Student Work:

Evolution of Flight

Christina Khalil
Diana Lu
Sam Tang
Maurice Hightower
Justin Geter
Nick Barnum
Christina Wagner
Louie Lau
David Ross
Jeremy Hui
Ryan Maxwell
Nancy Gallegos
Keithrie Jennings
Justin King
Adaysha Patton-Douglas
Joseph Chiang
Lauren Bell
David Nguyen
Johnson Chen
Brandon Williams
Jeff Huang
Peter Wong
 Mass Extinction
 Joseph Laurente
Ashley Mooring
Patricia Nolan
Mina Pan
Silvia Sanchez
Nancy Nguyen
Michael Vo
Peter Tran
Ursula Choice
May Dan Kuang
Kenny Wong
Jaime Respicio
Johnny Li
Bich Ha Tran
Peter Yee
Lori Cheng
Angel Xie
Rowena Kumar
Naeemah Hunt
Maria Silao
Danny Yu
Pei Xian Yu
Wardah Asaba
Helen Tran
Jing Chen

Evolution of Hominids

Tyrone Corley
Cherry Mendoza
David Liang
Kura Cohen
Diana Merino
Jessica Ramos
Dennis Lim
Reggie Moore
Yan Jun Lu
Jeffrey Cheng
Jacky Lao
Calvin Yao
Jing Liang
David Bituin
Diana Uriarte
Derrel Young
Ericka Bozman

Student Work

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Evolution Debates 2002

 

Evolution of Flight

Christina Khalil

Qutline

  1. Topic
  2. Theory/definition
  3. fight to air
  4. mammels...reptiles...birds
  5. flights and whats its capable of
  6. amazing thing bout evolution
  7. what the 3 has in common
  8. feathers... everything

Critique

Opening Statement:

There are two main theories, which are: Ground Up Scenario, and Trees Down Scenario. The Ground Up Scenario is the flight must have proceeded from grounded into air. The Trees Down Scenario is the leaping of trees that provide the acceleration and the speed necessary for flight. If the ancestor was a glider, its gliding structure tuned into wings. It had to flap its gliding membrane. If the ancestor was not a glider then its wings must have developed from another function of the air. Mammals, Reptiles, and Birds all evolve around the same things such as flight. Flight evolved millions of years ago in all of the groups, which are capable of flight today,

Evolution of Flight Summary

There are two main theories, which are, Ground Up Scenario, and Trees Down Scenario. The Ground Up Scenario theory is that the flight must have proceeded from grounded into air. The Trees Down Scenario theory is the leaping of trees that provide the acceleration and the speed necessary for flight. If the ancestor was a glider, its gliding structure tuned into wings. It had to flap its gliding membrane. If the ancestor was not a glider then its wings musty have developed from another function of the air. Mammals, Reptiles, and Birds all evolve around the same things such as flight. Flight had evolves millions of years ago in all of the groups, which are capable of flight today. The most amazing fact about the evolution of flight is the extent of convergent evolution between the three main groups that evolved it which are the pterosaurs, birds, and bats. Flight muscles stretch from the wing to the breast bone. A bird must be light in order to fly, which means birds have no teeth, either they tare the food with teeth or they eat only food they can swallow. The bones are fused (reduced in size) reducing mass of skeleton and distributes mass to center of body. Feathers provide lift to fly. Feathers have maximal flexibility and strength with minimal weight. Counter feathers cover body and wings, it often asymmetrical, and provides an aerodynamic shape to wings. Microscopic hooks give these feathers flexibility and strength. Down feathers are the ones with no hooks, it primary function is to insulate. When ends of feathers disintegrate, it is known as power down. Power down is known to cause things to be water proof. It mostly occurs on herons, parrots, and hawks. Semiphores crosses between contour and down feathers. It lies beneath down feathers. It provides insulation and it helps the birds to be more aerodynamic. Filplumes are long and hair like. It has sensory Corpuscles which lets birds know the levitation of its feathers during flight. Bristles only have a few hooks, found around eyes and nostrils and corners of mouth Maybe to sense positron of prey.

Diana Lu

Outline

  1. Feathers provide lift to fly.
    1. Feathers have maximal flexibility and strength and minimal weight.
      1. Contour Feathers- covers the body and wing, often asymmetrical, and provides an aerodynamic shape to the wings. Microscopic hooks give these feathers flexibility and strength.
  2. Flight
    1. Muscles stretch from the wing to breast bone
    2. To fly birds must be light weight: so birds have no teeth, either tear food with beak or eat only foods they swallow whole
    3. Bones are fused, so it is reduced in size, and distributes the mass of bones to the center of the body.
  3. Endothermic
    1. High temperature permits metabolism in bird's flight muscles.
    2. Rapid metabolism is needed to satisfy the large energy requirements for flight
  4. Archaeopteryx
    1. "Ancient wing"
    2. 150 million years old
    3. Size of a crow
    4. Earliest bird

Rebutal Statement

Ground Up Scenario: Given a bipedal cursorial (running) ancestor of a flying lineage, flight must have proceeded from the ground into the air, assuming that the ancestor did not normally live in trees, or if there were no trees around. We know from extant (living) animals that gliding is mainly useful from the trees, so we can be fairly safe in ruling out a gliding ancestor in this case. A quadrupedal al ancestor would have problems evolving flight from the ground up; it would have to be able to be bipedal in order to use its wings at all! A cursorial bipedal animal would have its arms free to do with them a while running, and its running speed would allow it to achieve the minimum speed necessary for liftoff.

Notes:

Birds wouldn't have enough energy

Evolution of Flight Summary

Evolution of flight has two main theories, which are ground up scenario and trees down scenario. The ground up scenario is flight must have proceeded from ground into air. The trees down scenario is when they leap off trees would provide acceleration and speed necessary for flight. Its ancestor was a glider and their gliding structure turned into wings. It had to flap its gliding membrane and if the ancestor wasn't a glider then its wings must have developed from another function of the air. Flight evolved for many reasons. They evolved to escape from predators, to catch flying or speeding prey, to help move from place to place, to free hind legs for use as weapons, to gain new food sources or an unoccupied niche. Feathers provide lift for birds to fly. Feathers have maximal flexibility and strength with minimal weight. There are Contour Feathers, Down Feathers, Semiplunes, Filoplumes, Bristles, etc. Contour Feathers cover the body and wing. It often is asymmetrical and provides an aerodynamic shape to wings. Microscopic hooks give these feathers flexibility and strength. Down Feathers has no hooks and their primary function is to insulate. Semiplumes cross between contour and down feathers. It provides insulation and helps the bird to be more aerodynamic. Filoplumes are long and hair like. They have sensory corpuscles at the base of each one that lets the bird know the position of each feather. Bristles only have a few hooks. Bristles are found around the eyes, their nostrils, and corners of their mouth. Every bird has its own features that help him or her fly. Muscles stretch from the wing to breastbone. To fly birds also must be light so birds have no teeth. In order for them to eat they either tear food with beak or they only eat food that they could just swallow as a whole. Bones are also fused (reduce in size) reducing mass of skeleton and distributes mass of centre of body. Birds are endothermic. It is high temperature permits metabolism in bird's flight muscles. Rapid metabolism is needed to satisfy the large energy requirements for flight.

Sam Tang

Outline

  1. Feathers provided lift to fly.
    1. Feathers have maximal flexibility and strength with minimal weight.
      1. Contour Featherscovers body and wings, often asymmetrical, and provides an aerodynamic shape to wings. Microscopic hooks give these feathers flexibility and strength.
      2. Down Feathers- no hooks, primary function is to insulate. Occurs in herons, parrots

Critique

Summary

The birds have many different abilities to help it fly. Feathers provide lift for birds to fly, because the feathers have maximum amount of flexibility and strength with the most minimum amount of weight. There are different kinds of feathers, one kind is the Contour Feather, it covers' the bird's body and wings. Contour Feathers are often asymmetrical, and provide an aerodynamic shape for the wings. Down Feathers have no hooks, and the primary function of it is to insulate heat. These Down Feathers occur in herons, parrots, and hawks. The Semiplumes is a cross between the Contour and Down Feathers. It lies beneath the Down Feathers. It provides insulation and more aerodynamic than the Down Feathers. The Filoplumes are long and hair-like. It has sensory corpuscles to let birds know where the location of it's feathers during flight. Bristles have a few hooks. Bristles are mainly found around the eyes, nostrils, and the corners of its mouth. For birds to fly, the muscles must be stretched from the wing to breastbone. Bird's head cannot be heavy, so they have no teeth. Birds must eat food that they can swallow whole, or they have to tear the food with their beaks. The bird's bones are fused together, to reduce size and distribute all the mass to the center of the body. Birds are endothermic, the high temperature permits metabolism in the bird's flight muscles. The rapid metabolism is needed to satisfy the large energy requirements for flight.

Maurice Hightower

Outline:

  1. Opening Statement
    1. Tree Down Scenario
      1. Climbing up a tree
      2. Jumpin goff and gliding
    2. Pelicans and Vultrures
    3. It would be easier to glide first, then achieve power flight.

Critique

Justin Getter

Outline

  1. tree down scenario
    1. body construction
      1. bones inflated with air so the bird body would be a lot lighter
      2. the feathers helped the flight of the birds cause of the shape of the feather
      3. the body parts and the bones are fussed to eachother for stronger body construction

Critique

Summary

The ground up scenario flight must have proceeded from ground into air. The trees down scenario leaping off trees would provide the acceleration and speed necessary for flight. If the ancestor was a glider it's gliding structure turned into wings. If the ancestors were not a glider then its wings must have developed from another function of the air. The used the evolution of flight to escape from predators, to catch flying or speeding prey, to help move place to place, to free hind legs for use as weapons, and to gain access to new food sources. The lack of teeth in birds is cause the birds head needs to be light for the to fly. A bird's skeleton is designed for flight; many bones are fused, or reduced in size, reducing the mass of the skeleton, and redistributing mass towards the centre of the body. Many bones in a bird's body are pneumatized, meaning that they contain large air pockets that are connected to the repertory system. Bird bones therefore are very light.

Nick Barnum

Outline

  1. Why tree down scenario is better than ground up?
    1. the bird is already is in the air
    2. so the bird can know how to land property
  2. feathers can play a role?
    1. certain feathers do certain things

Critique

Summary

The vertebate of flight consist if two main theories and thoose theories are ground up and tress down. Ground up consist of flight having to proceed from ground into air. Tress down consist of leaping off tress by that prosses that would provide the acceleration and speed necessary for flight. Flight evolved for a couple of reasons such as escaping from predators, catch flying or speeding prey, to move from place to place, to free hind legs for use as weapons, to gain access to new food sources or an unoccupied niche. That is what flight is mainly used for. The feathers are used with maximal flexibility and strenth with a little weight. The power of flight comes from the large breast muscles. The muscles get most of it's strenth from the wing to the breast bone. High temperature permits metabolism in birds flight muscles. Rapid metabolism is needed to satisfy the large energy requirements for flight. Feathers have evolved from reptitian scales which are composed of keratain and is complexed in structure. There are five different kinds of featers which are contour, down, semiplumes, filoplumes and bristles each as it's different shape and stucture. The contour featers cover the body and wings. They provide an aerodymamic shape to the wings. The contour feathers has both flexible and strength. The down feather has a simple structure their primary function is as insulation. These feathers produce an aid such as water proofing and grooming. This prosses is called powder down birds such as herons, parrots, and hawks have it. The semiplumes provides insulation and makes the bird more aerodynaic. The filoplume feathers are long and hair like also are sensory in function. The sensory corpuscles are located at the base of each filoplume. The bristle feathers only have a few hooks and barbules. The feathers are found around the eyes, nostrils and at the comers known as the ricta of the mouth. Usally the birds use the ricta bristles to sense position of prey.

Christina Wagner

Outline

  1. Scientist are confused by the debate over birds, and how flight evolved.
    1. Did birds come from small dinosaurs?
    2. Did they climb trees and glide on the way to flight.
    3. Did they run and jump form the ground?
  2. Modern Birds
    1. Legs are too frail to run and jump
    2. Whole suite ob behavioral and physical traits.
      1. geathers
      2. wings
      3. improved brood-care
      4. improved parenting

Summary

Evolution of flight muscles consumes 30 percent of the body's capacity. Mutation led to the wings o evolution. Archaeopteryx is 150 million years old, which is the oldest bird around. They have an attachment for flying muscles. They also need their wishbone to help them fly. Although they came about 150 million years ago they did not become known until the pterosaurus became extinct. Birds and dinosaurs have so many similarities to one another except for the feathers. Scientists say birds are feathered dinosaurs. Early birds had theeth but modern birds don't. Although modern birds and early birds have some simularitys, they are still unique in their own ways. Bats are the second group of mammals to evolve true powered flight. Bats came about from it's ancestor 60-65 million years ago. Scientist are still not sure that Chiroptera is a proper Monophylotic group. A guess has been made that they came from two different ancestors, if that is true it means that mammals evolved twice in flight and for times in vertebrates. The first vertebrates that evolved were the flying reptiles. In the 18th century the fossils Pterosaurs was discovered but they thought it was a failed experiment in flight. However they lasted for 140 million years. It takes alot for a pigeon to adapt to flying. It has a big breast bone and just like the Archaeopteryx's they have a lot of bone attachment for flying. Flight was evolved to escape predators, get food, travel, and to get more acces to food sources. Wings came about from arms. Their also known as a sexual structure. Inorder for you to get wings your ancestor behaviors ment something and so did their adaptions.

Louie Lau

Outline

  1. Winged reptiles included the pterodactyl, which, during this period, ranged in size from extremely small species to those with wingspreads of 1.2 m (4 ft).
  2. The wings were thin membranes of skin, similar to the wings of a bat, which extended along the sides of the body, and were attached to the extraordinarily long fourth digit of each arm
  3. Bat wings are supported internally by modified hand bones-a fact reflected in the name of the bat order, Chiroptera, which is Greek for "hand-wing." Each wing is made of a double layer of skin (called the wing membrane or patagium) that stretches between the bat's elongated finger bones and attaches to the side of the body and the hind leg. The clawed thumb is free of the wing, and the bat uses the thumb to cling to tree bark or the walls and ceiling of its roost.
  4. They had hollow bones, were lightly built, and had small bodies
  5. Quetzalcoatlus was a flying reptile whose wing-span was just under 36 feet wide (10.96 m). It was the largest flying animal ever found. It had hollow bones, was lightly built, and had a small body. Even though it was very big, it probably weighed only about 300 pounds (135 kg). It had toothless jaws and a long, thin beak. The neck was 10 feet (3 m) long. The legs were over 7 feet (2.1 m) in length, as was the long head

  6. As from the resources from starsandseas.com (Mr. Hartzogs web site) said pterodactyls probably hunted its prey by gliding toward the water and swooping up its meals

  7. The wings of such so-called flying animals as flying foxes, flying lizards, and the flying squirrel are merely expansions of the skin along the sides of the body to assist the animals in jumping from tree to tree, or from a tree to the ground.
  8. Archaeopteryx seemed to be part bird and part dinosaur. Unlike modern-day birds, it had teeth, three claws on each wing, a flat sternum (breastbone), belly ribs (gastralia), and a long, bony tail. Like modern-day birds, it had feathers, a lightly-built body with hollow bones, a wishbone (furcula) and reduced fingers. This crow-sized animal may have been able to fly, but not very far and not very well. Although it had feathers and could fly, it had similarities to dinosaurs, including its teeth, skull, lack of a horny bill, and certain bone structures. Archaeopteryx had a wingspan of about 1.5 feet (0.5 m) and was about 1 foot ( 30 cm) long from beak to tail. It probably weighed from 1 I to 18 ounces (300 to 500 grams

Rebuttal Outline:

  1. Birds with claws
    1. Fossils clearly shows bats have claw like fingers that they use to climb
    2. Birds we see today have feet with claws, which probably originated from having claws for climbing
  2. Reptiles flying
    1. Since Reptiles like the Archaeopteryx's fossil it shows sign of claw like fingers
    2. With no hallow bones this bird was probably climbed and glided off.

Critique

David Ross

Outline

  1. Ground up
    1. Small animals trying to capture insects with their forelimbs occasionally would leap up into the air after them. However, this particular theory does not explain how the insects got off the ground in the first place. Were they "leaping" after something, too?
  2. Tree down
    1. Animals that had climbed into the trees suddenly had to jump down to evade predators. eventually these jumping animals evolved wings in an effort to better escape predators. The pterosaur is a perfect example. It has strong claws for climbing. The wings of some flying dinosaurs are thin, which would serve as a good gliding purpose.
  3. Archaeopteryx
    1. has a wishbone (furcula) Some recent fascinating studies using moving X-rays of birds as they fly show how the shoulder girdle has to be flexible to cope with the incredible forces of the power-stroke in flight. You can actually see the wishbone flex with each wing-beat.
    2. has what is called a grasping hallux, or hind toe, pointing backwards. Rearward-facing toes may be found in some of the dinosaurs but not a true grasping hallux with curved claws for perching. Evolutionist John Ostrom speculates that feathers evolved from large scales on the forelimbs of dinosaurs and that these long feathers, as they developed, were used to catch insects! they're an incredibly complex structure to use just for this purpose. And they would blow the insect out of the way. Birds couldn't clap their limbs together in front.
      1. along with all perching birds,

Summary

The latter theory posits that tree climbing dinosaurs evolved mechanisms to glide from trees or other elevations to some distance away from that spot, landing on the ground. While the latter is more attractive than the prior on the surface level, the prior theory is most likely the correct theory. Most paleontologists of the 19th and early 20th centuries agreed that they could fly to some extent, though not necessarily as capable as today's birds and bats. After the 1920's, opinion seemed to go downhill: namely, that they were mere gliders, with weak, flimsy wings that easily suffered debilitating tears. With the growing popularity in the last few decades of the image of dinosaurs as agile, possibly warm-blooded animals, pterosaurs have been recognized as powered, highly successful flyers. The pterosaur body was highly adapted to enduring the rigors of flight. Many bones are fused together, providing a sturdy framework for the muscles and other organs. The pelvic vertebrae had in fact fused with the pelvic bones, providing a shock-absorbing structure (the synsacrum) that braced the animal when it landed. In larger pterosaurs, the pectoral vertebrae were similarly fused in a structure called the notarium. The sternum, or breastbone, had a keel that provided an attachment for large pectoral muscles, and a forward projection, the cristospine, may have functioned much like the furcula ("wishbone") in birds. Many rhamphorhynchoid fossils show the outline of a flap of skin at the tip of the tail that may have acted as a rudder, and the neural spines were likewise elongated in some. In order to reduce weight, pterosaur bones were hollow; indeed, they were even thinner than many avian bones. The later pterodactyloids, as mentioned earlier, lost all traces of teeth and may have had horny beaks. Most likely they were. Active flight is a strenous activity, and any creature that wants to fly must have a high metabolism. Birds and bats are definitely warm-blooded; the presence of fur, and the adaptations for flight that pterosaurs undertook surely imply that they were warm-blooded.

Flight Summery

Bats, also known as Chiropterans are the second most diverse groups of mammals to evolve the power of flight. You can see the striking resemblance between the archaeopteryx. The skeleton structure and organ placement is very similar. Even though there were only 7 archaeopteryx and bats still live today, a much simpler comparison can be made between the archaeopteryx and the modern day chicken. The bone structure is very similar and the wishbone has formed to give the bird a slight lift. However chickens cannot fly. An ancient flyer like the archaeopteryx, the pterosaur, was the first animal to obtain the power of flight as we know. Wings and feathers were developed for various reasons scientists believe. They were used to catch small prey, gliding from tree to tree or to obtain lift of the ground while running at high speeds. The archaeopteryx is about 150 million years old. Its wishbone showed that it could indeed fly. This bird/ dinosaur had teeth and had a very long tail. It had a collar bone to help absorb the stress from flying.

Jeremy Hui

Outline

  1. Ground Up Theory
    1. This theory proposes that flight evolved in running bipeds through a series of short jumps. As the jumps became more and more extended, the wings were used for balance and propulsion eventually resulting in flight without a gliding Intermediate. There are two models that attempt to explain this theory.
    2. It is proposed that bipedalism allowed fee movement of the forearms, making them available for catching prey As the feathers enlarged over time it would make them a better tool for batting and catching insects, by chasing and swatting them with their wings. As the forelimb enlarged, the notion would turn from swatting into actual flapping tight
  2. Arboreal Theory
    1. This theory states that a climbing proavian started to glide between trees eventually leading to wing strokes as the precursor to flight. The rudimentary feathers that developed from scales on arboreal reptilian birds acted like a parachute slowing the descent as the animals leaped from branch to branch, hence controlling their jumps and falls. It is suggested that proavians were ground foragers and used trees to nest, hide, and roost. The proavians would climb trees through the use of manual and pedal claw°s that are evident in the fossil record. As the jumps became a greater distance, an unspecialized glide with a steep angle would develop. Gliding would increase distance, maneuverability, and slow down landing. Once gliding became specialized then flapping would begin. During landing they would Clap their swings to -,low the decent. This motion would eventually give rise to active flight.
  3. Rebuttle
    1. When the Birds climb rip the trees their wings could leave gotten damaged

Rebutal Outline

  1. Climbing the trees would damage feathers
  2. With gravity and huge body weight how does it fight the gravity when it drops to glide.

Critique

Summary

How flight is evolved in a group depends on what ancestor's behavior and adaptations on the environment. Wings were evolved by gliding ancestors who began to flex and produce thrust. Wings were exaptation and decendents used them for flying. The reasons for wings is because they were used to catch small prey, gave them ability to leap, and sexual display structure. Wings were evolved because of small bipedal animals leaped which wings assisted leaping. Running ancestors of flying lineage show that flight was from ground up and that gliding began from top of trees which they would glide downward. If the species were to fly from straight ground then it would have to spread its arms free while running and the speed would began giving the specie flight. Arboreal ancestors of flying lineage went from trees to the air like a semi-bipedal gliding animal that leaped off of tress to get acceleration. The wings on these species must have flopped to do flight. The evolution of flight was for the specie to escape from predators, catch prey, move from place to place, use free hindlegs for use of weapons, and to gain access to new food sources. Species such as Archaeopteryx, the oldest extinct bird is about 150 million years old and is believed to have started it all. The Archaeopteryx has enlarged breastbones that is enlarged and has a keel down the midline that provide solid attachment for flying muscles. It also has collarbone that links to the shoulder which provides itself for flight. This specie is also similar to the pigeon specie because both of them have big breast bone, collarbone, and has a lot of adaptations for flying.

Ryan Maxwell

Outline

  1. Dromaeosaurs, Archaeopteryx, and early birds such as Sinornis, are animals that we must consider to understand the origin of flight in birds.
  2. Dromaeosaurs were all bipedal, fairly cursorial, and terrestrial. Many modern birds are arboreal, but modern birds have had 150 million years of evolutionary separation from their origin, so they are poor analogs for the origin of flight in birds
  3. To study the origin of flight is not to deal with why modern birds live in trees, but how ancient birds got into the air.
  4. Because Archaeopteryx shows basically the same features as dromaeosaurs except for its wings and feathers, the simplest explanation is that the origin of flight in birds was a "ground-up" scenario, almost identical to the scenario in the origin of flight in pterosaurs.
  5. Another note to make is that area where the original fossil bird was found does not show any evidence of large trees being present. This alone does not disprove arboreality, but is one more problem with the "trees-down" model.

Critique

Summary

The evolution of flight dates back to the dinosaurs. The first vertebrates to ever evolve flight were the pterosaurs that were flying archosaurian reptiles. However as a group the pterosaurs lasted about 140 million years meaning that flying may not have been adapted for escaping predators but for chasing prey and when it was all gone so were they. Birds such as Archaeoptery evolved from bipedal dinosaurs about 150 million years ago, it was not common until after the extinction of the pterosaur. However the two looked alike not counting the fact that one had feathers. The fact that Archaeoptery resembles pterosaur so closely could mean that they lived in the same conditions and so they had the same mutations but it most likely means that the two are related. There are many explanations for the evolution wings, some being they evolved from arms and were used as nets, they evolved to assist small bipedal animals in jumping, they were for sexual display, and they were for gliding. The one which seems the most reasonable based on the fact that the first bird evolved from a bipedal dinosaur is that they assisted bipedal animals in leaping and over time they learned to use them to fly, probably to get food, not be food or find a new, safer nesting place. The adaptation of flight would have added weight to each animal because it makes up about 30% of the body weight. Similarities between the archaeopteryx and modern birds are their feathers, their short tail bones and they all have a collar bone which is a torque absorbing strut linking the shoulders. However there are differences in that modern birds have an anchor flight muscle and hollow bones making them lighter for flight were, as early birds did not.

Nancy Gallegos

Outline

  1. One of the early birds that don't have strong legs that show that

Critique

Summary

Paleontology has us understand the unique evoluti on ary history of birds. One of the bird are a bats are th e second most diverse group of mammals ever to evolve d true power for flying. It about 60-65 million year ago flying evolved twice in mammals are four times in verb reates. Another bird is Pterosauria one of the first vert ebrates to evolved true flying. One of the early bird is Archaeopteryx about 150 million years old .As the foss il was found scientists saw that it was involved from a small bipedal dinosaurs. This fossil is the most importa nt fossil ever discovered. Archaeopteryx had a full set of teeth, had a flat breastbone, a long bony tail, Gastra lia (belly ribs), and three claws on the wings that was used to get it prey or maybe trees. However, its feather s, wings, fucula (wishbone) and lest finger are the same characteristics as a modern bird. It breastbone is enlar ged, has a keel down the midline to fall over the sidew ays that provide a solid attachment for better flying mu scles. Having a good collarbone that is called wishbone The wishbone is links to the shoulders, wishbone is n ceded so it could fly. The fossil was found that it had a lot of feathers and it could help to be warm. A modern fossil bird is a pigeon- s that has a lot of adaptation fo r flying. Has a big breastbone, has a lot of bone attach ment point for flying muscles. Has a collarbone that it help it absorb the stressed of flying. It very skinny it 1 ooks gentle and it has a short tailbone sticking out and it short. These bones are very interesting and it helps us see the evolution on birds into the earliest bird to th e modern birds.

Keithrie Jennings

Outline

  1. Opening Statement
    1. In the ground up theory, flight starts in the ground and later on preceeded into the air. This theory says that no trees were actually around. This cancels out gliding ancestors. A bird must be bipedal corsorial to be enable the bird of using both its hands and running at the same time. Its speed must let the bird have the necessary push for it to take flight.

Summary

When we think of flight, we think of insects, pterosaurs, birds, and bats. What was about these species that helped them to master the arts of flying and why. We will take a journey through the evolution of flight and explore these flying species inside and outside to find out what it takes to fly. To study the evolution of flight, we must go all the way back to the Jurrasic period where we will find the earliest bird known today, the archaepterx. Living 150 million years ago, the archaepteryx's fossil was found in the site, Solenhofen Limestone in Bavaria, Germany. With features we find in modern birds today, the archaepteryx is classied as a bird. With no breastbone, it anchored its flight muscles. It had solid bones and a super effecient lung. Another key feature that seperates the archaepterx from all the other flying species of it's time is it's feathers. The known bird related to the oldest group of living birds are ostrich. In the early cretaceous period, evolution brings up ducks, geese and waterfowls. Then comes woodpecks, parrots, swifts, owls. During the mid cretaceous, passeriformes and songbirds evolve. Then comes shorebirds, birds of prey, flammingos, and penguins during the late cretaceous period. The one essential key factor in a bird is it's feathers. It provides lift and conserves heat. The feather is perfect for flight because of it's maximal flexibility. It gave birds strength with less weight. A feather is made up of tiny pits containing follides. A shaft emerges from the follide. Then Pairs of vanes are developed from opposite sides of the shaft. Each vane is consisting of barbs.

Justin King

Summary

Flight is basically in insects, pterosaurs, birds, and bats. The feathers are from reptilian scales and are known as lightweight and easily replaced. One of the earliest flight creatures was Arcaetert which lived in Bavaria, Germany. The rock in that area is Solenhofen limestone and the area only know is about 150 millions years ago. The description about Arcahetert is that it had no breastbone, it only had solid bones, it did have feathers, anchor flight muscles, and it also had super efficient lung. The ostrich is known to have relatives belonging to the oldest group of living birds. Ducks, geese, and waterfowl have been around since the early Cretaceous period. Woodpeckers, parrots, swifts, owls, passerformes, and songbirds were around in the mid-Cretaceous period. And the flight animals around the late Cretaceous period were the shorebirds, birds of prey, flamingos, and penguins.

Adaysha Patton-Douglas

Closing Statement Outline

  1. Theory of gliding
    1. Present closing statement
    2. Restate theory

Critique

Joseph Chiang

Opening statement Outline

  1. Evolution of flight: theory of gliding
    1. Present opening statement
              1. Birds evolved though gliding
    2. Show proof
              1. Show essay
              2. UC Davis researcher proposes theory
    3. Explain how we are right
              1. James Carey's (UC Davis ecologist in essay) explanation
              2. Archaeopteryx fossil

Critique

Summary

Currently, there are a lot of flying creatures in the world today. Although there are a large number of these creatures, not many classes in the animal kingdom have this feature. Flight was used successfully in insects, pterosaurs, birds, and bats. These are the only known creatures that we know of that have wins and the ability top fly. The most successful of these creatures is the bird, since they are found all over the world, across many different species, and in many different evolutionary forms. There are two main features of a bird that separates it from the other flying creatures: the use of feathers and the use of amniotic eggs. The feathers evolved from reptilian scales, are lightweight, and can be easily replaced. They were used to provide lift and also to conserve heat. Feathers provide maximal flexibility and strength in exchange for a lighter weight load. The feathers evolved from the scales that grew on a reptile's feet, on their lower legs The earliest type of bird was the Archaeopteryx. It was discovered in Bavaria, Germany in the Solahofen Limestone, approximately 150 million years ago. It had no breastbone, which anchored its flight muscles, and solid bones, which weighed it down. The positive characteristics were that it had feathers instead of skin flaps and a super efficient lung. Since then, birds have evolved into the flightless ostrich (which has relatives to the oldest group of living birds), bucks, geese, and the waterfowl, all within the early Cretaceous period. During the mid-Cretaceous period, woodpeckers, parrots, swifts, owls, passeriformes, and songbirds evolved. In the late Cretaceous period, shorebirds, birds of prey, flamingos, and penguins also evolved.

Lauren Bell

Opening statement Outline

  1. To sum up our thoughts we think that basically
  2. The birds started from the ground.
  3. They practiced by leaping and gliding
  4. The birds learned how to fly by building up enough lineages to start to fly on their own.
  5. The ancestor birds began to use their arms for flapping instead of gliding
  6. The early ancient birds were bipedal, which means there wings were free to run around at their necessary speed
  7. I order to fly you have to fly at a certain speed, and have velocity.
  8. There ability to fly came from their wrists called the wishbone
  9. It also built up their arm mussels, that's why we see the ancestor birds in the past had strong mussels

Critique:

Closing statement Outline

  1. I feel the birds needed practice in order to start to fly.
  2. Why did they live in the tree?
  3. They would have to have had a fear of flying or possibly dying?
  4. The theory was that the early species needed to run in order to leap in the air to gain velocity.

David Nguyen

Rebuttal Outline

  1. The species had no way to get a jump-start to have a perfect way of flying off the tree
  2. Once the species jumped of the tree, they fell to the ground
  3. How could new species developed new traits from their ancestors and have the ability to fly off the tree?
  4. The only way to jump off the tree and begin to fly is when the species are small and has space to run across the tree leaping off and flying so only some species can
  5. From the tree there might be a fear from the species on the trees to jump off and attempt to fly.
  6. There is more room from the ground then from the tree
  7. In order for birds to fly, the bird like the archaeopteryx are suggested that the running speed must be at least 2 meters per second back in those days.

Critique

Summary of Flight

Flight has evolved millions of years ago in all the groups that is capable of flight today. Flight has only evolved a few times in the 500 million years of the vertebrate history and that is an accomplishment. There are four types of ways of flight that have evolved for the vertebrates: parachuting, gliding, flight, soaring. In order to find out how flight has evolved, we first must find out how wings evolved. There was a prediction that wings must have been exaptation by the ancestors for one function. There were hypothesis that showed the wings evolved from arms used to capture small prey, they evolved because of bipedal animals were leaping into the air and it assisted the arms. Another theory was that wings evolved from gliding ancestors who began to flap their gliding structure in order to produce thrust. How flight evolved in a group depends on what its ancestors were doing and the adaptation to them. To understand the evolution of the flying lineage, we must understand the phylogeny of that group, understand the functional morphology relevant to flight, find evidence explaining how flight evolved, and formulate an evolutionary hypothesis why flight evolved in that lineage. The latest sign of flight was when a 130 million year old fossil was digged up by farmers in northeastern China that was evidence of flight which turned out to be a Dromaeosaur. It is a skeleton of a 3 feet long duck-like dinosaur. Scientist believed that the Dromaeosaur and their kin were warmed blooded so t hat there feathers can served originally as insulation, then for display and then for flight. To find these environment where the organisms found also helps to constrain possible behavior. Flight is still a mystery to science today about how it really began and how it is passed on to the vertebrate that are living today. Though vertebrates now mainly evolve flight a few times, the invertebrates has only evolved flight once. The insects were the first animal to evolve flight and is still evolving flight today.

Johnson Chen

Outline

  1. Flight:
    1. The birds don't have hands or claws to climb on the tree.
    2. On the tree, they might don't have any space for pretest fly.
    3. The trees are small to have the specie leap off and begin to fly
    4. The Ground had a lot space to help the bird fly.
    5. There is a running start in order to leap off the ground.
    6. From the ground, they have more chose to jump and began to fly then from the trees.
    7. The birds practice more from the ground, because of the less chance of getting hurt.

Critique

Vertebrate Flight Summary

In last week, my group had study about Vertebrate Flight. It is kind of hard, but it is so cool, cooler then I never thought about it. Perhaps the most perplexing and controversial aspect of the study of flight is the study of how and why flight evolved. Since flight evolved millions of years ago in all the groups which are capable of flight today. We must know what is flight, base of that, we know about wings. We can use wings to fly, like birds. In the information that I had, it told me about the evolution of a flying lineage, and it told me the steps of it. 1. the phylogeny of that group, what its origins were. 2. the functional morphology relevant to flight, and how that changed from the nonflying ancestor to the earliest flyer. 3. accumulate empirical evidence explaining how flight evolved, using such tools as aerodynamic analyses, ichnology, and paleoenvironmental assessments. 4. formulate an evolutionary why flight evolved in that lineage, supported by and consistent with all of the evidence form the previous three steps.
And the information that I found in paper, had a lot about wings evolve. 1. Wings evolved from arms used to capture small prey, the large wing area acted as a net seems rational, but is not support by empirical evidence. 2. Wings evolved because bipedal animals were leaping into the air, large wings assisted leaping. 3. Wings evolved from gliding ancestors who began to flap their gliding structures in order to produce thrust.

Brandon Williams

Opening Statement Outline

  1. We say that birds learned to fly by jumping out of trees and flapping their wings to keep flight while in the air. Birds are light weight so the tree supports them, then when they jump out the tree and flap there wings they have more time to try and fly being light weight. Plus there is more protection for birds in trees then on the ground. and to ad to that the Archeaopteryx have found fossils of birds with forelimb claw supporting the concept that ancient birds were tree dwellers.

Critique

Jeff Huang

Rebutal Outline

  1. Flight:
    1. If they ran really fast their legs would have to have lots of muscle and there is no evidence that they did.
    2. From the feature of bird their legs are short.
    3. Being they had weak legs by time they picked up speed to fly they would be fatigued
    4. They would have to fight wind resistance because of there wing stand.
  2. Added during debate
    1. Like you guys said, if they used to run so fast, why did their leg muscles weak?
    2. From the ostrich, their leg is long so that good for running
      1. But they cannot fly, because it wings is short and overweight body.
      2. They lived in the ground, so that they used their wings less
      3. So their wings degenerate or not evolved at all.
    3. We know that, bird have to be light weight in order to fly.
    4. More protetion for bird in trees.
    5. An to add to that, the Archeopteryx have found fossil of birds with forelimb claw supporting the concept that ancient birds were tree dwellers

Critique

Summary on Flight

Flight is an amazing accomplishment, evolved only tree times in the 500 million years of vertebrate history. Flight evolved from the reptiles. Scientists have been arguing about the evolution of flight and according to the fossil records, Archaeopteryx was the earliest bird in the world. It is about 150 million years old. It had teeth and a long reptilian tail, and very few of its bones were fused to each other. These were the feature of dinosaurs. Being compare to the dinosaur, Archaeopteryx had a wishbone and dinosaurs had no wishbone. Unlike the modern day birds, Archaeopteryx had solid bone and modern birds had hollow bone. The solid bone was not good to fly. Archaeopteryx's wing was short and body was large. Modern bird's wing is long and body is small. It is the good feature for flying in the sky. Modern bird's breastbone is larger than the Archaeopteryx's. Ostrich, a largest bird in the world today, cannot fly. Because they have a large body and their wings are short. Its feature looks like some normal birds in the world today. Even though they could not fly, they can run extremely fast so that others animals cannot capture them easily. That's the reason they did not evolve to fly in the sky. And we could see the environment affected the old reptiles to evolve. Wing is the requirement for flight to fly. Wings evolved from arms used to capture small prey. Wing evolved because bipedal animals were leaping into the air, large wing assisted leaping. Wing also evolved from gliding ancestors who began to flap their gliding structures in order to produce thrust. The power for active flight comes from large breast muscles that can make up 30 percent of a bird's total body weight. Later on, the scientist had found a 130 million year-old fossil dug up by farmers in northeastern China that they think it might the ancestor of birds. It was Dromaeosaur, the skeleton of a 3 feet long duck- like dinosaur, a relative of the Velocirator of Jurassic park fame. It was indisputably covered with both feathers and protofeathers, from head to tail. Many scientists believe that Dromaeosaurs and their kin were warm- blooded, so it's good bet that feathers served originally as insulation, then later for display, and still later for flight.

Peter Wong

Closing Statement Outline

  1. Flight tree
    1. Fly by jumping out of trees
    2. Less weight
    3. More time
    4. Fossils

Critique

Summary

Many birds have their own way of flying. One of its abilities is feather it help to lift the bird so it can fly. Feathers have a lot of flexibility and strength with only a little weight. There are many different kind of feathers one of them is the contour, it covers the whole body and wings of the bird. The contour feathers are asymmetrical and provides aerodynamic. That helps the bird to fly better against wind force he down feather have no hooks and its use is to insulate heat. These type of feathers occur in herons, parrots and hawks. The semi plumes lies beneath the down feathers. It help to insulation and more aerodynamic then the down feather. The filoplunmes are long and have hair like, it have sensory corpuscles to let the bird know where its feather is when its flying. The bristlier have fewer hooks it is mainly found around the eyes and near the mouth. When birds fly the wing muscles have to stretch so it can touch the breast bone. The head of a bird can't b heavy or the weight wont be equal. The bird bones are hollow in the inside so it will be less weight so it is not as heavy.

Mass Extinction

Joseph Laurente

Opening Statement Outline

  1. Mass extinctions have caused drastic changes in the environment. -The species that once lived before is now extinct due to the course of evolution.
    1. Last dinosaur species died out 65 million years ago.
    2. Researchers discovered that species had been dying off since life began when they examined layers of rock.
  2. When did it happen? -Almost four billion years ago, and 98% of the species that once lived are now extinct.
  3. Differences in mass extinction theories
    1. A large asteroid that hit the Earth and caused mass extinctions.
      1. Caused tons of dust to get mixed with the atmosphere and changed the environment so that animals could not live.
    2. 240 million years ago, 80%-96% of species have disappeared because it is believed that the impact of the asteroid caused the mass extinctions and made it worse.
  4. What we believe: -We believe that the impact of the asteroid caused the mass extinctions and made it worse.

Critique

Opening Statement

Mass extinctions have caused drastic changes in the environment. The species that once lived before is now extinct due to the course of evolution. For example, the last dinosaur species died out 65 million years ago, and researchers discovered that species had been dying off since life began when they examined layers of rock. This happened almost four billion years ago, and 98% of the species that once lived are now extinct. It is believed that a large asteroid that hit the Earth caused mass extinctions. The asteroid caused tons of dust to get mixed with the atmosphere and changed the environment so that animals could not live. Although, our side believes that the impact of the asteroid caused the mass extinctions and made it worse.

Rebuttal Outline

  1. Why we believe that the impact of the asteroid caused mass extinctions and made it worse:
    1. If the impact occurred in the oceans, giant tsunamis would be generated, and flood the interior of continents.
    2. Pangaea split apart and tectonic plate action occurred.
    3. Massive earthquakes could occur if an object like an asteroid hit the earth
    4. The asteroid could have caused volcanoes to erupt.

Critique

Mass Extinctions Outline

  1. Mass extinctions have caused drastic changes in the environment.
    1. The species that once lived before is now extinct due to the course of evolution.
      1. Last dinosaur species died out 65 million years ago.
      2. Researchers discovered that species had been dying off since life began when they examined layers of rock.
  2. When did it happen?
    1. Almost four billion years ago, and 98% of the species that once lived are now extinct.
  3. Differences in mass extinction theories
    1. A large asteroid that hit the Earth and caused mass extinctions.
      1. Caused tons of dust to get mixed with the atmosphere and changed the environment so that animals could not live. The large quantities of dust put into the atmosphere would block incoming solar radiation. The dust could take months to settle back to the surface. The Earth would be in darkness and temperatures would drop throughout the world, creating global winter like conditions.
      2. 240 million years ago, 80%-96% of species have disappeared because it is believed that the impact of the asteroid caused the mass extinctions and made it worse.
  4. What we believe:
    1. We believe that the impact of the asteroid caused the mass extinctions and made it worse.
      1. Smaller objects would certainly destroy the ecosystem in the area of the impact, similar to the effects of a volcanic eruption, while larger objects could have a worldwide effect on life on the Earth.
      2. Waves of pressures traveled to the other side of the Earth and caused volcanic eruptions.
      3. Large amounts of nitrogen oxides would be produced from combining Nitrogen and Oxygen in the atmosphere due to the shock produced by the impact. The nitrogen oxides would combine with water in the atmosphere to produce nitric acid which would fall back to the surface as acid rain.
      4. If the impact occurred in the oceans, giant tsunamis would be generated. The leading edge would hit the seafloor of the deep ocean basins before the top of the object had reached sea level. The tsunami would produce high waves due to the impact, would could easily flood the interior of continents.
      5. A massive earthquake would result from the impact of the large asteroid with the Earth.
      6. The asteroid could not have caused the extinctions because fossil evidence shows that species had already been decreasing for thousands of years already.

Mass Extinction Summary

Mass extinctions have caused drastic changes in the environment. The species that once lived before is now extinct due to the course of evolution. For example, the last dinosaur species died out 65 million years ago, and researchers discovered that species had been dying off since life began when they examined layers of rock. This happened almost four billion years ago, and 98% of the species that once lived are now extinct. It is believed that a large asteroid that hit the Earth caused mass extinctions. The asteroid caused tons of dust to get mixed with the atmosphere and changed the environment so that animals could not live. Another reason why they were caused is due to the earth's climate and volcanic eruptions. However, the volcanoes could not have erupted if it wasn't for the impact of the asteroid when it hit the Earth. When the asteroid hit the Earth, waves of pressures traveled to the other side of the Earth and caused the volcanoes to erupt. At least 5 major episodes of mass extinctions occurred since life developed on Earth. 240 million years ago, 80%-96% of species have disappeared. Marine organisms and species that lived in the ocean died, such as flat shellfish called trilobites and a group of fish called placoderms. Then, two other mass extinctions occurred which marked the end of the Ordovician period about 435 million years ago and in the Devonian period about 360 million years ago. During these times, tens of thousands of marine species have died. Furthermore, another mass extinction occurred during 205 million years ago, ending the Triassic period. Many species of amphibians and reptiles died, and their extinction set the rise of the dinosaurs. And lastly, the end of the mass extinction occurred during the Mesozoic Era 65 million years ago. During this time, dinosaurs, terrestrial species and marine animals died. Their deaths lead to the rise of mammals and marked the beginning of the Cenozoic Era, the era, which we live in today.

Ashley Mooring

Refute Outline

  1. Problems with the Meteor
    1. The meteor could have caused the extinction of the dinosaurs, but it would have caused acid rain, atmospheric dust leading to darkness for years, wildfire and tidal waves kilometers high
    2. However, there are problems with this explanation
      1. Different fossils give different stories in different places
      2. There are some dinosaur fossils above the KT boundary
  2. Other Problems

Critique

Refute Outline

  1. Meteor could have caused the mass extinction.
  2. The meteor buried itself in the Southern Gulf of Mexico
  3. Such a meteor would have caused
    1. acid rain
    2. Atmospheric dust leading to darkness for years
    3. Wildfires
    4. Tidal waves kilometers high
  4. Problems with this explanation
    1. Different fossils were found in different places.
    2. Some dinosaur fossils found above the K/T boundary
  5. Problem with philosopy
    1. The lack of dinosaures in a geological bed is only falsified if the dinosaurs are found.
    2. Pehaps there was not an extinctions.
    3. Perhaps the dinosaurs never reached the place where the bed originated.
  6. Birds are descendents of the Therapid reptiles.
    1. If the birds are dinosaurs, then they din't die out.
    2. It’s a pseudo-extinction (false extinction)

Patricia Nolan

Outline

  1. The spices that appeared 3 billon years ago were in serious danger because of the change of the water level climate change and the salinity. basically the vast spectrums was

Critique

Summary

During or research on the dinosaurs of our time we found out that there were the last species that died millions years ago. There were rocks that had to be examined by the layer and the researchers found out that the species had been dying since life began which was 4 billon years ago. 98% of the species that once lived are now extinct. The species vanished from natural course of evolution. Many of the ecologists believe that the environment has the main powerhouse of evolution. I agree that the asteroid caused tons of dust that mixed up the atmosphere that change the environment, which also made it hard for them to survive. There were many arguments that were surrounded around extinction and what caused eruption and how it spreaded. Our out come of this was that the extinctions were linked to drastic change of the environment and the asteroid impact etc. The measurements of the different isotopes of gases trapped in the buck ball that revealed unusual ratios of helium and argon. 90% of life's oceans disappeared within a millons years the first vertebrates were the most improvement of the body at the end of the Triassic. The Triassic basically began with mass and extinction and ended with one.

Mina Pan

Outline for the Closing Statements:

  1. Main Topic Question: Did asteroid cause effects of mass extinctions?
    1. Geographic Evidence:
      1. Researchers in Japan and China has discover a space rock as large as seven miles wide has hit Earth
      2. Was during the Permian-Triassic extinction event period. II. The Asteroid's Effects:
      3. When the asteroid smashed to Earth it has set off an immense wave of superheated vapor that can roll for hundreds of miles.
      4. While the superheated vapor spread, it kills everything in its way.
      5. The asteroid also caused tidal waves that sent million tons of dust particles and vapor into the atmosphere.
      6. The dust particles and vapor in the atmosphere cause the sun to darken for months and cause the Earth's temperature to decrease.
  2. Particles Left from the Asteroids:
    1. The Permian-Triassic impactor, either an asteroid or comet, left behind subtle deposits of buckminsterfullerenes, or "Buckyballs,"
      1. A form of carbon shaped like a volley ball with a hollow cage-like cavity inside.
    2. Provides strong evidence that the Permian-Triassic extinction was either triggered or speeded up by a massive object falling from space

Critique

Massive Extinction Summary

In 65 million years ago, the very last dinosaur had died off. By examining the layers of the rocks, the researched found out that the species had been dying off since life began. Almost 4 billion years ago. The researcher also found out that 98 percent of the species that once lived are now extinct. People think that the species has vanished because of the natural causes of the evolution. Later on, ecologists stated that the environments have been the main "powerhouse" for the evolution. Theories also say that a large asteroid that hit the Earth causes extinctions of dinosaurs. The large asteroid caused tons of dust particles to get mixed with the atmosphere and caused the change in weather. The changes in the environment lead to the large species dying off. There were also other arguments that say extinctions could be also caused by the widespread volcanic eruptions. So now, this could be combination of factors, which had killed off the dinosaurs. Earth's climate could most likely cause for the dinosaurs to go extinct. Scientists are not sure if the extinctions are really caused be the asteroid because fossil evidence shows that the species had already been dying off for thousands of years. When the asteroid hit the Earth, it might not effects the whole Earth but the waves of pressures traveled to the other side of the Earth could cause the volcanic eruptions.

Silvia Sanchez

Outline

Critique

Summary

Mass Extinction Meteor caused dinosaur extinction It was like 12.0 earthquake The rock was 12 km across. When it hit the earth, helium from buckyball explore. buckyball has 60 carbon atoms The temperature rose up Fill with carbons Gases cover the skies Dust and aerosols were thrown in the air Sky became dark for months Block out the sun-like a nuclear war

Nancy Nguyen

Outline

  1. Opening Statement
    1. Definition of Mass Extinction
    2. Meteor hit 65 million years ago and that is what caused the dinosaur to extinct
  2. paleontologist Charles Marshall of UCLA and geologist Peter Ward of the University of Washington in Seattle
    1. also present evidence that other factors, including a drop in sea level prior to the assault by the massive asteroid or comet, also may have caused some of the extinctions at the end of what is known as the Cretaceous period. Marshall and Ward present evidence demonstrating that a combination of factors caused the mass extinctions.

Critique

Mass Extinction Outline

  1. Definition of mass extinction: Mass Extinction is when a whole group of species get extinct or by definition, dramatic events.
  2. Opening Statement: Of all the species that have lived on the Earth since life first appeared here 3 billion years ago, only about one in a thousand is still living today. All the others, the vast majority, became extinct, typically within ten million years or so of their first appearance. Today, we will debate on whether the dinosaur mass extinction was caused because a meteor hit and caused the extinction or whether the meteor hit and caused environmental problems. My team today will prove that the meteor hit Earth and it caused the extinctions. Another way is saying this is that the dinosaur extinction was caused by a catastrophic agent.
  3. Evidence
    1. Geologist Walter Alvarez of the University of California at Berkeley who first found the cause of the dinosaurs death across the globe in trace deposits of iridium, which is a metal element from outer space.
      1. Levels of iridium found in Gubbio, Italy were roughly 30 times the normal levels.
        1. Extremely rare element
      2. Calculated that a chondritic asteroid approximately 10km in diameter would contain enough iridium to account for the iridium spike contained in the clay layer.
    2. In 1990 a scientist called Alan Hildebrand 'found' a ring structure 180km in diameter which was called Chicxulub. The location of this structure was just off the northwest tip of the Yucatan Peninsula. The crater has been dated (using the 40Ar/39Ar method) as being 65 million years old. The size of the crater is comparable to that which would have been caused by an impacting body with a diameter of roughly l0km. So we now have some of the proof of the asteroid theory. We know that a chondritic meteorite with a diameter of l0km contains enough iridium to cause a spike. We also know that about 65 million years ago there was an impact of a large object.
      1. If a 10km diameter object impacted at the point at which it struck it would have a velocity of roughly 100,000 km/h. At this velocity there would have been an initial blast (with an estimated force of many millions of tons of TNT) which would have destroyed everything within a radius of between 400 and 500km, including the object.
      2. At the same time large fires would have been started by the intense shock wave which would have traveled long distances. Trillions of tons of debris (dust, gases and water vapour) would have been thrown into the atmosphere when the object vaporized. C. Tektites and stishovites, rocks that are made from great heat and pressure, have been found to be around 65 million years old. 1. Tektites were probably formed during a meteorite or comet collision.

Extinction Summary

Scientists say that 250 million years ago a comet or asteroid that hit earth is what caused the dinosaur extinction millions of years later. The crash could've set off violent volcanic eruptions that caused land to be covered with hot lava. Gas isotopes were trapped in carbons and eventually carried to earth by a comet or asteroid. 250 million years ago, when Permian period was ending, the tectonic processes of continental drift began splitting pangea apart. Carbon Dioxide made most existing species extinct. Only a few can survive. 185 million years after great dying, dinosaurs extinct 65 million years ago from crash of space object. The impact created a giant chicxulub crater. Cause of dinosaur's death across the globe in trace deposits of iridium, a metal element from outer space.

Michael Vo

Outline

  1. My Theory:
    1. My Theory Is That 65 Million Years Ago,
    2. When The Meteor Hits The Earth, It Kill about 20% of the dinosaurs,
    3. but after the meteor hit Earth,
      1. all kind of chain reaction happen and kill the rest of the creatures.
  2. info:
    1. Impact of meteorite, drop in sea level caused mass extinctions 65 million years ago

Critique

Mass Extinction Outline

  1. Know the Theory
    1. Asteroid slammed into Earth 65 million years ago, presaging the demise of the dinosaurs and the rise of mammals. There is a crater in Mexico to prove it, as well as heavy concentrations of iridium
    2. a signature of asteroids
    3. spread around the world in soil dated to that time.
  2. Evidence
    1. Earthquakes during the impact of asteroid.
    2. Iridium
    3. 70% of all living things was destroyed
  3. Shows How Evidence Supports Theory
    1. Earthquakes: The tremendous energy of the impact shattered the underlying bedrock into a pile of rubble small rocks and large boulders. It also generated vibrating acoustic waves (acoustic fluidization = solid to liquid)
    2. Iridium was found throughout the world, Iridium is extraterrestrial not found on Earth meaning impact was big.
    3. 70 percent of all living things was destroyed, since
      some predators needed certain preys to live, predators
      then died out.
  4. Master of Opposing Theory
    1. Volcanic activity or extreme climate changes from asteroid.
    2. Many species became extinct gradually due to climate and habitat changes. The meteor impact, followed by extended darkness from dust and debris thrown into the atmosphere, followed by more climate changes, probably weakened the last remaining dinosaurs. The giant meteor may have provided a dramatic ending, but probably was not the only cause of dinosaur extinction.

Peter Tran

Outline

none

Critique

Ursula Choice

Outline

  1. When a meteor hit 65 million years ago, it destroyed the environment and killed off the food sources for the dinosaurs.