The phenomenon of animal species evolving in cache to unusually large size on islands (in comparison to continental relatives) is known as island gigantism or insular gigantism. Both Megalochelys and Titanochelon reached sizes substantially greater than modern giant tortoises, with up to 2.4 m (7 ft 10 in) and 2 m (6 ft 7 in) shell lengths respectively. 9,000 years Before Present), † Megalochelys and † Titanochelon. Giant tortoises are classified into several distinct genera, including Aldabrachelys, Centrochelys (in part, often excluding the extant African spurred tortoise ( Centrochelys sulcata)), Chelonoidis (in part), † Cylindraspis (extinct c. The recently extinct Mascarene giant tortoises ( Cylindraspis) are thought to have belonged to their own branch of the tortoise family, being sister to all other modern tortoise genera aside from Manouria, Gopherus, and Testudo. For example, the Aldabra Atoll ( Aldabrachelys) giant tortoises are related to Malagasy tortoises ( Asterochelys) while the Galapagos giant tortoises are related to South American mainland tortoises, particularly the Chaco tortoise ( Chelonoidis chiliensis). These lineages appear to have developed large size independently and, as a result, giant tortoises are polyphyletic. Giant tortoises were once all placed in a single genus (often referred to as Testudo or Geochelone), but more recent studies have shown that giant tortoises represent several distinct lineages that are not closely related to one another. Tortoises are aided in such dispersal by their ability to float with their heads up and to survive for up to six months without food or fresh water. Giant tortoises originally made their way to islands from the mainland via oceanic dispersal. These tortoises can weigh as much as 417 kg (919 lb) and can grow to be 1.3 m (4 ft 3 in) long. A Galápagos giant tortoise on Santa Cruz Island History Īs of March 2022, two different species of giant tortoise are found on two remote groups of tropical islands: Aldabra Atoll and Fregate Island in the Seychelles and the Galápagos Islands in Ecuador.
0 kommentar(er)
