படிவளர்ச்சி காலக்கோடு

கட்டற்ற கலைக்களஞ்சியமான விக்கிப்பீடியாவில் இருந்து.
தாவிச் செல்லவும்: வழிசெலுத்தல், தேடல்
காலம்
(ஆண்டுகளுக்கு முன்பு)
நிகழ்வு
13,700,000,000
Universe expansion2.png
அண்டத்தின் தோற்றம்
4,500,000,000 பூமியின் தோற்றம்.
மேலும் தகவல்களுக்கு: பூமியின் வரலாறு
4,000,000,000 உயிர்களின் தோற்றம்
3,900,000,000 புரோகார்யோட்டுகளை ஒத்த உயிரணுக்களின் தோற்றம்
2,500,000,000 உயிர்வாயுவைப் பயன்படுத்தும் உயிர்கள் தோற்றம்.
2,100,000,000 கூடிய சிக்கலான Eukaryote தோற்றம்.
1,200,000,000 பாலியல் இனப்பெருக்கம், வேகமான படிவளர்ச்சி [1]
900,000,000

The choanoflagellates may look similar to the மூதாதை of the entire விலங்கு kingdom, and in particular they may be the direct ancestors of sponges.[2] Proterospongia (members of the Choanoflagellata) are the best living examples of what the ancestor of all விலங்குs may have looked like.

They live in colonies, and show a primitive level of cellular specialization for different tasks.

600,000,000 முதல் வகை பல் உயிரணு உயிரனம் கடல்பஞ்சு போன்றதென்று கருதப்படுகிறது.

Sponges (பஞ்சுயிரி) are the phylogenetically oldest விலங்கு தொகுதி (உயிரியல்) extant today.

580 Ma The movement of all animals may have started with cnidarians. Almost all cnidarians possess நரம்பு and தசைs and, because they are the simplest விலங்குs to possess it, their direct மூதாதைs were very likely the first animals to use nerves and muscles together. Cnidarians are also the first animals with an actual body of definite form and shape. They have radial symmetry.
550 Ma மூளையுடன் தோன்றிய முதல் ஊயிரினம் தட்டைப்புழுவாகும். The simplest animals alive to have bilateral symmetry. They are also the simplest animals with organs that form from three germ layers.
540 Ma Acorn worms are considered more highly specialised and advanced than other similarly shaped worm-like creatures. They have a சுற்றோட்டத் தொகுதி with a இதயம் that also functions as a சிறுநீரகம். Acorn worms have a செவுள்-like structure used for மூச்சுவிடல்ing, a structure similar to that of primitive fish. Acorn worms are thus sometimes said to be a link between முள்ளந்தண்டுளி and முதுகெலும்பிலி.
530 Ma

The earliest known ancestor of the முதுகுநாணி is Pikaia. It is the first known விலங்கு with a முதுகுநாண். Pikaia is believed to be the ancestor of all முதுகுநாணி and முள்ளந்தண்டுளி.[3]

The Lancelet, still living today, retains some characteristics of the primitive முதுகுநாணிs. It resembles Pikaia

Other earliest known chordate-like fossils is from a conodonts a "eel-shaped animal of 4-20 cm (1½-8 in) long" with a pair of huge eyes at the head end were and a complex basket of teeth.

505 Ma

The first முள்ளந்தண்டுளிs appear: the ostracoderms, jawless fish related to present-day lampreys and hagfishes. Haikouichthys and Myllokunmingia are examples of these jawless fish, or Agnatha. (See also prehistoric fish). They were jawless and their internal skeletons were cartilaginous. They lacked the paired (pectoral and pelvic) fins of more advanced மீன். They were the Precursors to the bony fish.[4]

480 Ma

The Placodermi were prehistoric fishes. Placoderms were the first of the jawed fishes, their jaws evolving from the first of their gill arches [5]. Their head and thorax were covered by articulated armoured plates and the rest of the body was scaled or naked.

400 Ma First Coelacanth appears; this order of animals had been thought to have no extant members until living specimens were discovered in 1938. It is often referred to as a வாழும் தொல்லுயிர் எச்சம்.
375 Ma Tiktaalik is a genus of sarcopterygian (lobe-finned) fishes from the late Devonian with many tetrapod-like features.
365 Ma

Some fresh water lobe-finned மீன் (Sarcopterygii) develop legs and give rise to the நாற்காலி (உயிரியல்).

The first tetrapods evolved in shallow and swampy நன்னீர் habitats.

Primitive tetrapods developed from a lobe-finned fish (an "osteolepid Sarcopterygian"), with a two-lobed மனித மூளை 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 எலும்புs. 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.[6]

Panderichthys is a 90–130 cm (35–50 in) long மீன் from the Late டெவோனியக் காலம். It has a large நாற்காலி (உயிரியல்)-like தலை. Panderichthys exhibits features transitional between lobe-finned fishes and early நாற்காலி (உயிரியல்).

நுரையீரல்மீன்es retain some characteristics of the early நாற்காலி (உயிரியல்)s. One example is the Australian Lungfish.

315 Ma

Acanthostega is an extinct நீர்நில வாழ்வன, among the first animals to have recognizable limbs. It is a candidate for being one of the first முள்ளந்தண்டுளிs to be capable of coming onto land. It lacked wrists, and was generally poorly adapted for life on land. The limbs could not support the animal's weight. Acanthostega had both நுரையீரல் and செவுள், also indicating it was a link between lobe-finned fish and terrestrial vertebrates.

Ichthyostega is an early நாற்காலி (உயிரியல்). Being one of the first animals with legs, arms, and finger bones, Ichthyostega is seen as a hybrid between a மீன் and an நீர்நில வாழ்வனn. Ichthyostega' had legs but its limbs probably weren't used for நடத்தல், they may have spent very brief periods out of water and would have used their legs to paw their way through the mud.[7]

நீர்நில வாழ்வன were the first four-legged animals to develop நுரையீரல்.

நீர்நில வாழ்வனns living today still retain many characteristics of the early நாற்காலி (உயிரியல்).

300 Ma

From amphibians came the first reptiles: Hylonomus is the earliest known ஊர்வன. It was 20 cm (8 in) long (including the tail) and probably would have looked rather similar to modern பல்லியோந்திகள்s. It had small sharp teeth and probably ate millipedes and early பூச்சிs. It is a precursor of later amniotes and mammal-like reptiles.

Evolution of the amniotic egg gives rise to the Amniota, ஊர்வனs that can reproduce on land and lay eggs on dry land. They did not need to return to water for reproduction. This adaptation gave them the capability to colonize the uplands for the first time.

Reptiles have advanced nervous system, compared to நீர்நில வாழ்வன. They have twelve pairs of cranial nerves.

256 Ma

Shortly after the appearance of the first ஊர்வனs, two branches split off. One branch is the Diapsida from which come the modern ஊர்வனs. The other branch is Synapsida which had தலையோடு, a pair of holes in their skulls behind the eyes, which were used to increase the space for jaw muscles.

The earliest mammal-like reptiles are the pelycosaurs. The pelycosaurs were the first animals to have temporal fenestra. Pelycosaurs are not Therapsida but soon they gave rise to them. The Therapsida are the direct ancestor of பாலூட்டி.

The therapsids have temporal fenestrae larger and more mammal-like than pelycosaurs, their teeth 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.[8]

220 Ma One sub-group of therapsids, the cynodonts evolved more mammal-like characteristics.

The jaws of cynodonts resemble modern mammal jaws. It is very likely this group of animals contains a species which is the direct ancestor of all modern mammals.[9]

220 Ma

From eucynodonts (cynodonts) came the first பாலூட்டிs. Most early mammals were small and shrew-like animals that fed on insects. Although there is no evidence in the fossil record, it is likely that these animals had a constant body temperature, milk glands for their young. The neocortex region of the மனித மூளை first evolved in mammals and thus is unique to them.

125 Ma

Eomaia scansoria, a eutherian mammal, leads to the formation of modern placental mammals. It looks like modern dormouse, climbing small shrubs in Liaoning, சீன மக்கள் குடியரசு.

100 Ma Common genetic மூதாதை of mice and humans.
65 Ma
A Plesiadapis without fur.

A group of small, nocturnal and arboreal, insect-eating mammals called the Euarchonta begins a speciation that will lead to the முதனி, treeshrew and flying lemur orders. The Primatomorpha is a subdivision of Euarchonta that includes the primates and the proto-primate Plesiadapiformes. One of the early proto-primates is Plesiadapis. 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 பழம்s and leaves. The Plesiadapiformes very likely contain the species which is the ancestor of all primates.[10]

One of the last Plesiadapiformes is Carpolestes simpsoni. It had grasping digits but no forward facing eyes.

40 Ma முதனிs diverge into suborders Strepsirrhini (wet-nosed primates) and Haplorrhini (dry nosed primates). Strepsirrhini contains most of the prosimians; modern examples include the லெமூர்s and lorises. The haplorrhines include the three living groups the prosimian tarsiers, the simian குரங்குs, and மனிதக் குரங்குs. One of the earliest haplorrhines is Teilhardina asiatica, a mouse-sized, diurnal creature with small eyes.
30 Ma

Haplorrhini splits into infraorders Platyrrhini and Catarrhini. Platyrrhines, New World monkeys, have prehensile tails and males are color blind. They may have migrated to South America on a raft of vegetation across the Atlantic ocean (circa 4,500 km, 2,800 mi). Catarrhines mostly stayed in ஆப்பிரிக்கா as the two continents drifted apart. One ancestor of catarrhines might be Aegyptopithecus.

25 Ma

Catarrhini splits into 2 superfamilies, Old World monkeys (Cercopithecoidea) and மனிதக் குரங்குs (மனிதக் குரங்கு).

Proconsul was an early பேரினம் (உயிரியல்) of catarrhine primates. They had a mixture of Old World monkey and மனிதக் குரங்கு characteristics. Proconsul's குரங்கு-like features include thin பல் enamel, a light build with a narrow chest and short forelimbs, and an arboreal quadrupedal lifestyle. Its ape-like features are its lack of a tail, ape-like elbows, and a slightly larger brain relative to body size.

Proconsul africanus is a possible ancestor of both great and lesser apes, and humans.

15 Ma Hominidae (great apes) speciate from the ancestors of the கிப்பன் (lesser apes).
13 Ma Homininae ancestors speciate from the ancestors of the ஒராங்குட்டான்[11].

Pierolapithecus catalaunicus is believed to be a பொது மரபுவழி of humans and the great apes or at least a species that brings us closer to a common ancestor than any previous தொல்லுயிர் எச்சம் discovery.

Pierolapithecus had special adaptations for tree climbing, just as humans and other great apes do: a wide, flat ribcage, a stiff lower spine, flexible wrists, and shoulder blades that lie along its back.

10 Ma Hominini speciate from the ancestors of the கொரில்லாs.
7 Ma

Hominina speciate from the ancestors of the chimpanzees. The latest common ancestor is Sahelanthropus tchadensis (ca. 7 Ma). The earliest known human ancestor post-dating the separation of the human and the chimpanzee lines is Orrorin tugenensis (Millennium Man, Kenya; ca. 6 Ma). Both chimpanzees and humans have a குரல்வளை that repositions during the first two years of life to a spot between the pharynx and the lungs, indicating that the common ancestors have this feature, a precursor of speech.

4.4 Ma Ardipithecus ramidus ramidus
4.4 Ma Some Australopithecus afarensis left footprints on volcanic ash in Laetoli, Kenya (Northern Tanzania) Strong evidence of bipedalism.
3.5 Ma Kenyanthropus platyops, a possible ancestor of Homo, emerges from the Australopithecus genus.
3 Ma The bipedal australopithecines (a genus of the Hominina subtribe) evolve in the savannas of ஆப்பிரிக்கா being hunted by Dinofelis. Loss of body hair takes place in the period 3-2 Ma, in parallel with the development of full இருகால் நகர்வு.
2.5 Ma

Appearance of Homo. Homo habilis is thought to be the ancestor of the lankier and more sophisticated, Homo ergaster. Lived side by side the Homo erectus until at least 1.44 Ma, making it highly unlikely that Homo erectus directly evolved out of Homo habilis. First stone tools, beginning of the Lower Paleolithic.

மேலும் தகவல்களுக்கு: Homo rudolfensis
1.8 Ma
A reconstruction of Homo erectus.

Homo erectus evolves in ஆப்பிரிக்கா. Homo erectus would bear a striking resemblance to modern humans, but had a brain about 74 percent of the size of modern man. Its forehead is less sloping and the teeth are smaller. It is believed to be an ancestor of modern humans (with Homo heidelbergensis usually treated as an intermediary step).

Homo erectus migrates out of Africa and colonizes ஐரோவாசியா.

1.5 Ma Dmanisi man / Homo georgicus (Georgia), tiny brain came from Africa, with Homo erectus and Homo habilis characteristics. Control of fire by early humans. Evolution of dark skin is complete by 1.2 Ma.
516 ka Common genetic ancestor of humans and Neanderthal.[12] At present estimate, humans have approximately 20,000–25,000 மரபணுs and share 99% of their டி. என். ஏ. with the now இனஅழிவு நியண்டர்தால் மனிதன் [13] and 95% of their டி. என். ஏ. with their closest living evolutionary relative, the chimpanzees[14].
355 ka

Three 1.5 m (5 ft) tall Homo heidelbergensis left footprints in powdery volcanic ash solidified in Italy. Homo heidelbergensis is the common ancestor of both நியண்டர்தால் மனிதன் and Homo sapiens. It is morphologically very similar to Homo erectus but Homo heidelbergensis had a larger brain-case, about 93% the size of that of Homo sapiens. The species was tall, 1.8 m (6 ft) on average, and more muscular than modern humans. Beginning of the Middle Paleolithic.

195 ka Omo1, Omo2 (Ethiopia, Omo river) are the earliest fossil evidence for archaic Homo sapiens, evolved from Homo heidelbergensis.
160 ka Homo sapiens (Homo sapiens idaltu) in Ethiopia, Awash River, Herto village, practise mortuary rituals and butcher hippos.
150 ka
Homo sapiens sapiens (Pioneer plaque)

இழைமணியப் பழையோள் கிழக்காப்பிரிக்காவில் வாழும் காலம். இழைமணியப் பழையோள் என்பது வாழும் மாந்தரின் தாய்வழி மூதாதையர்கள் அனைவருக்கும் பொதுவாக இருந்ததாகக் கருத இடம் தரும் ஒரு பெண் தொன்முது தாயைக் (மூதாயைக்) குறிக்கும் சொற்றொடர். இப்பெண்ணின் இழைமணி மரபுப்பொருளின் (மைட்டோக்கோன்றிய டி.என்.ஏ யின்) ஒரு படியுருதான் வழிவழியாக ஒவ்வொறு தாயிடமிருந்தும் குழந்தைகளுக்குச் சென்று இன்று வாழும் மனிதர்களின் கண்ணறைகளின் உள்ளுறுப்புகளானன இழைமணிகளுக்குள் இருக்கின்றன.

70 ka Appearance of mitochondrial haplogroup L2. Behavioral modernity. The ஃபாக்சு பீ2 gene (associated with the development of speech) appears in this period.[15]
60 ka Y-chromosomal Adam lives in Africa. He is the most recent common ancestor from whom all male human Y chromosomes are descended. Appearance of mitochondrial haplogroups M and N, which participate in the migration out of Africa.
50 ka Migration to South Asia. M168 mutation (carried by all non-African males). Beginning of the Upper Paleolithic. mt-haplogroups U, K.
40 ka Migration to Australia and Europe (குரோ-மாகுநன்).
25 ka Neanderthals die out. Y-Haplogroup R2; mt-haplogroups J, X.
12 ka Beginning of the இடைக் கற்காலம் / Holocene. Y-Haplogroup R1a; mt-haplogroups V, T. Evolution of light skin in Europeans (SLC24A5). First domestication of the dog. There is genetic evidence for much earlier split between dog/wolf lineages. Homo floresiensis dies out, leaving Homo sapiens as the only living species of the genus Homo.
10000 BCE Beginning of the புதிய கற்காலம் / Holocene. The invention of farming in the Fertile Crescent occurred during this time.

மேற்கோள்கள்[தொகு]

  1. "'Experiments with sex have been very hard to conduct,' Goddard said. 'In an experiment, one needs to hold all else constant, apart from the aspect of interest. This means that no higher organisms can be used, since they have to have sex to reproduce and therefore provide no asexual control.'
    Goddard and colleagues instead turned to a single-celled organism, yeast, to test the idea that sex allows populations to adapt to new conditions more rapidly than asexual populations." Sex Speeds Up Evolution, Study Finds (URL accessed on ஜனவரி 9, 2005)
  2. "Proterospongia is a rare freshwater protist, a colonial member of the Choanoflagellata." "Proterospongia itself is not the ancestor of sponges. However, it serves as a useful model for what the ancestor of sponges and other metazoans may have been like." http://www.ucmp.berkeley.edu/protista/proterospongia.html Berkeley University
  3. "Obviously vertebrates must have had ancestors living in the Cambrian, but they were assumed to be invertebrate forerunners of the true vertebrates — protochordates. Pikaia has been heavily promoted as the oldest fossil protochordate." ரிச்சர்ட் டாக்கின்சு 2004 The Ancestor's Tale Page 289, ISBN 0-618-00583-8
  4. These first vertebrates lacked jaws, like the living hagfish and lampreys. Jawed vertebrates appeared 100 million years later, in the Silurian. http://www.ucmp.berkeley.edu/vertebrates/vertintro.html Berkeley University
  5. "Bones of first gill arch became upper and lower jaws." (Image) (URL accessed on நவம்பர் 16, 2006)
  6. "Lungfish are believed to be the closest living relatives of the tetrapods, and share a number of important characteristics with them. Among these characters are tooth enamel, separation of pulmonary blood flow from body blood flow, arrangement of the skull bones, and the presence of four similarly sized limbs with the same position and structure as the four tetrapod legs." http://www.ucmp.berkeley.edu/vertebrates/sarco/dipnoi.html Berkeley University
  7. "the ancestor that amphibians share with reptiles and ourselves? " " These possibly transitional fossils have been much studied, among them Acanthostega, which seems to have been wholly aquatic, and Ichthyostega" ரிச்சர்ட் டாக்கின்சு 2004 The Ancestor's Tale page 250, ISBN 0-618-00583-8
  8. "In many respects, the pelycosaurs are intermediate between the reptiles and mammals" http://www.ucmp.berkeley.edu/synapsids/pelycosaurs.html Berkeley University
  9. "Tlvinaxodon, like any fossil, should be thought of as a cousin of our ancestor, not the ancestor itself. It was a member of a group of mammal-like reptiles called the cynodonts. The cynodonts were so mammal-like, it is tempting to call them mammals. But who cares what we call them? They are almost perfect intermediates." ரிச்சர்ட் டாக்கின்சு 2004 The Ancestor's Tale page 211, ISBN 0-618-00583-8
  10. "Fossils that might help us reconstruct what Concestor 8 was like include the large group called plesiadapi-forms. They lived about the right time, and they have many of the qualities you would expect of the grand ancestor of all the primates" ரிச்சர்ட் டாக்கின்சு 2004 The Ancestor's Tale page 136, ISBN 0-618-00583-8
  11. Raauma, Ryan, Sternera, K., (2005) "Catarrhine primate divergence dates estimated from complete mitochondrial genomes", Journal of Human Evolution 48: 237-257 [1]
  12. Green, R. E., Krause, J, Ptak, S. E., Briggs, A. W., Ronan, M. T., Simons, J. F., et al. (2006) Analysis of one million base pairs of Neanderthal DNA. Nature, 16, 330–336. http://www.nature.com/nature/journal/v444/n7117/abs/nature05336.html
  13. "Rubin also said analysis so far suggests human and Neanderthal DNA are some 99.5 percent to nearly 99.9 percent identical." Neanderthal bone gives DNA clues (URL accessed on நவம்பர் 16, 2006)
  14. "The conclusion is the old saw that we share 98.5% of our DNA sequence with chimpanzee is probably in error. For this sample, a better estimate would be that 95% of the base pairs are exactly shared between chimpanzee and human DNA." Britten, R.J. (2002). "Divergence between samples of chimpanzee and human DNA sequences is 5%, counting indels". PNAS 99: 13633. doi:10.1073/pnas.172510699. பப்மெட் 12368483. 
  15. Attempts to date the age of the gene have attracted controversy; e.g. Karl C. Diller and Rebecca L. Cann (2007). Evidence against a genetic-based revolution in language 50,000 years ago. http://www.clc.sun.ac.za/KEYNOTES%20%20&%20%20PAPERS/PAPER_Diller%20and%20Cann.pdf. பார்த்த நாள்: 2007-12-22. 
"http://ta.wikipedia.org/w/index.php?title=படிவளர்ச்சி_காலக்கோடு&oldid=1604785" இருந்து மீள்விக்கப்பட்டது