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73-675: The Eromanga Basin is a large Mesozoic sedimentary basin in central and northern Australia . It covers parts of Queensland , the Northern Territory , South Australia , and New South Wales , and is a major component of the Great Artesian Basin . The Eromanga Basin covers 1,000,000 km and overlaps part of the Cooper Basin . The basin is made of sandstone , siltstone , mudstone , coal , shale , and red beds . Two impact structures have been identified in

146-460: A Cretaceous radiation and the fossil record suggesting a Paleogene radiation. The latest attempts to reconcile the molecular and fossil evidence estimated the most recent common ancestor of modern birds at 95 million years ago and the split between Galloanseres and Neoaves at 85 million years ago. Notably, these studies show that the rapid proliferation of lineages in Neoaves seems to coincide with

219-414: A better "bird" than Archaeopteryx which lacks some of these modern bird features. Because some basal members of Dromaeosauridae , including Microraptor , were capable of powered flight, some paleontologists have suggested that dromaeosaurids are actually derived from a flying ancestor, and that the larger members became secondarily flightless, mirroring the loss of flight in modern paleognaths like

292-483: A boom of dinosaurian evolution on land as the continents began to separate from each other (Nyasasaurus from 243 to 210 million years ago, approximately 235–30 ma, some of them separated into Sauropodomorphs, Theropods and Herrerasaurids), as well as the first pterosaurs . During the Late Triassic, some advanced cynodonts gave rise to the first Mammaliaformes . All this climatic change, however, resulted in

365-594: A coating. This contrasts with the earth's current flora, in which the dominant land plants in terms of number of species are angiosperms . The earliest members of the genus Ginkgo first appeared during the Middle Jurassic. This genus is represented today by a single species, Ginkgo biloba . Modern conifer groups began to radiate during the Jurassic. Bennettitales , an extinct group of gymnosperms with foliage superficially resembling that of cycads gained

438-600: A decline in diversity of sauropods, stegosaurs, and other high-browsing groups, with sauropods particularly scarce in North America. Some island-hopping dinosaurs, such as Eustreptospondylus , evolved to cope with the coastal shallows and small islands of ancient Europe. Other dinosaurs rose up to fill the empty space that the Jurassic-Cretaceous extinction left behind, such as Carcharodontosaurus and Spinosaurus . Seasons came back into effect and

511-477: A few million years before the Triassic–Jurassic extinction event. Sea levels began to rise during the Jurassic, probably caused by an increase in seafloor spreading . The formation of new crust beneath the surface displaced ocean waters by as much as 200 m (656 ft) above today's sea level, flooding coastal areas. Furthermore, Pangaea began to rift into smaller divisions, creating new shoreline around

584-483: A global distribution during the Late Triassic, and represented one of the most common groups of Mesozoic seed plants. Flowering plants radiated during the early Cretaceous, first in the tropics , but the even temperature gradient allowed them to spread toward the poles throughout the period. By the end of the Cretaceous, angiosperms dominated tree floras in many areas, although some evidence suggests that biomass

657-671: A large die-out known as the Triassic–Jurassic extinction event, in which many archosaurs (excluding pterosaurs, dinosaurs and crocodylomorphs ), most synapsids , and almost all large amphibians became extinct, as well as 34% of marine life, in the Earth's fourth mass extinction event. The cause is debatable; flood basalt eruptions at the Central Atlantic magmatic province is cited as one possible cause. The Jurassic ranges from 200 million years to 145 million years ago and features three major epochs: The Early Jurassic,

730-496: A matter of debate. It is agreed that modern birds originated in the Cretaceous and that the split between Galloanserae and Neoaves occurred before the Cretaceous–Paleogene extinction event , but there are different opinions about whether the radiation of the remaining neognaths occurred before or after the extinction event. This disagreement is in part caused by a divergence in the evidence, with molecular dating suggesting

803-787: A scale far too slow to be witnessed by humans. However, bird species are currently going extinct at a far greater rate than any possible speciation or other generation of new species . The disappearance of a population, subspecies, or species represents the permanent loss of a range of genes. Another concern with evolutionary implications is a suspected increase in hybridization . This may arise from human alteration of habitats enabling related allopatric species to overlap. Forest fragmentation can create extensive open areas, connecting previously isolated patches of open habitat. Populations that were isolated for sufficient time to diverge significantly, but not sufficient to be incapable of producing fertile offspring may now be interbreeding so broadly that

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876-435: A variety of niches, beginning in the mid-Triassic 4 million to 6 million years after the extinction, and not fully proliferated until 30 million years after the extinction. Animal life was then dominated by various archosaurs: dinosaurs , pterosaurs, and aquatic reptiles such as ichthyosaurs, plesiosaurs, and mosasaurs . The climatic changes of the late Jurassic and Cretaceous favored further adaptive radiation. The Jurassic

949-559: Is a landmark work on the classification of birds (although frequently debated and constantly revised). A preponderance of evidence suggests that most modern bird orders constitute good clades . However, scientists are not in agreement as to the precise relationships between the main clades. Evidence from modern bird anatomy, fossils and DNA have all been brought to bear on the problem but no strong consensus has emerged. Structural characteristics and fossil records have historically provided enough data for systematists to form hypotheses regarding

1022-537: Is contested by most other paleontologists and experts in feather development and evolution. The basal bird Archaeopteryx , from the Jurassic , is well known as one of the first " missing links " to be found in support of evolution in the late 19th century. Though it is not considered a direct ancestor of modern birds, it gives a fair representation of how flight evolved and how the very first bird might have looked. It may be predated by Protoavis texensis , though

1095-468: Is set by the Permian–Triassic extinction event , during which it has been estimated that up to 90-96% of marine species became extinct although those approximations have been brought into question with some paleontologists estimating the actual numbers as low as 81%. It is also known as the "Great Dying" because it is considered the largest mass extinction in the Earth's history. The upper boundary of

1168-406: Is still under debate. There is significant evidence that birds emerged within theropod dinosaurs , specifically, that birds are members of Maniraptora , a group of theropods which includes dromaeosaurs and oviraptorids , among others. As more non-avian theropods that are closely related to birds are discovered, the formerly clear distinction between non-birds and birds becomes less so. This

1241-537: Is thought that a large meteor smashed into earth 66 million years ago, creating the Chicxulub Crater in an event known as the K-Pg Extinction (formerly K-T), the fifth and most recent mass extinction event, in which 75% of life became extinct, including all non-avian dinosaurs. Compared to the vigorous convergent plate mountain-building of the late Paleozoic, Mesozoic tectonic deformation

1314-588: The Aptian and Albian ages. 26°S 140°E  /  26°S 140°E  / -26; 140 Mesozoic The Mesozoic Era is the era of Earth's geological history , lasting from about 252 to 66 million years ago , comprising the Triassic , Jurassic and Cretaceous Periods . It is characterized by the dominance of gymnosperms such as cycads , ginkgoaceae and araucarian conifers, and of archosaurian reptiles such as

1387-637: The Cretaceous–Paleogene extinction event , suggesting a role for ecological opportunity stimulating diversification in the aftermath of the mass extinction. In contrast, another recent genomic study suggests that the Galloanserae and Neoaves diverged around the Early-Late Cretaceous boundary (100.5 million years ago), with the paleognaths and neognaths diverging even earlier (around 130 million years ago), and that most terrestrial neoavian orders gradually diverged from one another throughout

1460-592: The Enantiornithes , evolved into ecological niches similar to those of modern birds and flourished throughout the Mesozoic. Though their wings resembled those of many modern bird groups, they retained the clawed wings and a snout with teeth rather than a beak in most forms. The loss of a long tail was followed by a rapid evolution of their legs which evolved to become highly versatile and adaptable tools that opened up new ecological niches. The Cretaceous saw

1533-543: The Hesperornithiformes – a group of flightless divers resembling grebes and loons . While modern in most respects, most of these birds retained typical reptilian-like teeth and sharp claws on the manus. The modern toothless birds evolved from the toothed ancestors in the Cretaceous. Meanwhile, the earlier primitive birds, particularly the Enantiornithes, continued to thrive and diversify alongside

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1606-767: The Indian subcontinent , which collided with the Asian plate during the Cenozoic, giving rise to the Himalayas . The Triassic was generally dry, a trend that began in the late Carboniferous , and highly seasonal, especially in the interior of Pangaea. Low sea levels may have also exacerbated temperature extremes. With its high specific heat capacity , water acts as a temperature-stabilizing heat reservoir, and land areas near large bodies of water—especially oceans—experience less variation in temperature. Because much of Pangaea's land

1679-541: The Paleocene–Eocene Thermal Maximum . This clashes with previous studies that found a very rapid radiation of avian orders only after the K-Pg extinction. The results of this study have been disputed by other researchers, due to a lack of fossil evidence to support its conclusions. The birds that survived the end-of-Cretaceous extinction were likely ground-dwelling (not arboreal) and thus persisted despite

1752-561: The Permian Period allowed for the radiation of many new lifeforms. In particular, the extinction of the large herbivorous pareiasaurs and carnivorous gorgonopsians left those ecological niches empty. Some were filled by the surviving cynodonts and dicynodonts , the latter of which subsequently became extinct. Recent research indicates that it took much longer for the reestablishment of complex ecosystems with high biodiversity, complex food webs, and specialized animals in

1825-421: The compsognathid Sinosauropteryx and the microraptorian dromaeosaurid Sinornithosaurus . This has contributed to this ambiguity of where to draw the line between birds and reptiles. Cryptovolans , a dromaeosaurid found in 2002 (which may be a junior synonym of Microraptor ) was capable of powered flight, possessing a sternal keel and ribs with uncinate processes . Cryptovolans seems to make

1898-552: The dinosaurs ; a hot greenhouse climate; and the tectonic break-up of Pangaea . The Mesozoic is the middle of the three eras since complex life evolved : the Paleozoic , the Mesozoic, and the Cenozoic . The era began in the wake of the Permian–Triassic extinction event , the largest mass extinction in Earth's history, and ended with the Cretaceous–Paleogene extinction event , another mass extinction whose victims included

1971-411: The non-avian dinosaurs , pterosaurs , mosasaurs , and plesiosaurs . The Mesozoic was a time of significant tectonic, climatic, and evolutionary activity. The supercontinent Pangaea began to break apart into separate landmasses. The climate of the Mesozoic was varied, alternating between warming and cooling periods. Overall, however, the Earth was hotter than it is today. Dinosaurs first appeared in

2044-421: The ostrich . The discoveries of further basal dromaeosaurids potentially capable of powered flight, such as Xiaotingia , has provided more evidence for the theory that flight was first developed in the bird line by early dromaeosaurids rather than later by Aves as was previously supposed. Although ornithischian (bird-hipped) dinosaurs share the same hip structure as birds, birds actually originated from

2117-474: The phylogenetic relationships between birds. Imprecisions within these methods is the main factor for why a lack of exact knowledge with regards to the orders and families of birds exists. Expansions in the study of computer-generated DNA sequencing and computer generated phylogenetics has provided a more accurate method for classifying bird species - although DNA data studying can only go so far, and questions are still unanswered. Evolution generally occurs at

2190-446: The pterosaurs through this geologic period until they became extinct due to the K–T extinction event . All but a few groups of the toothless Neornithes were also cut short. The surviving lineages of birds were the comparatively primitive Palaeognathae ( ostrich and its allies), the aquatic duck lineage , the terrestrial fowl , and the highly volant Neoaves . Modern birds originated in

2263-603: The saurischian (lizard-hipped) dinosaurs if the dinosaurian origin theory is correct. They thus arrived at their hip structure condition independently . In fact, a bird-like hip structure also developed a third time among a peculiar group of theropods, the Therizinosauridae . An alternate theory to the dinosaurian origin of birds, espoused by a few scientists, notably Larry Martin and Alan Feduccia , states that birds (including maniraptoran "dinosaurs") evolved from early archosaurs like Longisquama . This theory

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2336-458: The Atlantic seaway, which has grown continually larger until today. The further separation of the continents gave opportunity for the diversification of new dinosaurs. The Cretaceous is the longest period of the Mesozoic, but has only two epochs: Early and Late Cretaceous. The Early Cretaceous spans from 145 to 100 million years ago. The Early Cretaceous saw the expansion of seaways and

2409-465: The Late Cretaceous declined for poorly understood reasons, though this might be due to tendencies of the fossil record, as their diversity seems to be much higher than previously thought. Birds became increasingly common and diversified into a variety of enantiornithe and ornithurine forms. Though mostly small, marine hesperornithes became relatively large and flightless, adapted to life in

2482-437: The Late Cretaceous, roughly in sync with the concurrent radiation of flowering plants . This would suggest that a majority of all terrestrial avian orders coexisted with the non-avian dinosaurs and are K-Pg extinction survivors. In contrast, most major radiations of seabirds and shorebirds (as well as in paleognaths, despite their ancient origins) were found to have only occurred after the K-Pg extinction event, and primarily after

2555-540: The Mesozoic is set at the Cretaceous–Paleogene extinction event (or K–Pg extinction event ), which may have been caused by an asteroid impactor that created Chicxulub Crater on the Yucatán Peninsula . Towards the Late Cretaceous, large volcanic eruptions are also believed to have contributed to the Cretaceous–Paleogene extinction event. Approximately 50% of all genera became extinct, including all of

2628-650: The Mesozoic, but would remain small—less than 15 kg (33 lb)—until the Cenozoic. Flowering plants appeared in the Early Cretaceous and would rapidly diversify through the end of the era, replacing conifers and other gymnosperms ( sensu lato ), such as ginkgoales , cycads and bennettitales as the dominant group of plants. The phrase "Age of Reptiles" was introduced by the 19th century paleontologist Gideon Mantell who viewed it as dominated by diapsids such as Iguanodon , Megalosaurus , Plesiosaurus , and Pterodactylus . The current name

2701-474: The Mid-Triassic, and became the dominant terrestrial vertebrates in the Late Triassic or Early Jurassic, occupying this position for about 150 or 135 million years until their demise at the end of the Cretaceous. Archaic birds appeared in the Jurassic, having evolved from a branch of theropod dinosaurs, then true toothless birds appeared in the Cretaceous. The first mammals also appeared during

2774-561: The Middle Jurassic, and the Late Jurassic. The Early Jurassic spans from 200 to 175 million years ago. The climate was tropical and much more humid than the Triassic, as a result of the large seas appearing between the land masses. In the oceans, plesiosaurs , ichthyosaurs and ammonites were abundant. On land, dinosaurs and other archosaurs staked their claim as the dominant race, with theropods such as Dilophosaurus at

2847-474: The Tethys Ocean. Temperatures continued to increase, then began to stabilize. Humidity also increased with the proximity of water, and deserts retreated. The climate of the Cretaceous is less certain and more widely disputed. Probably, higher levels of carbon dioxide in the atmosphere are thought to have almost eliminated the north–south temperature gradient : temperatures were about the same across

2920-486: The ability to fly independently, becoming an example of convergent evolution . However, the evidence about their evolution is still ambiguous, partly because there are no uncontroversial fossils from the Mesozoic and partly because their phylogenetic relationships are still uncertain. The basal divergence within Neognathes is between Galloanserae and Neoaves . The timing of divergence of these major groups are

2993-539: The basin, Mount Toondina crater and Tookoonooka crater . In Queensland and South Australia the Eromanga Basin has been explored and developed for petroleum production. Commercial quantities of gas were first discovered in 1976 and oil in 1978. The basin contains Australia's largest onshore oilfield, the Jackson oil field . Moomba is the centre of South Australia's oil production in the basin. The geology of

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3066-521: The beginnings of the breakup of Pangaea and the opening of the Tethys Ocean . Ecosystems had recovered from the Permian extinction. Algae, sponge, corals, and crustaceans all had recovered, and new aquatic reptiles evolved, such as ichthyosaurs and nothosaurs . On land, pine forests flourished, as did groups of insects such as mosquitoes and fruit flies. Reptiles began to get bigger and bigger, and

3139-431: The current level (about 21%) throughout the Mesozoic, some concluding they were lower in the Triassic and part of the Jurassic but higher in the Cretaceous, and some concluding they were higher throughout most or all of the Triassic, Jurassic and Cretaceous. The dominant land plant species of the time were gymnosperms , which are vascular, cone-bearing, non-flowering plants such as conifers that produce seeds without

3212-403: The dawn of the Mesozoic, ocean plankton communities transitioned from ones dominated by green archaeplastidans to ones dominated by endosymbiotic algae with red-algal-derived plastids. This transition is speculated to have been caused by an increasing paucity of many trace metals in the Mesozoic ocean. Evolution of birds Phylogenetically , Aves is usually defined as all descendants of

3285-605: The dramatic rifting of the supercontinent Pangaea, which gradually split into a northern continent, Laurasia , and a southern continent, Gondwana . This created the passive continental margin that characterizes most of the Atlantic coastline (such as along the U.S. East Coast ) today. By the end of the era, the continents had rifted into nearly their present forms, though not their present positions. Laurasia became North America and Eurasia , while Gondwana split into South America , Africa , Australia , Antarctica and

3358-436: The expanding arid and cool biomes . Bird skull evolution decelerated compared with the evolution of their dinosaur predecessors after the Cretaceous–Paleogene extinction event, rather than accelerating as often believed to have caused the cranial shape diversity of modern birds. The phylogenetic classification of birds is a contentious issue. Sibley & Ahlquist 's Phylogeny and Classification of Birds (1990)

3431-467: The fern prairies, chased by many new predators such as Allosaurus . Conifer forests made up a large portion of the forests. In the oceans, plesiosaurs were quite common, and ichthyosaurs flourished. This epoch was the peak of the reptiles. The Late Jurassic spans from 163 to 145 million years ago. During this epoch, the first avialans , such as Archaeopteryx , evolved from small coelurosaurian dinosaurs. The increase in sea levels opened up

3504-467: The first crocodilians and dinosaurs evolved, which sparked competition with the large amphibians that had previously ruled the freshwater world, respectively mammal-like reptiles on land. Following the bloom of the Middle Triassic, the Late Triassic, from 237 to 201 million years ago, featured frequent heat spells and moderate precipitation (10–20 inches per year). The recent warming led to

3577-487: The food web. In the oceans, mosasaurs ruled, filling the role of the ichthyosaurs, which, after declining, had disappeared in the Cenomanian-Turonian boundary event . Though pliosaurs had gone extinct in the same event, long-necked plesiosaurs such as Elasmosaurus continued to thrive. Flowering plants, possibly appearing as far back as the Triassic, became truly dominant for the first time. Pterosaurs in

3650-492: The fossil record. The Late Cretaceous spans from 100 to 66 million years ago. The Late Cretaceous featured a cooling trend that would continue in the Cenozoic Era. Eventually, tropics were restricted to the equator and areas beyond the tropic lines experienced extreme seasonal changes in weather. Dinosaurs still thrived, as new taxa such as Tyrannosaurus , Ankylosaurus , Triceratops and hadrosaurs dominated

3723-554: The fragmentary nature of this fossil leaves it open to considerable doubt whether this was a bird ancestor. The skeleton of all early bird candidates is basically that of a small theropod dinosaur with long, clawed hands, though the exquisite preservation of the Solnhofen Plattenkalk shows Archaeopteryx was covered in feathers and had wings. While Archaeopteryx and its relatives may not have been very good fliers, they would at least have been competent gliders, setting

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3796-478: The integrity of the original species may be compromised. For example, the many hybrid hummingbirds found in northwest South America may represent a threat to the conservation of the distinct species involved. Several species of birds have been bred in captivity to create variations on wild species. In some birds this is limited to color variations, while others are bred for larger egg or meat production, for flightlessness or other characteristics. In December 2019

3869-641: The late Cretaceous . They are split into the paleognaths and neognaths . The paleognaths include the tinamous (grouse-like birds, found only in Central and South America) and the ratites , which nowadays are found almost exclusively in the Southern Hemisphere. The ratites are large flightless birds, and include ostriches , rheas , cassowaries , kiwis and emus . The ratites are a paraphyletic (artificial) grouping because tinamous are part of their evolutionary clade and they have likely lost

3942-466: The most recent common ancestor of a specific modern bird species (such as the house sparrow , Passer domesticus ), and either Archaeopteryx , or some prehistoric species closer to Neornithes (to avoid the problems caused by the unclear relationships of Archaeopteryx to other theropods). If the latter classification is used then the larger group is termed Avialae. Currently, the relationship between non-avian dinosaurs, Archaeopteryx , and modern birds

4015-606: The non- avian dinosaurs. The Triassic ranges roughly from 252 million to 201 million years ago, preceding the Jurassic Period. The period is bracketed between the Permian–Triassic extinction event and the Triassic–Jurassic extinction event , two of the " big five ", and it is divided into three major epochs: Early, Middle, and Late Triassic. The Early Triassic, about 252 to 247 million years ago,

4088-459: The open sea. Metatherians and primitive eutherian also became common and even produced large and specialised genera such as Didelphodon and Schowalteria . Still, the dominant mammals were multituberculates, cimolodonts in the north and gondwanatheres in the south. At the end of the Cretaceous, the Deccan traps and other volcanic eruptions were poisoning the atmosphere. As this continued, it

4161-437: The planet, and about 10° C higher than today. The circulation of oxygen to the deep ocean may also have been disrupted, preventing the decomposition of large volumes of organic matter, which was eventually deposited as " black shale ". Different studies have come to different conclusions about the amount of oxygen in the atmosphere during different parts of the Mesozoic, with some concluding oxygen levels were lower than

4234-641: The poles got seasonally colder, but some dinosaurs still inhabited the polar forests year round, such as Leaellynasaura and Muttaburrasaurus . The poles were too cold for crocodiles, and became the last stronghold for large amphibians such as Koolasuchus . Pterosaurs got larger as genera such as Tapejara and Ornithocheirus evolved. Mammals continued to expand their range: eutriconodonts produced fairly large, wolverine -like predators such as Repenomamus and Gobiconodon , early therians began to expand into metatherians and eutherians , and cimolodont multituberculates went on to become common in

4307-644: The portion of the Eromanga Basin in New South Wales remains under-explored. During the middle of the Cretaceous period much of inland Australia was flooded by the Eromanga Sea , which shares its name with the contemporary Basin. Various fossil sites spanning the region record a diversity of marine life, including Plesiosaurs and Ichthyosaurs , that were abundant in the Eromanga Sea during

4380-584: The results of a joint study by Chicago's Field Museum and the University of Michigan into changes in the morphology of birds were published in Ecology Letters . The study uses bodies of birds which died as a result of colliding with buildings in Chicago, Illinois, since 1978. The sample is made up of over 70,000 specimens from 52 species and spans the period from 1978 to 2016. The study shows that

4453-550: The rise of more modern birds with a more rigid ribcage with a carina and shoulders able to allow for a powerful upstroke, essential to sustained powered flight . Another improvement was the appearance of an alula , used to achieve better control of landing or flight at low speeds . They also had a more derived pygostyle, with a ploughshare -shaped end. An early example is Yanornis . Many were coastal birds, strikingly resembling modern shorebirds , like Ichthyornis , or ducks, like Gansus . Some evolved as swimming hunters, like

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4526-464: The stage for the evolution of life on the wing. The evolutionary trend among birds has been the reduction of anatomical elements to save weight. The first element to disappear was the bony tail, being reduced to a pygostyle and the tail function taken over by feathers. Confuciusornis is an example of their trend. While keeping the clawed fingers, perhaps for climbing, it had a pygostyle tail, though longer than in modern birds. A large group of birds,

4599-506: The top of the food chain. The first true crocodiles evolved, pushing the large amphibians to near extinction. All-in-all, archosaurs rose to rule the world. Meanwhile, the first true mammals evolved, remaining relatively small, but spreading widely; the Jurassic Castorocauda , for example, had adaptations for swimming, digging and catching fish. Fruitafossor , from the late Jurassic Period about 150 million years ago,

4672-457: The worldwide destruction of forests. An analysis of the variation of diversification rates through time further revealed a potential effect of climate on the evolution diversification rates in birds in which the generation of new lineages accelerates during periods of global cooling. This can be the result of climate cooling fragmenting tropical biomes and producing widespread allopatric speciation plus an effect of some lineages diversifying in

4745-531: Was about the size of a chipmunk, and its teeth, forelimbs and back suggest that it dug open the nests of social insects (probably termites , as ants had not yet appeared) ; Volaticotherium was able to glide for short distances, such as modern flying squirrels . The first multituberculates such as Rugosodon evolved. The Middle Jurassic spans from 175 to 163 million years ago. During this epoch, dinosaurs flourished as huge herds of sauropods, such as Brachiosaurus and Diplodocus , filled

4818-928: Was comparatively mild. The sole major Mesozoic orogeny occurred in what is now the Arctic , creating the Innuitian orogeny , the Brooks Range , the Verkhoyansk and Cherskiy Ranges in Siberia, and the Khingan Mountains in Manchuria. This orogeny was related to the opening of the Arctic Ocean and suturing of the North China and Siberian cratons to Asia. In contrast, the era featured

4891-537: Was distant from its shores, temperatures fluctuated greatly, and the interior probably included expansive deserts . Abundant red beds and evaporites such as halite support these conclusions, but some evidence suggests the generally dry climate of the Triassic was punctuated by episodes of increased rainfall. The most important humid episodes were the Carnian Pluvial Event and one in the Rhaetian ,

4964-538: Was dominated by deserts in the interior of the Pangaea supercontinent. The Earth had just witnessed a massive die-off in which 95% of all life became extinct, and the most common vertebrate life on land were Lystrosaurus , labyrinthodonts , and Euparkeria along with many other creatures that managed to survive the Permian extinction. Temnospondyls reached peak diversity during the early Triassic. The Middle Triassic, from 247 to 237 million years ago, featured

5037-525: Was noted in the 19th century, with Thomas Huxley writing: We have had to stretch the definition of the class of birds so as to include birds with teeth and birds with paw-like fore limbs and long tails. There is no evidence that Compsognathus possessed feathers; but, if it did, it would be hard indeed to say whether it should be called a reptilian bird or an avian reptile. Discoveries in northeast China ( Liaoning Province) demonstrate that many small theropod dinosaurs did indeed have feathers , among them

5110-515: Was originally described as the "secondary" era, following the "primary" ( Paleozoic ), and preceding the Tertiary . Following the Paleozoic, the Mesozoic extended roughly 186 million years, from 251.902 to 66 million years ago when the Cenozoic Era began. This time frame is separated into three geologic periods . From oldest to youngest: The lower boundary of the Mesozoic

5183-592: Was proposed in 1840 by the British geologist John Phillips (1800–1874). "Mesozoic" literally means 'middle life', deriving from the Greek prefix meso- ( μεσο- 'between') and zōon ( ζῷον 'animal, living being'). In this way, the Mesozoic is comparable to the Cenozoic ( lit.   ' new life ' ) and Paleozoic ('old life') eras as well as the Proterozoic ('earlier life') Eon. The Mesozoic Era

5256-531: Was still dominated by cycads and ferns until after the Cretaceous–Paleogene extinction. Some plant species had distributions that were markedly different from succeeding periods; for example, the Schizeales , a fern order, were skewed to the Northern Hemisphere in the Mesozoic, but are now better represented in the Southern Hemisphere. The extinction of nearly all animal species at the end of

5329-485: Was the height of archosaur diversity, and the first birds and eutherian mammals also appeared. Some have argued that insects diversified in symbiosis with angiosperms, because insect anatomy , especially the mouth parts, seems particularly well-suited for flowering plants. However, all major insect mouth parts preceded angiosperms, and insect diversification actually slowed when they arrived, so their anatomy originally must have been suited for some other purpose. At

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