I have a soft spot for Anomalocaris. Of all the Cambrian oddballs, this segmented invertebrate was one of the strangest. The prehistoric creature’s stalked eyes, swim flaps, spiked grasping appendages, and plated mouth gave this predator an exceptionally alien appearance. Anomalocaris was so weird, in fact, that paleontologists only recently assembled a complete picture of what this animal looked like. For years, the various parts of Anomalocaris were believed to be parts of various other creatures. What was eventually recognized as the neo-predator’s mouth was especially perplexing.
The mouth of Anomalocaris started off as a jellyfish. That’s a historical quirk, not a biological one. A century ago, as he was cataloging 505-million-year-old fossils from the exceptional Burgess Shale site, paleontologist Charles Doolittle Walcott puzzled over what seemed to be a flattened ring. Walcott called the animal Peytoia, and suggested that it was a strange form of archaic jellyfish.
Walcott’s interpretation stayed in place for decades. When paleontologists Harry Whittington and Simon Conway Morris wrote an article about Cambrian life for Scientific American in 1979, they included the odd jelly in a reconstructed Burgess Shale habitat. As Stephen Jay Gould later commented in his book Wonderful Life, the artistically-reinvigorated Peytoia looked like “a kind of Frisbee cum flying saucer cum pineapple slice.”