A fossil found by a pair of hikers last year has turned out to be the skull of a huge new species of prehistoric fish that lived around 72 million years ago.
The hikers came across the fossil in February 2023 while walking through the North Saskatchewan River Valley in Edmonton, Canada. Initially, they thought the fossil might represent a fragment of dinosaur skin. But they subsequently took it to paleontologist Phil Currie at the University of Alberta (UA), who confirmed it was part of an ancient fish.
Currie then gave the fossil, which preserves a portion of the skull, to UA fish paleontologist Alison Murray and colleagues, who identified it as a previously unknown ancient sturgeon.
The new species, now described in a study published in the Journal of Vertebrate Paleontology, has been named Boreiosturion labyrinthicus. The fish also represents an entirely new genus (group of species).
The skull of the fish that the hikers found likely represents an individual that measured at least six-and-a-half feet in total length when it was alive, according to the researchers.
Sturgeons are a group of fish in North America and Eurasia that inhabit freshwater environments, including rivers and lakes, estuaries and coastal waters. These fish are long-lived, and some species can grow quite large, typically reaching around 7-12 feet in length.
Sturgeons have been around since the age of the dinosaurs. The immediate ancestors of these fish can be traced back to more than 200 million years ago, although the first true sturgeons appear somewhat later.
"They're some of the largest bony fish we have today and have been around since dinosaurs were walking around on land," Luke Nelson, one of the study's co-authors, said in a press release. "They almost look like dinosaurs, because they've got these massive sizes and enormous scales running down their back that make them look kind of wicked."
The body shape of sturgeons is almost shark-like while they also have a suctioning mouth on their undersides.
These fish have undergone relatively few changes since the Cretaceous period, which lasted from around 145-66 million years ago. In fact, they are often referred to informally as "living fossils." As far as the researchers can tell, the new species would have had many similarities to modern sturgeons, Nelson told Newsweek.
"Although this extinct species shared many traits with modern sturgeon, it had key differences in the patterning on the surfaces of the skull that helped us to determine it was a new species," Nelson said.
The fossil found in Edmonton comes from a geological formation that took shape roughly 73-72 million years ago during a stretch of the Cretaceous period known as the Campanian stage (roughly 84-72 million years ago).
The fossil is the first documented sturgeon from the latest parts of the Campanian found in North America, according to the study.
The newly discovered fossil fills a gap in our knowledge of when and where sturgeons lived during the end of the Cretaceous, shortly before the mass extinction event that wiped out all non-avian dinosaurs, along with much of life on Earth.
"There are almost 30 species of sturgeon alive in the world today, and we still have a lot of questions about how the different species are related," Nelson said. "As a new species, this fossil has the potential to help resolve relationships within the sturgeon family tree—so that we can have a better understanding of the evolutionary history of this long-lived group of fish."
The fossil is also significant because it is the first new species of fish described from within the Edmonton area, according to the researchers.
"It is fascinating to me that sturgeons were present in Edmonton over 70 million years ago, and still are alive in the city's North Saskatchewan River Valley today," Nelson said.
"I believe that fossils can help increase our appreciation for this group of fishes. Since they are a slow-maturing and large-bodied group of fish, they are particularly at risk to population declines from over-harvesting. The lake sturgeon is a protected species in Alberta, and hopefully exciting discoveries like this can help highlight why it's so important to conserve these species."
Do you have an animal or nature story to share with Newsweek? Do you have a question about paleontology? Let us know via science@newsweek.com.
Update 1/15/24, 7:59 a.m. ET: This article has been updated with comments from Luke Nelson and an additional image.
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