''Brachylophus gibbonsi'' is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of large (~1.2 m long)

iguanid The Iguanidae is a family of lizards composed of the iguanas, chuckwallas, and their prehistoric relatives, including the widespread green iguana. Taxonomy Iguanidae is thought to be the sister group to the collared lizards (family Crotaphy ...

lizard from

Tonga Tonga (, ; ), officially the Kingdom of Tonga ( to, Puleʻanga Fakatuʻi ʻo Tonga), is a Polynesian country and archipelago. The country has 171 islands – of which 45 are inhabited. Its total surface area is about , scattered over in ...

in the South

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...

. Its remains have been found associated with cultural sites on

Lifuka Lifuka is an island in the Kingdom of Tonga. It is located within the Ha'apai Group, Haapai Group in the centre of the country, to northeast of the national capital of Nukuʻalofa, Nukualofa. It is the administrative centre of the Haapai group of ...

, four other islands in the

Haʻapai Haʻapai is a group of islands, islets, reefs, and shoals in the central part of Tonga. It has a combined land area of . The Tongatapu island group lies to its south, and the Vavaʻu group lies to its north. Seventeen of the Haʻapai islands are ...

group, and

Tongatapu Tongatapu is the main island of Tonga and the site of its capital, Nukualofa. It is located in Tonga's southern island group, to which it gives its name, and is the country's most populous island, with 74,611 residents (2016), 70.5% of the nation ...

. It was consumed by the early Tongans and probably became extinct within a century of human colonization of the archipelago 2800 years ago. The four extant members of ''

Brachylophus The genus ''Brachylophus'' consists of four extant iguanid species native to the islands of Fiji and a giant extinct species from Tonga in the South West Pacific. One of the extant species, ''B. fasciatus'', is also present on Tonga, where it ha ...

'' are much smaller, and are found in nearby

Fiji Fiji ( , ,; fj, Viti, ; Fiji Hindi: फ़िजी, ''Fijī''), officially the Republic of Fiji, is an island country in Melanesia, part of Oceania in the South Pacific Ocean. It lies about north-northeast of New Zealand. Fiji consists ...

. '' B. fasciatus'' is now present on Tonga as well, but was probably brought there from Fiji by humans about 800 years ago. ''B. gibbonsi'' is estimated to have been about 1.8 times the length of its living relatives. An even larger Fijian iguana of the genus '' Lapitiguana'' was also formerly present, and also became extinct shortly after the arrival of humans. The genus ''Brachylophus'' is thought to have reached the South Pacific by

rafting Rafting and whitewater rafting are recreational outdoor activities which use an inflatable raft to navigate a river or other body of water. This is often done on whitewater or different degrees of rough water. Dealing with risk is often a ...

on the

South Equatorial Current The South Equatorial Current are ocean currents in the Pacific, Atlantic, and Indian Ocean that flow east-to-west between the equator and about 20 degrees south. In the Pacific and Atlantic Oceans, it extends across the equator to about 5 degr ...

9000 km westward from the Americas, where their closest extant relatives remain. Another theory is that the South Pacific iguanas descend from a more widespread lineage of (now extinct) Old World iguanids that diverged from their

New World The term ''New World'' is often used to mean the majority of Earth's Western Hemisphere, specifically the Americas."America." ''The Oxford Companion to the English Language'' (). McArthur, Tom, ed., 1992. New York: Oxford University Press, p. 3 ...

relatives in the

Paleogene The Paleogene ( ; British English, also spelled Palaeogene or Palæogene; informally Lower Tertiary or Early Tertiary) is a geologic period, geologic period and system that spans 43 million years from the end of the Cretaceous Period million yea ...

, migrated to either

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

Southeast Asia Southeast Asia, also spelled South East Asia and South-East Asia, and also known as Southeastern Asia, South-eastern Asia or SEA, is the geographical United Nations geoscheme for Asia#South-eastern Asia, south-eastern region of Asia, consistin ...

, and then somehow made their way to the Fijian and Tongan archipelagos. However, no living or fossil members of the putative lineage have been found outside Fiji and Tonga.

References

{{Taxonbar, from=Q4953482 Quaternary reptiles gibbonsi Fauna of Tonga Fossil taxa described in 2004 Holocene extinctions

See also

References