Sea Monsters of the North: Day 11-Skull Discovered at Last!

NG Emerging Explorer Jørn Hurum is currently on Spitsbergen Island in the Arctic Circle excavating the remains of ancient marine reptiles worthy of the most fantastic Norse legends. Follow the expedition here on Explorers Journal through updates from him and his team, and catch up on his previous expedition for more.

 

By Erik Tunstad

We found the head! And at the same time solved a 150-year-old mystery! What an ending–not only for this year’s season, but for the whole project of the Spitsbergen Jurassic Research Group!

The buildup was perfect.

The long necked plesiosaur we’ve nicknamed “Britney” was found last Sunday, and the digging started on Monday. At the beginning it didn’t stand out, except for giving a faint hope that somewhere, deep in the rocks, there could be a skull.

On Thursday we started to expand the already fair sized quarry by chain saw. At that point, the mud had already been bothersome for several days, and it would only get worse.

Saturday, Jørn asked us to tear down the mountain side. Since this is our final field season in Spitsbergen, this was absolutely our last chance to find the skull of a plesiosaur.

Sunday was horrible between the cold wet weather and the backbreaking labor of digging.

As other team members completed their excavations, more and more of the group’s attention turned to this extraordinarily big hole we had been digging–all the way up at the top of the slope.

Final Push

I went there with Pat this morning. Determined, he started breaking away shale like never before. We others sat there waiting. The wind was freezing, we hunched together–the excitement was tangible.

A couple of hours before lunch, we had 43 neck bones exposed. Just how many cervical vertebrae this animal could have, no one knew–but if it were to be a Colymbosaurus, we should end at 46. Unfortunately, no one had ever seen the skull of a Colymbosaurus.

Then we hit a downer: Pat noticed a layer of rock on the right side of the crater–and he didn’t find it again on the left. There must be a fault going through the hole –one side of the crater once upon a time having been displaced in relation to the other. What if the fault goes through the neck and at some point separated the head from the rest of the body–and transported the head deeper into the mountain? Or even worse; transported it up, where it became exposed and eroded away?

At five p.m. the chain of cervical vertebrae ends. And there is no sign of anything else, either.

The atmosphere hits rock bottom. Oh well, that’s that. I get up and take a few finishing shots of Pat and the others, deep down in the permafrost.

Reaching the end of the neck and finding no skull, everyone's body and spirit finally crash in disappointment. Photo by Erik Tunstad.

 

Well, it was a good try, someone says. Better to try and fail, than not to try at all and live in doubt, says another. Oh well…sad. I start to massage warmth into my limbs and prepare for the trip down to the mess tent, but then I see Pat is still picking in the shale, not at the end of the neck, but slightly to the left of it.

What is it?

“I don’t really know,” he answers. “There IS something there, but I don’t know what.”

First I think he is kidding. I can’t really see anything other than shale. But he doesn’t give up. He picks and brushes, itches his nose, enthusiastic.

Pat rises from his work and asks for a second opinion. Photo by Erik Tunstad.

Down in the hole again. Pat works on, even faster now. A bit confused, eager, disappointed, eager, disappointed. What in the world could this be?

At the end he gets up, pins and needles in his legs, leans against the rock wall and says, “Can someone take a look at this–and tell me if I am seeing something–or am I just fooling myself?”

Julie, who has been assisting him all day, gets down on her knees. YES, it is bone.

After a while the rest of us can see it to: The snout of a plesiosaur!

It can’t be!

The head must have been torn off and turned–for the snout is pointing the opposite way of the neck–but it is laying just a few centimeters from the rest of the animal.

The strong line at the top of the photo, and the triangular shape pointing to the left stand out to the well-trained eye as the skull of a plesiosaur. Photo by Erik Tunstad.

 

Mystery Solved

Thereby the Spitsbergen Jurassic Research Group has solved a 150-year-old mystery: Throughout the excavation Pat has believed it to be a species in the genus Colymbosaurus–several traits of the anatomy suggest this. Colymbosaurus is known from finds in Great Britain far back into the nineteenth century. No one on the other hand, had ever seen the skull of such a plesiosaur.

Colymbosaurus’ closest relatives are found in the genus Kimmerosaurus.

Yet, no one has ever found the body of a Kimmerosaurus. It is only known from skulls. Could it be that Colymbosaurus and Kimmerosaurus were the same animal? And that for some reason or another the body and head were always found separately? It has been suggested–but there is no certain answer.

Until lunch today.

An apparent bone crest at the top Britney’s skull shows how with wishful thinking, one can tell that she is of a different genus than Kimmerosaurus. Britney is not a Kimmerosaur–and we now know what the skull of a Colymbosaurus looks like.

To begin with it is tiny, surprisingly tiny: 20 centimeters long, for a five-meter-long body.

“I have never worked with a skull this fragile,” says Pat. “I haven’t found the teeth yet, but I believe they are small and needle-like.”

So, what kind of animal is this? How did it live? Pat contemplates the answers, they will bring a lot more sense to the Upper Jurassic ecosystem of Spitsbergen.

With such a small head and teeth–what did our Colymbosaurus eat? Probably invertebrates in the open waters, like squid. The fossils in the area show vast populations of ammonites and belemnites–quite small squid with either an inner or outer shell, probably too hard for Colymbosaurus. But the belemnites had relatives without inner shells. Therefore they haven’t been fossilized. However their characteristic tentacle hooks have been found in rock layers, although in small amounts.

Could Colymbosaurus have lived off these?

A pliosaur attacks a plesiosaur. Painting by Raul Martin (National Geographic Magazine Dec. 2008).

Such large hooks scientists only find in the Jurassic boreal seas in the north–at Andøya, Svalbard, Greenland, and Siberia. Could the seas here in the north have been ecologically separated from the oceans in the south–and could that be the reason why there are so many new species up here, including the predators like plesiosaurs and ichthyosaurs?

Jørn, Pat and others start to create an idea–so far just hypothetical–of how the ecosystem was up here.

Pat keeps speculating:

In the Upper Jurassic this sea was at 60 to 65 degrees north. Little is known about the water temperatures, but this can be tested through isotope analysis. It’s possible it was cold, even covered with ice at times. This far north, there would have been seasonal variations in the climate–maybe even with intense growth periods in the spring and summer due to the sunlight.

So, the squids could have migrated here during those periods to eat smaller animals living off plankton.

The plesiosaurs, like Britney, could have followed the squids. The ichthyosaurs could have done the same. These were, with their bigger teeth, probably more generalized predators–but squid could have been an important food source for these too.

The short-necked plesiosaurs, the top of the food chain up here, could have followed the ichthyosaurs and long-necked plesiosaurs here.

Still, we haven’t found fish here. Why not? Where there is water, there is fish. Or maybe not?

There are many unanswered questions. Others have described recent ecosystems without fish. Are we looking at such a situation here?

“We have an unfamiliar, slightly strange ecosystem from the north. We are working on it–and the conclusions are to follow,” Pat proclaims, and continues digging.

It is way past midnight. I’m alone in the mess tent. The rest of the team members are working on removing the traces of 14 days of hard work.

Far up on the hill, a lonely silhouette is picking and brushing. He won’t give up for several more hours.

Re-energized by his discovery, Pat keeps working till the wee hours. Photo by Erik Tunstad.

 

 

Read More From the Expedition

Sea Monsters of the North: Day 1

Sea Monsters of the North: Day 2

Sea Monsters of the North: Day 3

Sea Monsters of the North: Day 4

Sea Monsters of the North: Day 5

Sea Monsters of the North: Day 6–Mountain vs. Chainsaw

Sea Monsters of the North: Day 7

Sea Monsters of the North: Day 8

Sea Monsters of the North: Day 9

Sea Monsters of the North: Day 10

All Posts From Jørn Hurum

 

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Jørn Harald Hurum was born in Drammen, a city on southeastern Norway. Since childhood he has collected fossils and minerals in the Oslo region. Since 2000 he has been employed at the Natural History Museum of the University of Oslo where he works as an associate professor in vertebrate paleontology. At the University he teaches paleontology and evolutionary biology and supervises masters and Ph.D. students. One recent outreach effort brought him on stage before a general audience interested in his Arctic island project excavating fossils of ancient sea monsters. “There was a four-year-old in the front row and he couldn’t stop asking questions, really good questions” Hurum remembers. “This little boy was so excited to know there was somebody else who understood the things he was wondering about. He made my whole day! As a child, I felt very alone with my interest in fossils. Finally at age 13, I discovered there was a museum in Norway that actually employed people to study paleontology. I started corresponding with those scientists and it was such a relief, such an inspiration. I hope I can give some of that spirit back to the next generation.” Learn More About Jørn and His Work