Pembina Gorge Fossil Dig unearths new and rare finds

The annual Pembina Gorge Fossil Dig had a highly successful year with surprises and excitement for both the amateur paleontologist as well as the professional.

Posted 08/18/2017

By Melissa Anderson

The North Dakota Paleontological Resource Management Program, a department of the North Dakota Geological Survey (NDGS), holds fossil digs across the state during the summer.
“The dig went very well. We lost one day to rain, which is typical, but the other days were beautiful. The participants meshed really well and everyone seemed to enjoy themselves,” Clint Boyd, Senior Paleontologist with NDGS, said.
The most productive day turned out to be family day, which was great and packed full of people that joined the paleontology crew from as far away as Florida, Connecticut, and even Italy.
The Pembina dig gave adventure seekers five days of exploring the Pierre Formation. The site dates to the Late Cretaceous period that occurred 80 million years ago and holds some of the oldest surface rocks in North Dakota. The length of the dig is similar to the other digs that occur within the state.
“We fit all our public fossil digs into the time between when school gets out and when it starts again, which limits the amount of time available,” Boyd stated.
“Also, with the recent budget cuts we have had to focus more of our time at sites that we can travel to each day from Bismarck, eliminating lodging costs. We would love to spend more time in the Pembina Gorge, but with so many sites to visit each summer (not all of which get visited each year), we have to ration our time appropriately.”
The most common at the Pembina dig site are typically fish fossils. This includes mostly scales and vertebrae from the back. However, over the last few years, the site has been providing some very exciting finds for those who venture to the hillside fossil site.
A skull found two years ago and the three bones collected from last year turned out to be from the “new to North Dakota” species. The find highlights the importance of the fossils preserved in the Pembina Gorge area and their key role in helping to understand North Dakota’s prehistoric heritage.
Over the past few years one mosasuar had been mostly uncovered, the majority of which the NDGS team has found in parts and pieces. It was during the summer of 2015 that a chance discovery by visitors to the site led to the finding of another mosasuar skull. It is this most recent find that Boyd believes is the new species.
“This site was initially found because of the widening of the road, which makes it a catch 22 for us, where because of its positioning, it is easily accessible to everyone. When people visit the site and look around we hope that if they find anything that they report it rather than just walking off with it. Luckily, in 2015, the person who found the piece of jawbone to this new species skull reported it, otherwise it could have been years till we found it,” Boyd explained.
During this summer’s dig there were more new bones discovered that belong to the new to North Dakota “species”, a direct result of previous digs work of gently uncovering the fossils.
“We found at least six new bones from that specimen. Most of them were ribs from the neck, but one larger piece appears to be part of one of the paddles which may indicate that we will keep finding more of the skeleton the more we dig into the hillside,” Boyd shared.
The discovery of part of a mosasaur paddle from the new species gives hope that there is more to the skeleton to be found.
“We almost never find complete skeletons. There is almost always something missing. For this skeleton, we have about 50 percent of the skull and majority of the neck as well as the paddle. The more we keep digging the more we could possibly find,” Boyd stated.
From 2012 to 2014, the paleontologists were able to find a nearly complete skeleton of a specimen. The only piece missing was the skull. The find marks the Pembina Gorge site as having a history of nearly complete to complete fossilized specimens giving hope that this “new to North Dakota” specimen still has many pieces to be uncovered.
“The fact that we keep digging and finding post crania, or the back part of the skeleton, means we have a better chance of finding a nearly complete skeleton,” Boyd shared.
While this particular specimen shows sign of rotting prior to its being buried making the fossilized remains harder to locate due to being spread out rather than close together, finding the partial paddle is a good sign that there is much more still to be found.

The partial paddle was preserved by way of “capping”. Once the edges of the bones were found, the paleontologists and those present at the dig dug out the surrounding rock, making a pedestal. The rock and bone were then capped with burlap soaked in plaster to make a protective covering to transport the bones back to the lab in Bismarck where the paleontology crew will then work on the detailed cleaning process.
Besides finding additional fossils of the “new to North Dakota” species of mosasaur, the 2017 dig held a few other surprise finds for the participants. A partial skeleton of the flightless diving bird, Hesperornis, was found this year.
“This is not a very common animal to find. It was in a new spot in the hillside, indicating that there are many more bones at the site waiting to be found,” Boyd stated.
In addition to the Hesperornis find, Boyd believes that they may have also located a third mosasaur skeleton at the site.
“But it could have been a few isolated bones. We won’t know until we get back next year and do some more digging.” Boyd said.
After long years of work, Boyd feels that the paleontology crew is getting a good idea for where the most productive parts of the Pembina Gorge fossil site are situated.
“However, each year we make unexpected finds in spots we did not expect, so it’s important for us to continue working the entire site over time.”
While this year’s fossil dig is concluded, those interested in seeing fossils from the Pembina Gorge can still have the chance to view them. Fossils from the Pembina Gorge are on display at the Pembina State Museum in Pembina, the Cavalier County Museum in Dresden, the Heritage Center & State Museum in Bismarck, and Icelandic State Park in Cavalier.
“However, no fossils from the new mosasaur are on display yet. The bones are still being cleaned, and we hope to them mount the skull and neck to put on display somewhere in the state,” Boyd stated.
Boyd and his fellow team members would like to thank the North Dakota Parks and Recreation Department for hosting this dig each year and making this opportunity available to the public. The Pembina Gorge Foundation also played a big role in ensuring the public fossil dig was a success this year.