Insular dwarfism

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Skeletons of Malta's extinct Palaeoloxodon falconeri, the smallest known species of elephant. Adult males measured about one meter in shoulder height and weighed about 305 kg. Females were smaller. Elephas falconeri 4.JPG
Skeletons of Malta's extinct Palaeoloxodon falconeri , the smallest known species of elephant. Adult males measured about one meter in shoulder height and weighed about 305 kg. Females were smaller.

Insular dwarfism, a form of phyletic dwarfism, [1] is the process and condition of large animals evolving or having a reduced body size [lower-alpha 1] when their population's range is limited to a small environment, primarily islands. This natural process is distinct from the intentional creation of dwarf breeds, called dwarfing. This process has occurred many times throughout evolutionary history, with examples including dinosaurs, like Europasaurus and Magyarosaurus dacus , and modern animals such as elephants and their relatives. This process, and other "island genetics" artifacts, can occur not only on islands, but also in other situations where an ecosystem is isolated from external resources and breeding. This can include caves, desert oases, isolated valleys and isolated mountains ("sky islands").[ citation needed ] Insular dwarfism 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 (island gigantism), and large species tend to evolve smaller bodies. This is itself one aspect of island syndrome, which describes the differences in morphology, ecology, physiology and behaviour of insular species compared to their continental counterparts.

Contents

Possible causes

There are several proposed explanations for the mechanism which produces such dwarfism. [3] [4]

One is a selective process where only smaller animals trapped on the island survive, as food periodically declines to a borderline level. The smaller animals need fewer resources and smaller territories, and so are more likely to get past the break-point where population decline allows food sources to replenish enough for the survivors to flourish. Smaller size is also advantageous from a reproductive standpoint, as it entails shorter gestation periods and generation times. [3]

In the tropics, small size should make thermoregulation easier. [3]

Among herbivores, large size confers advantages in coping with both competitors and predators, so a reduction or absence of either would facilitate dwarfing; competition appears to be the more important factor. [4]

Among carnivores, the main factor is thought to be the size and availability of prey resources, and competition is believed to be less important. [4] In tiger snakes, insular dwarfism occurs on islands where available prey is restricted to smaller sizes than are normally taken by mainland snakes. Since prey size preference in snakes is generally proportional to body size, small snakes may be better adapted to take small prey. [5]

Dwarfism vs. gigantism

The inverse process, wherein small animals breeding on isolated islands lacking the predators of large land masses may become much larger than normal, is called island gigantism. An excellent example is the dodo, the ancestors of which were normal-sized pigeons. There are also several species of giant rats, one still extant, that coexisted with both Homo floresiensis and the dwarf stegodonts on Flores.

The process of insular dwarfing can occur relatively rapidly by evolutionary standards. This is in contrast to increases in maximum body size, which are much more gradual. When normalized to generation length, the maximum rate of body mass decrease during insular dwarfing was found to be over 30 times greater than the maximum rate of body mass increase for a ten-fold change in mammals. [6] The disparity is thought to reflect the fact that pedomorphism offers a relatively easy route to evolve smaller adult body size; on the other hand, the evolution of larger maximum body size is likely to be interrupted by the emergence of a series of constraints that must be overcome by evolutionary innovations before the process can continue. [6]

Factors influencing the extent of dwarfing

For both herbivores and carnivores, island size, the degree of island isolation and the size of the ancestral continental species appear not to be of major direct importance to the degree of dwarfing. [4] However, when considering only the body masses of recent top herbivores and carnivores, and including data from both continental and island land masses, the body masses of the largest species in a land mass were found to scale to the size of the land mass, with slopes of about 0.5 log(body mass/kg) per log(land area/km2). [7] There were separate regression lines for endothermic top predators, ectothermic top predators, endothermic top herbivores and (on the basis of limited data) ectothermic top herbivores, such that food intake was 7 to 24-fold higher for top herbivores than for top predators, and about the same for endotherms and ectotherms of the same trophic level (this leads to ectotherms being 5 to 16 times heavier than corresponding endotherms). [7]

Examples

Non-avian dinosaurs

Recognition that insular dwarfism could apply to dinosaurs arose through the work of Ferenc Nopcsa, a Hungarian-born aristocrat, adventurer, scholar, and paleontologist. Nopcsa studied Transylvanian dinosaurs intensively, noticing that they were smaller than their cousins elsewhere in the world. For example, he unearthed six-meter-long sauropods, a group of dinosaurs which elsewhere commonly grew to 30 meters or more. Nopcsa deduced that the area where the remains were found was an island, Hațeg Island (now the Haţeg or Hatzeg basin in Romania) during the Mesozoic era. [8] [9] Nopcsa's proposal of dinosaur dwarfism on Hațeg Island is today widely accepted after further research confirmed that the remains found are not from juveniles. [10]

Sauropods

ExampleSpeciesRangeTime frameContinental relative
AmpelosaurusScale.png
Ampelosaurus
A. atacis Ibero-Armorican Island Late Cretaceous / Maastrichtian Tapuiasaurus NT.jpg
Nemegtosaurids
Europasaurus skull.JPG
Europasaurus
E. holgeri Lower Saxony Late Jurassic / Middle Kimmeridgian Giraffatitan scale.png
Brachiosaurs
Magyarosaurus- human size.JPG
Magyarosaurus
M. dacus Hateg Island Late Cretaceous / Maastrichtian Rapetosaurus BW.jpg
Rapetosaurus
Lirainosaurus.jpg
Lirainosaurus [11]
L. astibiaeIbero-Armorican IslandLate Cretaceous
Paludititan nalatzsensis.jpg
Paludititan
P. nalatzensis Hateg Island Late Cretaceous / Maastrichtian Epachtosaurus sciuttoi.jpg
Epachthosaurus

Other

ExampleSpeciesRangeTime frameContinental relative
Langenburg theropod size.png
Langenberg Quarry
torvosaur (blue)
Unnamed Lower Saxony Late Jurassic / Middle Kimmeridgian Torvosaurus gurneyi.png
Torvosaurus
Struthiosaurus austriacus.jpg
Struthiosaurus [12]
S. austriacus

S. transylvanicus

S. languedocensis
Ibero-Armorican, Australoalpine, and Hateg islandsLate Cretaceous Edmontonia Scale.svg
Edmontonia
Telmatosaurus Scale.svg
Telmatosaurus
T. transsylvanicus Hateg Island Late Cretaceous Hadrosaurus Scale.svg
Hadrosaurids
Thecodontosaurus Scale.svg
Thecodontosaurus [9]
T. antiquus Southern England Late Triassic / Rhaetian Human-plateosaurus size comparison.svg
Plateosaurs
Iguanodontian Sizes.svg
Zalmoxes [9] (purple)
Z. robustus

Z. shqiperorum
Hateg Island Late Cretaceous Perot Museum Tenontosaurus.jpg
Tenontosaurus

In addition, the genus Balaur was initially described as a Velociraptor -sized dromaeosaurid (and in consequence a dubious example of insular dwarfism), but has been since reclassified as a secondarily flightless stem bird, closer to modern birds than Jeholornis (thus actually an example of insular gigantism).

Birds

ExampleBinomial nameNative rangeStatusContinental relativeInsular / mainland
length or mass ratio
Apteribis sp. (5212794163).jpg
Hawaiian flightless ibises
Apteribis glenos Molokai Extinct (Late Quaternary) White Ibis in Florida.jpg
American ibises
Apteribis brevis Maui
Cozumel curassow [13] Crax rubra griscomi Cozumel Unknown Crax rubra (Great Curassow) - female.jpg
Great curassow
Baudin emus.jpg
Kangaroo Island emu [14]
Dromaius novaehollandiae baudinianus Kangaroo Island, South AustraliaExtinct (c. AD 1827) Emu RWD1.jpg
Emu
Emu size.png
King Island emu [15] (black)
Dromaius novaehollandiae minor King Island, TasmaniaExtinct (AD 1822)LR ≈ 0.48 [lower-alpha 2]
Dwarf yellow eyed penguin [16] Megadyptes antipodes richdalei Chatham Islands, New ZealandExtinct (after 1300 AD) Megadyptes antipodes -Otago Peninsula, Dunedin, New Zealand -family-8.jpg
Yellow-eyed penguin
Naturalis Biodiversity Center - RMNH.AVES.128765 2 - Toxostoma guttatum (Ridgway, 1885) - Mimidae - bird skin specimen.jpeg
Cozumel thrasher [13]
Toxostoma gluttatum Cozumel Critically endangered Curve-billed Thrasher.jpg
Other thrashers

Squamates

ExampleBinomial nameNative rangeStatusContinental relativeInsular / mainland
length or mass ratio
20150510-IMG 0786.jpg
Madagascar dwarf chameleon
Brookesia minima Nosy Be island, MadagascarEndangered Brookesia species male female (Journal.pone.0031314.g010).png
Madagascar leaf chameleons
Brookesia micra on a match head.jpg
Nosy Hara chameleon [17]
Brookesia micra Nosy Hara island, MadagascarVulnerable
Roxby Island tiger snake [5] Notechis scutatusRoxby Island, South Australia Unknown Tiger snake 2.jpg
Tiger snake
Dwarf Burmese python Python bivittatus progschai Java, Bali, Sumbawa and Sulawesi, IndonesiaUnknown Burmese python (6887388927).jpg
Burmese python
LR ≈ 0.44 [lower-alpha 3]
Tanahjampea reticulated python [20] Python reticulatus jampeanus Tanahjampea, between Sulawesi and FloresUnknown Python reticulatus setchatyi piton-2.jpg
Reticulated python
LR ≈ 0.41, males
LR ≈ 0.49, females [lower-alpha 4]

Mammals

Pilosans

ExampleBinomial nameNative rangeStatusContinental relative
Bradypus pygmaeus.jpg
Pygmy three-toed sloth
Bradypus pygmaeus Isla Escudo de Veraguas, PanamaCritically endangered Bradypus variegatus, the Brown-throated Three-toed Sloth (12687597105).jpg
Brown-throated sloth
Habanocnus.JPG
Acratocnus
A. antillensis

A. odontrigonus

A. ye
Cuba, Hispaniola and Puerto Rico Extinct (c. 3000 BC) Megalonyx size.svg
Continental ground sloths
Imagocnus I. zazae Cuba Extinct (Early Miocene)
Megalocnus.jpg
Megalocnus
M. rodens

M. zile
Cuba and Hispaniola Extinct (c. 2700 BC)
Synocnus comes.jpg
Neocnus
Neocnus spp. Cuba and Hispaniola Extinct (c. 3000 BC)

Proboscideans

ExampleBinomial nameNative rangeStatusContinental relative
Sulawesi dwarf elephant Elephas celebensis Sulawesi Extinct (Early Pleistocene) Indian-Elephant-444.jpg
Asian elephant
Elephas beyeri-bpk.jpg
Cabarruyan dwarf elephant
Elephas beyeri Luzon Extinct
Cretanelephant-petermaas.jpg
Cretan dwarf mammoth
Mammuthus creticus Crete Extinct Mammuthus Scale.svg
Mammuthus
M. exilis skeletal.png
Channel Islands mammoth
Mammuthus exilis Santa Rosae islandExtinct (Late Pleistocene) M. columbi skeletals.png
Columbian mammoth
Sardinian mammoth Mammuthus lamarmorai Sardinia Extinct (Late Pleistocene) Steppe mammoth size 2.jpg
Steppe mammoth
Saint Paul Island woolly mammoth [23] [24] Mammuthus primigenius Saint Paul Island, AlaskaExtinct (c. 3750 BC) M. primigenius.png
Woolly mammoth
Elephas skeleton.JPG
Siculo-Maltese elephants
Palaeoloxodon antiquus leonardi

P. mnaidriensis

P. melitensis

P. falconeri
Sicily and Malta Extinct Palaeoloxodon-Species-Scale-Diagram-SVG-Steveoc86.svg
Straight-tusked elephant
(left)
Cretan elephants Palaeoloxodon chaniensis

P. creutzburgi
Crete Extinct
Elephas cypriotes Tusk and Molar.jpg
Cyprus dwarf elephant
Palaeoloxodon cypriotes Cyprus Extinct (c. 9000 BC)
Naxos dwarf elephantPalaeoloxodon sp. Naxos Extinct
Rhodes and Tilos dwarf elephantPalaeoloxodon tiliensis Rhodes and Tilos Extinct
Bumiayu dwarf sinomastodont [25] Sinomastodon bumiajuensisBumiayu Island (now part of Java)Extinct (Early Pleistocene) Sinomastodon.png
Sinomastodon
nonhoipaku - akebonozou.jpg
Japanese stegodont [26] [27]
Stegodon miensis

Stegodon protoaurorae

Stegodon aurorae
Japan (Also Taiwan for S. aurorae) [28] Extinct (Early Pleistocene) Stegodon skeletal.png
Chinese Stegodon
Greater Flores dwarf stegodont [3] Stegodon florensis Flores Extinct (Late Pleistocene) Stegodon's ivory displayed at Philippine National Museum.jpg
Sundaland Stegodon
Javan dwarf stegodontsStegodon hypsilophus [25]

S. semedoensis [29]

S. sp. [25]
Java Extinct (Quaternary)
Mindanao pygmy stegodont [30] Stegodon mindanensis Mindanao and Sulawesi Extinct (Middle Pleistocene)
Sulawesi dwarf stegodont [25] Stegodon sompoensis Sulawesi Extinct
Lesser Flores dwarf stegodont [3] Stegodon sondaari Flores Extinct (Middle Pleistocene)
Sumba dwarf stegodont [31] Stegodon sumbaensis Sumba, IndonesiaExtinct (Middle Pleistocene)
Timor dwarf stegodont [25] Stegodon timorensis Timor Extinct
Dwarf stegolophodont [32] Stegolophodon pseudolatidens Japan Extinct (Miocene) Stegolophodon latidens.JPG
Stegolophodon

Primates

ExampleBinomial nameNative rangeStatusContinental relative
Nosy Hara dwarf lemur [33] Cheirogaleus sp. Nosy Hara island off MadagascarUnknown Cheirogaleus-medius.jpg
Dwarf lemurs
Specimen LB1.jpg
Flores Man [34]
Homo floresiensis Flores Extinct (Late Pleistocene) Homme de Tautavel 01-08.jpg
Homo erectus
LuzonensisMolars.jpg
Callao Man
Homo luzonensis [35] [36] Luzon, PhilippinesExtinct (Late Pleistocene)
Modern pygmies of Flores [37] Homo sapiens Flores Extantother members of Homo sapiens
Early Palau modern humans (disputed) [38] Homo sapiens Palau Extinct (?)
Andamanese [39] Homo sapiens Andaman Islands Extant
Macaca majori.JPG
Sardinian macaque [40]
Macaca majori Sardinia Extinct (Pleistocene) Barbary macaques of Gibraltar in search of food.jpg
Barbary macaque
Red Colobus 7.jpg
Zanzibar red colobus
Piliocolobus kirkii Unguja Endangered Udzungwa Red Colobus Stevage.JPG
Udzungwa red colobus

Carnivorans

ExampleBinomial nameNative rangeStatusContinental relativeInsular / mainland
length or mass ratio
Canis lupus cristaldii subsp. nov.png
Sicilian wolf
Canis lupus cristaldii Sicily Extinct (AD 1970) Canis lupus Europe.jpg
Gray wolf
Honshu-wolf4.jpg
Japanese wolf
Canis lupus hodophilax Japan (excluding Hokkaido)Extinct (AD 1905)
Adaptations of the Pleistocene island canid Cynotherium sardous (2006) Fig. 1.png
Sardinian dhole
(forward)
Cynotherium sardous Corsica and Sardinia Extinct (c. 8300 BC) Xenocyon lycanoides restoration.jpg
Xenocyon
Trinil dog Mececyon trinilensis Java Extinct (Pleistocene)
Cozumel Island coati [13] Nasua narica nelsoni Cozumel Critically endangered White nosed Coati.jpg
Yucatan white-nosed coati
Zanzibar Leopard 2.JPG
Zanzibar leopard
Panthera pardus pardus Unguja Critically endangered or Extinct Male leopard samburu 2, crop.jpg
African leopard
Bali tiger zanveld.jpg
Bali tiger
Panthera tigris sondaica Bali Extinct (c. AD 1940) Panthera tigris sumatrae (Sumatran Tiger) close-up.jpg
Sumatran tiger
Panthera tigris sondaica 01.jpg
Javan tiger
Java Extinct (c. AD 1975)
Cozumel Raccoon2.jpg
Cozumel raccoon
Procyon pygmaeus Cozumel Critically endangered Raccoon-10.png
Common raccoon
Urocyon littoralis pair.jpg
Island fox
Urocyon littoralisSix of the Channel Islands of California Near Threatened Grey Fox (Urocyon cinereoargenteus).jpg
Gray fox
LR ≈ 0.84 [lower-alpha 5]
LR ≈ 0.75 [lower-alpha 6]
Cozumel fox Urocyon sp. Cozumel Critically endangered or Extinct

Non-ruminant ungulates

ExampleBinomial nameNative rangeStatusContinental relative
Eumaiochoerus etruscus mandible.jpg
Eumaiochoerus
Eumaiochoerus etruscus Baccinello, Montebamboli Extinct (Miocene) Microstonyx skull.jpg
Microstonyx
Hippo1 final.jpg
Malagasy dwarf hippopotamuses
Hippopotamus laloumena

H. lemerlei

H. madagascariensis
Madagascar Extinct (c. AD 1000) Nijlpaard.jpg
Common hippopotamus
Bumiayu dwarf hippopotamus [25] Hexaprotodon simplexBumiayu Island (now Java)Extinct (Early Pleistocene) Hexaprotodon sivalensis.jpg
Asian hippopotamuses
Hippopotamus cruetzburgi.JPG
Cretan dwarf hippopotamus
Hippopotamus creutzburgi Crete Extinct (Middle Pleistocene) Museo di paleologia, scheletro di hippopotamus antiquus, recuperato presso figline valdarno.JPG
European hippopotamus
Hippopotamus amphibius Linn at Ghar Dalam, Malta.png
Maltese dwarf hippopotamus
Hippopotamus melitensis Malta Extinct (Pleistocene)
Hippo-Cyprus.JPG
Cyprus dwarf hippopotamus
Hippopotamus minor Cyprus Extinct (c. 8000 BC)
Hippopotamus pentlandi 3.JPG
Sicilian dwarf hippopotamus
Hippopotamus pentlandi Sicily Extinct (Pleistocene)
Cozumel collared peccary [13] Pecari tajacu nanus Cozumel Unknown Running Javelina.jpg
Collared peccary
Philippine rhinoceros [43] Nesorhinus philippinensis Luzon Extinct (Middle Pleistocene) Javan Rhino 1900.jpg
Javan rhinoceros

Bovids

ExampleBinomial nameNative rangeStatusContinental relative
Sicilian bison [26] Bison priscus siciliae Sicily Extinct (Late Pleistocene) Prazubr rysunek 600.jpg
Steppe bison
Sicilian aurochs [44] Bos primigenius siciliae [26] Sicily Extinct (Late Pleistocene) Aurochs reconstruction.jpg
Eurasian aurochs
Cebu tamaraw Bubalus cebuensis Cebu, PhilippinesExtinct Indian Water Buffalo Bubalus arnee by Dr Raju Kasambe IMG 0347 (11) (cropped).jpg
Wild water buffalo
Lowland anoa.jpg
Lowland anoa
Bubalus depressicornis Sulawesi and Buton, IndonesiaEndangered
Bubalus grovesi Bubalus grovesi Sulawesi, IndonesiaExtinct
Bubalus mindorensis by Gregg Yan 01.jpg
Tamaraw
Bubalus mindorensis Mindoro, PhilippinesCritically endangered
Buablus quarlesi2.jpg
Mountain anoa
Bubalus quarlesi Sulawesi and Buton, IndonesiaEndangered
Myotragus balearicus.JPG
Balearic Islands cave goat
Myotragus balearicus Majorca and Menorca Extinct (after 3000 BC)Gallogoral
Nesogoral [45] Nesogoral spp. Sardinia Extinct
Dahlak Kebir gazelle [46] Nanger soemmerringi ssp. Dahlak Kebir island, EritreaVulnerable The book of antelopes (1894) Gazella soemmerringi (white background).png
Soemmerring's gazelle
Tyrrhenotragus gracillimus mandible.jpg
Tyrrhenotragus
Tyrrhenotragus gracillimus Baccinello Extinct Antilopinae sp.

Cervids and relatives

ExampleBinomial nameNative rangeStatusContinental relative
Candiacervus ropalophorus.jpg
Cretan dwarf megacerines [lower-alpha 7]
Candiacervus spp. Crete Extinct (Pleistocene) Praemegaceros verticornis.JPG
Praemegaceros verticornis [9]
Praemegaceros cazioti A6 digital.jpg
Sardinian megacerine [9]
Praemegaceros cazioti Sardinia Extinct (c. 5500 BC)
Cervus astylodon.jpg
Ryukyu dwarf deer [49]
Cervus astylodon Ryukyu Islands Extinct The deer of all lands (1898) Manchurian sika white background.png
Sika deer (?)

Cervus praenipponicus (?)
Jersey red deer population [50] Cervus elaphus jerseyensis Jersey Extinct (Pleistocene) Rothirsch.jpg
Red deer
CervusElaphusCorsicanus-pjt.jpg
Corsican red deer
Cervus elaphus corsicanus Corsica and Sardinia Near Threatened
Pleistocene Sicilian deer [26] Cervus siciliae Sicily Extinct (Late Pleistocene)
Hoplitomeryx matthei.jpg
Hoplitomeryx [lower-alpha 8]
Hoplitomeryx spp. Gargano Island Extinct (Early Pliocene) Antilocapra americana male (Wyoming, 2012).jpg
Pecorans
Sicilian megacerine [26] Megaloceros carburangelensis Sicily Extinct (Late Pleistocene) Megaloceros B&W rogne.png
Irish elk
Key deer male.jpg
Florida Key deer
Odocoileus virginianus clavium Florida Keys Endangered White-tailed deer.jpg
Virginia deer
Spitsbergen reindeer01.jpg
Svalbard reindeer
Rangifer tarandus platyrhynchus Svalbard Vulnerable Fjellrein.jpg
Reindeer
Rusa marianna by Gregg Yan.jpg
Philippine deer
Rusa marianna Philippines Vulnerable Sambar (Rusa unicolor cambojensis) (7109798353).jpg
Sambar deer

Plants

Possible exampleBinomial nameNative rangeStatusContinental relative
El Tecolote.JPG
Insular elephant cacti [51] [52]
Pachycereus pringlei Remote islands in the Sea of Cortez
(e.g. Santa Cruz, San Pedro Mártir)
Not evaluated Pachycereus pringlei cardon sahueso.JPG
Mainland elephant cacti

See also

Notes

  1. An example of noninsular phyletic dwarfism is the evolution of the dwarfed marmosets and tamarins among New World monkeys, culminating in the appearance of the smallest example, Cebuella pygmaea . [2]
  2. Based on the heights in Fig. 1 of Heupink et al., 2011 [15]
  3. Based on maximum lengths of 2.5 m for the dwarf form [18] and 5.74 m for the mainland form [19]
  4. Based on maximum Tanahjampea python total lengths (TL) of 2.10 m for males and 3.35 m for females [20] and maximum southern Sumatra python snout to vent lengths (SVL) of 4.5 m for males and 6.1 m for females [21] with SVLs corrected to TLs by multiplying by a factor of 1.127, derived from the average relative tail length (0.113) of African and Indian rock pythons [22]
  5. For nearby mainland gray foxes [41]
  6. For mainland gray foxes in general [42]
  7. Like Hoplitomeryx, Candiacervus appears to be an unusual case in that members of this genus evolved into insular species of a wide range of sizes, not only dwarf forms but also some that might be considered giants. [47] [48]
  8. Hoplitomeryx is evidently quite an unusual case, because members of this genus apparently evolved into both dwarf and giant insular forms on the same island(s). [47]

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Magyarosaurus is a genus of dwarf sauropod dinosaur from late Cretaceous Period in Romania. It is one of the smallest-known adult sauropods, measuring only 6 m (20 ft) in length and 750–1,000 kg (1,650–2,200 lb) in body mass. The type and only certain species is Magyarosaurus dacus. It has been found to be a close relative of Rapetosaurus in the family Saltasauridae in the sauropod clade Titanosauria in a 2005 study.

<span class="mw-page-title-main">Island gigantism</span> Evolutionary phenomena leading to an increase of the size of species with insularity

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. 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, many giant as well as other island endemics have become extinct. A similar size increase, as well as increased woodiness, has been observed in some insular plants such as the Mapou tree in Mauritius which is also known as the "Mauritian baobab" although it is member of the grape family (Vitaceae).

<i>Telmatosaurus</i> Extinct genus of dinosaurs

Telmatosaurus is a genus of basal hadrosauromorph dinosaur from the Late Cretaceous of Romania. It was a relatively small hadrosaur, measuring approximately 5 m (16 ft) in length and 600 kg (1,300 lb) in body mass, which has been explained as an instance of insular dwarfism.

<i>Zalmoxes</i> Extinct genus of dinosaurs

Zalmoxes is a genus of rhabdodontid ornithopod dinosaur from the Maastrichtian age of the Late Cretaceous in what is now Romania. The genus is known from specimens first named as the species Mochlodon robustum in 1899 by Franz Nopcsa before being reclassified as Rhabdodon robustum by him in 1915. In 1990, this name was corrected to Rhabdodon robustus by George Olshevsky and, in 2003, the species was once more reclassified as the type species Zalmoxes robustus. Zalmoxes refers to the Dacian deity Zalmoxis and robustus refers to the robustness of the remains. Also in 2003, another species was named, Zalmoxes shqiperorum, named for the Albanian name for Albanians.

<span class="mw-page-title-main">Hațeg Island</span> Prehistoric island

Hațeg Island was a large offshore island in the Tethys Sea which existed during the Late Cretaceous period, probably from the Cenomanian to the Maastrichtian ages. It was situated in an area corresponding to the region around modern-day Hațeg, Hunedoara County, Romania. Maastrichtian fossils of small-sized dinosaurs have been found in the island's rocks. It was formed mainly by tectonic uplift during the early Alpine orogeny, caused by the collision of the African and Eurasian plates towards the end of the Cretaceous. There is no real present-day analog, but overall, the island of Hainan is perhaps closest as regards climate, geology and topography, though still not a particularly good match. The vegetation, for example, was of course entirely distinct from today, as was the fauna.

<i>Hatzegopteryx</i> Genus of large azhdarchid pterosaur from the Late Cretaceous

Hatzegopteryx is a genus of azhdarchid pterosaur found in the late Maastrichtian deposits of the Densuş Ciula Formation, an outcropping in Transylvania, Romania. It is known only from the type species, Hatzegopteryx thambema, named by Buffetaut et al. in 2002 based on parts of the skull and humerus. Additional specimens, including a neck vertebra, were later placed in the genus, representing a range of sizes. The largest of these remains indicate it was among the biggest pterosaurs, with an estimated wingspan of 10 to 12 metres.

<i>Candiacervus</i> Extinct genus of deer

Candiacervus is an extinct genus of deer native to Pleistocene Crete. Due to a lack of other herbivores, the genus underwent an adaptive radiation, filling niches occupied by other taxa on the mainland. Due to the small size of Crete, some species underwent insular dwarfism, the smallest species, C. ropalophorus, stood about 40 centimetres (16 in) at the shoulders when fully grown, while other species were relatively large and comparable in size to mainland deer species. Some species are noted for their peculiar, elongate club-shaped antlers, though other species have more normal antlers.

<span class="mw-page-title-main">Cyprus dwarf hippopotamus</span> Species of mammal (fossil)

The Cyprus dwarf hippopotamus or Cypriot pygmy hippopotamus is an extinct species of hippopotamus that inhabited the island of Cyprus from the Pleistocene until the early Holocene. The 200-kilogram (440 lb) Cyprus dwarf hippo was roughly the same size as the extant pygmy hippopotamus. Unlike the modern pygmy hippo, the Cyprus dwarf became small through the process of insular dwarfism. H. minor is the smallest hippopotamus of all known insular hippopotamuses. It is estimated to have measured 76 cm (2.5 ft) tall and 121 cm (4.0 ft) long.

<i>Asoriculus</i> Extinct genus of red-toothed shrew

Asoriculus is an extinct genus of terrestrial shrews in the subfamily Soricinae and tribe Nectogalini, native to Europe and North Africa.

<i>Palaeoloxodon mnaidriensis</i> Extinct species of elephant

Palaeoloxodon mnaidriensis is an extinct species of dwarf elephant belonging to the genus Palaeoloxodon, native to the Siculo-Maltese archipelago during the late Middle Pleistocene and Late Pleistocene. It is derived from the European mainland straight-tusked elephant.

<i>Balaur bondoc</i> Extinct genus of dinosaurs

Balaur is a genus of theropod dinosaur from the late Cretaceous period, in what is now Romania. It is the type species of the monotypic genus Balaur, after the balaur, a dragon of Romanian folklore. The specific name bondoc means "stocky", so Balaur bondoc means "stocky dragon" in Romanian. This name refers to the greater musculature that Balaur had compared to its relatives. The genus, which was first described by scientists in August 2010, is known from two partial skeletons.

<i>Leithia</i> Extinct genus of giant dormice

Leithia is an extinct genus of giant dormice from the Pleistocene of the Mediterranean islands of Malta and Sicily. It is considered an example of island gigantism. Leithia melitensis is the largest known species of dormouse, living or extinct, being twice the size of any other known species.

<span class="mw-page-title-main">Island syndrome</span> Set of phenotypical features likely to occur in geographically-isolated populations

Island syndrome describes the differences in morphology, ecology, physiology and behaviour of insular species compared to their continental counterparts. These differences evolve due to the different ecological pressures affecting insular species, including a paucity of large predators and herbivores as well as a consistently mild climate.

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