Brachylophus gibbonsi
Encyclopedia
Brachylophus gibbonsi is an extinct species of large (~1.2 m long) iguanid
lizard from Tonga
in the South Pacific Ocean
. Its remains have been found associated with cultural sites on Lifuka
, four other islands in the Haʻapai Group, and Tongatapu
. It was consumed by the early Tongans and probably went extinct within a century of human colonization of the archipelago 2800 years ago.
The three extant members of Brachylophus
are much smaller, and are found in nearby Fiji
. 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 went extinct shortly after the arrival of humans.
The genus Brachylophus has been suggested to have reached the South Pacific by rafting
on the South Equatorial Current
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
relatives in the Paleogene
, migrated to either Australia
or Southeast Asia
, 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.
Iguanidae
Iguanidae is a family of lizards, composed of iguanas and related species.-Classification of Iguanidae:Two different classification schemes have been used to define the structure of this family. These are the "traditional" classification and the classification presented by Frost et al. .Frost et...
lizard from Tonga
Tonga
Tonga, officially the Kingdom of Tonga , is a state and an archipelago in the South Pacific Ocean, comprising 176 islands scattered over of ocean in the South Pacific...
in the South Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
. Its remains have been found associated with cultural sites on Lifuka
Lifuka
Lifuka is an island in the Kingdom of Tonga. It is located within the Haapai Group in the centre of the country, to northeast of the national capital of Nukualofa...
, four other islands in the Haʻapai Group, and Tongatapu
Tongatapu
Tongatapu is the main island of the Kingdom of Tonga and the location 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 approximately 71,260 residents , 70.5% of the national population...
. It was consumed by the early Tongans and probably went extinct within a century of human colonization of the archipelago 2800 years ago.
The three extant members of Brachylophus
Brachylophus
The genus Brachylophus consists of three extant iguanid species native to the islands of Fiji and a giant extinct species from Tonga in the South Pacific. One of the extant species, B...
are much smaller, and are found in nearby Fiji
Fiji
Fiji , officially the Republic of Fiji , is an island nation in Melanesia in the South Pacific Ocean about northeast of New Zealand's North Island...
. B. fasciatus
Brachylophus fasciatus
The Fiji banded iguana is an arboreal species of lizard endemic to some of the southeastern Fijian islands. It is found in Tonga, where it was probably introduced by humans. It is one of the few species of iguanas found outside of the New World and one of the most geographically isolated members...
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
Lapitiguana
Lapitiguana is an extinct genus of giant iguanid from Fiji. It probably went extinct following the human colonization of Fiji 3000 years ago....
was also formerly present, and also went extinct shortly after the arrival of humans.
The genus Brachylophus has been suggested to have reached the South Pacific by rafting
Rafting event
Oceanic dispersal is a type of biological dispersal that occurs when organisms transfer from one land mass to another by way of a sea crossing on large clumps of floating vegetation. Such matted clumps of vegetation are often seen floating down major rivers in the tropics and washing out to sea,...
on the South Equatorial Current
South Equatorial Current
The South Equatorial Current is a significant Pacific, Atlantic, and Indian Ocean current that flows 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 degrees north....
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
New World
The New World is one of the names used for the Western Hemisphere, specifically America and sometimes Oceania . The term originated in the late 15th century, when America had been recently discovered by European explorers, expanding the geographical horizon of the people of the European middle...
relatives in the Paleogene
Paleogene
The Paleogene is a geologic period and system that began 65.5 ± 0.3 and ended 23.03 ± 0.05 million years ago and comprises the first part of the Cenozoic Era...
, migrated to either Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
or Southeast Asia
Southeast Asia
Southeast Asia, South-East Asia, South East Asia or Southeastern Asia is a subregion of Asia, consisting of the countries that are geographically south of China, east of India, west of New Guinea and north of Australia. The region lies on the intersection of geological plates, with heavy seismic...
, 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.