Steven Kruse went hunting on the North Sulphur River last spring, 2022 in Fannin County, Texas. His hunt was highly successful. He bagged an 80,000,000 year-old mosasaurus. Well, Steven did not really bag the ancient marine lizard. He was looking for a shortcut back to his truck when he spotted a black, 5 to 6-inch vertebrae in the river bed shale. 

Steven is no stranger to fossil hunting. He hunted fossils with his brother when he was a kid. A more inexperienced eye may never have noticed that it saw a vertebrae, or even a bone at all. However, fossil hunters know well the North Sulphur River. It’s a thing. Ladonia, Texas, established a small park at the bridge where you can park off of TX SH 34. Texas-sized stairs lead to the river bed. 

Steven’s mosasaur find was a tremendous victory for paleontologists, as in it was almost a complete 30-foot skeleton. As Steven followed the path of the vertebrae, he realized the bones could be more than the little pieces usually found at this river bed. He excitedly climbed the river bank and called paleontologist Mike Polcyn, a mosasaur expert at Southern Methodist University. 

In turn, Mike helped Steven contact Ron Tykoski, the Perot Museum's director of paleontology and curator of vertebrate paleontology. Ron and his team asked for and received permission from the Upper Trinity Regional Water District to excavate the mosasaur. The team investigated Steven’s mosasaur site in June. Digging began in July, 2022. 

The dry river bed lined with clay-like brown and gray rock found Ron and Perot Museum paleontologists uncovering the mystery of the mosasaur. This July was hotter than a habanero’s armpit. They arrived at the dig site early mornings followed by a Perot Museum photographer and videographer, and of course, Steven Kruse, plus a high school summer intern.

The team dug into the river bed with picks and shovels. As they got closer to prying out the pieces of vertebrae, they used paint brushes and probes. To distinguish between rock and bone, they tapped it with a metal probe. If it was soft rock, it peeled away from the creek bed with a small amount of force, soundless. If it was bone, it made a sharp, metallic clink against the probe.

However, that did not mean they could easily pull these fossils out of the shale. They had to shoot glue made of plastic and acetone into the mosasaur’s bone cracks to keep the fossils from breaking apart. Then, they had to dig under the fossil making a kind of mushroom-shaped pit. 

After all that hard work, the team made casts called "field jackets" from burlap dipped in plaster and poured that over the fossil to hold the bones in place, like a cast for setting broken bones. When the plaster set, the team carried the vertebrae in sections out of the river bed. But all in all, the entire process took only six days. 

Mr. or Miss Mosasaur is now resting peacefully at the Perot Museum in Dallas. Seventeen-year-old high school summer intern, Rithvik Shroff, reported, “Maintaining stamina and staying cool was difficult, but seeing the fossils come out of the ground made it worth it. I mean, you see them in the museum, but then actually coming out here and seeing how they dig it up…It’s really cool!”

What on God’s green earth is a mosasaur? Scientifically, Steven’s catch is a mosasaurus, an ocean predator in the dinosaur age. The mosasaurus used to be a ferocious predator in the oceans of the Cretaceous period, which was 145.5 million to 65.5 million years ago. 

The mosasaurus species were among the largest members of the mosasaur family. The mosasaurs ruled the ocean in the late Cretaceous period. They were not sea dinosaurs, but a separate group of reptiles, more closely related to modern snakes and lizards, according to the Philip J. Currie Dinosaur Museum. Mosasaurs went extinct 65.5 million years ago.

As the ocean's most dominant predator at the end of the Cretaceous period who thrived in oceans all over the earth, mosasaurs likely would have  eaten almost any kind of prey they could devour, including fish, sharks, seabirds, turtles, and possibly other mosasaurs, according to the U.S. National Park Service. Mosasaurs were top-of-the-food-chain predators and are compared to orca whales.

It is indeed a thing, fossil hunting on the North Sulphur River, that is. And, there is a reason for that. The paleontologists, upon their initial investigation of Steven’s find, noticed more marine lizard bones embedded into the river bed. Unfortunately, they could not unearth those fossils without crushing the jawbones of Steven’s mosasaurus. 

Central Texas was submerged under water 80 million years ago. Its shallow, warm seawater and plenty of food resources in the sea created the perfect habitat for ocean monsters like mosasaurs. Fast forward to the 1920s, when farmers working lands in the North Sulphur River watershed witnessed their flooded crops and the destruction of their livelihoods. 

The powers that be 100 years ago came up with a plan, and they channelized, or otherwise straightened out the North Sulphur River. This allowed the water to drain more quickly and turned disgruntled farmers into happy farmers, but their engineering actions in controlling this river led to a huge archaeological revelation. 

The North Sulphur River can be dry as a bone with mud puddles or it can rage in flowing currents during heavy rains. Its summer river bed is like the perfect spot for mudding in a big ol’, four-wheeling, pickemup truck or on a dirt bike or ATV during dry spells. Rainwater erodes this river’s soft rock and shale and reveals pieces of past creatures we can never truly realize. 

The Ladonia Fossil Park at the TX 34 bridge on the North Sulphur River is well picked over for fossil hunting. If you want to go fossil hunting there, you will need to do a fair bit of hiking. The best time to find fossil treasures at the North Sulphur River is the day after a good rain when the shale and silt is soft in the river bed. 

Mosasaur photo courtesy of MCDinosaurhunter, via CC BY-SA 3.0

Mosasaur cloud photo courtesy of Jay Neitzel, Pottsboro, Texas