that spiral dentition has been fossilized in rock formations all over the globe.
“It was widespread 250 to 270 million years ago,” said Leif Tapanila, curator of earth sciences at Idaho State University’s Museum of Natural History. “That was well before the Bonneville Flood.”
ISU’s museum is home to 29 of the approximate 100 known Helicoprion fossils known to exist. The abundance of the fossils at the Pocatello university has a lot to do with the geology of Southeast Idaho and the abundance of phosphate mining.
Scraping away at the earth has revealed secrets from the past.
Tapanila said the Monsanto employee recognized what had been exposed immediately and made a call to ISU – a call the museum professor was excited to field.
“They call them Mayan calendars,” Tapanila said about the spiral shape of the fossilized teeth. “It was extremely convenient they found another one.”
Last week’s discovery comes just as Tapanila and his associates at the university are holding a summit with other experts on Helicoprion to discuss the potential features of the giant shark. The largest fossil at ISU would indicate the animal was 20 to 30 feet in length.
“It was likely the largest fish in the sea,” Tapanila said.
The professor and his undergraduate assistant Jesse Pruitt immediately drove to Soda Springs to retrieve the latest discovery from an area known as the Enoch Valley. The fossil was extremely fragile and broke into many pieces when they removed it, but some of the fossilized teeth remained nearly intact.
Tapanila has plans for those teeth. He will take thin sections from those teeth and examine them under microscopes to gather more data about the molecular composition of the giant shark.
The ISU professor who came to the university in 2005 from Ontario, Canada also has plans for a large intact set of Helicoprion teeth encased in solid rock which has a diameter of nearly two feet. A CT scan will give the scientist a better look at the exact structure of the dentition.
“We can take these physical objects and make a 3-D image of them and put it in a world where it can be manipulated,” Tapanila explains.
That manipulation has been taking place in the Idaho Virtual Lab inside the museum building. Lab manager Robert Schlander has taken known dimensions and structures from the fossilized shark teeth and applied them to software on computers to attempt to recreate what the Helicoprion actually looked like.
“It’s reverse engineering,” Schlander said.
Scientists have many surviving pieces of one part of a monster shark that roamed the warm seas of the relatively warm Permian seas – like the one that covered southern Idaho, Utah and parts of Wyoming.
And they are fascinating survivors of the extinct species because the whirl pattern of the teeth reveals that this shark never shed it’s teeth. It simply created rows coiled inside each other with the newest, longest and sharpest teeth in the front row.
The big puzzle for scientists like Tapanila is where did those teeth exist in the anatomy of the fish. Some schools of thought place the teeth in the throat of the shark, which would explain why none of the recovered fossils shows wear or breakage of those teeth.
“Or they may have lived on soft food like squids,” Tapanila said.
The scientist is sure of one thing. Although the creatures had a wide range across the oceans of the world at that time, they disappeared. Whatever evolutionary advantage those swirl-shaped teeth might have held disappeared with them.
The Bonneville Flood
The Bonneville Flood occurred about 14,500 years ago when a giant inland lake that once filled all of the Salt Lake basin experience a break in the mountain range southeast of Downey and began flooding Idaho and even eastern Washington. Experts estimate the flood reached a peak flow of 33 million cubic feet per second which lasted weeks. Flooding continued for years and formed the canyons of the Snake River.
The Bonneville flood took place about the same time as the Missoula Floods in the Pacific Northwest and is believed to be the second largest in known geologic history.