Scientists have recorded the first known case of a “virgin birth” in a female crocodile that had no contact with males for about 16 years. The reptile was able to produce a fully formed foetus that was 99.9% genetically identical to her. The researchers said this discovery, reported in the journal Biology Letters, provides “tantalising insights”, suggesting its evolutionary ancestors such as the dinosaurs may also have been capable of self-reproduction. Also known as facultative parthenogenesis, virgin birth has been documented in species of birds, fish, lizards and snakes, but never before in crocodiles. It is the process by which an egg develops into an embryo without fertilisation by sperm. The American crocodile (Crocodylus acutus) was taken into captivity in 2002 when she was two years old and placed in an enclosure in Costa Rica. She remained there alone for the next 16 years. In January 2018, zookeepers discovered a clutch of 14 eggs in the enclosure. These eggs did not hatch but one contained a fully formed foetus. Genetic analysis of the tissues from the foetus’s heart and from the mother’s shed skin revealed a 99.9% match – confirming the offspring had no father. Facultative parthenogenesis is rare but is thought to occur when a species faces challenging or unfavourable conditions, such as environmental stress or lack of mates.