With 5 eyes, a backward-facing mouth, and an extended, claw-tipped trunk the place its nostril needs to be, Opabinia regalis is among the strangest-looking celebrities of the Cambrian interval. The truth is, this historical sea-dweller is so distinctive that scientists have by no means found one other species within the fossil report that seems to suit into its alien-faced household.
That’s, till now.
Meet Utaurora comosa — a small, spiky-tailed marine animal that lived just a few million years after Opabinia in what’s now North America. First described in 2008, U. comosa was initially categorised as a relative of the fearsome Anomalocaris, a claw-faced apex predator that terrorized the Cambrian seas. However a brand new examine means that U. comosa could have been far more than simply one other historical predator.
Associated: Why do Cambrian creatures look so bizarre?
In a paper printed Feb. 9 within the journal Proceedings of the Royal Society B, researchers reexamined the one recognized U. comosa fossil, evaluating it with greater than 50 residing and extinct animal specimens. The crew concluded that U. comosa is nearly definitely a relative of Opabinia — and never a relative of Anomalocaris — making U. comosa solely the second member of Opabinia‘s household ever found and the primary one discovered in additional than 100 years.
“The weirdest surprise of the Cambrian not stands alone,” the researchers wrote of their paper.
Terror of the seas?
From 541 million to 485 million years in the past, Earth‘s seas bloomed with biodiversity for the primary time. This period, generally referred to as the Cambrian explosion, was when the family of all main animal teams alive at the moment first appeared within the water. The Cambrian explosion additionally gave rise to the world’s first really fearsome apex predators.
These carnivorous killers are referred to as the radiodonts — a reference to the circular-saw-shaped mouths on the undersides of their heads. A lot of them — together with the notorious Anomalocaris — additionally had greedy, claw-like appendages on the fronts of their heads, doubtless for snatching unsuspecting prey and delivering it to their hungry mouths.
The one recognized fossil of U. comosa — found in Utah’s Cambrian Wheeler Formation — had no such appendages on its head. In the meantime, its inch-long physique was segmented into 14 or 15 furrows, every tipped with a sharp flap, very like Opabinia. Regardless of these particulars, the U. comosa fossil was categorised as a radiodont in 2008.
That did not sit proper with paleontologist Stephen Pates, a former Harvard graduate pupil and lead creator of the brand new examine. So, of their new paper, Pates and his colleagues reexamined the U. comosa fossil, evaluating 125 of the fossil’s traits with greater than 50 teams of residing and extinct arthropods, which is the most important phylum within the animal kingdom and contains all bugs, crustaceans and arachnids.
The crew’s evaluation confirmed that just about none of U. comosa‘s traits slot in with the radiodont household; somewhat, the fossil creature was virtually definitely associated to Opabinia.
“This implies Opabinia was not the one opabiniid,” Pates mentioned in a assertion. “Opabinia was not as distinctive a species as we thought.”
These findings are thrilling for just a few causes, not the least of which is that Opabinia can now invite not less than one different species to its household reunions.
In a broader sense, the existence of one other opabiniid exhibits that this wasn’t only a household of weirdos however that each creatures had been “a part of a much bigger image” of Cambrian evolution, Pates advised The New York Occasions. With their backward-facing mouths and furrowed our bodies that seem virtually segmented, Opabinia and U. comosa appear to be clear predecessors of recent arthropods, a lot of which possess these identical traits, Pates added.
Initially printed on Dwell Science.