Oxygen may be the clue to first appearance of large animals, says Queen’s prof The sudden appearance of large animal fossils more than 500 million years ago – a problem that perplexed even Charles Darwin and is commonly known as “Darwin’s Dilemma” – may be due to a huge increase of oxygen in the world’s oceans, says Queen’s paleontologist Guy Narbonne, an expert in the early evolution of animals and their ecosystems. In 2002, Dr. Narbonne and his research team found the world’s oldest complex life forms between layers of sandstone on the southeastern coast of Newfoundland. This pushed back...