Jakarta – an international research team has successfully reconstructed the hearts, brains, and ancient fish fins from fossil fragments as small as a fingernail using advanced imaging techniques. The bizarre creature, a mix of tadpole, horseshoe crab, and snail, has astonished scientists and could potentially rewrite a key chapter in animal evolution.
Published on August 6 in Nature, the findings detail an ancient fish that challenges established evolutionary timelines.
The earliest fish, appearing around half a billion years ago, didn’t swim in open waters. rather,they stayed close to the seabed,absorbing food before
“There’s a large data gap behind this change,” explained Michael Coates,a biologist at the University of Chicago and senior author of the study. “We lose footage from fossil records that can help us sort important events.”
For decades, crucial evidence lay hidden in a paleontology archive. An expedition in 1969 to Norway’s Spitsbergen islands yielded thousands of fossil-bearing sandstone chunks. It took researchers 40 more years to dedicate the time needed to sort through them.
amidst the sandstone, the study’s authors discovered a perfectly preserved half-inch skull of a fish called norselaspis, dating back 410-407 million years.The team sent their findings to the Paul Scherrer Institute in Switzerland. There, specialists used synchrotron-based X-ray microtomography to scan the specimens layer by layer.
After thousands of hours of digital reconstruction, the 3D scans revealed delicate bones and well-preserved organs and muscles in unprecedented detail. “With this unbelievable digital atlas, we now understand Norselaspis with greater anatomy than many surviving fish,” stated lead author and paleobiologist Tetsuto Miyashita.
Strikingly Unique Features
Norselaspis possessed anatomical characteristics previously thought to exist onyl in later, jawed fish. Notably, it had a robust heart and widened blood vessels to facilitate blood flow. Miyashita humorously noted, “It’s like it had a shark heart under lamprey skin.”
Its sensory organs were also remarkable. Seven small muscles controlled its eyes, and its inner ear was relatively large. “If Norselaspis were scaled to our size, each inner ear would be the size of an avocado, and its heart would be as big as melons,” Miyashita added.
The fish swam using angled, oar-like fins behind its gills, allowing for quick spins, stops, and acceleration.however, given its lack of jaws and teeth, these adaptations were likely for evading predators rather than hunting. This interaction spurred a biodiversity boom in the oceans.
“When jaws evolved alongside these features, it created a powerful combination of sensory systems, swimming, and eating, ultimately driving the diversity and abundance of Devonian fish,” said Coates.
Beyond its evolutionary placement, Norselaspis also presented new insights into the development of limbs.The nerves connected to its shoulders were separate from those reaching its gills. This lead researchers to theorize that the shoulders seen in tetrapods (four-limbed vertebrates) evolved as a new structure linked to the neck, separating the torso from the head.
While most jawless fish have torsos that seamlessly merge into their heads, vertebrates developed necks and throats. Norselaspis falls in between, a transition researchers liken to humans having arms extending from behind their cheeks.
While the exact trigger for jaw formation remains elusive, Norselaspis demonstrates that vertebrate evolution wasn’t a straightforward, linear path. “It’s not as simple as moving directly from being prey to being a top predator,” Miyashita concluded.
