Scientists have discovered a brain that is half-billion years old. This brain was found by a Cambridge researcher. This latest discovery identifies the key moment in evolution from soft bodies to hard bodies during the Cambrian Explosion. It is a breakthrough in understanding the origins of the first arthropod ancestors. Invertebrates have an exoskeleton which includes a sectioned body and joined appendages like insects, crustaceans, and spiders. Javier Ortega-Hernandez is a postdoctoral researcher at Cambridge’s Department of Earth Sciences. He wrote in Current Biology about his discovery. The research focused on two kinds of arthropod ancestrals: a soft-bodied Trilobite, which was a fossil marine archthropod, and Odaraia Alata, an odd-looking creature, that looked almost like a submarine. An Odaria alata, a submarine-like arthropod from the middle Cambrian Burgess Shale. Image: Cambridge. He discovered that their hard plates (anterior skullsclerites) and their eye-like features were linked via nerve traces from their front brains. This corresponds to how modern arthropods see the world. These new findings allowed for comparisons to anomalocaridids which are large, aquatic predators from the same period. Dr. Ortega-Hernandez discovered key similarities in the anterior sclerite, and the plate on the anomalocaridid’s head. This suggests that they share a common origin. Although anomalocaridids are early arthropod ancestors, the bodies of these species are quite distinct. Researchers can recognize the anterior sclerite in fossil specimens as the bridge that links the heads of anomalocaridids and the joined arthropods. This is thanks to their well-preserved brains. Ortega Hernandez explained that soft-bodied animals became harder-bodied when they got stronger. As in modern arthropods, the photoreceptors are connected to the front end of the fossilised skull. The ancient brains likely processed data in the same way as modern arthropods. They were vital for interactions with the environment and for finding food. Cambrian Radiation or the Cambrian Explosion was a brief evolutionary event. It occurred around 542million years ago during the Cambrian Period. This period saw the appearance of most major animal phyla, according fossil records. During the Cambrian Explosion, arthropods that had hard exoskeletons or joined limbs first appeared 500million years ago. Before that time, jellyfish and other algae-like organisms with soft bodies were the most common living thing on Earth. The fossils are from the Smithsonian Institution in Washington D.C. and the Royal Ontario Museum in Toronto. They were sourced from Western Canada’s Burgess Shale, one of the most important fossil resources of that period. Because brains are composed of soft tissue (mainly fatty-like substances), it is difficult for scientists to determine how they evolved. It is rare to find brain tissue even in places like the Burgess Shale where there are many fossilised specimens. Dr. Ortega Hernandez explained that brains are becoming more complicated over the years. What we see here is an answer for the question about how arthropods transformed their bodies from soft and hard.” This study was funded by Emmanuel College in Cambridge. A separate study was also conducted at Cambridge by Dr. Martin Smith (a junior research fellow), and uncovered a new type of Penis Worm at Burgess Shale, which dates back to 500 millions of years ago. The creature could open its mouth and reveal a tooth-lined throat that resembles a cheese grator. Reference: Javier Ortega-Hernande. Current Biology. “Homology in Burgess Shale Euarthropods: The Homology of Head Sclerites.” DOI: 10.1016/j.cub.2015.04. 034.
