Evolutionary History

Interview with Jack Horner, Paleontologist, Museum of the Rockies, Bozeman, MT

“We have very good evidence that this sturgeon lived during the Cretaceous period at the same time as the dinosaurs. When sturgeons were swimming through the waters, there were Tyrannosaurus Rex’s walking in Montana. If we look at the ecosystem, basically what we see is a situation very similar to what we see in the lower Mississippi with sturgeon, garfish, turtles, crocodilians, and alligators running around on the banks of the rivers, in between rivers. We’d see Tyrannosaurs, duck billed dinosaurs, armored dinosaurs, horned dinosaurs, and the vegetation at that time in Montana was pretty much the same as it is in Louisiana today.

We have a specimen from the Cretaceous period, and that’s the time when T-Rex and Hadrosaurs and Ceretopsians lived.  We have  this beautiful specimen right here at the Museum. This sturgeon fossil is the most complete fossil we have anywhere in the world and it came from the Judith River formation here in Montana.”

Sturgeon Fossil – A nearly complete articulated sturgeon skeleton approximately 800 mm or 31 inches in total length, from the Upper Cretaceous Lower Judith River Formation, northeastern Montana. It is the most complete and best-preserved fossil sturgeon yet known. It is approximately 70 million years old. (Used with permission from The Field Museum photo archives image ID A93851c, Chicago, IL.)

Additional Evolutionary History

Today, wild pallid sturgeon living in the waters of the upper Missouri River are one of the rarer fish species in North America. After millions of years of ancestral survival through environmental disruptions, mass extinctions and multiple glaciations of North America, this fish is in murky water both literally and figuratively and may be on the brink of disappearing forever.

Sturgeon as a family are very old, with an ancestry dating back 200 million years.  By comparison, the salmonid family, which includes trout and salmon, are only 45 million years old.  The pallid sturgeon we see today is a fish descended from sturgeon that lived nearly 80 million years ago.

 These species have existed since the time of the dinosaurs and basically they have seen everything from the extinction of the dinosaurs… to the ice ages… to changes in river course…. Major landscape type level shifts in what the habitat look like. And in all those cases they were able to adapt, evolve, and move forward as a species. 

As the Rocky Mountains began forming some 70 million years ago; a vast inland sea slowly retreated over the eons and a massive drainage system gradually formed. A drainage system that eventually emptied into a mighty river – The Missouri.

Its headwaters are in SW Montana and it winds its way some 2300 miles downstream draining parts of ten states and two Canadian provinces until it joins the Mississippi River at St. Louis. The Missouri was historically a fairly shallow, warm, free flowing river with a meandering tendency and a muddy consistency.  It contained both swift and slow moving sections with numerous side channels… sand bars…. islands and cottonwood snags.  Its flood plains were awash with sloughs and backwaters.

But this relatively placid river could sometimes transform into a wild torrent and flood extensively in the spring. During the winter it is not uncommon for ice jams to occur, which can also cause flooding.

The Missouri drainage became home to many wildlife species, including a wide variety of fish. This abundance also attracted prehistoric humans about 11,000 years ago.

The pallid sturgeon is native to the Missouri and Mississippi river systems and exists nowhere else in the world. One other sturgeon species, the shovelnose sturgeon, also lives in the same waters as the pallid.