User:Mateuszica/timeline
| Multicellularity to chordates | |
|---|---|
| Date | Event |
| 900 MYA | Choanoflagellates is belivied to be the ancestor of all animals |
| 800 MYA |
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| 730 MYA |  Cnidaria and Ctenophora are some of the earliest creatures to have neurons, in the form a simple net - no brain or nervous |
| 590 MYA | Flatworms Platyhelminthes was the first billateral animals. they are the simplest bilateral animals today. Caenorhabditis elegans |
| 590 MYA | minhocasss (sem nochocord) complexas
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| 570 MYA |  |
| Vertebrates - Tetrapoda | |
|---|---|
| Date | Event |
| 505 MYA
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| 365 MYA |  Some fresh water lobe-finned fish (Sarcopterygii) develop legs and give rise to the Tetrapoda.
The first tetrapods evolved in shallow and swampy freshwater habitats, towards the end of the Devonian, a little more than 360 million years ago. By the late Devonian, land plants had stabilized freshwater habitats, allowing the first wetland ecosystems to develop, with increasingly complex food webs that afforded new opportunities. Primitive tetrapods developed from a lobe-finned fish (an "osteolepid Sarcopterygian"), with a two-lobed brain in a flattened skull, a wide mouth and a short snout, whose upward-facing eyes show that it was a bottom-dweller, and which had already developed adaptations of fins with fleshy bases and bones. The "living fossil" coelacanth is a related lobe-finned fish without these shallow-water adaptations. These fishes used their fins as paddles in shallow-water habitats choked with plants and detritus. The universal tetrapod characteristics of front limbs that bend backward at the elbow and hind limbs that bend forward at the knee can plausibly be traced to early tetrapods living in shallow water. The evolution of the air-breathing lung from the primitive swim bladder of lobe-finned fishes has not yet been worked out in detail. However, functioning internal gills were present in at least one late Devonian tetrapod, Acanthostega. These earliest tetrapods were not terrestrial. The earliest confirmed terrestrial forms are known from the early Carboniferous deposits, some 20 million years later. Still, they may have spent very brief periods out of water and would have used their legs to paw their way through the mud. |
| 315 MYA | Ichthyostega , Acanthostega and Pederpes finneyae . See Prehistoric amphibian. |
| Reptiles to Mamals | |
|---|---|
| Date | Event |
| 300 MYA | Evolution of the amniotic egg gives rise to the Amniota, reptiles who can reproduce on land.
Reptiles have Advanced nervous system, compared to amphibians. They have twelve pairs of cranial nerves. |
| 280 MYA |
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| 256 MYA | Diictodon, Cistecephalus, Dicynodon, Lycaenops, Dinogorgon and Procynosuchus, are a few of the many mammal-like reptiles known from South Africa and Russia. |
| 220 MYA |  mammal-like reptilian The origin of the mammals can be traced back through a series of reptilian groups called the mammal-like reptiles. This is an informal name for the reptilian group Synapsida. They evolved over an approximately 100 million year period from the Pennsylvanian to the end of the Triassic, when the first true mammals appear. The interesting feature of the evolution of the mammal-like reptiles, for our purposes, is what they suggest about how a major new group originates. Three main phases in mammal-like reptilian evolution; 1. The first phase corresponds to one of the two major divisions of the group, the pelycosaurs. Pelycosaur fossils are preserved from the Pennsylvanian and Permian. Pelycosaurs lived there about 300 million years ago. The distinctive difference from other reptile groups is an opening in the bones behind the eye. The opening is called a temporal fenestra, and in the living animal a muscle passed through it. The muscle acted to close the jaw, and the opening up of the temporal fenestrae is the first sign of the more powerful jaw mechanism of the mammals. 2. The evolution of the therapsids makes up the second main phase of the mammal-like reptiles, in the Permian and Triassic. Therapsid fossils are found in many regions of the world. The therapsids have temporal fenestrae which are generally larger and more mammal-like than pelycosaurs; their teeth in some cases show more serial differentiation; and later forms had evolved a secondary palate. A secondary palate enables the animal to eat and breathe at the same time and is a sign of a more active, perhaps warm-blooded, way of life. 3. One sub-group of therapsids, the cynodonts (pictured opposite), make up the third phase of mammal-like reptilian evolution. The jaws of cynodonts resemble modern mammal jaws more closely and their teeth are multi-cusped and differentiated down the jaw. The cynodonts complete the story of the mammal-like reptiles, because it was from a line of cynodonts that the ancestors of the modern mammals evolved. From synapsids came the first mammal precursors, therapsids, and more specifically the eucynodonts. Initially, they stay small and shrew-like. Constant body temperature. All mammals have milk glands for their young. One of a pair of autosomes acquires a SRY gene derived from SOX3 from X chromosome to become the Y chromosome, which has been decreasing in length since.
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| 125 MYA | MAMMALS
 Mammals belong among the amniotes, and in particular to a group called the synapsids, distinguished by the shape of their skulls, in particular the presence of a single hole where jaw muscles attach, called temporal fenestra. In comparison, dinosaurs, birds, and most reptiles are diapsids, with two temporal fenestrae; and turtles, with no temporal fenestra, are anapsids. From synapsids came the first mammal precursors, therapsids, and more specifically the eucynodonts, 220 million years ago (mya) during the Triassic period. Pre-mammalian ears began evolving in the late Permian to early Triassic to their current state, as three tiny bones (incus, malleus, and stapes) inside the skull; accompanied by the transformation of the lower jaw into a single bone. Other animals, including reptiles and pre-mammalian synapsids and therapsids, have several bones in the lower jaw, some of which are used for hearing; and a single ear-bone in the skull, the stapes. This transition is evidence of mammalian evolution from reptilian beginnings: from a single ear bone, and several lower jaw bones (for example the sailback pelycosaur, Dimetrodon) to progressively smaller "hearing jaw bones" (for example the cynodont, Probainognathus), and finally (possibly with Morganucodon, but definitely with Hadrocodium), true mammals with three ear bones in the skull and a single lower jaw bone. Hence pelycosaurs and cynodonts are sometimes called "mammal-like reptiles", though this is strictly incorrect since in modern parlance these two are not reptiles, but rather synapsids. During the Mesozoic Period mammals diversified into four main groups: multituberculates, monotremes, marsupials, and placentals. Multituberculates went extinct during the Oligocene, about 30 million years ago, but the three other mammal groups are all represented today. Most early mammals remained small and shrew-like throughout the Mesozoic, but rapidly developed into larger more diverse forms following the Cretaceous-Tertiary extinction event 65 mya. The names "Prototheria", "Metatheria" and "Eutheria" expressed the theory that Placentalia were descendants of Marsupialia, which were in turn descendants of Monotremata, but this theory has been refuted. However, Eutheria and Metatheria are often used in paleontology, especially with regards to mammals of the Mesozoic. Mammal evolutionary progression is below:
In the MesozoicMost early mammals were small shrew-like animals that fed on insects. However, in January 2005, the discovery was reported of two fossils of Repenomamus around 130 million years old, one more than a meter in length, the other having remains of a baby dinosaur in its stomach (Nature, Jan. 15, 2005 [1].) The earliest mammals include:
Although mammals existed alongside the dinosaurs, mammals only began to dominate after the mass extinction of the dinosaurs 65 mya, in the Cenozoic. In the PaleoceneDuring the next 8 million years, the Paleocene period (64–58 mya), mammals exploded into the ecological niches left by the extinction of the dinosaurs. Small rodent-like mammals still dominated, but medium and larger-sized mammals evolved.
Eomaia scansoria, a eutherian mammal, which leads to the formation of modern placental mammals. Looks like modern dormouse, climbing small shrubs in Liaoning, China. |
| 100 MYA |  |
| EuPrimates to Hominids | |
|---|---|
| Date | Event |
| 65 MYA | A group of small, nocturnal and arboreal, insect-eating mammals called the Archonta branches into the primates, tree shrews and bats. Primates have binocular vision and grasping digits, features that help them to jump from one tree branch to another. One example is Plesiadapis which is extinct by 45 million years ago. Plesiadapis is one of the oldest known primates who lived 60 mya during the paleocene on europe and north america, it looked like the moderm squirrel . Plesiadapis still had claws and the eyes located on each side of the head, because of that they were faster on the ground than on the top of the trees , but they begin to spend long times on lower branches of trees, feeding on fruits and leafs. The characteristics that separate primates from other mammals are a large brain; the ability to grasp, which requires opposable thumbs and big toes; the ability to leap; eyes in the front of the face rather than on the side; and nails instead of claws. |
| 55 MYA | The earliest true primates is called euprimates. One is Carpolestes simpsoni . It has grasping digits but no forward facing eyes. Another (earliest?) euprimate Teilhardina asiatica is mouse-sized, diurnal and has small eyes and were tree-living fruit eaters. Carpolestes combines features of the earlier plesiadapiforms with primate-like and is viewed as a transitional animal .It had very primate like teeth that were highly specialized for eating flowers, seeds, and fruit. The opposable big toe gave it a grasping ability that indicates it spent most of its time climbing trees. also had a nail on its big toe, but its eyes were not forward facing, and it did not have the bone structure that would allow for specialized leaping, like some of the earliest primates. as the diversity of fruits, flowers, leaf buds, and nectar increased in the Paleocene, 65 to 55 million years ago, Carpolestes took to the trees to exploit a new food source and to avoid competition with early rodents. |
| 40 MYA | Primates (order) diverge into suborders Prosimians (a primitive monkey) and Anthropoids, the latter is diurnal and herbivorous. Examples of today's prosimians are tarsiers, lemurs, lorises. Anthropoids, The simians (infraorder Simiiformes) are the "higher primates" very common to most people: the monkeys and the apes, including humans. Simians tend to be larger than the "lower primates" or prosimians. The simians are split into three groups. The first division is literally as wide as the Atlantic Ocean. The New World monkeys in clade Platyrrhini split from the simian line about 40 million years ago, leaving clade Catarrhini occupying the Old World. This group split about 25 mya between the Old World monkeys and the apes. Earlier classifications split the primates into two large groups: the "Prosimii" (strepsirrhines and tarsiers) and the "Anthropoidea" (simians). |
| 30 MYA | Anthropoid (suborder) splits into infraorders Platyrrhini (New World Monkeys) and Catarrhini (Old World Primates). New World Monkeys have prehensile tails and migrated to South America. Catarrhines stayed in Africa as the two continents drifted apart. One ancestor of catarrhines might be Aegyptopithecus. New world monkey males are color blind. Anthropoids: Bugtipithecus inexpectans, Phileosimias kamali and Phileosimias brahuiorum similar to today's lemurs, lived in rainforests on Bugti Hills of central Pakistan. |
| 25 MYA | Catarrhini males gain color vision but lose the pheromone pathway. Catarrhini (infraorder)(Old World Primates) splits into 2 superfamilies, Old world monkeys (Cercopithecoidea) and Hominoids. The Old world monkey does not have a prehensile tail (e.g. Baboon); some do not have tails at all. All hominoids have no tails (e.g. the lesser apes, great apes and hominids). |
| 15 MYA |  Human ancestors speciate from the ancestors of the gibbon. Orangutans, gorillas and chimpanzees are great apes. Humans are hominids. |
| 13 MYA | Human ancestors speciate from the ancestors of the orangutan. Pierolapithecus catalaunicus, Spain, common ancestor of great apes and humans. |
| 10 MYA | The climate begins to dry, savannas and grasslands take over the earlier forests. Human ancestors speciate from the ancestors of the gorillas. |
| 5 MYA | 
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