Fossils of pterosaurs !!!

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Fossils of pterosaurs !!!

by AIM GMAT » Wed Jan 26, 2011 7:43 am
The fossil remains of the first flying vertebrates, the pterosaurs, have intrigued paleontologists for more than two centuries. How such large creatures, which weighed in some cases as much as a piloted hang-glider and had wingspans from 8 to 12 meters, solved the problems of powered flight, and exactly what these creatures were-reptiles or birds-are among the questions scientists have puzzled over.
Perhaps the least controversial assertion about the pterosaurs is that they were reptiles. Their skulls, pelvises, and hind feet are reptilian. The anatomy of their wings suggests that they did not evolve into the class of birds. In pterosaurs a greatly elongated fourth finger of each forelimb supported a wing-like membrane. The other fingers were short and reptilian, with sharp claws. In birds the second finger is the principal strut of the wing, which consists primarily of feathers. If the pterosaurs walked on all fours, the three short fingers may have been employed for grasping. When a pterosaur walked or remained stationary, the fourth finger, and with it the wing, could only turn upward in an extended inverted V-shape along each side of the animal's body.
The pterosaurs resembled both birds and bats in their overall structure and proportions. This is not surprising because the design of any flying vertebrate is subject to aerodynamic constraints. Both the pterosaurs and the birds have hollow bones, a feature that represents a savings in weight. In the birds, however, these bones are reinforced more massively by internal struts.
Although scales typically cover reptiles, the pterosaurs probably had hairy coats. T. H. Huxley reasoned that flying vertebrates must have been warm-blooded because flying implies a high rate of metabolism, which in turn implies a high internal temperature. Huxley speculated that a coat of hair would insulate against loss of body heat and might streamline the body to reduce drag in flight. The recent discovery of a pterosaur specimen covered in long, dense, and relatively thick hairlike fossil material was the first clear evidence that his reasoning was correct.
Efforts to explain how the pterosaurs became airborne have led to suggestions that they launched themselves by jumping from cliffs, by dropping from trees, or even by rising into light winds from the crests of waves. Each hypothesis has its difficulties. The first wrongly assumes that the pterosaurs' hind feet resembled a bat's and could serve as hooks by which the animal could hang in preparation for flight. The second hypothesis seems unlikely because large pterosaurs could not have landed in trees without damaging their wings. The third calls for high waves to channel updrafts. The wind that made such waves however, might have been too strong for the pterosaurs to control their flight once airborne.


Q1] .It can be inferred from the passage that which of the following is characteristic of the pterosaurs?
(A) They were unable to fold their wings when not in use.
(B) They hung upside down from branches as bats do before flight.
(C) They flew in order to capture prey.
(D) They were an early stage in the evolution of the birds.
(E) They lived primarily in a forest-like habitat.



Q2] . It can be inferred from the passage that some scientists believe that pterosaurs
(A) lived near large bodies of water
(B) had sharp teeth for tearing food
(C) were attacked and eaten by larger reptiles
(D) had longer tails than many birds
(E) consumed twice their weight daily to maintain their body temperature

Q3] The ideas attributed to T. H. Huxley in the passage suggest that he would most likely agree with which of the following statements?
(A) An animal's brain size has little bearing on its ability to master complex behaviors.
(B) An animal's appearance is often influenced by environmental requirements and physical capabilities.
(C) Animals within a given family group are unlikely to change their appearance dramatically over a period of time.
(D) The origin of flight in vertebrates was an accidental development rather than the outcome of specialization or adaptation.
(E) The pterosaurs should be classified as birds, not reptiles.



OA after disscussion
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by bblast » Wed Jan 26, 2011 11:41 am
A
A
B

friendly and interesting passage. I'll give my reasoning if m correct, else I'll be beating around the bush :)

this is a kind of an easier passage. You will be lucky to get such passages on the GMAT. I personally hate the political, women activists type passages.
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by AIM GMAT » Wed Jan 26, 2011 11:03 pm
bblast wrote:A
A
B

friendly and interesting passage. I'll give my reasoning if m correct, else I'll be beating around the bush :)

this is a kind of an easier passage. You will be lucky to get such passages on the GMAT. I personally hate the political, women activists type passages.
Bang on !!! All correct . Can u give explanatiion especially for 1 and 2 . This is LSAT passage , it originally have 7 questions , do u want to solve the rest as well. I stumped at 1 and 2 :)
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by bblast » Thu Jan 27, 2011 1:01 am
1>The answer to the first question lies in the last line of the second paragraph. Take out 4 fingers of ur right hand and try and imitate what the author is describing.


When a pterosaur walked or remained stationary, the fourth finger, and with it the wing, could only turn upward in an extended inverted V-shape along each side of the animal's body.



the plet$#@sauras has the 4th finger as its wing, in birds the second finger is the wing.



2>Now this one is really really tricky :


Q2] . It can be inferred from the passage that some scientists believe that pterosaurs

(A) lived near large bodies of water hmmmmmm
(B) had sharp teeth for tearing food no mention of this
(C) were attacked and eaten by larger reptiles useless, no other reptiles mentioned
(D) had longer tails than many birds useless, no mention of tails
(E) consumed twice their weight daily to maintain their body temperature hmmmmmmmmmm


E comes really close as prof Huxley talks of warm blooded animals, but the problem is that nowhere does he talk about consumtion of food.(I am sure this is the answer u would have gone for ?)


But the start of para 2 says->>Perhaps the least controversial assertion about the pterosaurs is that they were reptiles. Their skulls, pelvises, and hind feet are reptilian. The anatomy of their wings suggests that they did not evolve into the class of birds.
bang on this implies that they were reptiles, (mind u this answer aint too convincing either, but u gotta pick the best out of the crap)

This made me choose A. However I wont bank 2 much on this answer. There is no other mention is the passage which would interest u to choose any other option.
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by AIM GMAT » Thu Jan 27, 2011 1:10 am
Thanks Kumar Pushkal . yes you are absolutely right about the Q2 no reference about any of the option .

I started practicing LSAT passages because they are longer than GMAT ones , to imporve the endurance , is my strategy correct ? Any views on this ............... ?
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by bblast » Thu Jan 27, 2011 2:17 am
AIM GMAT wrote:Thanks Kumar Pushkal . yes you are absolutely right about the Q2 no reference about any of the option .

I started practicing LSAT passages because they are longer than GMAT ones , to imporve the endurance , is my strategy correct ? Any views on this ............... ?
yes do the lsat passages.

but do not time the entire 7 questions, only set a timer of 7-8 minutes, read the passage, solve the 4 questions.(u can solve all 7 questions for additional practice)



also dont be disheartened if u get like 4/7 correct.

but make sure u get at least 3 out of the first 4 correct, and more often than not, get 4/4 correct for the 1st four questions.

it is easy to loose the context of the passage after question 5-6(after 10 mins), so dnt worry if u get answers wrong then,
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by bblast » Tue Mar 15, 2011 12:34 pm
aim...r u done with ur exam ?
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by AIM GMAT » Tue Mar 15, 2011 11:14 pm
bblast wrote:aim...r u done with ur exam ?
Nope , not yet but soon will get past GMAT . :)
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by HSPA » Wed Mar 16, 2011 3:35 am
Wow... AIM GMAT... welcome to RC

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by HSPA » Wed Mar 16, 2011 4:39 am
topic : ptrosaurs
scope: bird/reptile and flight

2nd para: pov on reptile
3rd para: pov on bird
4th: Some doctor and his proof
5th: flight control

Q1] .It can be inferred from the passage that which of the following is characteristic of the pterosaurs?
(A) They were unable to fold their wings when not in use. [they have v shaped wings when folded]
(B) They hung upside down from branches as bats do before flight. [they cannot land on trees as wings may get damaged]
(C) They flew in order to capture prey. [ Not mentioned any where or I missed in last para]
(D) They were an early stage in the evolution of the birds. [least controversila assertion is reptiles.. copy paste from para2]
(E) They lived primarily in a forest-like habitat. [they cannot land in trees]

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by bblast » Wed Mar 16, 2011 7:04 am
AIM GMAT wrote:
bblast wrote:aim...r u done with ur exam ?
Nope , not yet but soon will get past GMAT . :)
i might be back soon with a bigger plan,,,,watch out,,,:)
Cheers !!

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