Prehistoric creatures by VK9

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  • 1.Prehistoric creatures By VISHAL KANHAIYA 1By VISHAL KANHAIYA 12/7/2012

2. LifeLife on Earth started around 3.8billion years ago and has sinceevolved and diversified throughthe process of natural selectionto be adapted to almost everyenvironment possible. Thereare currently an estimated 1.9million animals, plants, andother forms of life on Earth.Life can be found in every nookand cranny/niche of the globe,from the extremeenvironments of deep seahydrothermal vents and thefreezing conditions of the polarregions to the lush habitatsfound at the equator.Looking back through time, bymeans of the fossil andphylogenetic record, we cansee that the Earth has beenhome to many more speciesthan are alive today. Taking ahistorical perspective showsthat life is constantly evolving,with the success anddominance of different groupswaxing and waning over time.By VISHAL KANHAIYA 12/7/2012 2 3. History of life on EarthThe history of life on Earth began about 3.8 billion years ago, during the Archean era, initially withsingle-celled prokaryotic cells, such as bacteria. Multicellular life evolved over a billion years later andits only in the last 570 million years that the kind of life forms we are familiar with began to evolve,starting with arthropods, followed by fish 530 million years ago (Ma), land plants 475Ma and forests385Ma. Mammals didnt evolve until 200Ma and our own species, Homo sapiens, only 200,000 yearsago. So humans have been around for a mere 0.004% of the Earths history.Tree of lifeWith the publication of On the Origin of Species by meansof Natural Selection on the 24th November 1859, Charles The centre represents the last universal ancestor ofDarwin not only explained how and why we have the all life on earth, the outer branches the majordiversity of life we see all around us, but also showed how biological groups.all life is connected.The tree is based on research carried out by: DavidSince then we have continued to gather evidence from a Hillis, Derrick Zwickl and Robin Gutell from therange of different disciplines including physiology,University of Texas. It is based on analysis of smallbiochemistry and DNA analysis. The evidence indicates thatsub-unit RNA sequences sampled from about 3,000all organisms on Earth are genetically related, a species from throughout the Tree of Life.genealogical relationship that can be represented as anevolutionary tree known as the Tree of Life.The Tree of Life illustrates how different species arise fromprevious species via descent with modification, and that allof life is connected. The diagram above shows therelationship between the major biological groups.By VISHAL KANHAIYA 12/7/2012 3 4. Archelon (ARK-eh-lon)This giant turtle could live to100 years old, possibly thanksto taking long sleeps on theseabedType: ReptileSize: 4.6mDiet: OmnivorousPredators: Mosasaurs and sharksLived: Late Cretaceous, 75-65million years agoArchelon was a slow mover and found most of its food drifting near the sea surface. It had littleneed to dive deep except when hibernating on the seabed. It was an omnivorous grazer,sweeping up drifting fish, jellyfish and dead carrion as well as plants. Its sharp, powerful beakcould break open shelled animals such as ammonites.Its huge flippers suggest it was a long distance swimmer happiest in the open ocean. It wouldnever be alone, as its huge size attracted a squadron of hangers-on such as juvenile fish as wellas barnacles and parasites. It couldnt withdraw its head or flippers inside its bony shell forprotection so, despite its size, it was an easy target for large predators.Like modern turtles, it laid eggs by burying them in sandy beaches under cover of darkness. Its4nearest living relative is the worlds largest turtle, the By VISHAL KANHAIYA 12/7/2012 leatherback. 5. Arsinoitherium(aars-in-oh-ith-EAR-ee-um)Non-stop eating for this gentlegiant of Eocene mangroveswamps.Type: MammalSize: 1.8m high at the shoulderDiet: HerbivorePredators: CreodontsLived: Late Eocene and earlyOligocene, from 36 to 30 millionyears ago.Its most distinctive feature was the two large horns on their snouts. The horns were hollow andpossibly used to produce loud mating calls as well as to compete with rival males. It was a heftycreature with thick, hairless skin resembling elephant hide.It was very selective in the types of fruit and leaves it ate. Its size meant it had to eat a lot offood - it probably spent much of its day chewing on something.It lived in small groups and would have been in the water most of the time. It couldntstraighten its legs, suggesting they were better for wading and swimming than for walking. Itslarge size kept it safe from most predators, although creodonts might tackle a youngBy VISHAL KANHAIYA 12/7/2012 5Arsinoitherium. 6. Coelursaur (See-LUR-oh-sawr)Coelurosaurs are some of the mostprimitive of all the dinosaurs. It isfrom them that we getTyrannosaurus and other giant meat-eaters.Type: Primitive theropodSize: 2-3m longDiet: CarnivorePredators: Large land reptiles like PostoschusLived: Mid Triassic to Early Jurassic, 230-200 millionyears ago.Around 230 million years ago the first dinosaur fossils started to be found in places such as South America,Madagascar and Europe. These dinosaurs were much smaller than their later descendents and can be divided intotwo groups: The prosauropod dinosaurs, which are the primitive vegetarian forerunners of sauropods such asDiplodocus, and the more common coelurosaurs which were two-legged meat-eaters that would later evolve intogiants such as Tyrannosaurus and Allosaurus.The Triassic coelurosaur dinosaurs were small, nimble and built tosurvive in the harsh Triassic landscape. Unlike many of the four-legged lumbering reptiles around them, thecoelurosaurs could use their two legs to travel at speed and to manoeuvre themselves out of dangerous situations.Their light skulls, long snout and flexible necks were ideal for hunting small animals such as insects, amphibiansand other reptiles but the They could also live by scavenging when times were hard.The arrival of these dinosaurswas a landmark in evolution. They quickly evolved into newer and larger species and spread themselves aroundthe globe until, by the start of the Jurassic period, the dinosaurs dominated the land. These helped found adynasty that produced the largest and most feared land predators of all time. After the giant extinction event of 65million years ago the only Earthly legacy of the dinosaurs are the birds which split from the coelurosaur dinosaurssometime during the Late Jurassic period.By VISHAL KANHAIYA 12/7/20126 7. BasilosaurusScientific name:BasilosaurusRank: GenusCommon names:king lizardA pair of the early whales known as BasilosaurusBasilosaurus ("King Lizard") is a genus of cetacean that lived from 40 to 34 million years ago in the Late Eocene. Itsfossilized remains were first discovered in the southern United States (Louisiana), and were initially believed to besome sort of reptile, hence the suffix -"saurus", but later found to be a marine mammal. Richard Owen wished torename the creature Zeuglodon ("Yoked Tooth"), but, per taxonomic rules, the creatures first name remainedpermanent. Fossils from at least two other species of this taxon have been found in Egypt and Pakistan.Basilosaurus averaged about 18 meters (60 ft) in length, and is believed to have been the largest animal to havelived in its time. It displayed an unparalleled degree of elongation compared with modern whales. Their very smallvestigial hind limbs have also been a matter of interest for paleontologists. The species is the state fossil ofMississippi and Alabama in the United States. They lived in the Eocene epoch.Basilosaurus fossils were first discovered in Louisiana, USA in the 1830s. Believed to be giant reptilian seamonsters, they were named Basilosaurus, or king lizards. Later, they were shown not to be reptilian but gigantic,ancient whales. They were more elongated than modern whales and had a pair of small legs, that could have beena hangover from their terrestrial ancestry. A large number of fossils of these marine predators has been found todate, leading to the conclusion that Basilosaurus were common By VISHAL KANHAIYA 12/7/2012of the time. in the warm shallow seas 7 8. Cymbospondylus(sim-bow-spon-DEE-lus) Type: Marine reptile Size: 10m long Diet: Carnivore Predators: Few, if any, predators once fully grown Lived: Late Triassic, 240-210 million years ago. A powerful dolphin-like swimmer whose sharp teeth ruled the Triassic seas.It was an early member of the Icthyosaur group, which looked slightly like modern dolphins.It had no dorsal fin and its tail was long like an eels.Its long tail made it a powerful swimmer, it patrolled in deep offshore waters looking for prey.It had a skull 1m long with short, sharp teeth good for grabbing quite large reptiles but it favored fishand cephalopods such as ammonites. These appears to have given birth to live young as it had no wayto lay eggs. By VISHAL KANHAIYA 12/7/2012 8 9. Dunkleosteus(dunk-lee-OWE-stee-us) Speedy, powerful and happy to eat most things - this was the creature to avoid, 360 millionType: Placoderm fish years ago.Size: 8 to 10mDiet: CarnivorePredators: Probably noneLived: Late Devonian, 370-360 million yearsago.It looked like the violent brute it was: powerfully built and armour-plated round its head. It was streamlined andshark-like. It lacked true teeth, instead it had two long bony blades that could snap and crush almost anything.Pigment cells suggest Dunkleosteus had dark colors on its back and was silvery on its belly.This fish was anything but picky with its food. It ate fish, sharks and even its own kind. And it seems that It sufferedfrom indigestion as a result: its fossils are often associated with regurgitated, semi-digested remains of fish. It mayhave been one of the earliest animals to exist as male or female, meaning that pairs of fish had to mate physically.By VISHAL KANHAI