# Island gigantism

Island gigantism, or insular gigantism, is a biological phenomenon in which the size of an animal species isolated on an island increases dramatically in comparison to its mainland relatives. Island gigantism is one aspect of the more general "island effect" or "Foster's rule", which posits that when mainland animals colonize islands, small species tend to evolve larger bodies, and large species tend to evolve smaller bodies (insular dwarfism). This is itself one aspect of the more general phenomenon of island syndrome which describes the differences in morphology, ecology, physiology and behaviour of insular species compared to their continental counterparts. Following the arrival of humans and associated introduced predators (dogs, cats, rats, pigs), many giant as well as other island endemics have become extinct (e.g. the dodo and Rodrigues solitaire, giant flightless pigeons related to the Nicobar pigeon). A similar size increase, as well as increased woodiness, has been observed in some insular plants such as the Mapou tree (Cyphostemma mappia) in Mauritius which is also known as the "Mauritian baobab" although it is member of the grape family (Vitaceae).

## Possible causes

Large mammalian carnivores are often absent on islands because of insufficient range or difficulties in over-water dispersal. In their absence, the ecological niches for large predators may be occupied by birds, reptiles or smaller carnivorans, which can then grow to larger-than-normal size. For example, on prehistoric Gargano Island in the Miocene-Pliocene Mediterranean, on islands in the Caribbean like Cuba, and on Madagascar and New Zealand, some or all apex predators were birds like eagles, falcons and owls, including some of the largest known examples of these groups. However, birds and reptiles generally make less efficient large predators than advanced carnivorans.
Since small size usually makes it easier for herbivores to escape or hide from predators, the decreased predation pressure on islands can allow them to grow larger. Small herbivores may also benefit from the absence of competition from missing types of large herbivores.
Benefits of large size that have been suggested for island tortoises include decreased vulnerability to scarcity of food and/or water, through ability to survive for longer intervals without them, or ability to travel longer distances to obtain them. Periods of such scarcity may be a greater threat on oceanic islands than on the mainland.
Thus, island gigantism is usually an evolutionary trend resulting from the removal of constraints on the size of small animals related to predation and/or competition. Such constraints can operate differently depending on the size of the animal, however; for example, while small herbivores may escape predation by hiding, large herbivores may deter predators by intimidation. As a result, the complementary phenomenon of island dwarfism can also result from the removal of constraints related to predation and/or competition on the size of large herbivores. In contrast, insular dwarfism among predators more commonly results from the imposition of constraints associated with the limited prey resources available on islands. As opposed to island dwarfism, island gigantism is found in most major vertebrate groups and in invertebrates.
Territorialism may favor the evolution of island gigantism. A study on Anaho Island in Nevada determined that reptile species that were territorial tended to be larger on the island compared to the mainland, particularly in the smaller species. In territorial species, larger size makes individuals better able to compete to defend their territory. This gives additional impetus to evolution toward larger size in an insular population.
A further means of establishing island gigantism may be a founder effect operative when larger members of a mainland population are superior in their ability to colonize islands.
Island size plays a role in determining the extent of gigantism. Smaller islands generally accelerate the rate of evolution of changes in organism size, and organisms there evolve greater extremes in size.

## Examples

Examples of island gigantism include:

### Mammals

Many rodents grow larger on islands, whereas carnivorans, proboscideans and artiodactyls usually become smaller.

#### Eulipotyphlans

| Example | Binomial name | Native range | Current status | Continental relative |
| Balearic giant shrew | Nesiotites hidalgo | Mallorca and Menorca | Extinct (3000-2000 BC) | Red-toothed shrews |
| Sardinian giant shrew | Asoriculus similis | Sardinia and Corsica | Extinct (Holocene) | Red-toothed shrews |
| Sicilian giant shrew | Asoriculus burgioi | Sicily | Extinct (Early Pleistocene) | Red-toothed shrews |
| Deinogalerix | Deinogalerix spp. | Gargano Island | Extinct (Late Miocene) | Moon rats |

#### Rodents

| Example | Binomial name | Native range | Current status | Continental relative | Insular / mainland length or mass ratio |
| Capybara | Hydrochoerus hydrochaeris |
| Blunt-toothed giant hutia | Amblyrhiza inundata | Anguilla and Saint Martin | Extinct (Pleistocene) | Neotropical spiny rats | |
| Larger Jamaican giant hutia | Clidomys osborni | Jamaica | Extinct (Late Pleistocene) | Neotropical spiny rats | |
| Plate-toothed giant hutia | Elasmodontomys obliquus | Puerto Rico | Extinct (c. 1 AD) | Neotropical spiny rats | |
| Twisted-toothed mouse | Quemisia gravis | Hispaniola | Extinct | Neotropical spiny rats | |
| Arboreal giant hutia | Tainotherium valei | Puerto Rico | Extinct | Neotropical spiny rats | |
| Lesser Jamaica giant hutia | Xaymaca fulvopulvis | Jamaica | Extinct | Neotropical spiny rats | |
| Majorcan giant hamsters | Apocricetus darderi Tragomys macpheei | Majorca | Extinct | Apocricetus alberti Cricetus kormosi | |
| Gargano giant hamster | Hattomys gargantua | Gargano Island | Extinct | Apocricetus alberti Cricetus kormosi | |
| St Kilda field mouse | Apodemus sylvaticus hirtensis | St Kilda | Least Concern | Wood mouse | MR ≈ 2 |
| Hensel's field mouse | Rhagamys orthodon | Corsica and Sardinia | Extinct (After 1300 BC) | Wood mouse | |
| Tenerife giant rat | Canariomys bravoi | Tenerife | Extinct (Late Pleistocene) | African rufous-nosed rats | |
| Gran Canaria giant rat | Canariomys tamarani | Gran Canaria | Extinct (before AD 1500) | African rufous-nosed rats | |
| Formentera black-tailed garden dormouse | Eliomys quercinus ophiusae | Formentera | Rare (Introduced by humans) | Garden dormouse and other Leithiinae dormice | |
| Balearic giant dormice | Hypnomys spp. | Mallorca & Menorca | Extinct (Holocene) | Garden dormouse and other Leithiinae dormice | |
| Leithia melitensisSicilian-Maltese giant dormice | Leithia cartei | Sicily and Malta | Extinct | Garden dormouse and other Leithiinae dormice | |
| Leithia melitensisSicilian-Maltese giant dormice | Leithia melitensis | Sicily and Malta | Extinct | Garden dormouse and other Leithiinae dormice | |
| Orkney vole | Microtus arvalis orcadensis | Orkney Islands | Vulnerable | Common vole and other meadow voles | |
| Gargano giant voles | Mikrotia magna M. maiuscula M. parva | Gargano Island | Extinct (Early Pliocene) | Common vole and other meadow voles | |
| St Kilda house mouse | Mus musculus muralis | St Kilda | Extinct (c. AD 1930) | House mouse | |
| Flores giant rat | Papagomys armandvillei | Flores | Near Threatened | North African black rat and other true rats | |
| Sulawesi giant rat | Paruromys dominator | Sulawesi | Least Concern | North African black rat and other true rats | |
| Admiralty giant rat | Rattus detentus | Manus Island | Unknown / Likely threatened | North African black rat and other true rats | |
| Congreso black rat population | Rattus rattus | Isla del Congreso | Least Concern | North African black rat and other true rats | |
| Channel Islands deer mice | Peromyscus anyapahensis P. nesodytes | Northern Channel Islands of California | Extinct (c. 6000 BC) | North American deer mouse | |
| Gargano giant dormouse | Stertomys laticrestatus | Gargano Island | Extinct | Glirinae dormice | |

#### Lagomorphs

| Example | Binomial name | Native range | Current status | Continental relative |
| Minorcan giant lagomorph | Nuralagus rex | Minorca | Extinct (Middle Pliocene) | Alilepus (?) Trischizolagus (?) |
| | Prolagus imperialis | Gargano Island | Extinct | Pikas |
| Sardinian pika | Prolagus sardus | Corsica, Sardinia and Tavolara | Extinct (c. AD 1800) | Pikas |

#### Primates

| Example | Binomial name | Native range | Current status | Continental relative |
| Hispaniola monkey | Antillothrix bernensis | Hispaniola | Extinct (before AD 1600) | Cheracebus |
| Haitian monkey | Insulacebus toussaintiana | Southwestern Haiti | Extinct | Cheracebus |
| Cuban monkeys | Paralouatta marianae P. varonai | Cuba | Extinct (Pleistocene) | Cheracebus |
| Jamaican monkey | Xenothrix mcgregori | Jamaica | Extinct | Cheracebus |
| Gorilla lemur | Archaeoindris fontoynontii | Central Madagascar | Extinct (c. 350 BC) | Lorisoids |
| Baboon lemurs | Archaeolemur spp. Hadropithecus spp. | Madagascar | Extinct (before AD 1280) | Lorisoids |
| Sloth lemurs | Babakotia spp. Palaeopropithecus spp. | Western and Central Madagascar | Extinct (c. AD 1500) | Lorisoids |
| Koala lemurs | Megaladapis edwardsi M. grandidieri M. madagascariensis | Madagascar | Extinct (AD 1280–1420) | Lorisoids |

#### Carnivorans

| Example | Binomial name | Native range | Current status | Continental relative |
| Sardinian giant otter | Megalenhydris barbaricina | Sardinia | Extinct (Late Pleistocene) | Otters |
| Fossa | Cryptoprocta ferox | Madagascar | Vulnerable | Mongooses |
| Giant fossa | Cryptoprocta spelaea | Madagascar | Extinct (before AD 1400) |

### Gondwanatherians

| Example | Binomial name | Native range | Current status | Continental relative |
| Vintana | Vintana sertichi | Madagascar | Extinct (Late Cretaceous) | South American and Antarctic gondwanatheres. |
| Adalatherium | Adalatherium hui | Madagascar | Extinct (Late Cretaceous) | Same as above. |

### Birds
#### Stem birds

| Example | Binomial name | Native range | Current status | Continental relative |
| Balaur | B. bondoc | Hateg Island | Extinct (Late Cretaceous) | Jeholornis |
| Gargantuavis | G. philohinos | Ibero-Armorican Island | Extinct (Late Cretaceous) | Patagopteryx (?) |

#### Ratites

| Example | Binomial name | Native range | Current status | Continental relative |
| Kiwis | Apterygidae | New Zealand | Variable | Proapteryx |
| Greater elephant birds | Aepyornithidae | Madagascar | Extinct (c. AD 1700) | Proapteryx |
| Lesser elephant birds | Mullerornithidae | Madagascar | Extinct (c. AD 1260) | Proapteryx |
| Giant moas | Dinornithidae | New Zealand | Extinct (c. AD 1450) | Tinamous |
| Lesser moas | Emeidae | New Zealand | Extinct (c. AD 1460) | Tinamous |
| Upland moas | Megalapterygidae | New Zealand | Extinct (c. AD 1300) | Tinamous |

#### Waterfowl

| Example | Binomial name | Native range | Current status | Continental relative |
| New Zealand musk duck | Biziura delautouri | New Zealand | Extinct (after AD 1500) | Australian musk duck |
| New Zealand geese | Cnemiornis calcitrans C. gracilis | New Zealand | Extinct | Cape Barren goose |
| Garganornis | G. ballmanni | Gargano and Scontrone islands | Extinct (Late Miocene) | Geese |
| Turtle-jawed moa-nalo | Chelychelynechen quassus | Kauai | Extinct (c. AD 1000) | Dabbling ducks |
| Small-billed moa-nalo | Ptaiochen pau | Maui | Extinct (c. AD 1000) | Dabbling ducks |
| Large-billed moa-nalo | Thambetochen chauliodous | Maui Nui | Extinct (c. AD 1000) | Dabbling ducks |
| O'ahu moa-nalo | Thambetochen xanion | O'ahu | Extinct (c. AD 1000) | Dabbling ducks |
| Giant swan | Cygnus falconeri | Sicily and Malta | Extinct (Middle Pleistocene) | Mute swan |
| Scarlett's duck | Malacorhynchus scarletti | New Zealand | Extinct (after AD 1500) | Pink-eared duck |

#### Pangalliformes

| Example | Binomial name | Native range | Current status | Continental relative |
| Pile-builder megapode | Megapodius molistructor | New Caledonia and Tonga | Extinct (c. 1500 BC) | Scrubfowl |
| Megavitiornis | Megavitiornis altirostris | Fiji | Extinct | Galliformes |
| Sylviornis | Sylviornis neocaledoniae | New Caledonia and Isle of Pines | Extinct | Galliformes |

#### Gruiformes

| Example | Binomial name | Native range | Current status | Continental relative |
| Red rail | Aphanapteryx bonasia | Mauritius | Extinct (c. AD 1700) | Rails |
| Hawkins' rail | Diaphanapteryx hawkinsi | Chatham Islands | Extinct (c. AD 1900) | Rails |
| Antillean cave rail | Nesotrochis debooyi | Puerto Rico and Virgin Islands | Extinct | Rails |
| Cuban cave rail | Nesotrochis picapicensis | Cuba | Extinct | Rails |
| Haitian cave rail | Nesotrochis steganinos | Hispaniola | Extinct | Rails |
| South Island takahē | Porphyrio hochstetteri | South Island, New Zealand | Endangered | Rails |
| North Island takahē | Porphyrio mantelli | North Island, New Zealand | Extinct (before AD 1900) | Rails |
| Adzebills | Aptornis defossor A. otidiformis | New Zealand | Extinct | Madagascar flufftail |
| Chatham coot | Fulica chathamensis | Chatham Islands | Extinct (after AD 1500) | Red-knobbed coot and other coots |
| Mascarene coot | Fulica newtonii | Mauritius and Réunion | Extinct (c. AD 1700) | Red-knobbed coot and other coots |
| New Zealand coot | Fulica prisca | New Zealand | Extinct (after AD 1280) | Red-knobbed coot and other coots |
| Réunion swamphen | Porphyrio coerulescens | Plaine des Cafres, Réunion | Extinct (c. AD 1730) | Purple swamphens |

#### Pigeons

| Example | Binomial name | Native range | Current status | Continental relative |
| Viti Levu giant pigeon | Natunaornis gigoura | Viti Levu, Fiji | Extinct | Crowned pigeons |
| Kanaka pigeon | Caloenas canacorum | New Caledonia | Extinct (c. 500 BC) | Nicobar pigeon |
| Rodrigues solitaire | Pezophaps solitaria | Rodrigues | Extinct (before AD 1778) | Nicobar pigeon |
| Dodo | Raphus cucullatus | Mauritius | Extinct (c. AD 1662) | Nicobar pigeon |

#### Birds of prey

| Example | Binomial name | Native range | Current status | Continental relative |
| Liko Cave golden eagle | Aquila chrysaetos simurgh | Crete | Extinct (Late Pleistocene) | Golden eagle |
| Giant crab-hawk | Buteogallus borrasi | Cuba | Extinct | Great black hawk and other hawks |
| Giant hawk | Gigantohierax sp. | Cuba | Extinct | Great black hawk and other hawks |
| Titan-hawk | Titanohierax gloveralleni | Cuba, Hispaniola and the Bahamas | Extinct | Great black hawk and other hawks |
| Jamaican caracara | Caracara tellustris | Jamaica | Extinct | Caracaras |
| Eyles' harrier | Circus eylesi | New Zealand | Extinct (c. AD 1000) | Swamp harrier |
| Gargano Island eagles | Garganoaetus freudenthali G. murivorus | Gargano Island | Extinct (Late Miocene) | Aquila delphinensis |
| Haast's eagle | Hieraaetus moorei | New Zealand | Extinct (c. AD 1400) | Little eagle |
| Philippine eagle | Pithecophaga jefferyi | Philippines | Critically endangered | Bateleur |

#### Parrots

| Example | Binomial name | Native range | Current status | Continental relative |
| Hercules parrot | Heracles inexpectatus | New Zealand | Extinct (Miocene) | Other parrots |
| Kākāpō | Strigops habroptilus | New Zealand | Critically Endangered | Other parrots |
| Broad-billed parrot | Lophopsittacus mauritianus | Mauritius | Extinct (c. AD 1680) | Psittaculine parrots |

#### Owls

| Example | Binomial name | Native range | Current status | Continental relative |
| Cretan owl | Athene cretensis | Crete | Extinct (Pleistocene) | Little owl |
| Cuban giant owls | Ornimegalonyx spp. | Cuba | Extinct (Pleistocene) | Wood owls |
| Greater Gargano giant owl | Tyto gigantea | Gargano Island | Extinct (Late Miocene) | Barn owls |
| Andros Island barn owl | Tyto pollens | Andros Island, Bahamas | Extinct (before AD 1600) | Barn owls |
| Rivero's barn owl | Tyto riveroi | Cuba | Extinct | Barn owls |
| Lesser Gargano giant owl | Tyto robusta | Gargano Island | Extinct (Early Pliocene) | Barn owls |

#### Caprimulgiformes

| Example | Binomial name | Native range | Current status | Continental relative |
| New Zealand owlet-nightjar | Aegotheles novazelandiae | New Zealand | Extinct (c. AD 1200) | Australian owlet-nightjar |
| New Caledonian owlet-nightjar | Aegotheles savesi | New Caledonia | Critically endangered | Australian owlet-nightjar |

#### Passeriforms

| Example | Binomial name | Native range | Current status | Continental relative |
| Chatham raven | Corvus moriorum | Chatham Islands | Extinct | New Zealand raven |
| Long-legged bunting | Emberiza alcoveri | Tenerife | Extinct (after AD 1) | Cabanis's bunting |
| Giant nukupu'u | Hemignathus vorpalis | Hawaii | Extinct (after AD 1000) | Finches |
| Tasmanian superb fairywren | Malurus cyaneus cyaneus | Tasmania | Least Concern | Superb fairywren |
| Kangaroo Island superb fairywren | Malurus cyaneus ashbyi | Kangaroo Island | Least Concern | Superb fairywren |
| Stout-legged wren | Pachyplichas yaldwyni | South Island of New Zealand | Extinct | Other passeriforms |
| St Kilda wren | Troglodytes troglodytes hirtensis | St Kilda, Scotland | Unknown | Eurasian wren |
| Capricorn silvereye | Zosterops lateralis chlorocephalus | Capricorn and Bunker Group of the Australian Great Barrier Reef | Unknown | Silvereye |

### Reptiles
#### Iguanids

| Example | Binomial name | Native range | Current status | Continental relative | Insular / mainland length or mass ratio |
| Tongan giant iguana | Brachylophus gibbonsi | Tonga | Extinct (c. 800 BC) | South American iguanas | |
| Fijian giant iguana | Lapitiguana impensa | Fiji | Extinct (c. 1000 BC) | South American iguanas | |
| Angel Island chuckwalla | Sauromalus hispidus | Isla Ángel de la Guarda, Baja California | Near Threatened | Peninsular chuckwalla | MR ≈ 5 |
| San Esteban chuckwalla | Sauromalus varius | San Esteban Island, Baja California | Endangered | Peninsular chuckwalla | MR ≈ 5 |

#### Geckos

| Example | Binomial name | Native range | Current status | Continental relative | Insular / mainland length or mass ratio |
| Delcourt's giant gekko | Gigarcanum delcourti | New Caledonia | Extinct (c. AD 1870) | Diplodactylid geckos | LR ≈ 6.75 |
| New Caledonian giant gecko | Rhacodactylus leachianus | New Caledonia | Least Concern | Diplodactylid geckos | LR ≈ 4.4 MR ≈ 60 |
| Rodrigues giant day gecko | Phelsuma gigas | Rodrigues | Extinct (c. AD 1850) | Day geckos | |

#### Skinks

| Example | Binomial name | Native range | Current status | Continental relative |
| Vaillant's mabuya | Chioninia vaillanti | Cape Verde | Endangered | Mainland mabuyine skinks |
| Cape Verde giant skink | Chioninia coctei | Cape Verde | Extinct (after AD 1900) | Mainland mabuyine skinks |
| Mauritius giant skink | Leiolopisma mauritiana | Mauritius | Extinct (after AD 1600) | Mainland eugongyline skinks |
| Terror skink | Phoboscincus bocourti | Île des Pins off New Caledonia | Endangered | Mainland eugongyline skinks |
| Kishinoue's giant skink | Plestiodon kishinouyei | Miyako Islands and Yaeyama Islands, Japan | Vulnerable | Plestiodon tamdaoensis |

#### Wall lizards

| Example | Binomial name | Native range | Current status | Continental relative |
| La Palma giant lizard | Gallotia auaritae | La Palma | Critically endangered | Mediterranean sandrunner lizards |
| La Gomera giant lizard | Gallotia bravoana | Gomera | Critically endangered | Mediterranean sandrunner lizards |
| Tenerife giant lizard | Gallotia goliath | Tenerife | Extinct (c. AD 1500) | Mediterranean sandrunner lizards |
| El Hierro giant lizard | Gallotia simonyi | El Hierro | Critically endangered | Mediterranean sandrunner lizards |
| Gran Canaria giant lizard | Gallotia stehlini | Gran Canaria | Least Concern | Mediterranean sandrunner lizards |

#### Snakes

| Example | Binomial name | Native range | Current status | Continental relative |
| Angel de la Guarda Island speckled rattlesnake | Crotalus mitchellii angelensis | Isla Ángel de la Guarda off Baja California | Least Concern | Speckled rattlesnake |
| Tadanae-jima striped snake population | Elaphe quadrivirgata | Tadanae-jima island off Tokyo | Unknown | Japanese striped snake |
| Island tiger snake populations | Notechis scutatus | Islands Mount Chappell (Tasmania); Williams, Hopkins, and the Nuyts Archipelago (all South Australia) | Least Concern | Tiger snake |
| Isla Cerralvo long-nosed snake | Rhinocheilus lecontei etheridgei | Jacques Cousteau Island off Baja California Sur | Unknown | Long-nosed snake |

#### Dubious examples

* The Komodo dragon of Flores and nearby islands, the largest extant lizard, and a similar (extinct) giant monitor lizard from Timor have been regarded as examples of giant insular carnivores. Since islands tend to offer limited food and territory, their mammalian carnivores (if present) are usually smaller than continental ones. These cases involve ectothermic carnivores on islands too small to support much mammalian competition. However, these lizards are not as large as their extinct Australian relative Megalania, and it has been proposed based on fossil evidence that the ancestors of these varanids first evolved their large size in Australia and then dispersed to Indonesia. If this is true, rather than being insular giants they would be viewed as examples of phyletic gigantism. Supporting this interpretation is evidence for a lizard in Pliocene India, Varanus sivalensis, comparable in size to V. komodoensis. Nevertheless, given that Australia is often described as the world's largest island and that the related Megalania, the largest terrestrial lizard known in the fossil record, was restricted to Australia, the perception of the largest Australasian/Indonesian lizards as insular giants may still have some validity.
* Giant tortoises in the Galápagos Islands and the Seychelles, the largest extant tortoises, as well as extinct tortoises of the Mascarenes and Canary Islands, are often considered examples of island gigantism. However, during the Pleistocene, comparably sized or larger tortoises were present in Australia (Meiolania), southern Asia (Megalochelys), Europe (Titanochelon), Madagascar (Aldabrachelys), North America (Hesperotestudo) and South America (Chelonoidis, the same genus now found in the Galápagos), and on a number of other, more accessible islands of Oceania and the Caribbean. In the late Pliocene they were also present in Africa ("Geochelone" laetoliensis). The present situation of large tortoises being found only on remote islands appears to reflect that these islands were discovered by humans recently and have not been heavily populated, making their tortoises less subject to overexploitation.
* Hatzegopteryx has features of island gigantism such as a more robust bodyplan and occupying niches taken by megafauna elsewhere (in this case, theropod dinosaurs). However, similar sized giant pterosaurs occurred elsewhere, though nowhere near as robust.

### Amphibians

| Example | Binomial name | Native range | Current status | Continental relative | Insular / mainland length or mass ratio |
| São Tomé giant tree frog | Hyperolius thomensis | São Tomé Island | Endangered | African reed frogs | |
| Palm forest tree frog | Leptopelis palmatus | Príncipe Island | Vulnerable | Red tree frog | LR ≈ 1.2 |
| Giant Fiji ground frog | Platymantis megabotoniviti | Viti Levu, Fiji | Extinct | Asian platymantines | |
| São Tomé giant grass frog | Ptychadena newtoni | São Tomé Island | Endangered | Mascarene grass frog | |

### Arthropods

| Example | Binomial name | Native range | Current status | Continental relative |
| Coconut crab | Birgus latro | Indian Ocean islands and Polynesia | Vulnerable | Coenobita hermit crabs |
| Giant weta | Deinacrida spp. | New Zealand | Variable | South African king crickets |
| Giant pseudoscorpion | Garypus titanius | Boatswain Bird Island | Critically Endangered | Garypoids |
| Hissing cockroaches | Gromphadorhini spp. | Madagascar | Unknown | Blaberids |
| Saint Helena earwig | Labidura herculeana | Saint Helena | Extinct (c. AD 1967) | Shore earwig |
| Wallace's giant bee | Megachile pluto | North Moluccas | Vulnerable | Callomegachile |
| Megalara | Megalara garuda | Mekongga Mountains, Sulawesi | Unknown | Crabronine wasps |
| Madagascan giant pill-millipedes | Microsphaerotherium spp. Sphaeromimus spp. Zoosphaerium spp. | Madagascar | Unknown | Indian giant pill-millipedes (Arthrosphaera) |
| Orsonwelles | Orsonwelles spp. | Hawaii | Unknown | Money spiders |
| Conant's giant Nihoa tree cricket | Thaumatogryllus conanti | Nihoa | Unknown | Tree crickets |
| Giant Fijian long-horned beetle | Xixuthrus heros | Viti Levu, Fiji | Endangered | Australasian Xixuthrus |
| Taveuni beetle | Xixuthrus terribilis | Taveuni, Fiji | Unknown | Australasian Xixuthrus |

### Gastropods

| Example | Binomial name | Native range | Current status | Continental relative |
| Kauri land snails | Paryphanta spp. Powelliphanta spp. | New Zealand | Near Threatened | Other rhytidids |

### Flora

In addition to size increase, island plants may also exhibit "insular woodiness". The most notable examples are the megaherbs of New Zealand's subantarctic islands. Increased leaf and seed size was also reported in some island species regardless of growth form (herbaceous, bush, or tree).
| Example | Binomial name | Native range | Current status | Continental relative |
| Campbell Island carrot | Anisotome latifolia | Campbell and Auckland Islands | Unknown | Apiaceae |
| Ross lily | Bulbinella rossii | Campbell and Auckland Islands | Naturally Uncommon | New Zealand Maori lily |
| Chatham Islands korokio | Corokia macrocarpa | Chatham Islands | Unknown | New Zealand korokio |
| Black-eyed daisy | Damnamenia vernicosa | Auckland and Campbell Islands | Naturally Uncommon | Astereae |
| Cucumber tree | Dendrosicyos socotranus | Socotra | Vulnerable | Gourds |
| Coco de mer | Lodoicea maldivica | Seychelles | Endangered | Borassoid palms |
| | Pleurophyllum criniferum | Antipodes, Auckland and Campbell Islands | Unknown | Cineraria |
| Silver-leaf daisy | Pleurophyllum hookeri | Macquarie Island, Auckland and Campbell Islands | Unknown | Cineraria |
| Campbell Island daisy | Pleurophyllum speciosum | Campbell and Auckland Islands | Naturally Uncommon | Cineraria |
| Macquarie Island cabbage | Stilbocarpa polaris | Macquarie Island and New Zealand subantarctic islands | Vulnerable | Araliaceae |