Did our earliest ancestor really have no bum?
Scientists believe they may have found our oldest known ancestor. They say that fossilised traces of the 540-million-year-old creature are "exquisitely well preserved".
The research team says that Saccorhytus is the most primitive example of a category of animals called "deuterostomes" which are common ancestors of a broad range of species, including vertebrates.
Professor Simon Conway Morris, Fellow of St John's College Cambridge, wrote the paper on Saccorhytus. He told the Today programme our earliest ancestor "appears not to have had an anus"... in essence, no bum.
31 Jan 2017