Characterized by a finless torpedo-shaped body, Nuucichthys rhynchocephalus is the first soft-bodied vertebrate known from the American Great Basin.
Nuucichthys rhynchocephalus swam in the Cambrian oceans between 505 and 500 million years ago.
The ancient animal had a finless torpedo-shaped body that includes a number of markers characteristic of vertebrates.
It is one of only four species documenting the early evolutionary stage of vertebrate lineage.
“The discovery of Nuucichthys rhynchocephalus is a valuable contribution to early vertebrate evolution and biodiversity because of the dearth of these types of organisms in Cambrian fossil sites — including South China, the Northeastern United States, and British Columbia,” said Harvard University paleontologists Rudy Lerosey-Aubril and Javier Ortega-Hernández.
“Early vertebrates start to have big eyes and a series of muscle blocks that we call myotomes, and this is something we recognize very well in our fossil.”
The studied material of Nuucichthys rhynchocephalus consists of a single partial fossil discovered in the Marjum Formation in the House Range of western Utah, the United States.
“Nuucichthys rhynchocephalus is the first soft-bodied vertebrate to be discovered in the Marjum Formation of the American Great Basin,” the paleontologists said.
The new species also confirms that, despite their overall similarities to larval fish — having a cavity that is a sort of rudimentary gill system — they were devoid of fins and therefore had limited swimming capabilities.
“But all of these characteristics clearly point to some vertebrate affinities,” Dr. Lerosey-Aubril said.
“And because it’s very early in the evolution of the vertebrates, they don’t have bones yet — this is why these fossils are exceedingly rare.”
The authors speculate that Nuucichthys rhynchocephalus likely lived high up in the water column of the ocean.
Because of this, and because it possessed no biomineralized…
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