Dinosaur questions

[sojourner]

^You mean like Tigons, Ligars and mules?

 

[The Dominion]

I was thinking trees (true story) horses and yes, mules.

 

[sojourner]

Have you been to Tijuana? I hear there is a whole show on the concept.

 

[Ln X]

Evidence suggests that they originally evolved in the tropical environment of a super continent nowhere near the poles (that's why you find them on every continent now), in a climate so warm that to be ektothermic was no disadvantage. The disintegration of that continent, and exposure to colder climates later on turned some subspecies warm blooded, encouraged the growth of feathers, brooding, and upbringing. Only eight different species of dinosaur fossils have been found on Antartica so far, none of them younger than 100 million years. When it started to get real cold. No problem for todays population of warm-blooded birds and mammals.
The only family of animals with a more complete fossil record than dinosaurs is even far older, trilobites. Almost 50,000 species have been identified.

What you're missing is that those species of dinosaurs living near the poles lived in ecosystems that were, as far as the fossil record shows, devoid of ectoterms like crocodiles, turtles, etc. This is highly suggestive that the environment was too cold for contemporary non-avian reptiles but not too cold for dinosaurs. The fact that dinosaurs but not "reptiles" could live in these high latitudes is suggestive of the fact that they were in fact warm-blooded to some degree.

Dinosaurs may not be warm blooded, but it is believed that many of them had feathers covering their skin as an extra insulative layer. Perhaps that allowed dinosaurs to live in colder climates than other reptiles?

 

[Sean Aaron]

Except that reptiles absorb energy from the sun through their skin/scales. Feathers would inhibit that ability, which is why the presence of an outer covering of feathers/fur would be interpreted as strong evidence of endothermy.

When you get really big it's easier to maintain body temperature, but you still need to heat up. Whether or not the large herbivores were endothermic is more in dispute, but given the apparent growth rate about the biggest like the Titanosaurs ectothermy isn't convincing. As I said upstream discoveries made in the past decade beyond the feathered therapods has changed a lot of thinking. Not that things are set in stone or there aren't disputes, but it's been quite an exciting time so if people aren't as current on the research then it might be surprising what the current theories are.

I strongly suggest anyone with an interest in the subject check out the BBC's recent series "Planet Dinosaur" which nicely summarises recent findings and has fantastic animation to boot. If you're in the New York City area the American Museum of Natural History also has a special exhibit on Titanosaurs which I had the good fortune to see when I was there on holiday this month.

 

[Cutter John]

This is a new spin on the current knowledge of the masses

Comes up with a message that it won't play outside the UK.

Try the tube.

http://www.youtube.com/watch?v=_bMCSKdgIA4

Though I have to say, its odd that the animation looks less convincing than Walking With Dinosaurs that came out nearly twelve years ago.

 

[Kemaiku]

T-Rex + Pterodactyl = Dragon.

Gentlemen. We have a Jurrasic Park 5 script.

 

[Sean Aaron]

Though I have to say, its odd that the animation looks less convincing than Walking With Dinosaurs that came out nearly twelve years ago.

I thought that initially, but if you get chance to see it full screen in HD, it's pretty impressive and the subtlety of the behaviour is really nicely done. I quickly forget I'm watching CGI.