Dinosaurs and Birds...
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There's a ton of literature on this topic, but here's a couple of links that might be interesting...
One of my favourite science papers of all time, by paleontologist Paul Sereno, is a review of the Evolution of Dinosaurs, and includes a discussion of the origin of flight. The topic is vast, but Sereno's review does a brilliant job of pulling together some of the most important (and interesting) themes. The paper is available here (http://www.sciencemag.org/content/284/5423/2137), but you may need a subscription. Anyway, incase you can't access it, here's a screengrab of a figure showing how the various features that birds possess that enable flight originally appeared in various dinosaur species at different periods of time.
This figure was included in a recent journal article on the 'controversy surrounding the dinosaurian origin of birds' (free text available here: http://link.springer.com/article/10.1007/s12064-013-0192-5). I found this latter article by searching 'dinosaurs birds' here: http://www.ncbi.nlm.nih.gov/pubmed/. It concludes:
As for Sereno's paper, I literally carry a copy of it everywhere I go (it's on my phone
)
One of my favourite science papers of all time, by paleontologist Paul Sereno, is a review of the Evolution of Dinosaurs, and includes a discussion of the origin of flight. The topic is vast, but Sereno's review does a brilliant job of pulling together some of the most important (and interesting) themes. The paper is available here (http://www.sciencemag.org/content/284/5423/2137), but you may need a subscription. Anyway, incase you can't access it, here's a screengrab of a figure showing how the various features that birds possess that enable flight originally appeared in various dinosaur species at different periods of time.
This figure was included in a recent journal article on the 'controversy surrounding the dinosaurian origin of birds' (free text available here: http://link.springer.com/article/10.1007/s12064-013-0192-5). I found this latter article by searching 'dinosaurs birds' here: http://www.ncbi.nlm.nih.gov/pubmed/. It concludes:
As for Sereno's paper, I literally carry a copy of it everywhere I go (it's on my phone
)
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Not quite on the subject of Dinosaur/Bird genetics, but it made me think of this:
...
Dinosaurs... a Breakfast 65,000,000 years in the making.
...
Dinosaurs... a Breakfast 65,000,000 years in the making.
Dotini
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The ostrich is a heavy but flightless bird.
What are some of the largest and heaviest birds that can fly? What are their wingspans and weight?
On my nearby beach, I can see eagles and great blue herons. In South America, I've seen the very impressive and stately condor. The albatross, a.k.a. "gooney bird", is a large and ungainly, almost laughable thing when trying to land or take to flight, but once aloft is quite graceful.
In my back yard, I have a bird bath - heated in freezing weather - and several kinds of feeders.
To me, the most fascinating of all birds or dinosaurs is the extinct pterosaur.
From wikipedia:
Some species of pterosaurs grew to very large sizes and this has implications for their capacity for flight. Many pterosaurs were small but the largest had wingspans which exceeded 9 m (30 ft). The largest of these are estimated to have weighed 250 kilograms (550 lb). For comparison, the Wandering Albatross has the largest wingspan of living birds at up to 3.5 m (11 ft) but usually weighs less than 12 kilograms (26 lb). This indicates that the largest pterosaurs may have had greater wing loadings than modern birds (depending on wing profile) and this has implications for the manner in which pterosaur flight might differ from that of modern birds.
I've heard some paleontologists speculate the pterosaur had to jump off a cliff or mountain top in order to fly, soar, glide or whatever they did. But because this would leave them terribly vulnerable on low ground, and they flourished from 225 million years to 65 million years ago (a not inconsiderable span of time), it seems unlikely to me that they were particularly vulnerable.
What do you suppose was the purpose of the enormous crest carried on the skull? I have my ideas but they would make you laugh.
Do you think the skeletons of these creatures were the basis of worldwide legends of dragons? If not, what was??
What are some of the largest and heaviest birds that can fly? What are their wingspans and weight?
On my nearby beach, I can see eagles and great blue herons. In South America, I've seen the very impressive and stately condor. The albatross, a.k.a. "gooney bird", is a large and ungainly, almost laughable thing when trying to land or take to flight, but once aloft is quite graceful.
In my back yard, I have a bird bath - heated in freezing weather - and several kinds of feeders.
To me, the most fascinating of all birds or dinosaurs is the extinct pterosaur.
From wikipedia:
Some species of pterosaurs grew to very large sizes and this has implications for their capacity for flight. Many pterosaurs were small but the largest had wingspans which exceeded 9 m (30 ft). The largest of these are estimated to have weighed 250 kilograms (550 lb). For comparison, the Wandering Albatross has the largest wingspan of living birds at up to 3.5 m (11 ft) but usually weighs less than 12 kilograms (26 lb). This indicates that the largest pterosaurs may have had greater wing loadings than modern birds (depending on wing profile) and this has implications for the manner in which pterosaur flight might differ from that of modern birds.
I've heard some paleontologists speculate the pterosaur had to jump off a cliff or mountain top in order to fly, soar, glide or whatever they did. But because this would leave them terribly vulnerable on low ground, and they flourished from 225 million years to 65 million years ago (a not inconsiderable span of time), it seems unlikely to me that they were particularly vulnerable.
What do you suppose was the purpose of the enormous crest carried on the skull? I have my ideas but they would make you laugh.
Do you think the skeletons of these creatures were the basis of worldwide legends of dragons? If not, what was??
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Cap'n Jack
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Well, there's one theory about the cassowary - a large flightless bird native to Australia, which carries a large crest (known as a "casque") on its head is that it acts as a resonating chamber. Cassowaries have an extremely low frequency call, one that humans can only barely hear, so this helps amplify the sound. And if anyone has any doubt that birds have descended from dinosaurs, one look at the cassowary will definitely convince you!
I prefer not to discuss because I don't have a clue. I don't know anything about dinosaurs and birds and the palaeontologist don't either. 
/joke ofcourse before I get accused of being negative again.
Although I'm very much interested in palaeontology, I can't say anything interesting, to my regrets. I'm though, going to read this thread with a lot of interest.
/joke ofcourse before I get accused of being negative again.
Although I'm very much interested in palaeontology, I can't say anything interesting, to my regrets. I'm though, going to read this thread with a lot of interest.
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Cap'n Jack
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Oops...
Dilong paradoxus
From the article 'Basal tyrannosauroids from China and evidence for protofeathers in tyrannosauroids' (from here or here)
Also, T. rex is more closely related to modern-day birds than most other dinosaurs...
http://tolweb.org/Coelurosauria/15769
Note that the classification used here is taken from the paper I referenced above:
http://www.sciencemag.org/content/284/5423/2137.full.pdf
Dotini
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A crocodile is a dinosaur, pure and simple, exactly like it was millions of years ago. Right?
It has short legs, slithers on its belly, and does well in water and mud. If it came after you on dry land, perhaps you could outrun it on good legs before you had to wrestle it and put duct tape around its snout.
Dotini
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The Cretaceous ended with a large mass extinction, the Cretaceous–Paleogene extinction event, in which many groups, including non-avian dinosaurs, pterosaurs and large marine reptiles, died out. The end of the Cretaceous is defined by the K–Pg boundary, a geologic signature associated with the mass extinction which lies between the Mesozoic and Cenozoic eras.
From wikipedia: http://en.wikipedia.org/wiki/Cretaceous
The alligator, or crocodile, was a survivor. How?
Dotini
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So it would seem - except for crocodiles.
Crocodyliforms[edit]
Ten families of crocodilians or their close relatives are represented in the Maastrichtian fossil records, of which five died out prior to the K–Pg boundary.[67] Five families have both Maastrichtian and Paleocene fossil representatives. All of the surviving families of crocodyliforms inhabited freshwater and terrestrial environments—except for the Dyrosauridae, which lived in freshwater and marine locations. Approximately 50% of crocodyliform representatives survived across the K–Pg boundary, the only apparent trend being that no large crocodiles survived.[22] Crocodyliform survivability across the boundary may have resulted from their aquatic niche and ability to burrow, which reduced susceptibility to negative environmental effects at the boundary.[49] Jouve and colleagues suggested in 2008 that juvenile marine crocodyliforms lived in freshwater environments like modern marine crocodile juveniles, which would have helped them survive where other marine reptiles became extinct; freshwater environments were not as strongly affected by the K–Pg extinction event as marine environments.[68]
The Choristodera, a generally crocodile-like group of uncertain phylogeny (possibly archosaurian) also survived the event, only to go extinct in the Miocene.[69]
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Dotini
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They do seem similar in ways, but apparently they had a somewhat different evolutionary path.
From wikipedia:
Pterosaurs are often referred to in the popular media and by the general public as flying dinosaurs, but this is incorrect. The term "dinosaur" is restricted to just those reptiles descended from the last common ancestor of the groups Saurischia and Ornithischia (clade Dinosauria, which includes birds), and current scientific consensus is that this group excludes the pterosaurs, as well as the various groups of extinct marine reptiles, such as ichthyosaurs, plesiosaurs, and mosasaurs.[7] Pterosaurs are also incorrectly referred to as pterodactyls, particularly by journalists.[8] "Pterodactyl" refers specifically to members of the genus Pterodactylus,[9] and more broadly to members of the suborder Pterodactyloidea of the pterosaurs.[10][11]
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Birds with the power of flight already existed during dinosaur times. They largely resemble modern birds with the addition of still possessing teeth. The feathers in birds are modified scales, whereas pterosaurs have skin membranes that stretch from their ankles to a very long fourth finger, similar to a bats. Pterosaur flight was probably far less efficient than bird flight, as the membranes could be damaged easily, particularly among trees, and their great size meant the largest ones were probably pretty damn heavy. They were also probably very slow-moving on the ground, as they would have to crawl on all fours with their wings folded round their backs, putting them at the mercy of predators.
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