A very bizarre-looking, shrimp-like, five-eyed creature that lived in the ocean more than 500 million years ago may be the “missing link” in the evolution of arthropods. Six very well preserved fossils were unearthed in the Yu’anshan Formation in the southern part of China and the newly discovered creature has been named Kylinxia zhangia.
Arthropods began thriving during the Cambrian period (between 543 million and 490 million years ago) and there are still plenty of them today. They are defined as being invertebrates with an exoskeleton, segmented body, and appendages with joints. Insects (bees, dragonflies, ants), arachnids (scorpions, spiders), myriapods (centipedes, millipedes), and crustaceans (shrimp, crabs, lobsters) are all examples of arthropods.
The Kylinxia zhangia had five compound eyes (two that were twice as large as the rest), a jointed upper portion to its body; big “arms” that curved upwards; and 15 jointed limbs that had spines at the end. It measured approximately 3 inches long. While some of its features coincide with other arthropods from ancient times, it also had very bizarre features that were present in other species.
The remains were so well preserved that several tissues and digestive glands were still present. In a statement, Fangchen Zhao, who is a professor with the Nanjing Institute of Palaeontology and Geology (NIPG) at the Chinese Academy of Sciences in Nanjing, China, as well as a co-author of the study, said, “The Kylinxia fossils exhibit exquisite anatomical structures,” adding, “For example, nervous tissue, eyes and digestive system – these are soft body parts we usually cannot see in conventional fossils.”
There are still missing pieces to the evolutionary history of arthropods which is why the discovery of the Kylinxia zhangia is so important. Since several of its features were known to be present in other species, it is believed that the Kylinxia zhangia is the “missing link” that scientists have been searching for.
Researchers compared the features of the Kylinxia zhangia to around 300 features of other arthropods in over 80 taxonomic groups. An ancient ancestor of arthropods called Opabinia also had five eyes, and a three-foot-long Cambrian marine arthropod named Anomalocaris had appendages that looked like those of the Kylinxia zhangia.
Han Zeng, who is a NIPG assistant professor and the lead author of the study, explained this further, “Kylinxia represents a crucial transitional fossil predicted by Darwin’s evolutionary theory.” “It bridges the evolutionary gap from Anomalocaris to true arthropods and forms a key ‘missing link’ in the origin of arthropods, contributing strong fossil evidence for the evolutionary theory of life.” The study was published in the journal Nature where it can be read in full.
Images of what the Kylinxia zhangia would have looked like more than 500 million years ago can be seen here.