Extinct reptiles: Data & facts (as of 09/2023)
The Red List of the International Union for Conservation of Nature (IUCN) currently lists 32 reptile species as extinct, but it is highly likely that many more species have disappeared. For instance, an unknown number of reptile species have not been detected for decades due to factors such as the destruction of their natural habitats. It is also reasonable to assume that some of the 433 reptile species listed as “critically endangered” have already vanished forever. Additionally, more than 1,500 species are not even documented, meaning they have not yet been included in the IUCN list.
The 32 extinct reptile species listed by the IUCN consist of 8 turtle species and 24 squamates: skinks and skink-like species (10), geckos and gecko-like species (4), iguanas and iguana-like species (4), snakes and snake-like species (4), and rail lizards (2).
The demise of giant tortoises
The main causes for the decline of reptiles since 1500, or since the colonization of many parts of the world by Europeans, also apply to all other classes of vertebrates: the intentional or unintentional introduction of non-native species, the destruction of natural habitats, and hunting by humans.
(© J. Terrier, Public domain, via Wikimedia Commons)
The most famous example of extinct reptiles is arguably the giant tortoises. Various species of land tortoises inhabited different islands of the Mascarene island chain in the Indian Ocean and the Galápagos Islands in the Pacific. Four of the Galápagos species are now extinct (such as the Rabida giant tortoise in 1906), and none of the five endemic giant tortoises from the Mascarenes exist today: for instance, the Rodrigues giant tortoise disappeared in 1802, the Mauritius saddleback giant tortoise by at least 1844, and the Reunion giant tortoise in 1840.
The main reason for the disappearance of these giant tortoises was the systematic slaughter by Europeans, who colonized Rodrigues at the end of the 17th century and Réunion and Mauritius in the mid-17th century. The dead land tortoises served as food for humans and the pigs brought to the islands. Additionally, the new settlers burned the tortoises to extract fat and oil from them. In the process, they deforested the islands, leading to the extinction of further animal species, such as the dodo.
Extinct reptiles mostly inhabited islands
Similar to extinct birds, almost all extinct reptiles lived on islands – one of the few exceptions being the Viesca mud turtle, a freshwater turtle from Mexico, discovered in 1961 and last sighted in 1970. It likely disappeared due to pollution of the waters where it lived and because much of its habitat is now dried up.
The once largest gecko in the world lived on New Caledonia – the Gigarcanum. It is known from only a single specimen measuring 60 centimeters in length and likely went extinct in the mid-19th century because introduced rats on New Caledonia preyed on its offspring and humans diminished its habitat by deforesting the forests. For similar reasons, the Tongan ground skink disappeared from the Tonga archipelago in the South Pacific in the early 19th century.
Many reptiles are lost or known only from a single specimen
In fact, many of the extinct reptiles are known only from a single specimen or a few specimens. This includes, for example, the Antiguan ground iguana, described based on bone fragments and disappeared either in the 15th century or much later. The Mauritius giant skink is known only from subfossil material and likely went extinct around 1500.
Many other species now considered extinct have been missing for many years, and it can only be speculated that they no longer exist. For example, the Rodrigues giant gecko was last seen in 1841, the Jamaican galliwasp in 1851, the Cape Verde giant skink in 1912, the Martinique ameiva, a lizard from the family of rail lizards, in 1928, the Jamaican racer in the 1940s, and the Mauritius boa was last recorded in 1975.
The officially last extinct reptile species is considered to be the Christmas Island forest skink, which disappeared from the Australian Christmas Island in the Indian Ocean in 2014. Here too, introduced animals – mostly cats, rats, mongooses, and pigs – and loss of habitat due to urbanization were the causes of its extinction.