User:Amakuru/Clades
| Time of MRCA | Clade name | Class | Joining clade | Examples of joining clade |
|---|---|---|---|---|
| Homo sapiens | Species | N/A | N/A | |
| 6 mya | Hominini | Tribe | Panina (Chimpanzees) | Chimpanzees, Bonobos |
| 7 mya | Homininae | Subfamily | Gorillini (Gorillas) | Gorillas |
| 14 mya | Hominidae (Great apes) |
Family | Ponginae (Orangutans) | Orangutans |
| 18 mya | Hominoidea (Apes) | Superfamily | Hylobatidae (Gibbons) | Hoolocks, Gibbons, Siamangs, Crested Gibbons, |
| 25 mya | Catarrhini | Parvorder | Cercopithecidae (Old World monkeys) | Macaques, Baboons, Mandrill, Guenons, Langurs, Proboscis monkeys, Colobus monkeys |
| 40 mya | Haplorrhini | Suborder | Platyrrhini (New World monkeys) | Tamarins, Marmosets, Night monkeys, Capuchin monkeys, Squirrel monkeys, Spider monkeys, Howler monkeys, Woolly monkeys, Sakis, Uakaris, Titis |
| 58 mya | ||||
| 8 | 63 mya | Lemurs, Bushbabies and their kin (Strepsirrhini) |
Non-primate mammals[edit]
| Rendezvous point | Time | Joining party | Story |
|---|---|---|---|
| 9 | 70 mya | Colugos and Tree Shrews (Dermoptera and Scandentia) | The Cretaceous–Tertiary extinction event occurred at 65 million years ago, due to both large scale volcanic activities in the Deccan traps over a period of time, and the final asteroid impact event which created the Chicxulub Crater. The sudden temperature change and sunlight reduction caused massive disruptions to Earth's ecosystem. As a result, all dinosaurs except the birds, as well as numerous other species went extinct. The disappearance of dinosaurs made it possible for many different species of shrew-like, nocturnal insectivores to evolve into hippos, lions, elephants, etc. to fill the new ecological voids, an example of evolutionary radiation. One of these shrew-like creatures was the concestor of the current pilgrimage party and the new joiners, the colugos and tree shrews. |
| The tree shrews resemble the squirrels. The colugos resemble flying squirrels. In both cases, the resemblance is only superficial, due to convergence; the squirrels are rodents and will meet us further down the pilgrimage. At the present, scientists are not yet sure about the exact relationships among the tree shrews, the colugos and us. Dawkins provisionally accepts the view that they join forces first, before meeting the pilgrimage party. This would place our concestor 9 at a time before K-T boundary which marked the extinction of the dinosaurs. The Colugo's Tale warns us that even though the general structure of the family tree is sound, some of the details could change as more evidences become known. | |||
| 10 | 75 mya | Rodents and Rabbitkind (Glires) | Rodents comprise the largest number of species in mammalia, more than 40 percent of all mammalian species. Members include rats, mice, lemmings, beavers, squirrels, etc. The Mouse's Tale explains how mammals possess similar and relatively small genomes in the order of 30,000 genes, yet each animal exhibits distinct features and surprising complexities. Dawkins debunks the popular description of genome as blueprints which give rise to the misconception that the more complex the animal, the more complex the blueprint ought to be. Instead, genes in a genome should be thought of as words or sentences in a language, and embryonic development over time is akin to 'order' of words and sentences in a book. While the number of genes are limited, the endless number of 'orders' by which similar genes in mice and humans are deployed during embryonic development can generate astonishing complexity and distinguish a mouse from a man. |
| The Beavers's Tale revisits the key insights that Dawkins contributed to the field of evolution in his book The Extended Phenotype. A beaver's body is known as a phenotype, an external and visible manifestation of the internal and hidden genotype. In the same way the beaver body is regarded as an expression of its genes, beaver dams or beaver lakes can be considered 'extended phenotypes' of the same beaver genes. Better beaver genes make better beaver bodies, beaver dams and beaver lakes. In other words, beaver genes are selected not only by the fitness of beaver bodies, but also by the effectiveness of beaver dams and beaver lakes they produce. | |||
| 11 | 85 mya | Laurasiatheres (Laurasiatheria) | An extremely diverse group of animals join the pilgrimage, including Carnivora (dogs, cats, bears and seals), Perissodactyla (horses, tapirs and rhinos), Cetartiodactyla (deer, cattle, pigs and hippos), Chiroptera (bats), Insectivora (moles and shrews), etc. Some of them fly, others swim, and yet many of them gallop. Half of them are predators which hunt the other half of the group. The only thing they share in common is that they join up with one another before the group joins us to meet concestor 11. This group of animals belong to the Laurasiatheria clade as all of them originated from the supercontinent of Laurasia. |
| The Hippo's Tale is really the whale's tale. All cetaceans, including whales, dolphins and porpoises, are descendants of land-living mammals of the Artiodactyl order (even-toed ungulate animals). Both cetaceans and artiodactyl are now classified under the super-order Cetartiodactyla which includes both whales and hippos. In fact, whales are the closest living relatives of hippos; they evolved from a common ancestor at around 54 million years ago. This story illustrates how a species can flip into evolutionary overdrive when it enters into a new environment, while its closest relatives remain unchanged for long time in their static environment. | |||
| The Seal's Tale illustrates how a sex ratio of 50:50 (males to females) is found in most sexually reproducing animals from both monogamous and polygamous species. In a harem-based (polygynous) system such as that of elephant seals where 4 percent of males account for 88 percent of all copulations, the actual sex ratio of 50:50 seems to produce an excess of males who consume resources but end up leaving no offsprings. This puzzle is solved by the concept of parental expenditure proposed by R.A. Fisher. More importantly, the elephant seal typifies sexual dimorphism, as a bull elephant seal can grow to be three times the size of a cow seal, thanks to sex-limited genes which exist in both male and female bodies, but remain turned off in females. The degree of sexual dimorphism is correlated with the harem size, which allows us to draw inferences about our immediate human ancestors: they were probably mildly polygynous. | |||
| 12 | 95 mya | Xenarthrans (Xenarthra) | The Armadillo's Tale reminds us of the aye-aye's tale, except that instead of Madagascar, the speciation hotbed is the continent of South America. This continent broke off from Gondwana in Early Cretaceous period, then joined North America which broke off from Laurasia. During its long period of isolation, South America was host to marsupials which flourished and took up all carnivorous niches. The placental mammals (including armadillo) and now-extinct ungulates evolved to fill the rest of the ecosystem. When South America joined North America during the Great American Interchange at 3 million years ago, animals and plants cross the Isthmus of Panama in both directions, introducing new species to new land and driving some local species to extinction. Jaguars and other carnivorous placental mammals were introduced to South America, while armadillos migrated to North America. |
| 13 | 105 mya | Afrotheres (Afrotheria) | The pilgrimage party is joined by the last of the placental mammals: elephants, elephant shrews, dugongs, manatees, hyraxes, aardvarks, etc. They all hail from Africa, as hinted by the name of their clade, Afrotheria. The concestor we greet at this point, as well as those we met earlier at rendezvous 12 and 11, all look like insectivorous shrews. |
| 14 | 140 mya | Marsupials (Metatheria) | The entire band of placental mammals meet up with the other great group of mammals, the marsupials. Even though present-day marsupials are mostly found in Australia and New Guinea, they originally flourished and diversified for a period of time in South America. Evidence points to the migration of a single species of opossum-like marsupial from South America to Australia before 55 million years ago, when it was still possible to make the journey through Antarctica before Australia pulled too far away from Gondwana. Once settled in the isolated Australia, the founding marsupials quickly evolved into distinct species and, for the next 40 million years, took up the entire range of 'trades' previously occupied by dinosaurs, in the absence of any placental mammals. |
| The Marsupial Mole's Tale again highlights the wonders that convergent evolution can create. Despite great evolutionary distance between marsupial moles in Australia and the golden moles in Africa, they are remarkably similar in terms of phenotypes, with the exception that the marsupial moles sport a pouch as all marsupials do. There are also marsupial mice (Dasyuridae), marsupial flying squirrels (Sugar Glider) and marsupial wolf (Thylacine), not to mention the equivalent of antelopes and gazelles, the kangaroos and wallabies which despite great differences in shape, cover the same range of diet and way of life as their African counterparts. | |||
| 15 | 180 mya | Monotremes (Monotremata) | The monotremes are the last of the mammals to join us, and we meet a concestor for the first time in the then-contiguous supercontinent of Pangea. The monotremes consititutes only a few genera: Platypus, Short-beaked Echidna and Long-beaked echidna. They are mammals and have typical mammalian features such as warm-bloodedness, hair and milk production. But they resemble reptiles and birds in their possession of the cloaca and their egg-laying mode of reproduction. |
| The Duckbill's Tale warns us about the fallacy of labeling a half-mammal and half-reptile animal such as the duckbill platypus as primitive. The platypus has exactly the same time to evolve as the rest of mammals, even if it does resemble our concestor 15 on the surface. In fact, it has evolved a highly developed form of electroreception served by 40,000 electric sensors, and 60,000 mechanical push rods, both on its large bill to aid it in search of crustaceans in the mud. In human, the brain dedicates disproportionally large amount of cells to the two hands as illustrated by the Penfield brain map, or Penfield homunculus. When the same somatotopic map is drawn for platypus brain, the bill is served by equally prominent percentage of the brain. |