Lizard is the common name used for all squamate reptiles other than snakes, encompassing over 7,000 species, ranging across all continents except Antarctica, as well as most oceanic island chains. The grouping is paraphyletic as some lizards are more closely related to snakes than they are to other lizards. Lizards range in size from chameleons and geckos a few centimeters long to the 3-meter-long Komodo dragon.
Ratites are a polyphyletic group consisting of all birds within the infraclass Palaeognathae that lack keels and cannot fly. They are mostly large, long-necked, and long-legged, the exception being the kiwi, which is also the only nocturnal extant ratite.
In zoology, megafauna are large animals. The precise definition of the term varies widely, though a common threshold is approximately 45 kilograms (99 lb), with other thresholds as low as 10 kilograms (22 lb) or as high as 1,000 kilograms (2,200 lb). Large body size is generally associated with other traits, such as having a slow rate of reproduction and, in large herbivores, reduced or negligible adult mortality from being killed by predators.
Giant tortoises are any of several species of various large land tortoises, which include a number of extinct species, as well as two extant species with multiple subspecies formerly common on the islands of the western Indian Ocean and on the Galápagos Islands.
Bergmann's rule is an ecogeographical rule that states that, within a broadly distributed taxonomic clade, populations and species of larger size are found in colder environments, while populations and species of smaller size are found in warmer regions. The rule derives from the relationship between size in linear dimensions meaning that both height and volume will increase in colder environments. Bergmann's rule only describes the overall size of the animals, but does not include body proportions like Allen's rule does.
Flightless birds are birds that cannot fly. They have, through evolution, lost the ability to fly. There are over 60 extant species, including the well-known ratites and penguins. The smallest flightless bird is the Inaccessible Island rail. The largest flightless bird, which is also the largest living bird in general, is the common ostrich.
Foster's rule, also known as the island rule or the island effect, is an ecogeographical rule in evolutionary biology stating that members of a species get smaller or bigger depending on the resources available in the environment. For example, it is known that pygmy mammoths evolved from normal mammoths on small islands. Similar evolutionary paths have been observed in elephants, hippopotamuses, boas, sloths, deer and humans. It is part 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.
Myotragus is an extinct genus of goat-antelope in the tribe Caprini which lived on the Balearic Islands of Mallorca and Menorca in the western Mediterranean until its extinction around 4,500 years ago. The fossil record of Myotragus on the Balearic Islands extends over 5 million years back to the early Pliocene on Mallorca, where it presumably arrived after the evaporation of the Mediterranean Sea during the Messinian Salinity Crisis.
Insular dwarfism, a form of phyletic dwarfism, is the process and condition of large animals evolving or having a reduced body size 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 various species of dwarf elephants that evolved during the Pleistocene epoch, as well as more ancient examples, such as the dinosaurs Europasaurus and Magyarosaurus. 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. 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, 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.
Nuralagus is an extinct genus of leporid, with a single species, Nuralagus rex, described in 2011. It lived on Menorca, one of the Balearic Islands in the western Mediterranean during the Pliocene epoch. It is the largest known lagomorph to have ever existed, with an estimated weight of 8–12 kilograms (18–26 lb), nearly double the weight of the average Flemish Giant rabbit. It likely went extinct at the Pliocene-Pleistocene transition when Mallorca and Menorca were united as one island, letting the mammalian fauna of Mallorca, including the goat-like ungulate Myotragus, colonize Nuralagus's habitat.
Palaeoloxodon falconeri is an extinct species of dwarf elephant from the Middle Pleistocene of Sicily and Malta. It is amongst the smallest of all dwarf elephants, under 1 metre (3.3 ft) in height as fully grown adults. A member of the genus Palaeoloxodon, it derived from a population of the mainland European straight-tusked elephant.
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.
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.
In zoology, deep-sea gigantism or abyssal gigantism is the tendency for species of deep-sea dwelling animals to be larger than their shallower-water relatives across a large taxonomic range. Proposed explanations for this type of gigantism include necessary adaptation to colder temperature, food scarcity, reduced predation pressure and increased dissolved oxygen concentrations in the deep sea. The harsh conditions and inhospitality of the underwater environment in general, as well as the inaccessibility of the abyssal zone for most human-made underwater vehicles, have hindered the study of this topic.
Island ecology is the study of island organisms and their interactions with each other and the environment. Islands account for nearly 1/6 of earth’s total land area, yet the ecology of island ecosystems is vastly different from that of mainland communities. Their isolation and high availability of empty niches lead to increased speciation. As a result, island ecosystems comprise 30% of the world’s biodiversity hotspots, 50% of marine tropical diversity, and some of the most unusual and rare species. Many species still remain unknown.
Hypnomys, otherwise known as Balearic giant dormice, is an extinct genus of dormouse (Gliridae) in the subfamily Leithiinae. Its species are considered examples of insular gigantism. They were endemic to the Balearic Islands in the western Mediterranean from the Early Pliocene until their extinction around the 3rd millennium BC. They first appeared in the fossil record on Mallorca during the Early Pliocene, presumably as a result to the evaporation of the Mediterranean sea during the Messinian salinity crisis connecting the Balearic Islands with mainland Europe. They later spread to Menorca, and a possible molar is also known from Ibiza. Hypnomys became extinct during the late Holocene likely shortly after human arrival on the Balearics. They were one of only three native land mammals to the islands at the time of human arrival, alongside the shrew Nesiotites and goat-antelope Myotragus.
The Diplodactylidae are a family in the suborder Gekkota (geckos), with over 150 species in 25 genera. These geckos occur in Australia, New Zealand, and New Caledonia. Diplodactylids are the most ecologically diverse and widespread family of geckos in both Australia and New Caledonia, and are the only family of geckos found in New Zealand. Three diplodactylid genera have recently been split into multiple new genera.
A biological rule or biological law is a generalized law, principle, or rule of thumb formulated to describe patterns observed in living organisms. Biological rules and laws are often developed as succinct, broadly applicable ways to explain complex phenomena or salient observations about the ecology and biogeographical distributions of plant and animal species around the world, though they have been proposed for or extended to all types of organisms. Many of these regularities of ecology and biogeography are named after the biologists who first described them.
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.
Kritimys, also known as the Cretan giant rat is an extinct genus of murid rodent that was endemic to the island of Crete during the Early and Middle Pleistocene. There are two known species, K. kiridus from the Early-Mid Pleistocene, and its descendant K. catreus from the Middle Pleistocene. It is suggested to be closely related to and probably derived from Praomys. As with most island rodents, Kritimys was larger than its mainland relatives, with its size increasing over time, with K. catreus estimated to weigh 518 grams (1.142 lb), around 6.7 times the weight of its mainland ancestor, an example of island gigantism. The temporal range of the genus is considered to define the regional Kritimys biozone, during which time there were only two other species of mammal native to the island, a species of dwarf mammoth, Mammuthus creticus and the dwarf hippopotamus Hippopotamus creutzburgi. It became extinct during the late Middle Pleistocene, following the arrival of the Mus bateae-minotaurus lineage to the island, exhibiting a decrease in size shortly before its extinction.
