Delcourt’s Giant Gecko, also known by its scientific name Gigarcanum delcourti, is one of the most intriguing and mysterious gecko species. It stands out due to its immense size, far surpassing other known geckos. However, very little is definitively known about it, as its existence is based on a single preserved specimen. This rarity and enigmatic nature have captivated researchers and enthusiasts.
A Colossal Discovery
The story of Delcourt’s Giant Gecko begins not in the wild, but in a museum collection in France. In the early 1980s, Alain Delcourt, a collections manager at the Natural History Museum of Marseille, found a forgotten specimen that had been on public display for years. This preserved gecko was unlike any known species and significantly larger than any other gecko recorded. The specimen lacked labels indicating its origin or date, adding to its mystery.
Its unusual preservation method—gutted, dried, and mounted on a branch rather than preserved in alcohol—suggested it entered the museum’s collection between 1833 and 1869. American herpetologist Aaron M. Bauer of Villanova University, then a doctoral student, arrived in 1983 to study this find. Three years later, Bauer, along with paleontologist Anthony P. Russell, formally described the new species, naming it Hoplodactylus delcourti in honor of Alain Delcourt. This identification brought the “largest known gecko” to scientific attention.
Anatomy of a Giant
Delcourt’s Giant Gecko, classified as Gigarcanum delcourti, is truly giant. The single known specimen measures at least 60 centimeters (about 2 feet) from snout to tail tip, making it the largest gecko ever recorded. This size is striking compared to the next largest living gecko, the New Caledonian Giant Gecko (Rhacodactylus leachianus), which reaches around 40 centimeters. The preserved specimen exhibits a thick trunk and a bulbous head, giving it a robust appearance.
Its skin is brown with faint red bands, suggesting a camouflage pattern. While specific details about its scale patterns are limited due to the specimen’s preserved state, its sheer size and overall body structure set it apart. The gecko’s toe pads and long claws indicate an arboreal, or tree-dwelling, lifestyle, though its considerable weight likely pushed the limits of a gecko’s ability to adhere to vertical surfaces using its sticky grip. The original stuffed specimen lacked internal organs and most of its axial skeleton, but its skull and limb bones were retained.
Habitat and Enduring Mystery
The presumed natural habitat of Delcourt’s Giant Gecko has been a subject of scientific debate and mystery. Initially, based on morphological characteristics and Maori oral traditions about a giant lizard called the “kawekaweau,” scientists, including Bauer and Russell, assumed its origin was New Zealand. A single report from Major W.G. Mair in 1873 detailed a Maori chief claiming to have killed a kawekaweau in 1870 in New Zealand’s Waimana Valley, describing it as “brownish with reddish stripes” and “as thick as a man’s wrist,” which aligned with the gecko’s appearance.
However, recent DNA analysis conducted in 2023 on the specimen’s femur rewrote this origin story. This genetic material revealed that G. delcourti is not closely related to New Zealand geckos but belongs to a group whose living species are endemic to New Caledonia. This finding supports earlier suggestions by paleontologists like Trevor Worthy, who noted the absence of large gecko fossils in New Zealand’s extensive fossil record. The lack of live sightings since its discovery and the single known specimen lead scientists to presume it is extinct, possibly vanishing in the mid-19th century due to factors like introduced animal species or habitat loss. Despite strong evidence of extinction, some researchers maintain a faint hope that this elusive giant might still exist in the remote treetops of New Caledonia, as new gecko species continue to be discovered there.