Evolutionary anachronism

The biology of the Ginkgo, a living fossil virtually unchanged for the past 270 million years, shows signs of having coevolved with entirely extinct groups of tree ferns, pollinating mecopterans and theropod dinosaurs.

Evolutionary anachronism is a concept in evolutionary biology, named by Connie C. Barlow in her book The Ghosts of Evolution (2000),^[1] to refer to attributes of living species that are best explained as a result of having been favorably selected in the past due to coevolution with other biological species that have since become extinct. When this context is removed, the said attributes appear as unexplained energy investments on the part of the living organism, with no apparent benefit extracted from them, and perhaps are prejudicial to the continued reproduction of the surviving species.

The general theory was formulated by Costa Rican-based American botanist Daniel Janzen and University of Arizona-based geologist Paul S. Martin (a prominent defender of the overkill hypothesis to explain the Quaternary extinction event) in a Science article published in 1982, titled Neotropical Anachronisms: The fruit the gomphotheres ate.^[1][2] Previously, in 1977, Stanley Temple had proposed a similar idea to explain the decline of the Mauritius endemic tree tambalacoque following the extinction of the iconic dodo.^[3]

Janzen, Martin and Barlow mainly discussed evolutionary anachronisms in the context of seed dispersal and passive defense strategies exhibited by plants that had evolved alongside disappeared megaherbivores. However, some examples have also been described in animal species. John Byers used the name relict behavior for animal behavior examples.^[4]

Evolutionary anachronisms should not be confused with examples of vestigiality. Though both concepts refer ultimately to organs that evolved to deal with pressures that are no longer present today, in the case of anachronisms, the original function of the organ and the capacity of the organism to use it are retained intact. An example is the absence of gomphotheres eating avocados does not render the avocado's pulp vestigial, rudimentary or incapable of playing its original function of seed dispersal if a new suitable ecological partner appears. A truly vestigial organ like the python's pelvic spurs cannot be used to walk again.

Megafauna dispersal syndrome[]

Dispersal syndromes are complexes of fruit traits that enable plants to disperse seeds. The kind of fruits that birds are attracted to are usually small, with only a thin protective skin, and the colors are red or dark shades of blue or purple. Fruits categorized as mammal syndrome are bigger than bird fruits. They possess a tough rind or husk, emit a strong odor when ripe but retain a dull coloration of brown, burnished yellow, orange or remain green, because most mammals have a powerful sense of smell but poor color vision in general, primates being the most notable exception. The megafauna dispersal syndrome refers to those attributes of fruits that evolved in order to attract megafauna (animals that weigh or weighed more than 44 kilograms) as primary dispersal agents. Since the Holocene extinction, large herbivores have become extinct outside Africa and to a lesser extent Asia, leaving these fruits without a suitable dispersal mechanism in the absence of agriculture.

Common megafaunal dispersal traits[]

Avocados are exceptionally fatty fruits, with seeds far too large to be successfully dispersed by any wild animal presently alive in the Americas.

• Large fruit, best suited to be consumed whole by large animals without seed loss.
• Fruit grows on or close to the trunk, or on stout branches.
• Indehiscent fruit that retains its seeds upon ripening.
• Seeds deter or elude being ground up by teeth through having a thick, tough or hard endocarp; or bitter, peppering or nauseating toxins. They are also difficult to separate from the pulp, which is tasty and soft, to deter seed spitting.
• The seeds benefit from—or even require—physical or chemical abrasion to germinate.
• If tropical, the fruit drops on or just before ripening, stopping monkeys from eating them. In colder climates, the fruit stays on the branch for a prolonged time, keeping it away from predation by ineffectual seed dispersers like rodents.
• "Looks, feels, smells, and tastes" like other fruits known to be dispersed by megafauna where megafauna still exists.^[1]

Ecological indicators of missing dispersal partners[]

Osage orange (Maclura pomifera) left rotting on the ground in Iowa

• The fruit either rots where it falls or is ineffectually disseminated by current dispersal agents.
• The plant is more common where livestock (proxy for megafauna) are present.
• The seeds germinate and grow well in upland habitats where planted, but the species almost exclusively inhabits floodplains (where water flow disperses the seeds) in the wild.
• The geographic range is inexplicably patchy or restricted.^[1]

Proposed examples in plants[]

Afrotropical realm[]

Example	Binomial name	Native range	Anachronism description	Suggested extinct coevolutionary partners
Balanites	Balanites wilsoniana	West and Central Africa	Described as an "anachronism in the making", with seed dispersal being extremely limited or even unrecorded in areas where elephants have been extirpated. At least one forest in Kenya is known to lack seedlings and young balanites altogether, with all trees present being older than the local extinction of elephants.[1]	Forest elephant[1] Bush elephant[1]
Double coconut	Lodoicea maldivica	Praslin and Curieuse islands (Seychelles)	The fruit weighs over 20 kg and contains the largest seeds in the world. No known animal eats the fruit, and the surviving trees appear to be the result of vegetative reproduction. Mature fruits do not float and are killed by sea water, unlike real coconuts.[5] The species is not thought to have dispersed over water, but to have evolved locally in the Seychelles after they broke off from the Indian plate 66 million years ago.[6]
Makak	Mimusops petiolaris	Mauritius	In decline due to the absence of animals removing its pulp. As a result, the fruit is colonized by fungi hyphae and the seeds rot without germinating. The fruit is only sporadically consumed by the Mauritian flying fox, which does not ingest the seeds.[7]
Tambalacoque	Sideroxylon grandiflorum	Mauritius	Peach-sized fruit that ripens from green to brown, much larger than its relatives present in the island and which are eaten by flying birds. The seed is in fact too large to be ingested by flying birds, and introduced pigs and monkeys destroy the seeds rather than disperse them. The tambalacoque evolved locally from smaller-seeded species in the genus Calvaria, which is found in Africa and Madagascar. Stanley Temple reported in 1977 that only 13 trees were left, all of them over three hundred years old, and that seeds could not germinate at all without being ingested and abraded first. However, these claims have since been debunked.[1]	Temple proposed that the tambalacoque had a strict mutualist relation with the dodo, extinct since c.1662.[1] Critics of Temple proposed that the seeds were originally dispersed by a giant tortoise instead, and that the tambalacoque might even have descended from seeds contained in a tortoise drifting from Madagascar, since tortoises are buoyant and colonize islands easily. In the Galapagos, ingestion by giant tortoises reduces seed dormancy in the Galapagos wild tomato, Solanum galapagense. Two species of giant tortoise were originally present in Mauritius and went extinct around the same time, the Domed Mauritius giant tortoise and the Saddle-backed Mauritius giant tortoise. However, tambalacoque seeds have harder covers than seeds usually eaten by tortoises, which have no gizzard; this might imply to a mutualistic relation with a bird after all, and the dodo was the only bird large enough to ingest the seeds. In any case, it was later found that germination was not favored by ingestion and abrasion of the seeds, but by pulp removal. As with Mimusops, the fruit that remains whole is colonized by fungi and its seeds rot.[1] The broad-billed parrot was also a large bird, although a flying one, and had an even more powerful beak than the dodo.[7] The Mauritian giant skink is presumed to have been omnivorous.[7] The coconut crab existed formerly in Mauritius, but has since disappeared from the island.[7]

Madagascar[]

Example	Binomial name	Native range	Anachronism description	Suggested extinct coevolutionary partners
	Alluaudia spp.	Southwestern Madagascar	Heavily spined stems, apparently as defense against climbing browsers, but browsing lemurs are rare in their area of distribution. The only known living predator is the ring-tailed lemur.[8]	Isotope testing found that the extinct monkey lemur genera Mesopropithecus and Hadropithecus likely fed on these plants.[8]
Borassoid and arecoid palms	Borassus spp. Hyphaene spp. Bismarckia spp. Satranala decussilvae Voanioala gerardii Orania spp. Lemurophoenix halleuxii	Madagascar	Large seeded palms. Their relatives outside Madagascar are dispersed by elephants, bats, orangutans, baboons, capuchin monkeys, peccaries and tapirs.[5]	Elephant bird[5][9]
	Canarium paniculatum	Mauritius	Hard seeds and fleshy pulp. Though common in the high forest vegetation, it has a poor regeneration rate.[7]
	Commiphora guillaminii	Western Madagascar	Endozoochorous dry forest tree with high genetic variation among subpopulations at the local scale but similar genetic differentiation among populations at the regional scale as relatives in South Africa, suggesting that the dispersal distance shrunk in the recent past.[10]	Giant lemurs[10]
Dilobeia	Dilobeia tenuinervis D. thouarsii	Eastern Madagascar	Fruit with a single seed measuring 3–4 cm by 2-2.5 cm, too large to be dispersed by any extant animal in Madagascar.[5]
Grandidier's baobab Suarez baobab	Adansonia grandidieri A. suarezensis	Madagascar	Fruit with fragile pericarp, tasty and nutritious pulp, and seeds with a tough, thick testa, clearly adapted for animal dispersal but lacking any known disperser. Relatives in continental Africa dispersed by elephants and baboons. Very restricted geographic distribution.[5]	Archaeolemur,[5][10] a semiterrestrial, generalist lemur similar to a baboon, extinct since the Middle Ages Pachylemur[10]
Malagasy pandan	Pandanus utilis	Madagascar, Mauritius and Seychelles	Seeds of variable size, the largest suited to be eaten by lemurs slightly larger than the extant species. Hard cover.[5]
Malagasy wire plants	Several unrelated species	Madagascar	Plants convergent with New Zealand's divaricating plants, adapted to resist browsing by large birds, rather than like their continental African relatives, which have defenses against ungulate browsers.[11]	Elephant bird[11]
Ramy nut	Canarium madagascariense	Madagascar	Fruits 6–7 cm long and 4–5 cm wide, with substantial flesh and a single seed 4 cm long and 2 cm wide. The flesh is eaten by aye-ayes but rarely whole, and they may be satiated without removing all the flesh from the seed, indicating that they are not the intended disperser. Its Asian relatives are dispersed by large parrots and hornbills.[5]	Elephant bird[5] Pachylemur, a close relative of the living black-and-white ruffed lemur, but larger and more robust.[5]
Traveller's tree	Ravenala madagascariensis	Madagascar	Plants often thrive and even form monocultures in degraded areas, due to their efficient vegetative reproduction. Hard, one centimeter long seeds, not adapted for wind or water dispersal, surrounded by odoriferous, light blue arils. The only viable seeds were found in the dung of the black-and-white ruffed lemur, the largest living lemur.[5]	Pachylemur[5]

Australasian realm[]

Example	Binomial name	Native range	Anachronism description	Suggested extinct coevolutionary partners
Birds-nest wattle Needle wattle	Acacia pickardii A. carneorum	Central Australia	Endangered spiny plants with extremely patchy populations. Both have low seed regeneration and reproduce mainly clonally.[12]
Bowgada	Acacia ramulosa	Central Australia	Unlike related species, the seeds are too large to be dispersed by ants and their low energy-to-water ratio make them unattractive to birds. The large legumes can be found directly beneath the shrub, in abundance and unopened, months after the end of the fruiting season.[1] Defensive spines are also common[citation needed], despite consumption of Acacia leaves by living marsupials being generally rare.[13]
Burrawang	Macrozamia spp.	Australia	Poor seed dispersal in spite of bright red, fleshy coatings. Brushtail possums eat the flesh but rarely carry the seeds. Many fruits fall in place and rot on the ground.[14]	Genyornis[14]
Bush tomato	Solanum spp.	Australia	Several species with a variable amount of defensive spines in the branches. Strikingly, the most spiny species live in the Australian desert, where browsing marsupials are most rare.[13]
Crystal Creek walnut	Endiandra floydii	Queensland-New South Wales border	Rare rainforest species with a massive seed per fruit[12]	Cassowaries[12]
Cypress-pine	Callitris spp.	Australia	Fossil pollen records show a great abundance of this species 50,000 years ago (after the extinction of the megafauna) compared to 100,000 years ago, despite the climate being similar and in contrast to other tree species which declined.[13]	There is direct evidence of predation by Diprotodon[13]
	Dacrydium guillauminii	New Caledonia (Holocene)	Critically endangered and limited to New Caledonia in the present, but pollen records show that it was also present in Australia before the Last Glacial Maximum. It is mostly found in the margins of streams and the seeds are dispersed by large birds.[13]	Extinct flightless birds[13]
Desert lime	Citrus glauca	Eastern and southern Australia	Defensive spines up to seven centimeters long.[15]	Giant marsupials[15]
Durobby	Syzygium moorei	Mount Warning, New South Wales	Large fruit and very small distribution.[12]	Cassowaries[12]
Hairy walnut	Endiandra pubens	New South Wales and Queensland	Massive red fruit compared to other rainforest fruits[12]	Cassowaries[12]
Idiot fruit	Idiospermum australiense	Daintree lowlands, Mount Bellenden Ker and Mount Bartle Frere in Tropical North Queensland	Largest seeds of any plant in Australia (225 grams), which are only sporadically dispersed by gravity and water. As a result, its range is extremely limited and largely restricted to lowly elevations and the margins of streams. However, translocation experiments have found that the species germinates easily in upland rainforests. The seeds are nutritious but contain toxins that make them severely poisonous to small mammals. The fruit has no pulp, but the seeds are easily divided into cotyledons, each of which can produce a different seedling. A large-jawed mammal currently absent might be able to feed on the seeds and disperse some of the seedlings uphill, if these fell from its mouth while chewing the seeds.[13]	Diprotodon[citation needed]
Lady apple	Syzygium suborbiculare	Northern Australia and Papua New Guinea	Tasty, red, apple-sized fruits encasing big round seeds, with no animals in their native range suited to eat them.[14]	Genyornis[12][14]
Leopardwood	Flindersia dissosperma F. maculosa	Inland Australia	Several defensive measures against large browsers, including wide, divaricate angle of branching, stiff and spiky twig tips, and small leaves widely separated along branchlets.[13] The defensive measures are lost when the plant reaches four meters, way above the reach of the largest local browsers - swamp and rock wallabies.[12]	Browsing flightless birds[12]
Myall Creek wattle	Acacia atrox	Tamworth, New South Wales	Spiny species found only in two stands. Low seed regeneration and mostly clonal reproduction.[12]
Narrow-leafed bumble tree	Capparis loranthifolia	Australia	[13]
Nutwood	Terminalia arostrata	Western Australia, Northern Territory and Queensland[16]	Defenses against browsers lost around four meters tall, like the divaricate growth pattern.[12]	Browsing flightless birds[12]
	Oldenlandia gibsonii	Gladstone, Queensland	Spiny and divaricate shrub, also the only woody member of its genus in Australia.[12]	Browsing megafauna[12]
Omphalea	Omphalea queenslandiae	Queensland	12.5 cm wide fruit similar to African and Asian fruits dispersed by elephants.[12]	Giant marsupials[12]
Pincushion tree	Hakea spp.	Australia	Spiny leaves that are not eaten by any living mammal.[13] At least one species (H. eyreana) has cammouflaged flowers, despite no living animal browsing it.[17]	Dromornithids[17]
Rosewood tree	Alectryon oleifolius	Australia	Trees growing in semi-circular stands sprouted around ancient burrow systems, possibly in soil once covered by dung of digging megafauna.[15]	Giant rat kangaroos[15] Phascolonus[15]
Scrub guava	Siphonodon australis	Northeastern Australia[18]	Big musky fruit.[15]	Diprotodon[15]
Southern ironwood	Acacia estrophiolata	Central Australia	Intricately branched and tangled with small phyllodes at shrub level; erect and with long pendulous phyllodes at tree level.[13]
Spiny everlasting	Acanthocladium dockeri	Laura, South Australia	Woody, spiny herbaceous species with relatives that are neither woody nor spiny. Presumed extinct until 1992, when a few clonal populations were discovered.[12]	Browsing megafauna[12]
Spiny peppercress	Lepidium archersonii	Eastern and Western Australia[19]	Woody, spiny herbaceous species with relatives that are neither woody nor spiny. Only a few widely scattered populations remaining.[12]	Browsing megafauna[12]
Touriga	Mammea touriga	Tropical Queensland	Large-fruited plant with a restricted range. A close relative, M. africana, is dispersed by elephants in Congo.[12]	Giant marsupials[12]
Vicious hairy Mary	Calamus radicalis	Daintree rainforest[20]	Defensive spines.[15]	Giant marsupials[15]
Waddywood	Acacia peuce	Margins of the Simpson Desert	Three anti-browser responses depending of its height: at grass level, the plant is soft but has a strong smell similar to stale urine, and induces headaches in humans; at shrub level, the plant is densely branched and has rigid, sharply pointed and outwardly reaching phyllodes; and at tree level (starting between two and three meters), the plant grows vertically, with soft phyllodes, and sheds all the rigid ones. However, the largest mammal in the area, the red kangaroo, rarely reaches two meters and is a grazer, not a browser. There are only three disjunct populations, but genetic testing shows that each is highly diverse, and similar in its genetic makeup to the others, indicating that they are recent remnants of a larger range area.[13] Seed regeneration is low and the species reproduces mainly clonally. The dense phyllodes of the shrub stage make it very vulnerable to fire, which might be another reason for its decline, as forest fires increased after the extinction of the megafauna.[12]	Browsing megafauna[12]
White bark	Endiandra compressa	Eastern Australia	Northern populations widespread and dispersed by cassowaries; southern populations restricted to stream banks.[12]	Pygmy cassowary[12]
Wild orange	Capparis mitchellii	Australia	Large, round fruits, with drab color and alluring aroma, typical of fruits ingested by mammals. Hooked spines also present.[14]	Diprotodon[14]
Wild pomegranate	Capparis canescens	Northeastern Australia[21]	[13]

New Zealand[]

Example	Binomial name	Native range	Anachronism description	Suggested extinct coevolutionary partners
Divaricating plants of New Zealand	54 unrelated species[1][22]	New Zealand	10% of New Zealand plants have a divaricating pattern of growth (i.e. they grow in thickets), a much larger proportion than elsewhere in the world. Like spines, a divaricating growth pattern reduces the action of large browsers, but it is more effective against browsing birds, while spines are more effective against browsing mammals. However, the only large browsers in New Zealand today are introduced deer.[1] These defenses disappear three meters above ground, at most.[12]	Moas - the larger species in particular, which have been identified as browsers from their preserved gizzard contents.[1] The largest species of all, the South Island giant moa, matches the height where the plant defenses disappear.[12]
Karaka	Corynocarpus laevigatus	New Zealand, including the Chatham Islands	Fruit with typical lizard dispersal syndrome features like most plants in New Zealand, but too large to be swallowed by any wild animal in the islands.[1]	New Zealand's kawekaweau was the second largest gecko in the world after the Rodrigues giant day gecko (also extinct). It was last observed in 1870.[1][23]
Tussock grass	Several unrelated species	New Zealand	[1]	Moas[1]

Indomalayan realm[]

Example	Binomial name	Native range	Anachronism description	Suggested extinct coevolutionary partners
Ginkgo	Ginkgo biloba	China (Holocene) Northern Hemisphere (Jurassic related forms)	An extreme living fossil, the same genus existed already in the Jurassic and the species might go back to the Middle Cretaceous. Ginkgos were widespread through the Northern Hemisphere until the Paleocene, survived in North America until the end of the Miocene, and in Europe and Japan until the Pleistocene. Seeds are protected by a shell too fragile to deter mammals, since they are capable of mastication, but the pulp is poisonous to frugivores (including humans). Red-bellied tree squirrels (in China) and eastern gray squirrels (in North American parks and plantations) are known to extract seeds from the pulp and store them, but are only secondary dispersers. Fallen diaspores smell like rotten flesh after a few days on the ground, attracting carnivorans like the masked palm civet, the leopard cat and the raccoon dog which eat them whole; however, their marking of their territory through defecation also limits their ability as seed dispersers.[1] The species is entirely pollinated by the wind in the present, but the chemical profile of its pollination drops is similar to those of insect-pollinated, or mixed wind and insect-pollinated Gnetophyta[24]	Squirrel-like multituberculates, particularly Ptilodus[1] Small carrion-eating dinosaurs both lived on the ground and lacked the more powerful masticatory apparatus and gizzard stones of the vegetarian species[1] Several extinct, early pollinating insect lineages are known from the Middle Jurassic to the Early Cretaceous, before modern flowers evolved. Most of these are long-proboscid scorpion flies (Mecoptera), and include Juracimbrophlebia, whose shape mimicked ginkgo leaves.[24] The unusual trunk and root growth pattern may have evolved in a pre-angiosperm world where the main competitors of the ginkgo were tree ferns, cycads and cycadeoids[25]
Plum-Yew	Cephalotaxus spp.	East Asia	Gymnosperm widespread through the Northern Hemisphere in the Tertiary.	Multituberculates[1]
Rafflesia	Rafflesia spp.	Southeast Asia	Between 14 and 28 species of dioecious parasitic plants with no visible stems, branches or leaves, but that produce enormous red flowers with a fetid, carrion-like smell. The smell attracts flies but they are poor pollinators. The fruits are giant berries around 14 centimeters long, with woody, cryptic cover; and smooth, oily flesh which smells and tastes like ripe (or rotten) coconut. The only observed dispersers are small rodents and treeshrews that eat part of the pulp and sometimes swallow seeds. Most species are endangered and have disjunct and extremely limited ranges.[1]	The original main pollinators might have been dung or carrion-eating beetles that became rarer as the megafauna declined.[1] The Asian elephant, Javan rhinoceros and Sumatran rhinoceros all used to, but are no longer present in Rafflesia's range, and might have been its intended seed dispersers.[1]

Nearctic realm[]

Example	Binomial name	Native range	Anachronism description	Suggested extinct coevolutionary partners
American persimmon	Diospyros virginiana	Southeastern United States	Seeds difficult to separate from the pulp, like in its Old World relatives, and highly toxic unless swallowed whole. Gray foxes, raccoons and American black bears are well known dispersers of seeds, but they used to be less abundant before their natural predators and competitors like gray wolves, cougars and grizzlies were extirpated by humans, and they tend to defecate in certain places in order to mark their territory, limiting their dispersal potential. Virginia opossums consume the pulp but never swallow the seeds. The fruit is edible for a month before it falls from the tree and remains so for several months afterward.[1]	American Mastodon[1]
Buffalo gourd	Cucurbita foetidissima	Southwestern United States and Mexico	Squash relative with orange-sized fruit that often rots and dries on the ground next to the plant while the next year's fruit is already ripening. The plant grows well in dry uplands, yet is more commonly encountered in floodplains where flash floods provide occasional dispersal, to the point that hydrochory was proposed once as the main dispersal syndrome of buffalo gourd, but this has been rejected since. High concentrations of cucurbitacin in its pulp and, to a lesser extent, seeds, makes it bitter to most animals. Domestic cattle and donkeys eat it rarely and mostly as a last resource. If eaten by a cow, the cow's milk will become bitter to humans, and it is deadly to sheep and cattle if eaten in enough quantity. In Africa and Asia, such bitter fruit is most commonly eaten by the largest megaherbivores of all, elephants and rhinoceros. Its distribution is also extremely patchy.[1]	Proboscideans[1] American horses[1] Toxodon[1] Camelids[1] Hesperotestudo[1]
Cocklebur	Xanthium spp.	Americas and Eastern Asia	One of the best known examples of zoochory that does not involve eating the fruit. In New Mexico, the burs, each containing two seeds, adhere to horse fur with such tenacity that they will remain there until they are retrieved by humans or the fur is shed. However, the burs fail to adhere to the fur of the largest wild ungulates in the area, deer.[1]
Creosote bush	Larrea tridentata	Western United States and Mexico	One of the plants readily eaten by the animals of the United States Camel Corps, a 19th-century experimental unit of the United States Cavalry active in Texas and California.[1]	Western camel[1]
Devil's walkingstick	Aralia spinosa	Southeastern United States	Defensive spines appear at a particular height, but neither above nor below. However, this height is considerably higher than that of the current tallest browser in the area, the white-tailed deer.[26]	Columbian mammoth[26] Ground sloths[26]
Florida nutmeg	Torreya taxifolia	Apalachicola river	Historically reduced to northern Florida's Apalachicola river, which acted as a refuge for many temperate trees during the ice ages. Unlike other species, the Florida nutmeg did not expand north again when the climate became warmer in the Holocene, and successive blights killed all trees starting in the 1950s. The species survives mostly through asexual reproduction, generating new trees from surviving roots, and it is estimated that it will become extinct when the roots run out of reserves in about 50 years. However, trees introduced to colder, mountain areas in North Carolina thrive and are free of disease, suggesting that the species is better adapted to the climate currently found there than in its Pleistocene refuge.[27]	The Florida nutmeg might have depended on an unknown large mammal for long range seed dispersal, which became extinct before the ice age ended. Living squirrels are known to provide some dispersal, but this was only enough to ensure the species's survival up to recent times, not its re-expansion after the glaciers retired north.[27] Because the genus Torreya goes back to the Eocene, it has been suggested that squirrel-like multituberculates dispersed the seeds before squirrels evolved.[1]
Hawthorn	Crataegus spp.	Temperate Northern Hemisphere	Long, widely spaced and insufficiently densed thorns, better at dissuading larger African browsers like rhinoceroses and kudus than the local, narrow-muzzled white-tailed deer.[1]	Ground sloths[1] American mastodon[1]
Honey locust	Gleditsia triacanthos	Mississippi river basin	Weather-resistant fruit (pods) that remains on the tree or the ground from one year to another, too large to be eaten by any wild animal in the area, but the seeds need abrasion to germinate. Horses ignore the fruit, but donkeys and mules will eat it on occasion. Large defensive thorns sometimes up to 20 cm are also present, usually high above ground.[1]	Columbian mammoth[1] American mastodon[1] American horses[1] Ground sloths[26] Brontotheres[1] Indricotherium[1] Aepycamelus[1]
Joshua tree	Yucca brevifolia	Mojave desert	The fruit is much larger than in related species dispersed by birds and fruit-eating bats, a considerable investment in a desert. Fruit-eating bats are not present in the Mojave, and birds eat parasitic insects living in the Joshua tree's fruit but not the fruit itself. Among rodents, ground squirrels eat the seeds but only sporadically, and pack rats eat the fruits both on the tree and the ground, but avoid the seeds, leaving them in place and not acting as seed dispersers. The fruit is eaten full both by the largest wild mammals in the area (mule deer and bighorn sheep) and livestock species including horses, donkeys and cattle, but adult trees are so tall that they are only able to eat fruit from the ground or the lowest branches, leaving the numerous spines on the rest of the plant unexplained.[28] The fruit may grow at three meters above ground.[1]	The western camel was 20% larger than the modern dromedary, allowing it to browse up to 4 meters. Although dromedaries have trouble swallowing whole seeds and are very selective eaters and poor seed dispersers as a result, this might have been different in western camels due to their greater size. However, known western camel fossil dung contains only finely chewed plant remains, like in modern camels.[28] The American mastodon, Columbian mammoth and Gomphotherium all lived within the modern range of the Joshua tree and could reach even its tallest branches. Like modern elephants, they are presumed to have had an inefficient digestive system, making them both voracious eaters and perfect seed dispersers.[28] The Shasta ground sloth was common in western North America during the Pleistocene and has been identified as a primary yucca feeder from its fossil feces, which are commonly found in caves of the desert. However, it was only the size of an American black bear and would have been limited to eating only Joshua tree fruits from the lower branches or already on the ground. It probably fed more on smaller species of yucca.[28]
Jumping cholla	Cylindropuntia fulgida	Arizona and Sonora	The defensive spines have backward-pointing teeth that attach to passing animals and the stems detach easily. The portions of the stem are transported for a while until they fall to the ground and grow into a new plant. The fruit is also ingested by many desert animals, but it grows above their reach as often as it does below. The fruit that grows in higher branches may remain in place for months after ripening. It falls after desiccating, when it is no longer attractive for potential seed dispersers.[1]	Western camel[1] Shasta ground sloth[1] Gomphotheres[1]
Kentucky coffeetree	Gymnocladus dioicus	Midwestern United States	Large distribution area but very low density in its whole range. Like the buffalo gourd, it is more common in floodplains even though it grows upland with no problem. The seeds are the largest of any species in the contiguous United States, but they are not harvested by rodents because they cannot break the pod's tough walls. They need abrasion to germinate. The pulp is very sweet and slightly bitter, similar in taste to the honey locust, but also poisonous to both livestock and humans because of its high content in saponin and alkaloids (nevertheless, it was used historically as a substitute for coffee in the Kentucky area, hence the name, because the toxins are destroyed in the roasting process). The seeds are more poisonous than the pulp, and often, large numbers of fallen pods and non-germinated seeds from preceding years can be found on the ground around a tree, trampled and rotten. The seeds die if they are not removed from the pod in time. Similar, related species in Africa are dispersed by elephants.[1][26][27]	American mastodon[1]
Mesquite	Prosopis spp.	Tamaulipan Mezquital	Sweet and nutritious pods edible to humans and livestock. Horses and cattle both act as dispersers and also abrade the seeds walls, helping it germinate; foxes and coyotes eat the pods and disperse the seeds but do not abrade them. As a result, the mesquite's range began to expand after European colonization. The rest of the plant, however, is armed with thorns and is poisonous to livestock, which makes it unpopular with farmers. Mesquite also limits the growth of grass and favors the establishment of nopales, and once it grows to tree size, it is very hard to kill because it will grow back from the root after being knocked down (currently only possible with tractors).[26][1]	Western camel. One of the species sought by the animals of the United States Camel Corps while ignoring the grasses. Along with their resistance to drought, this makes camel ranching a viable (though unexplored) alternative to horse and cattle ranching in the Mezquital.[1] Gomphotheres were large enough to knock adult trees, like elephants do to similar species in Africa, and might have fed on mesquite pods and prickly pears during their respective fruiting seasons.[1]
Nopal	Opuntia ficus-indica	Central Mexico	Defensive spines at heights far above the range of current browsers. The whole plant is consumed by camels in North Africa and Australia, where animal and plant alike have been introduced and are now feral, and was sought by the camels of the United States Camel Corps. Camels and other livestock also disperse the seeds.[1]	Western camel[1] Gomphotheres[1]
Osage orange	Maclura pomifera	East Texas	The orange-sized fruit is eaten in place by mice, rats, rabbits, hares, squirrels (mostly tree squirrels), and deer, but they do not swallow nor store the seeds. It is eaten less discriminately by domestic horses and mules.[27] The defensive spines on its branches are also too wide spaced to dissuade deer-sized ungulates from eating the leaves, making them only effective against larger animals that are not alive in the wild in Texas. In addition, fossils show that this species used to be distributed all the way to southern Canada during previous interglacials, suggesting that its range area shrank dramatically after its seed dispersal capacity was diminished.[26][27] Distribution might have been even smaller before the introduction of horses to Texas in the 16th century, even though the wood was favored by many Native American peoples to fashion bows and the local tribes profited greatly from its trade.[27] A close African relative is dispersed by forest elephants in Gabon.[1]	Columbian mammoth[26] Ground sloths[26] American mastodon[27] American horses[27] Gomphotheres[1]
Pawpaw	Asimina triloba	Eastern North America	The species largely reproduces asexually today, sprouting patches of small, clonal trees that live around 50 years, from a root system that can live tens of thousands. Its sexual reproduction is elaborate but ineffective. The flower mimics carrion or dung (brown color, fetid odor), but it is rarely visited and pollinated by flies. The downward-facing flower is better suited to be pollinated by beetles, as it is known to happen in related species, all of which live in warmer climates. The fruit is similar in taste and nutritious value to cherimoya and it is the largest edible and the most fleshy in the United States. However, the fruiting season is short and the fruit rots soon after falling from the tree; for this reason the pawpaw's consumption was abandoned when commercial tropical fruits became available. The seeds are also large and encased in a sweet, but slippery aril that is difficult to remove from them. The species distribution is very patchy and it is more abundant in floodplains and where it was cared for by indigenous peoples of the Eastern Woodlands. However, the plant grows with no problem in uplands and humans eat the pulp without swallowing the seeds. The seed dispersal capacity of foxes, raccoons, skunks and American black bears is unclear.[1]	American mastodon[1] Dung beetles could have been the main pollinators of the pawpaw before they became rarer after the extinction of the megafauna[1]
Red Devil's claw	Proboscidea parviflora	Southwestern United States and northern Mexico	Sticky, repugnant leaves invulnerable to herbivore predation. The fruit divides in two opposite claws when it browns and hardens, the circumference of each being larger than a human leg. Though an obvious zoochoric mechanism, this is far larger than the leg thickness of the largest wild mammals in the area (deer, peccaries, coyotes), and as a result the seed is mostly dispersed by humans, horses and cattle. Though already cultivated by Native Americans to make baskets, the species greatly expanded its range after the Europeans introduced livestock in the area. The range now expands into Louisiana and Iowa.[1]
Squash	Cucurbita pepo	Mexico, Texas, and the Eastern United States	Unlike its many domestic varieties, the wild form is bitter to humans.[1]	Seeds found in association with American mastodon fossils in Florida, including stomach contents.[1]
Yellow tomato Wild tomato	Solanum elaeagnifolium S. carolinense	Western North America and South America Southeastern United States	Mostly found in disturbed sites and floodplains. Fruit often remains on the branch for months or over a year after ripening, when it is already rotten or desiccated, holding the seeds trapped in its interior. Mammals and birds shun the fruit for its high glycoalkaloid content, which is even lethal to livestock. Reptiles, on the other hand, are not affected by them, and the fruit has features that makes it attractive to turtles (yellow-orange color and right height of fructification), just like other related plants.[1]	The Box turtle and Gopher tortoise inhabited many areas where wild tomatoes are found, before they went locally extinct.[1] Hesperotestudo[1]

Neotropical realm[]

Example	Binomial name	Native range	Anachronism description	Suggested extinct coevolutionary partners
	Acacia riparia	Central America, South America and the Caribbean[29]	Recurved thorns on twigs and leaves.[2]	Ground sloths[2] Gomphotheres[2]
Almendro	Dipteryx panamensis	Honduras to Colombia[30]	[2]	Gomphotheres[2]
American figs	Ficus spp.	Neotropics	Excessive fruit yield, more than bats and spider monkeys can take.[2]
Ara a gato	Senegalia tenuifolia	California to Bolivia and Brazil, including the Caribbean	Recurved thorns on twigs and leaves.[2]	Ground sloths[2] Gomphotheres[2]
Avocado	Persea americana	Mesoamerica	Although the pulp is nutritive and eaten by many animals (even carnivores), the seeds are too large to be swallowed by most. Zoochory is limited to seeds hoarded by agoutis or eaten by jaguars, but this is more occasional than common. Avocado relatives in different latitudes have smaller fruits and seeds, and are eaten by vegetarians. The pulp is so soft that it does not need chewing, but the seeds are poisonous. Forest Elephants have been observed entering plantations in Cameroon and feeding on avocados.[1][31]	Reaching up to six meters tall, the adults of the giant ground sloth Eremotherium could have gained access to the ripe avocados before any other mammal (and the juveniles, small enough to climb trees, might have reached even higher). The soft, fatty pulp might have made avocados more attractive to ground sloths than other fruits, because ground sloths lacked both incisors and canines[1] Cuvieronius[1] Toxodon[1] Glyptodonts[1] Brontotheres[1]
Baboonwood	Virola surinamensis	Costa Rica to Brazil and Peru	Fruit with typical features of those dispersed by birds and monkeys (bright red, dehiscent, with seeds individually coated with fleshy aril), if slightly larger than usual. However, its known assemblage of bird and mammal dispersal agents is anomalously small and the fruit is often found rotting on the ground. The plant sprouts better from larger seeds, but the seeds better dispersed are the smaller ones that can be ingested by birds.[1]	Protopithecus, a distant relative of howler and spider monkeys but twice the size of the largest living New World monkey.[1][32]
Black calabash	Amphitecna macrophylla	Small patches of Mexico and Guatemala	[2]	Gomphotheres[2]
Black palm	Astrocaryum standleyanum	Nicaragua to Ecuador	[2]	Gomphotheres[2]
Black sapote	Diospyros nigra	Eastern Mexico, the Caribbean, Central America, and Colombia	[1]
Boat-spine acacia	Acacia cochliacantha	Mexico	Extremely thorny at shrub level, almost entirely unarmed at tree level.[2]
	Bunchosia biocellata	Southeastern Mexico to Nicaragua[33]	[2]
Cabbage tree	Andira inermis	Southern Mexico to Northern South America	Fruit eaten by bats but often found felled under the tree; passed over by domestic pigs, horses and cattle, possibly due to high antibiotic content in its pulp. The seeds of the uneaten fruit are in turn killed by weevil larvae.[2]	Gomphotheres[2] Toxodon[2]
Calabash tree	Crescentia cujete	Central and South America	Fruit the size of a soccer ball, with a hard rind that is tough to crack. The largest living native mammal, Baird's tapir, cannot open its mouth wide enough to position its incisors in a way capable of biting it. The only animals ever witnessed feeding on the fruit are domestic horses, which step on top of the fruit and must employ as much as two hundred kilograms of pressure to open it. The seeds are rubbery and surrounded by slimy black tissue that is both fetid and very sweet. The fruit falls to the ground while it still is green, and ripens after a month on the forest floor.[1]	American horses[1] Toxodon, a rhinoceros-sized tropical notoungulate with enormous, unusually oriented incisors whose function is poorly understood. These might have evolved specifically to peel fruits of this type[1]
Carao	Cassia grandis	Southern Mexico to Venezuela and Ecuador	Hard, cylindrical, half-meter long fruit with an inch and a half of diameter, containing large seeds 2 centimeters long, 1.5 cm wide and 0.5 cm thick, embedded in sweet molasses-like pulp. Currently, the fruit often remains on the tree long enough for bean weevils and moths to kill all the seeds, making it an obvious maladaptation.[1]	Ground sloths[1] Cuvieronius[1]
Cedron	Simaba cedron	Colombia and Central America	[2]	Gomphotheres[2]
Ceiba tree	Ceiba aesculifolia[2] C. pentandra[2] C. speciosa[citation needed]	Tropics, mostly in America but also Africa and southeast Asia	Prominent trunk spines (only saplings in C. pentandra's case).[2]	Browsing megafauna[2]
Central American burs[34]	Aeschynomene spp. Bidens riparia Desmodium spp. Krameria cuspidata Petiveria alliacea Pisonia macrunthocarpa Triumfetta lappula	Central America	Burs stick to the dense hair of horses and cattle, but not to native wild mammals like tapirs, pacas, collared peccaries or white-lipped peccaries. Excluding Pisonia and Krameria, all are herbaceous species that occur on open, well-trampled habitats.[2]	Gomphotheres Toxodon Ground sloths
Cherimoya Custard apple and relatives	Annona cherimola[1] A. reticulata[1] A. muricata[1] A. squamosa[1] A. purpurea[2] A. holosericea[2] A. reticulata[2] Sapranthus palanga[2]	Neotropics		Cuvieronius[1]
Chilean mesquite	Prosopis chilensis	Peru, eastern Argentina and central Chile	Sweet fruit with hard seeds. Grows mostly in floodplains and stream margins, in natural corridors followed by livestock herds.[2]
Christ's Crown of Thorns	Gleditsia amorphoides	Argentina	Defensive trunk spines up to forty centimeters long.[1]	American horses[1] Proboscideans[1]
Cocoa tree	Theobroma spp.	Central and South America	[2]	Gomphotheres[2]
Divi-divi	Caesalpina coriacea	Caribbean, Mexico, Central and Northern South America	[2]
Dyer's mulberry	Maclura tinctoria	Mexico to Argentina	Saplings with trunk spines.[2]	Browsing megafauna.[2]
Genipapo	Genipa americana	Southern Mexico to Peru	[2]
Grangel	Randia echinocarpa	Mexico	Sweet fruit with hard seeds. Grows mostly in floodplains and stream margins, in natural corridors followed by livestock herds.[2]
Grugru	Acrocomia aculeata[2]	Southern Mexico and the Caribbean to Paraguay and northern Argentina	Large fruit and seeds, with tough epicarp, sticky pulp and very hard endocarp. The fruit grows at heights suitable for terrestrial mammals, but it is often found in piles on the ground under the tree, uneaten, and accompanied by thousands of even older, ungerminated seeds. Young trees are heliophilous, requiring the clearing of older trees to grow. Domestic cattle ingest the fruit, dispersing the seeds when they regurgitate them during rumination, and also help the establishment of new plants through trampling of older vegetation.[35] Long trunk and leaf spines ill-suited to dissuade smaller predators like rodents.[2]	Browsing megafauna[2]
Guanacaste tree	Enterolobium cyclocarpum	Central Mexico to northern Brazil and Venezuela	The flowers grow rapidly into a large, fleshy, ear-shaped pod during the dry season a year after they are fertilized. The ripe pods are brown and cacao-flavored, and fall to the ground over the space of a month. Though many wild animals eat the pods' flesh, only tapirs are large enough to also swallow and disperse the seeds. The pods are also eaten and dispersed with ease by domestic horses and cattle, however, and as a result the trees are common in areas cleared for pasture or near them.[1][2][36]	American horses[36] Gomphotheres[36] Glyptodonts[36] Ground sloths[36] Columbian mammoth[36] Toxodonts[36]
Guapinol	Hymenaea courbaril	Caribbean, Central and South America	Thick woody pod with dry sugary pulp of the same color as the honey locust. Although showing obvious signs of megafaunal dispersal syndrome, the species is currently dispersed almost exclusively by a seed-hoarding rodent, the agouti.[1]	Gomphotheres[2]
Guatemalan zizfum	Ziziphus guatemalensis	Chiapas to Costa Rica[37]	[2]
Guayabillo	Chloroleucon mangense	Central, Northern South America and the Caribbean	Sweet fruit with hard seeds. Grows mostly in floodplains and stream margins, in natural corridors followed by livestock herds.[2]
Indigoberry	Randia echinocarpa	Mexico	[2]
Ixtle	Aechmea magdalenae	Southern Mexico to Ecuador	[2]	Gomphotheres[2]
	Jacquinia pungens	Southern Mexico to Costa Rica	Produces leaves with needle-sharp tips only in the dry season. Spines best developed within four to six meters of the ground.[2]	Ground sloths[2] Gomphotheres[2]
Locust bean	Parkia pendula	Honduras to Bolivia and Brazil[38]	[2]	Gomphotheres[2]
Manchineel	Hippomane mancinella	Southern North America and Northern South America	Small seeds imbedded in a hard core.[2]
Maya nut	Brosimum alicastrum	Yucatan and Guatemala to the Amazon	[2]
Mexican calabash	Crescentia alata	Mesoamerica and Central America	Close relative of the calabash tree, with white, orange-sized fruit. If not mechanically broken, the seeds will die either from desiccation (in a dry environment) or when the pulp ferments (in moist).[1] The fruit is often consumed by free-ranging horses, and the tree's size (3–4 meters tall) and shape is similar to an African tree typically dispersed by megafauna.[2]	Fossils of the native horse Amerhippus have been found in the plant's current range area.[2]
Mexican ebony	Pithecellobium mexicanum	Sonora, Sinaloa and Baja California Sur[39]	Sweet fruit with hard seeds. Grows mostly in floodplains and stream margins, in natural corridors followed by livestock herds.[2]
Mimosa	Mimosa eurycarpa M. guanacastensis	Central and South America	Recurved thorns in twigs and leaves.[2]	Ground sloths[2] Gomphotheres[2]
Monkeypod	Pithecellobium dulce	Pacific coast of Mexico, Central and northern South America	Sweet fruit with hard seeds. Grows mostly in floodplains and stream margins, in natural corridors followed by livestock herds.[2]
Nance	Byrsonima crassifolia	Central Mexico to Bolivia and Brazil, including the Caribbean	[2]
Nicaragua persimmon	Diospyros nicaraguensis	Eastern Yucatan, southern Nicaragua and northern Costa Rica[40]	Large fruit production that just rots on the ground.[1]
Forest palm		Central America[41]	Large fruit and seeds, with tough epicarp, sticky pulp and very hard endocarp. The fruit grows at heights suitable for terrestrial mammals, but it is often found in piles on the ground under the tree, uneaten, and accompanied by thousands of even older, ungerminated seeds. Young trees are heliophilous, requiring the clearing of older trees to grow. Domestic cattle ingest the fruit, dispersing the seeds when they regurgitate them during rumination, and also help the establishment of new plants through trampling of older vegetation.[35]	Cuvieronius[2]
Jobo	Spondias mombin S. purpurea S. radlkoferi	Neotropics	Excessive fruit crop with small seeds imbedded in a hard core.[1][2]
Ojo de Buey	Dioclea megacarpa	Western Nicaragua[42]	[2]
Papaya	Carica papaya	Central and northern South America	The fruit is already large in the wild form, reaching about ten centimeters. The pulp is soft and does not require chewing, but the seeds are poisonous. The seeds are small but clustered at the center, and have a pungent, peppery taste. Forest Elephants have been observed entering plantations in Cameroon and feeding on papayas.[26][27]	Cuvieronius[1] Ground sloths[1] Toxodon[1]
Peine de mico	Apeiba tibourbou	Caatinga, Cerrado and Costa Rica	[2]
Piñuela	Bromelia karatas B. pinguin	Sinaloa to Brazil	[2]
Pochote	Pachira quinata	Costa Rica to Colombia and Venezuela	Prominent trunk spines, especially in younger trees.[2]	Browsing megafauna[2]
Pouteria tree	Pouteria spp.	Neotropics	[2]	Gomphotheres[2]
Pupunha	Bactris guineensis[2] B. major[2]	Mexico to Colombia, Venezuela and Trinidad	Large fruit and seeds, with tough epicarp, sticky pulp and very hard endocarp. The fruit grows at heights suitable for terrestrial mammals, but it is often found in piles on the ground under the tree, uneaten, and accompanied by thousands of even older, ungerminated seeds. Young trees are heliophilous, requiring the clearing of older trees to grow. Domestic cattle ingest the fruit, dispersing the seeds when they regurgitate them during rumination, and also help the establishment of new plants through trampling of older vegetation.[35] Long leaf spines ill-suited to dissuade smaller predators like rodents.[2]
Purui	Alibertia edulis	Caribbean coast of Central America	[2]
Rain tree	Albizia saman	Mexico to Peru and Brazil	Fruit eaten by domestic horses and cattle.[2]
Sachamango	Gustavia superba	Central and Northwestern South America	[1]
Sali	Tetragastris panamensis	Guatemala to Bolivia and Brazil[43]	Fruit very similar to Baboonwood. Seed waste deemed "enormous" and known dispersal agents "inefficient".[1]	Protopithecus[1]
Sandbox tree	Hura crepitans	Tropical North and South America	Prominent trunk spines, especially in young trees.[2]	Browsing megafauna[2]
Sapodilla	Manilkara zapota	Mexico, Central America and the Caribbean	[2]
Shinglewood	Nectandra hihua	Southern Sonora	Sweet fruit with hard seeds. Grows mostly in floodplains and stream margins, in natural corridors followed by livestock herds.[2]
	Sphinga platyloba	Central America	Recurved thorns on twigs and leaves.[2]	Ground sloths Gomphotheres[2]
Sweet acacia	Vachellia farnesiana	Mexico and Central America	Fruit sought by domestic cattle and horses.[2]
Taruma	Vitex mollis	Southern Sonora	Sweet fruit with hard seeds. Grows mostly in floodplains and stream margins, in natural corridors followed by livestock herds.[2]
Tempisque	Sideroxylon capiri	Mesoamerica and the West Indies	[2]
Velvetseed	Guettarda macrosperma	Chiapas to Costa Rica[44]	[2]
West Indian elm	Guazuma ulmifolia	Neotropics	Sweet fruit with hard seeds, which is eaten by domestic horses and cattle. Grows mostly in floodplains and stream margins, in natural corridors followed by livestock herds.[2] The pulp has woody obstacles that prevent mastication.[1]
White bayahonda	Prosopis juliflora	Mexico, South America and the Caribbean	Very localized and patchy distribution along margins of mangrove swamps and beaches. Ingested by cattle and horses.[2]
	Zamia spp.	Mexico to Bolivia, including the West Indies	[2]	Gomphotheres[2]
	Zanthoxylum setulosum	Costa Rica to Colombia and Venezuela[45]	Prominent trunk spines, especially in young trees.[2]	Browsing megafauna[2]

Oceanian realm[]

Example	Binomial name	Native range	Anachronism description	Suggested extinct coevolutionary partners
Hawaiian lobelioids	Cyanea spp.	Hawaii	Defensive thorns in leaves and stems despite no native browsers being found in the islands.	Moa-nalo, four extinct species of flightless ducks identified as browsers from their beak morphology and fossil excrements
Mountain hibiscus	Hibiscadelphus spp.	Hawaii	Eight extinct or endangered species of Hibiscus relatives whose flowers remain folded in a tube, limiting pollination	Several species of Hawaiian honeycreepers, some extinct and others endangered, with varying beak lengths and curvatures suited to feed in the nectar of different tubular flowers

Palearctic realm[]

Example	Binomial name	Native range	Anachronism description	Suggested extinct coevolutionary partners
European holly	Ilex aquifolium	Western Europe	Leaves with defensive spiny edges up to four or five meters, when they are replaced by smooth leaves.[1] This is more than twice the reach of the current largest browsers in the area, the red deer and the wisent.
Hazel Oak	Corylus spp. Quercus spp.	Temperate Northern Hemisphere	Inability to regenerate in either the deep shade of a forest canopy or under heavy browsing in the open. Though some Eurasian megafauna capable of clearing forests survived into the Holocene (red deer, aurochs, tarpan, wisent, Eurasian beaver and wild boar), differences in the composition of pollen records between the earliest Holocene previous to large human-induced clearing and the interglacial MIS 5 suggests that further clearing was done by even larger megaherbivores disappeared in the Late Pleistocene.[46] Furthermore, oak is often positively associated with thorny shrub, benefiting from a process called associational resistance. The oak sapling profits from the thorn protection of the shrub, but also from sufficient light availability in contrast to closed forest.[47]	Hippopotamus[46][48] Straight-tusked elephant[46][48] Narrow-nosed rhinoceros[46][48]
Juniper	Juniperus spp.	Northern Hemisphere	Reduction of fossil pollen concentration in Ireland and subsequent increase unrelated to climate change.[46]	The giant deer Megaloceros colonized Ireland right around the time juniper numbers went down and became extinct when they went up.[46] Megaloceros browsed juniper and other shrubs because of their high phosphorus concentration, which was needed in turn to grow the giant deer's massive antlers for the mating season.[49] This predation caused in turn the descent of juniper and its replacement by grasses.[46]
Mammoth steppe	Several unrelated species	Altai-Sayan Mountains	Dry, but botanically diverse biome, composed of grasses, forbs and sedges, which occupied most of northern Eurasia and North America during the Pleistocene and was associated with high concentrations of large grazers. Starting about 13,000 years ago, the steppe was replaced by wet mossy and shrub tundra, taiga and deciduous forests with reduced plant diversity. The change has been traditionally attributed to a climatic shift to warmer, wetter, less continental conditions in the transition to the Holocene, and in turn used to explain the extinction of the local megafauna. Sergey Zimov proposes the opposite: That the extinction of the fauna caused the change in vegetation, and that this would not have happened if the megafauna was still around, just like it did not happen in previous interglacials.[46]	Woolly mammoth[46][1] Muskox[1] Steppe bison[1] Wild horse[1]
Mediterranean dwarf palm	Chamaerops humilis	Southwest Mediterranean	Successful seed dispersal by introduced feral goats and European pine martens in the Balearic Islands.[50]	Balearic cave goat
Argan tree	Argania spinosa	Morocco	Thorns actually protect against goats climbing the trees, but there are no native herbivores capable of reaching the branches.	North African elephant Northern giraffe
Carob pods	Ceratonia siliqua	Mediterranean	Similar to related species of Gymnocladus and Gleditsia, carob often fails to propagate naturally due to the hard seed coat that is impenetrable to water.[51] Seeds are presumably viable after passing through an animal's digestive track, but require treatment with acid or hot water to encourage artificial germination, due to the thick coat.[52] Related species with timilar seed characteristics are often dispersed by megafaunal animals or thought to have evolved alongside now-extinct megafauna which they presumably benefited from.[53]	Straight-tusked elephant

Proposed examples in animals[]

Example	Binomial name	Native range	Anachronism description	Suggested extinct coevolutionary partners
Australian bush fly	Musca vetustissima	Australia	Native dung fly dependent on introduced cattle, and before cattle was introduced, on human dung. The flies ignore kangaroo dung because it is drier and not as abundant.[15]	Australian megafauna
Brown-headed cowbird	Molothrus ater	North America	Flocks follow horse and cattle herds, feeding on insects stirred up by the ungulates' trampling. Their numbers and eastern range expanded greatly after these were introduced to the area with European colonization; however, fossils show that they were just as numerous or more in the Pleistocene, and also that there were two other species in North America that disappeared during the transition to the Holocene.[54]	American bison[54] Harlan's muskox and shrub-ox[54] American horses[54] North American llama[54] Western camel[54] Columbian mammoth[54] American mastodon[54]
California condor	Gymnogyps californianus	Western North America	Critically endangered and only found in a few areas of California and Arizona. Before the human settlement of the Americas, however, the same species (as well as related species and similar but distantly related species) were commonly found through North America, Central America, Cuba, and South America, as far south as Peru.	North American megafauna It was suggested that condors survived near the Pacific by feeding mostly on beached whales and elephant seal carcasses, which provide a lot of meat, but have skin soft enough to be pierced by the condor's weak beak. Elsewhere, the condor would have fed on terrestrial megafauna, but only after larger carrion birds like Teratornis had pierced their tough, furry skin, mirroring the symbiotic relationship between African white-backed vultures and the larger lappet-faced vultures and white-headed vultures.[1] Coincidentally, the only other living condor, the Andean condor, is also limited to the Pacific coast of South America and is known to feed on beached whales, but the lack of a fossil record for this species means that it is impossible to know if it existed previously in other areas (though given the range of most condor species in the past, it is possible to have existed previously in those areas in the past, but there are yet to be fossil and subfossil remains to be found in order to fully confirm this).
Cuban crocodile	Crocodylus rhombifer	Cuba's Zapata Swamp and Isle of Youth	Critically endangered species that was once widespread through Cuba and also present in the Cayman Islands and the Bahamas. One of the smallest crocodiles in the world, it is also among the most terrestrial and intelligent. Observations in captivity revealed previously unknown pack-hunting behavior, which would make it capable of taking down animals larger than the largest ones currently found in Cuba.[55]	Six Caribbean ground sloths,[55] the largest of which was the size of an American black bear[1]
	Helictopleurus giganteus	Eastern Madagascar	The largest and most rare of native dung beetle species in Madagascar, apparently entirely dependent on human feces. Yet humans arrived in Madagascar for the first time only 2000 years ago.[56]	Giant lemurs[56]
Hyacinth macaw Indigo macaw	Anodorhynchus hyacinthinus A. leari	South America	Both species follow cattle herds in Brazil (mostly of the zebu-crossed Brahman race, which is a bigger fruit eater) and extract partially digested seeds from their dung. They have adaptations to terrestrial locomotion not present in other macaws, and they ignore the same fruit species while still on the tree, even when ripe, suggesting that this behavior is an ancient adaptation rather than recently learned. Grey parrots do the same with dung of African elephants.[35] It is unknown if the same behavior was exhibited by the third Anodorhynchus species, A. glaucus, which was originally present in Paraguay and northern Argentina and is probably extinct.	Cuvieronius[1]
Komodo dragon	Varanus komodensis	Flores and other Indonesian islands, such as Komodo	Though an endemic species, this large reptile survives largely by hunting or scavenging artiodactyls like Javan rusa deer, banded pig and water buffalo, all of which were introduced to the islands by humans.	Dwarf stegodonts (Stegodon florensis),[57] pygmy elephants around the same size as bovines, horses, and large pigs. More recently, it was suggested that the Komodo dragon's ancestors, including Megalania the largest terrestrial lizard ever, evolved their large size in northern Australia and then spread north to colonize Indonesian islands including Flores.[58] If true, this would make the Komodo dragon a double example, as they would have originally preyed on giant marsupials such as Diprotodon. Interestingly, pigs, cattle, deer, camels, horses, and buffaloes have all been introduced to Australia, where they have no predators and are now overpopulated and causing ecological and agricultural concerns. It has been suggested to introduce Komodo dragons as part of rewilding efforts and to control populations of these introduced feral livestock species[59]
	Merobruchus columbinus	Central America and the Caribbean[60]	Bean weevil parasiting the fruit of Albizia saman. The animals leave the fruit just before the fall, even though it is still nutritive then.[2]	The rapid exit may be an adaptation to avoid accidental ingestion by large mammals, now extinct[2]
Pronghorn	Antilocapra americana	Western North America	Capable of sustaining speeds of 60 miles per hour, making it the second fastest land animal in the world, after the cheetah, and the fastest long-endurance runner. No carnivores found in its range approach this speed.[4] Cougars are the only regular predators of adult pronghorns, but can only hunt them when the terrain allows for a stealthy approach. Wolves and coyotes may prey on the young but are poorly suited to hunt adults. American black bears have also been known to attempt ambushes on pronghorns on occasion, typically unsuccessfully.[4] The leg muscles are so overbuilt towards sustained speed that pronghorns cannot jump and will try to cross fences by going under rather than above them.[1]	Both the giant short-faced bear and the extinct American lion were larger and better built for sustained speed than their living relatives, the spectacled bear and the lion, respectively[4] The jaguar was present in large areas of the United States during the Pleistocene and might have hunted pronghorns by stealth, just like the cougar[4] The extinct American cheetahs (Miracinonyx inexpectatus and particularly M. trumani) were explosive runners very similar to the living cheetah, though not closely related to it. If they could reach the same speed (70 mph), they would have been the most successful predators of pronghorns in short distances, and also explain the pronghorn's evolution towards sustained running, since modern cheetahs cannot keep running for long[4] Chasmaporthetes, the only hyena that ever colonized North America successfully, had cheetah-like proportions and was better built for speed than its living relatives[4]
Ring-tailed lemur Sifakas	Lemur catta Propithecus diadema P. verreauxi	Madagascar	The adults practice measures against predation by birds of prey, even though they are too large to be hunted by birds currently found on the island.[61][62]	Malagasy crowned eagle, a relative of the African crowned eagle extinct since c. 1500 AD Extinct Malagasy Aquila eagle

See also[]

• Brugmansia
• Coevolution
• Coextinction
• Evolutionary arms race
• Evolutionary mismatch
• Evolutionary trap
• Holocene extinction
• Keystone species
• Pleistocene extinction
• Pleistocene rewilding

References[]

External links[]

• Youtube video "Why are Lemurs Terrified of Predators that don't Exist?"
• Gourds and squashes (Cucurbita spp.) adapted to megafaunal extinction and ecological anachronism through domestication