Spike-Toothed Worm and Other Creatures Lived in Grand Canyon 500 Million Years Ago
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Spike-Toothed Worm and Other Creatures Lived in Grand Canyon 500 Million Years Ago
Fossils of Cambrian-era animals from the Grand Canyon have been discovered. The animals lived between 507 million and 502 million years ago. The fossils include tiny rock-scraping molluscs, filter-feeding crustaceans, spiky-toothed worms, and even fragments of the food they likely ate. Researchers say that during the Cambrian Period, the Grand canyon was like a “goldilocks zone” that had the perfect conditions for animals to evolve rapidly. The discovery was made by a group of researchers from the University of Cambridge and is the first of its kind in the canyon. The fossilized animals tell a story of evolutionary progress during one of the most consequential periods in Earth’s history, the researchers say. They also identified a fossil of a new species of priapulids, also known as penis or cactus worms, which were widespread in the area but are nearly extinct today. They say the fossils show that Cambrian animals had wide variety of feeding styles, some of which have modern counterparts.
Long before the Grand Canyon became a hotspot for tourism, it was a hub of ancient animal activity. All kinds of marine animals lived in the area back when it was submerged in the ocean during the Cambrian explosion, more than 500 million years ago. During this watershed event, life flourished as most major animal groups emerged for the first time.
When it comes to Cambrian-era fossil finds, a new study published in Science Advances has struck gold. After dissolving rocks obtained during an expedition in the Grand Canyon, researchers found an astonishing assortment of fossils that illustrate the weird and wonderful quirks of many ancient creatures. From crustaceans and molluscs to a spike-toothed worm, the animals that once occupied the Grand Canyon tell a story of evolutionary progress during one of the most consequential periods in Earth’s history.
An Ancient Goldilocks Zone
A treasure trove of exceptionally well-preserved early animals from more than half a billion years ago has been discovered in the Grand Canyon, one of the world’s most iconic natural sites. The rich fossil discovery – the first such find in the Grand Canyon – includes tiny rock-scraping molluscs, filter-feeding crustaceans, spiky-toothed worms, and even fragments of the food they likely ate. (Image Credit: Mussini et al.)
A group of researchers from the University of Cambridge, who authored the new study, discovered the fossils during a 2023 expedition through the Grand Canyon while traveling along the Colorado River. Upon returning to Cambridge, they dissolved rock samples in a solution of hydrofluoric acid and passed the sediment through multiple sieves.
This process revealed thousands of tiny fossils, and although none were entirely preserved, the researchers were able to piece together recognizable structures to identify which animals once called the Grand Canyon home.
The fossilized animals lived in the Grand Canyon between 507 million and 502 million years ago. The researchers say that during the Cambrian Period, the Grand Canyon was like a “goldilocks zone” that had the perfect conditions for animals to evolve rapidly. The water there was oxygen-rich, and it was neither too deep nor too shallow. As a result, animals were protected from wave damage and UV radiation from the Sun.
Read More: Prehistoric Rock Art Lies Hidden Throughout the Grand Canyon
A Motley Crew of Marine Creatures
The reason why these fossils are so important is that they’ve preserved softer, non-mineralized body parts. According to the researchers, most Cambrian-era fossils are of hard-shelled creatures, but the newly discovered Grand Canyon fossils are a rare exception.
Many fossils in the collection are of crustaceans that possibly belong to the same group as brine shrimp. These fossils indicate that the tiny creatures had hair-like extensions on triangular grooves around their mouths. They swept up food particles with their hairy limbs and then ground them up with their teeth. Remnants of their meals even remained on the fossils, as the researchers found plankton-like particles near the crustaceans’ mouths.
Another group of fossils were preserved molluscs that boasted a set of teeth similar to modern garden snails, using them to scrape algae or bacteria from rocks.
The researchers also identified a fossil of a new species of priapulids, a group of unsegmented marine worms. The priapulid found at the Grand Canyon used hundreds of branching teeth to collect food. Inspired by the size of the fossil and its abundance of teeth, the researchers named the species Kraytdraco spectatus after a fictional creature from the Star Wars universe called the krayt dragon.
“We can see from these fossils that Cambrian animals had wide variety of feeding styles used to process their food, some which have modern counterparts, and some that are more exotic,” said first author Giovanni Mussini, a Ph.D. student in Cambridge’s Department of Earth Sciences in a press release.
The Race to Evolve in the Grand Canyon
Since the Grand Canyon had the ideal living conditions for animals to thrive during the Cambrian explosion, it also facilitated major leaps in evolution. The researchers say that because animals had access to plenty of food, they were able to take more risks, which allowed them to triumph in the evolutionary race. As a result, animals developed a range of traits — including adaptations related to food, movement, and reproduction — that continue to shape their lives to this day. “Animals needed to keep ahead of the competition through complex, costly innovations, but the environment allowed them to do that,” said Mussini in the press release. “In a more resource-starved environment, animals can’t afford to make that sort of physiological investment. It’s got certain parallels with economics: invest and take risks in times of abundance; save and be conservative in times of scarcity. There’s a lot we can learn from tiny animals burrowing in the sea floor 500 million years ago.”
Read More: Meteor Crash May Have Caused an Ancient Lake to Form in the Grand Canyon
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Jack Knudson is an assistant editor at Discover with a strong interest in environmental science and history. Before joining Discover in 2023, he studied journalism at the Scripps College of Communication at Ohio University and previously interned at Recycling Today magazine