Scientists found a fossilized brain and intact central nervous system of a prawn-like creature with three eyes that swam 500 million years ago. The creature was called Stanleycaris hirpex with two eyes on stalks and a third eye on the middle of its head and a circular mouth with teeth and frontal claws that had an impressive line of spines, MailOnline reported.
S. hirpex lived during the Cambrian explosion, a time when rapid evolution is observed in major species. It belonged to an ancient and extinct group of the arthropod evolutionary tree known as Radiodonta, which is a distant relative of insects and spiders. Scientists are most excited about its brain and central nervous because it could shed new light on the evolution of the arthropod brain, vision, and structure of its head.
The Stuff of Nightmares
Stanleycaris was described as the "stuff of nightmares" because of its unique appearance. Scientists studied 250 fossilized specimens of Stanleycaris and 84 of them still have remains of the brain and nerves are still preserved even after 506 million years.
Study lead author Joseph Moysiuk from the University of Toronto and a Ph.D. candidate based at the Royal Ontario Museum explained that the discovery stood out because of the quality of preservation and the large number of specimens available.
It allowed the team to make out the details of the large eyes and traces of nerves entering the appendages. Moysiuk said that it was so clear that the specimens could be mistaken for an animal that just died yesterday, EurekAlert! reported.
The fossils show that the brain has two segments - the protocerebrum is connected to the eyes and the deutocerebrum is linked to frontal claws. Moysiuk believed that a two-segmented head and brain have deep roots that explain arthropod lineage, suggesting that evolution likely happened before the three-segmented brain evolved into the modern members of the diverse animal phylum.
Though it might not be a game-changer, researchers noted that studying how repeated copies of many arthropod organs found in segmented bodies could have radical scientific implications. It could lead to understanding how structures diversified across the group, making it a Rosetta Stone that helps link traits in radiodonts and other early species to their living members today.
Unique Eye Structure Never Seen In Radiodonts Before
The stanleycaris was less than 8 inches ( 20 centimeters) in length, which was quite small for radiodonts. However, it is still considered an impressive predator in an age when most animals are no larger than a human's finger.
According to Nation World News, the term radiodont means "radiating teeth" and animals in this group have toothed, rounded jaws that were adapted to the darkness in deep waters. Researchers said that the sophisticated sensory and nervous system of Stalincaris may have enabled it to efficiently prey on smaller animals in the dark.
More so, the unique structure of its eyes that had never been seen before in any radiodont was unexpected. It emphasized that these ancient animals were more bizarre-looking than previously thought and that early arthropods evolved many complex visual structures, like many of the modern insects and spiders.
The discovery is a significant leap in understanding how early arthropods looked and lived in the past. The team described the results in full in the study titled "A Three-Eyed Radiodont With Fossilized Neuroanatomy Informs the Origin of the Arthropod Head and Segmentation," published in Current Biology.
Take a look at the incredible structure of Stanleycaris hirpex in the video below:
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