Anomalocarids are one of the oldest families of animals on Earth, and they looked like nightmarish sea scorpions. But a new fossil discovery actually contains traces of their brain structure — and amazingly, their half-billion-year-old brains look a lot like an arthropod's.
Anomalocarid illustration by John Meszaros
Though some anomalocarids may have been as big as 7 feet long, these newly-discovered specimens are closer to the size of today's large insects. The critters you see fossilized below are about 8 cm long. Still, they look pretty insane — especially when you consider that their segmented heads are so similar to what we'd see in an arthropod today. A team of paleontologists led by Peiyun Cong found the three gorgeously-preserved anomalocarid fossils in Yunnan Province, and described them today in Nature.
The fossils have been photographed with a blue digital filters, which enhance physical features like the muscles (the dark blobs next to the vascular system running from the head down), the eye stalks (branching off the head), and turns the mouth cone a reddish brown. Because of course there is a "mouth cone," along with those eye stalks and enormous things that the paleontologists call "frontal appendages."
520 million-year-old fossils of Lyrarapax unquispinus. Image by Peiyun Cong
The connection between anomalocarids and today's animals has long been a source of debate, and some paleontologists believed that there was no way to classify them properly. But thanks to Cong and his team, we have some strong evidence that arthropods — a group containing spiders, crabs, scorpions, and centipedes — are the distant descendants of these anomalocarids.