Forskel mellem versioner af "Fuglenes oprindelse"

1.591 bytes fjernet ,  for 5 år siden
Det er kun press releaset som siger at fugle ikke er dinosaurer, ikke papirer. Vi bør ikke citere press releases. Se
m (Gendannelse til seneste version ved Addbot, fjerner ændringer fra (diskussion | bidrag))
(Det er kun press releaset som siger at fugle ikke er dinosaurer, ikke papirer. Vi bør ikke citere press releases. Se
<ref>[ 11 July 2006, Big dinosaurs 'had warmer blood'] Citat: "...The bigger a dinosaur was, the warmer its blood...smallest dinosaurs had temperatures of around 25C, close to environmental temperatures...biggest dinosaurs – had a body temperature of just over 40C...Most animals cannot tolerate body temperatures of above 45C, so [[Apatosaurus]] is both near the upper limit..."</ref>
Der er en lille minoritet af forskere, mest prominent [[John A. Ruben]], som prøver at argumentere for at fugle ikke nedstammer fra dinosaurer.<ref></ref>
Senest er der dog igen dukket tvivl op om fugle stammer fra dinosaurer, da man har fundet fugle fra før dinosaurernes tid.
<ref>[ Oregon State University (2009, June 9). Discovery Raises New Doubts About Dinosaur-bird Links. ScienceDaily. Retrieved June 13, 2009] Citat: "..."This discovery probably means that birds evolved on a parallel path alongside dinosaurs, starting that process before most dinosaur species even existed."...Warm-blooded birds need about 20 times more oxygen than cold-blooded reptiles, and have evolved a unique lung structure that allows for a high rate of gas exchange and high activity level. Their unusual thigh complex is what helps support the lung and prevent its collapse...The implication, the researchers said, is that birds almost certainly did not descend from theropod dinosaurs, such as tyrannosaurus or allosaurus..."For one thing, birds are found earlier in the fossil record than the dinosaurs they are supposed to have descended from," Ruben said. "That's a pretty serious problem, and there are other inconsistencies with the bird-from-dinosaur theories..."</ref>
Herudover har man opdaget at [[alligator]]er ånder ligesom fugle.
<ref>[ University of Utah (2010, January 15). Alligators breathe like birds, study finds. ScienceDaily. Retrieved January 24, 2010] Citat: "...By demonstrating one-way or "unidirectional" airflow within the lungs of alligators, the new study -- published in the Jan. 15 issue of the journal Science -- means that such a breathing pattern likely evolved before 246 million years ago, when crocodilians split from the branch of the archosaur family tree that led to [[pterosaur]]s, [[dinosaur]]s and [[fugle|birds]]..."</ref>
Liste over primitive fugle: