The three-horned lizard that conquered Hawaii by looking like a miniature dinosaur

Nature · Published 3 October 2026 Swipe more like this →

In short: Native to the high-altitude forests of East Africa, Jackson's chameleon is famous for the three distinct horns sported by males. Though they resemble a prehistoric Triceratops, these arboreal lizards are modern-day invaders, having established thriving populations in Hawaii and beyond, where they now threaten fragile, endemic island ecosystems.

Formally described by George Albert Boulenger in 1896, the Jackson's chameleon (Trioceros jacksonii) takes its name from Frederick John Jackson, an English explorer and the first Governor of Kenya. The genus name, Trioceros, literally translates from Greek as 'three horns,' a feature that distinguishes the males of the species. These horns, one on the nose and two above the eyes, are absent or minimal in females, who are generally smaller than the males' maximum length of 38 centimeters.

Unlike most chameleons, which lay eggs, this species is ovoviviparous. Females carry their young internally for five to six months before giving birth to live offspring, typically ranging from eight to thirty per litter. They are cruise foragers, actively hunting a wide variety of prey including insects, spiders, and snails. In their native range across Kenya and Tanzania, they thrive in cool, wet, high-altitude woodlands, often at elevations exceeding 2,000 meters.

The species' global footprint expanded significantly after the yellow-crested subspecies (T. j. xantholophus) was introduced to Hawaii in 1972. It has since become an invasive menace, particularly to the critically endangered O'ahu tree snails. While they were once a staple of the exotic pet trade, Hawaii has banned their export to prevent further intentional releases. Today, they are found in various regions, including California and Florida, where their presence continues to spark concern among conservationists regarding the impact on local biodiversity.

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