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The Period - 251 to 205 MY - Tectonics and climate Life in the Oceans Jarðsaga 1 - Saga Lífs og Lands – -Ólafur Ingólfsson The Triassic Period

The first period of the Mesozoic Era is the Triassic Period, which lasted from 251 to 205 million years ago. The name Triassic comes from Germany where it was originally named the Trias in 1834 by Friedrich August Von Alberti (1795- 1878) because it is represented by a three-part division of rock types in Germany. Triassic tectonic development

In many ways, the Triassic was a time of transition. Pangea was fully assembled and remained so through the Triassic, affecting global climate and ocean circulation... Early Triassic climate

The Triassic was a greenhouse world, with no evidence of ice at the poles. The interior of Pangea was hot and dry, and warm, temperate climates extended to the Poles. Pangea starts breaking up towards the end of the Triassic

Towards the end of the Triassic, a rift develops between Gondwana and Laurasia The first chapter in the formation of the Atlantic Ocean... climate

Global climate was warm during the Late Triassic. There was no ice at either North or South Poles. More pronounced climate zonation than during the Early Triassic, less extension of arid areas. Warm temperate conditions extended towards the poles. Space for new life forms to develop

The Triassic followed the largest event in the history of life, when 75-90% of all marine species vanished at the end of the . This provided an opportunity for new lifeforms... Triassic marine deposits rather rare Sea level was fairly constant through the Triassic; lack of transgressions makes marine deposits rather rare in the geological record.

Recovery from the Pemian extinction was slow for many groups. It has been suggested that increased salinity of shallow sea areas caused problems for many marine organisms. Slow start in the seas

The survivors of the Permian mass extinction:

- Geographically widespread - From temperate areas (not tropical) - Opportunistic ecologic generalists (meaning they can live in many ways/settings) - Tend to be mobile (not sessile)

These features suggest the survivors were those who were suited to large changes in the physical environment...not competitively superior groups. Pelagic life Planktonic organisms are at the base of the food chain in the Oceans, but most kinds leave little or no fossil record. In Triassic times, dinoflagellates (skorusvipungar) were one very important group of plankton. Pherhaps the slow early Triassic recovery of marine life was caused by a mass-extinction crisis of pelagic life?

Dinoflagellates are microscopic, unicellular, often photosynthetic protists, commonly regarded as "algae" (Division Dinoflagellata). They form a significant part of primary planktonic production in oceans and lakes. A gradual diversification of marine life through the Triassic Early Triassic: Bivalves (samlokur), ammonoids, a few brachiopods (armfætlur) – other groups very rare. Diversity is low. Stromatolites (strýtuþörungar) briefly return – can live where grazing are excluded. Middle Triassic: Gastropods (sniglar) radiate. Echinoids (íguldýr) become more common First appearance of scleractinians (stein- kórallar) – modern reef-building corals. Marine conditions are returning to normal from high salinity conditions. Late Triassic: Molluscs, echinoids, bony fish, and large marine diversify. By the end of the Triassic, the modern marine fauna is taking off. Modern molluscs originate during Triassic

Bivalves and gastropods re-expanded Molluscs are a to become more diverse than in very diverse Paleozoic. They filled many of the groups of animals. niches previously occupied by the They first brachiopods. evolved in the . There are about 60,000 living species, and at least 35,000 known fossil species. Two of the most impor- tant groups are bivalves and cephalopods Triassic ammonides expanded rapidly

The ammonides just barely es- caped extinction in the Permian mass-extinction. One genera, the Ophiceras gave rise to an enormous Triassic expansion.

Adaptive radiation of ammonoids from 2 to 100 genera. Belemnides (álfasmokkar) also had a great success

The belemnites had a straight, chambered shell, similar to that of the nautiloids. The strong, massive, projectile-like calcareous shell, called the rostrum, is what usually is found fossilised. The hard-parts were internal in the living . The belemnites are known from the late until the latest . They were marine animals, who developed strongly during the Triassic. They were very abundant during the and Cretaceous periods. The modern reef builders stem from the Triassic

Modern reef-building corals appeared in mid-Triassic times (Hexacorals or scleractinian corals – sexukóralar, steinkóralar). They are probably not closely related to the extinct tabulate or rugose corals (pípukóralar, hrukkukóralar) , but arose independently from a sea anemone (sæfífill) ancestor. Bony-fishes continue to develop Paleozoic ray-finned fishes gave rise to forms that were successful in early Mesozoic times, but were still primi- tive compared to most modern-day fishes. They had partly cartillageous skeletons, primitive jaws and assymmetrical tails.

Cleithrolepsis minor, a Triassic Lissodus africanus, another bony-fish from South Africa Triassic fish from South Africa The sharks Sharks were numerous in the early Mesozoic. Most lived in near-shore or freshwater habitats.

Helicoprion, 2-3 m. Carbon-Triassic shark, probably lived off shellfish. Marine reptiles Reptiles increasingly took to the sea during the Triassic.

The placodonts (broteðlur, 1-3 m) were blunt-toothed shell crushers, with a broad, armoured body that made them look like large turtles.

Placodonts evolved during 35 MY. They were never fully adapted to the open sea, but lived in the shallow coastal waters of the Tethys Sea. Others tried to have the best of both worlds...

The characteristic long neck of a Triassic protorosaur (frumeðla) reached its extreme in Tanystropheus -its neck was longer than body and tail combined, but with only 10 neck vertebrae. The length of the neck suggested that it may have lived in water, but there are no obvious water adaptations. It may have lived on the seashore and eaten shellfish or fish. Length: 6 m; weight: 300 kg The Nothosaurs (slóðeðlur) The Nothosaurs were 3-4 m long aquatic reptiles with a long neck, a long low with sharp teeth and a long, narrow tail. Its limbs were paddle-shaped. Nothosaurus probably ate fish and shellfish. The Plesiosaurs (svaneðlur) The placodonts (broteðlur) and and the nothosaurs (slóðeðlur), which were probably not completely aquatic, did not survive the Triassic Period. Their descendants, the Plesiosaurs, developed to a major group of predatory marine reptiles.

The plesiosaurs, which appeared in the mid-Triassic, played an important role through the Mesozoic The Plesiosaurs - svaneðlur

Plesiosaurs were an important Mesozoic group of marine reptiles.They were very well adapted for life in the oceans. One group of plesiosaurs, the elasmosaurs, had short tails and long necks. The longest neck in the Ocean

The large Triassic elasmosaur (svaneðla -Thalassomedon hanningtoni) was about 14 m long. The “Head-on-tail” plesiosaur It is well known in the history of paleontology that Edward Cope of Philadelphia, who first described the E. Platyurus, initially reconstructed the skeleton with the head on the wrong end, that is, on the end of the tail.

His error was pointed out by Othniel C. Marsh, thus precipitating a life-long feud, and a mortified Cope attempted to buy up the plates with the erroneous reconstruction and replace them with correct versions. Ancestors of Plesiosaurs (?)

Paleontologists are uncertain what the ancestors of the first plesiosaurs looked like but it is probable that they came from primitive aquatic reptiles found in China (Keichousaurus hui). In these animals, the limbs were probably used as paddles to some extent, but could also still move the animal on land. The long neck and small head are also early plesiosaur traits. A complete Plesiosaur skeleton

The first nearly complete plesiosaur was discovered in the Jurassic rocks of Lyme Regis, England in the winter of 1820-21. The name Plesiosaurus means "near-", a reference to the view of the time that plesiosaurs were closer to reptiles than were the more fish-like ichthyosaurs. How did they swim?

The plesiosaur limbs were very large and modified into well developed, paddles which were the main means of propulsion. Recent studies the limbs were 'flapped' up and down much like the wings of a bird or the paddles of a turtle. The plesiosaur, in effect, 'flew' through the water like a modern penguin. How did they reproduce?

There is still some controversy about if they laid eggs or not, but the evidence seems to point toward plesiosaurs giving live birth like ichthyosaurs. It is hard to imagine a 14 m plesiosaur struggling up on a beach to lay eggs like a sea turtle. Besides having limbs that were unsuitable for travel on land, there are several good reasons (such as over-heating, and not being able to breathe) why egg laying would not be possible for plesiosaurs... What did they eat? Plesiosaurs ate fish, ammonites and other invertebrates - many specimens have been discovered with stomach stones in their abdomens. Gastrolites - magasteinar For digestion and buyoancy The Ichthyosaurs

The most fish-like reptiles of the Mesozoic seas were the ichthyosaurs – fiskeðlur. Superficially the ichthyosaurs bear a close resemblance to modern dolphins (höfrungur = sjávarspendýr) . Development of the Ichthyosaurs

Ichthyosaur = fiskeðla

The most obvious transformation for aquatic life is the one from feet to flippers. What were the ichthyosaurs like?

Ichthyosaurs were stream-lined in form, and ranged in size from 4-23 m. They had sharp teeth in long jaws, and big eyes. They had four crescent-shaped fins, a stabilizing dorsal fin, and a fish-like tail with two lobes. They breathed air with lungs through nostrils which were close to the eyes near the top of the snout. They gave birth to life offsprings

A remarkable fossil from Posidonienschiefer, Germany Numerous fossils

Fossil remains of ichthyosaurs have been widely found in North and South America, China, Australia and Europe. They had a varied diet...

Ichthyosaurs probably specialized on ammonites amd belemnites, but were probably pretty opportunistic when it came to food...

The preserved stomach contents of a 110 million- year- old fossilized ichthyosaur revealed that they ate ammonites, belemnites, fish and turtles. Even the remains of a small bird, whose corpse the beast probably swallowed, have been found in their stomach. ...and could move long distances in search of food The ichthyosaurs were adapted to swimming long distances, and deep diving. Perhaps the best evidence for the deep-diving habits of later ichthyosaurs is their remarkably large eyes, up to 23 centimeters across in the case of Ophthalmosaurus. Relative to body size, that fish-shaped ichthyosaur had the biggest eyes of any animal ever known. Sometimes paleontologists work with intresting materials... British scientists discovered the world's oldest fossilized vomit, believed to have come from a large marine reptile 160 million years ago. The vomit contains the remains of dozens of belemnites, eaten in great numbers by ichthyosaurs.

National Geographic News, 12th of February 2002: "We believe that this is the first time the existence of fossil vomit on a grand scale has been proven beyond reasonable doubt." Enormous Ichthyosaurs The Late Triassic produced some enormous Ichthyosaurs, the largest of which was the Shonisurus (15-23 m). It has been described from Nevada, USA, and British Columbia, Canada The development of terrestrial life during the Triassic Period 250-205 MY

Jarðsaga 1 - Saga Lífs og Lands – Ólafur Ingólfsson Triassic critical for terrestrial life

The Triassic Period was critical for Terrestrial life because all of the living dominant groups of tetrapods evolved by its end. These include •TURTLES

• THECODONTS (boleðlur) and their descendants, the , PTEROSAURS (flugeðlur) and BIRDS •MAMMALS • • LIZARDS (incl. snakes) Development of plants

Unlike terrestrial animals, land plants do not appear to have undergone a dramatic mass extinction by the end of the Permian Period.

Early species of conifers dominated the early Triassic terrain. Cycads Leptocycas was a cycad, a primitive seed plant (köngulpálmar), with tough, palm-like fromthelateTriassic leaves and a woody trunk, were period. It was a palm- abundant in the Triassic. Lycopods like tree with a long, (jafnar) and sphenopsids (elftingar), woody trunk and tough mosses, ferns (burknar), tree ferns leaves. It lived in warm climates. This tree was and ginkgophytes (musteristré) were about 1.5 m tall. also around... Triassic development of plants...

• The great coal swamp lycopods, sphenopsids, and tree-ferns, which reproduced by spores and hence required moist habitats, didn't do too well in the dry Triassic climate. • Vegetation became increasingly dominated by evergreen trees (conifers and other gymnosperms). • In spite of the single global landmass, Triassic terrestrial biotas were quite provincial, probably due to climatic rather than geographical factors: monsoon and extreme seasonality caused by symmetrical placement of Pangea over the equator.

Biotas are divided into a northern, Pangean, and a southern, Gondwanan, province, Gondwana vegetation

The Permian Glossopteris flora disappears, to be replaced by the seed-fern Dicrodium.

Dicrodium occurs in all assemblages, from heath and broad- leafed forest to dry woodlands. Often it is the only species present. Other seed-ferns, conifers, cycads and ginkgos also occur in Gondwanan floras. Laurasia development of plants

The Laurasian Flora is made up of; a mixture of primitive conifers, along with cycads, ginkgos ground and tree ferns, and sphenopsids (elftingar). The conifers and ginkgos seem to have been medium-sized to large trees that formed diffuse canopies. Development of plants... Horsetails (elftingar) were an important source of nutrition for plant-eating dinosaurs. These primitive vascular plants were fast-growing and resilient. Their underground stems meant that a hungry could eat the plant without killing it, since the plant would regrow from the rhizome (jarðstöngull). Triassic landscape

“Triassic Landscape” by Caren Carr; The Sam Noble Oklahoma Museum of Natural History Triassic insect development Hymnoptera – bees, wasps, ants

Pasmida – walking sticks “True Flies”

The Permian extinction wiped out nine orders (ættbálkur) of insects. However, surviving orders such as Neuroptera (netvængjur), Mecoptera (sporðflugur), Diptera (tvívængjur), and Coleoptera (bjöllur) underwent further adaptive radiation throughout the Mesozoicum, establishing many families extant in modern times. Most insect groups were well formed by the Cretaceous and remain largely unchanged in appearance during modern times.

Góð vefsíða með upplýsingum um hvenær mismunandi ætbbálkar skordýra komu fram: http://www.fossilmall.com/Science/Taxonomy/Insects/subphylum_insecta_fossils.htm Spiders develop as predators The spinning organs of spiders developed significantly during the Mesozoic. Spinning of silk and weaving of net became much more advanced. Triassic spiders also developed a range of prey catching strategies. Many were ambush hunters, with good eyesight. Triassic reptile development The Mesozoic began with several major reptile groups evolving. These groups were named from the number of holes behind the eyes on each side of the skull - holes that left room for jaw muscles to contract. ANAPSIDS (no holes) include tortoises and turtles. SYNAPSIDS (single hole) made up a group of mammal- like reptiles (the Therapsids - þelskriðdýrin) that ruled for 70 million years and gave rise to true mammals before becoming extinct. The largest group was the DIAPSIDS (2 openings) that contained 2 subgroups (snakes and lizards, and - frumeðlur). Turtles evolved during the Triassic Turtles first appeared on Earth by the end of the Triassic Period. Proganochelys quenstedi was the first known turtle. It had a fully devel- oped shell and a turtle-like skull and beak. However, Proganochelys had several primitive features not found in turtles today. These traits The turtle shell is a remark- included small teeth in its able evolutionary novelty, a development of the verte- mouth and a simple ear. This brate skeleton unique among early turtle also was unable to . No other verte- withdraw its head or legs into brate has a casing made its shell. almost exclusively of bone. Triassic therapsid (þelskriðdýr) evolution Diagram showing the relationships between the various mammal-like reptiles, the Therapsids. They did not survive beyond the end of the Triassic period, but one group, the Cynodontia (“hundtennungar”), gave rise to the first mammals at the end of the Triassic, about 200 million years ago. The Dicynodonts – “Tvær alvöru tennur” There were numerous therapsids of the genus (ættkvísl) Dicynodon in Triassic land environments. These bulky animals made their way through coastal vegetation, feeding on soft and juicy under-ground parts of large horstails. With the exception of its prominent tusks, this animal was toothless. Much like a turtle, it cropped vegetation with a horny beak. Dicynodonts were one of the more successful of the later therapsids, persisting until the very end of the Triassic. Lystrosaurus (“skóflueðla”) – a dicyodont

Lystrosaurus is known from many parts of the ancient megacontinent Gondwana. It is known from India, Antarctica, Africa, Russia, China and Mongolia. The teeth of Lys- trosaurus were reduced to a pair of tusks. Probably it was an amphibious feeder, in much the same fashion as the living hippopotamus. Lystrosaurus dwelt in coastal environments, and their wide paws permitted them to walk in the most boggy places. Silphedosuchus orenburgensis Early Triassic, 240 MY ago Many Early Triassic therocephalians (“skrýmslishöfuð”) were relatively small (<0.3 m), such as the insectivorous Silphedosuchus (“Lítill Skógarkrókodíll”) Sil (Silva=skógur); Phedo (lítill; barn); Suchus (krókodíll)

Ericolacerta was another small (0.2 m) insect-eating Early Triassic therocephalian Cynodontia (“hundstennungar” eða”alvörutennungar”)

The Cynodonts were the last and most advanced of the therapsids, from which the true mammals developed. - early , an cynodont ages/img4.mpg m

Thrinaxodon rimitive p of

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Thrinaxodon http://www.tmm.utexas.edu/research/ctlab/i Skeleton Triassic like features. Body length was ca. 0,5 m. – resembled osture. It p legged

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Oligokyphus ( 0.5 m creature of enlarged incisors like a cate that it was reptilian. is pair pright, four a u y a full eeth, and ad t h last cynodonts, th he anine t c o n Among a weasel, and had beaver. For a long time this animal was classified as mammal, but the jaw bones indi The cynodonts developed increasingly towards small, mammal-like animals

AstheTriassicPeriodworeon, thecynodonts increasingly developed towards smaller animals. This was probably an evolutionary answer to escaping the rapidly developing reptiles and dinosaurs. Dvinia prima – a step towards mammals... The cynodonts fed on anything theycouldfind, butmostlikelyon insects.This small, omnivorous therapsid Dvinia, probably had whiskers on its long snout and the body might have been covered by a tousled rigid fur, that made this animal similar externally to some mammals.

In contrast to mammals, the brain in cynodonts was comparatively much less advanced. The jaws and eyes constituted the main part of their skull, whereas the brain case occupied a relatively small space The Procynosuchus “First dog

One small, seemingly insignificant, otter-like therapsid — Procynosuchus — is thought to be the distant ancestor of the hot-blooded mammals. Fossil occurrance in South Africa and Germany The first mammals

Reconstruction of the skeleton of Megazostrodon, one of the earliest mammals known. Megazostrodon, with a body length of about 13 cm, is from the Upper Triassic Red Bed series of the Karoo, South Africa, and was possibly a nocturnal, insect-eating animal. The first mammals had to wait long for their chance...

Megazostrodon evolved in a world where other groups of animals, notably the dinosaurs, were developing towards total dominance. Their survival strategy was to lay low, move about during the night and try not to draw any attention... The evolution of dinosaurs and birds The evolution of dinosaurs and birds... Dinosaur evolution

Dinosaurs direct ancestors came from group of early archosaurs, the thecodonts (“socket toothed”), which were mostly big, heavy, 4-legged reptiles that ate flesh. These competed so successfully with the therapsids (mammal-like reptiles) that the latter died out during the Triassic period. The early thecodonts were crocodile-like beasts. Next in line were the pseudosuchians (sham crocodiles) with long back legs and much shorter front legs. Although they walked on all fours, the short front legs made running difficult so they ran on their rear legs for short sprints, balanced by their long tail. By 215 MY, these pseudosuchians had given rise to the first flesh eating dinosaurs, most likely from the erythrosuchians of the ornithosuchian sub-group. The dinosaurs developed from the reptilian thecodonts (Archosaurs)

The archosaurs ('ruling reptiles') were the direct ancestors of the dinosaurs. They evolved from more primitive reptiles in the Triassic, following the Permian mass extinction.

The evolution of the archosaurs is a very significant event in the history of life on land, since they not only led to the evolution of dinosaurs and birds, but also to the pterosaurs and crocodiles. The Archosaurs The first archosaurs appear in the fossil record in the Early Triassic; about 245 million years ago, just after the great end-Permian extinction. They include weird The primitive hippo-size beaked herbivores , from the lower Triassic. This (called rhynchosaurs), long-necked reptile, about 50 cm long, reptiles called (prolacertiforms), was related to the evil-looking terrestrial predators ancestors of dinosaurs, (like the erythrosuchians and crocodiles and birds. proterosuchians), and close Euparkeria probably raised itself on to its relatives of the Euparkeria. Many hind-legs when running. of these early groups are limited to the Triassic period. late frica. to a A id m and of bottom with ow r of the merica the A hich plant-eaters reptiles w South ndia and Scotland. Size: 1.3 m. d everywhere at this time. I in nto n i i hynchosaurs found R abundant most . Fossils The he f upper teeth t o heavy, barrel-shaped period, particularly ere row w were

Hyperodaspedon These Triassic They double teeth fitted, giving them a very efficient chopping action ideal for the seed ferns foun These ferns were replaced in the early Jurassic by conifers, and the rhynchosaurs also died out. The proterosuchians

The Early Triassic (240 MY) proterosuchian Garjainia triplicostata, the size of a lion. Garjainia was a carni- vore, which probably hunted therapsids like the dycinodonts. By Early Triassic some dicynodonts got as large as modern rhinoceroses. But the increase in size in hervivorous animals is always accompanied by a parallel increase in size of the predators hunting for them... The (“lizzard crocodile”) A Late Triassic carnivorous thecodont reptile, with a lot of smile. This animal was a huge predator, reaching length of up to 7 meters. It was not in the evolutionary line of crocodiles. It was a Rauisuchian. They were large- skulled archosaurs from the mid to late Triassic period.

These meat-eating reptiles had powerful jaws and were the top predators of their time, but went extinct at the end of the Triassic. Simplified phylogeny of the dinosaurs

The Saurischia (“reptile- hipped”- eðlungar) dinosaurs and the Ornithishia (“bird- hipped” -fleglar) dinosaurs Evolution of dinosaurs

From thecodonts to dinosaurs. A. Euparkeria, Early Triassic, length 50 cm. B. Lagosuchus, Middle Triassic, length 30 cm. C. Staurikosaurus, very primitive dinosaur, Middle-Late Triassic, length 2.1 m. D. , Late Triassic, length 2.5 m. E. Dilophohosaurus, Early Jurassic, length 6 m. The figures below the diagonal line are drawn to scale. of

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hérakrókódíll rocodile” – c

Lagosuchus “rabbit ( “pre-dinosurs”, which have been found in agosuchus L The archosaurs, or Argentina. They were small animals (40 cm, weighed 80- 100 gr),

a in was reached of 7 m, Triassic Plateocaurus (“flateðla”) herbivorous dinosaur, living Late times. It a length and was one of the biggest early dinosaurs. It has been found in France, Germany and Switzerland

Plateocaurus Coelophysis, a Late Triassic dinosaur This small dinosaur was built for speed and agility. While Coelophysis (“hollow form”) stood about 2.5 m tall, its powerful rear legs and slender body made it a fast and deadly predator. It had a long narrow head and a mouth filled with numerous razor-edged teeth. Unlike other dinosaurs, the leg bones of Coelophysis were hollow, which helped reduce body weight and increase its speed. Coelophysis... Coelophysis was one of the earliest-known dinosaurs. It lived in what was then a seasonally dry, desert-like environment, a savanna-type climate (perhaps like modern-day Kenya). Coelophysis was a carnivore, and a scavenger. Coelophysis' fossilized stomach remains have been found containing small reptiles, fish, and other Coelophysis bones of different sizes, indicating that it was a cannibal. Coelophysis probably lived and hunted in packs; this is suggested by the existence of fossil bonebeds of hundreds of Coelophysis at one location, found at the Ghost Ranch in New Mexico, USA. 228 MY) ( has been found lunderer”) was p riassic T inosaur. It was small,

Eoraptor d 1 m long. It ate (“early L gentina Eoraptor another carnivorous only about in Ar ate L izzard”) l another et y Herrerosaurus (“Herreras was carnivorous Triassic dinosaur. It was up to 3 m long. Found in Argentina. Herrerosaurus Enter the Early and extinct forms of crocodiles descended from crocodiles... archosaurs who walked on their hind legs, and lived during the late Triassic period. Theskullof thecrocodilestill resembles in many ways those of the primitive archosaurs. Though modern crocodiles walk on 4 legs, their two legged ancestry is revealed by their hind legs which are longer than the front legs, making them slant forward when they stand. The crocodilian skull still has a basically archosaurean shape.. Crocodile evolution

A. Hesperosuchus, Late Triassic, length 1.3 m. B. , Late Triassic, length 4 m. C. Saltoposuchus, Late Triassic, length 1 m. D. Tanystropheus, Middle Triassic, length 3 m. E. Gracilisuchus, Late Triassic, length 30 cm. F. Terristrisuchus, length 50 cm. Figures not drawn to scale. he t skull, among and animal, l a modern firmly it Gracilisuchus' unlike of lace p well-adapted very a oints j tructure was s 30 cm) is ankle ( Gracilisuchus nd a

racilisuchus y a double row of bony plates that inter- b carnivore vertebrae tiny This crocodile. However, the neck crocodiles. G protected locked down the length of its backbone, to tip tail. It probably chased after small lizards on its long hindlegs, snatching them up in its powerful jaws, with sharp, recurved teeth. f o line rchosaur, a developing Triassic he t o t a Late as w linked

Proterosuchus closely is Proterosuchus that crocodiles. It was 1.5 m long, and probably lived in a similar habitat to modern crocodiles. This a ength. l n i

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During Protorosuchus africanus. stocky creature It was the largest creature of its day, being size a large crocodile, and must have been a fearsome predator on contemporary large herbivores, such as the Kanneymerya dicynodonts. 0 7

s Orthosuchus ossil f hu the c 200 MY ago, riassic

T Orthosuchus

reconstructed Orthosu bout ate a he L t long The crocodile and animal. Although cm lived it already had many of the characteristics of todays living crocodiles. Its fossils have been found in South Africa Snakes and lizzards The ancestors of our modern snakes and lizards appeared during the late Triassic period, although fossil records of these reptiles are sparse. The modern lizards (suborder Lacertilia) are likely to have branched off from the primitive order Eosuchia during the Triassic period, but the oldest definite fossil links between modern lizards and their ancestors originated in the Upper Jurassic period, about 140 million years ago.

It is generally accepted that modern snakes (suborder Serpentes) arose from the lizards in the early Cretaceous period, about 130 million years ago, but there is no hard and fast fossil evidence to link the two suborders. Frogs: Triadobatrachus massinoti

Triadobatrachus massinoti, a small Triassic . It is not a true frog - it lacks the characteristic skull and strong hind legs – but is regarded the ancestor of modern frogs. It probably could not jump, but rather waddled about the marshes of the Triassic, relying on camouflage to protect it from predators. Fossil finds in Madagaskar. Creatures that took to the air... Late in the Triassic Period, animals first took to the air as the pterosaurs (flugeðlur) came into beeing. n i rams to g lightly built, few reptiles, ranging eighin w ones, were b f flying o ollow h 13 m, and > o had order Pterosaurs t m an c were a few 100 kg. They from Pterosaurs size almost and had small bodies. They large brains good eyesight. Some pterosaurs had fur on their bodies, while others had leathery skin. Triassic Mass Extinction

The Triassic Period ended with a large mass extinction. This crisis struck both on land and in the sea: • About 20% of all marine families went extinct. • Conodonts, and placodont reptiles went extinct. • So did most species of marine bivalves, ammonoids, plesiosaurs and ichthyosaurs (these groups recovered in Jurassic times). • The terrestrial victims included most genera of therapsids and large , as well as the large sauropods. Stanley´s presentation of the Triassic mass extinction What caused the Triassic mass extinction? The main beneficiaries of the mass extinction were the dinosaurs, which came out of it as the rulers of the world. Terrestrial plants were also unaffected by the mass extinction.

The cause of the Triassic extinction remains unknown. Climate changes, sea-level changes, changes in the chemistry of the atmosphere or the oceans, asteoride impact, volcanism... We just do not know! References, web resources •Stanley, Earth System History, kafli 16 • Skemmtileg heimasíða frá BBC, Walking With Dinosaurs http://dsc.discovery.com/stories/dinos/bbc/chronology/220/index.html • http://www.ucmp.berkeley.edu/mesozoic/triassic/triassic.html • http://www.palaeos.com/Mesozoic/Triassic/Triassic.htm • http://leute.server.de/frankmuster/S/Shonisaurus.htm • http://leute.server.de/frankmuster/I/Ichthyosaurus.htm • www.fossilmall.com/Science/Taxonomy/Insects/subphylum_insecta_fossils.htm • http://www.sunshine.net/www/2100/sn2192/therapsid-index.htm • http://www.mathematical.com/dinosilphed.html • www.oceansofkansas.com/placodnt.html • http://palaeo.gly.bris.ac.uk/communication/Mcgowan/MAMS • http://www.scotese.com/earth.htm • http://palaeo.gly.bris.ac.uk/Palaeofiles/Triassic/titlepage.htm • http://www.mathematical.com/dinoindex.html