oocyte
oocyte The cell that, following
meiosis, forms the
ovum. Most of the cytoplasmic growth involved in ovum formation is accomplished by the primary oocyte; this undergoes the first meiotic division, giving rise to two cells, the polar body, with very little
cytoplasm, and the secondary oocyte, which has a large amount of cytoplasm. This latter oocyte undergoes the second meiotic division to give rise to another polar body and an ovum. Fertilization often takes place without the formation of an ovum at one of the two oocyte stages.
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Posture, Locomotion, and Paleoecology of Pterosaurs
Magazine article from: Journal of Paleontology; 5/1/2005; ; 700+ words
; ...general review of pterosaurs and their literature...understanding of pterosaur flight. The majority...general review of pterosaurs that is rather...misinterpretations of pterosaurs. The interpretation of pterosaur wing structure...
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Pterosaur footprints show it touched down like most modern birds.
News Wire article from: Asian News International; 8/19/2009; 700+ words
; ...whether the largest pterosaurs could fly at all...some answers to pterosaur behaviour. "They...in the life of a pterosaur", they offer...that the largest pterosaurs took flight by...the other hand, pterosaurs seem perfectly...depending on the pterosaur," he said...
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Estimating the effects of sampling biases on pterosaur diversity patterns: implications for hypotheses of bird/pterosaur competitive replacement
Magazine article from: Paleobiology; 7/1/2009; ; 700+ words
; ...terrestrial abilities of pterosaurs, their apparent...fragile nature of the pterosaur wing apparatus...and Cretaceous pterosaurs and birds and identified...gradual decline in pterosaur diversity beginning...may have driven pterosaur decline, with...competitively) replacing pterosaurs ...
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 "Rocky Mountain News (Denver, CO)")
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PTEROSAURS: MORE LIZARD THAN BIRD NEW EVIDENCE PRESENTED ON PREHISTORIC CREATURES.(News)
Newspaper article from: Rocky Mountain News (Denver, CO); 11/5/2004; ; 700+ words
; ...turtles. The word "pterosaur," in fact, means...that the parents (of pterosaurs) incubated their eggs...readiness of newborn pterosaurs after examining the...they studied an intact pterosaur embryo recently uncovered...Nature, showed that pterosaurs laid soft-shelled...
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Four, Three, Two, One ... Pterosaurs Have Lift Off! Hopkins Researcher Reports That Ancient Flying Reptiles Used Four Legs to Launch.
News Wire article from: Ascribe Higher Education News Service; 1/6/2009; 700+ words
; ...6 (AScribe Newswire) -- Pterosaurs have long suffered an identity...heft into flight required pterosaurs to use four limbs: two were...classical bipedal model of pterosaur take-off was first championed...EDITORS: Illustrations of pterosaurs available for download at...
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Test flight: look! Up in the sky! It's a bird! It's a plane! It's ... a pterosaur?(LIFE/PHYSICAL)
Magazine article from: Current Science, a Weekly Reader publication; 3/3/2006; ; 700+ words
; ...learn about a pterosaur from its fossilized...extinction of the pterosaurs? National...once thought pterosaurs were shaky fliers. A pterosaur wing was essentially...extraordinarily difficult pterosaur to build...constructed. Pterosaurs' wing bones...
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Fossil pterosaur egg found in Jehol Biota
Newspaper article from: China Daily; 6/14/2004; ; 700+ words
; ...published their fossil find of a pterosaur embryo, the first of its...corroborate the belief that the pterosaur was an egg-layer. Pterosaurs were contemporaries of the...the world, but so far no pterosaur embryos have been reported...
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Ancient pterosaur's wings unlike any found in living animals.
News Wire article from: Asian News International; 8/5/2009; 700+ words
; ...had been found on pterosaurs before, but researchers...newly examined pterosaur has the hairlike...have helped the pterosaurs control their body...said. The fossil pterosaur, Jeholopterus...Previous studies of pterosaur wings had shown...fibers unique to pterosaurs called ...
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Pterosaurs waddled when they walked? (dinosaur research)
Magazine article from: Science News; 5/30/1987; 579 words
; ...relativelyuncrushed pterosaur pelvises that were...suggesting that pterosaurs' legs were splayed...Unwin argues that pterosaurs were probably good...too far, since pterosaur anatomy is quite different. Pterosaurs, he writes...
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On the trail of pterosaurs. (tracks of winged reptiles indicate they walked on all four limbs)(Paleontology)(Brief Article)
Magazine article from: Science News; 11/2/1996; ; 700+ words
; ...supported the wing, which pterosaurs could fold backward over their...with trace prints made by pterosaurs," he says. Despite the new evidence, the debate over pterosaur locomotion marches on...these are convincing tracks of pterosaurs," declares Kevin Padian...
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pterosaur
Book article from: The Columbia Encyclopedia, Sixth Edition
pterosaur [Gr.,&thinsp...least 60 genera of pterosaurs have been found...flying apparatus of pterosaurs comprised a membranous...unique to the pterosaur group, attached...now believe that pterosaurs were adapted for...
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pterosaurs
Book article from: The Oxford Companion to the Earth
pterosaurs Pterosaurs are one of the three groups of terrestrial vertebrates that have...first to become extinct, dying out at the end of the Cretaceous. Pterosaurs were archosaurs, closely related to dinosaurs, and both groups...
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Solnhofen lithographic limestone fauna
Book article from: The Oxford Companion to the Earth
...including the wing membranes of pterosaurs (flying reptiles) and the...organisms such as dinosaurs, pterosaurs, and the earliest bird...of skeletal material. Some pterosaurs, such as the small form Pterodactylus...As the Archaeopteryx and pterosaur skeletons are generally complete...
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Convergence
Book article from: Animal Sciences
...different vertebrate taxa: pterosaurs (extinct flying reptiles...patterns with similar functions. Pterosaurs, like birds, had hollow...analogous to bird feathers. The pterosaur wing was supported primarily...surface area to the wing. In pterosaurs and bats the digits are elongated...
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Flight
Book article from: Biology
...tens of millions of years before the pterosaurs (extinct flying dinosaurs), and hundreds...vertebrates at least three times: in pterosaurs, birds, and bats. Although scientists know that pterosaurs, like bats, flew on wings consisting...
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