Is progress real?

[Azathoth]

recently some of you rember my rebuking of another member for mentioning-even jokingly, that dinosaurs are cold-blooded.

Aren't dinosaurs a mix of cold-blooded and warm-blooded species?

[Foot]

Aren't dinosaurs a mix of cold-blooded and warm-blooded species?

Only when you do a poor job of categorising Dinosaurs.

The Dimetrodon is not a dinosaur, though it is often assumed to be so (I know I did). It is a lizard and is cold-blooded (one theory states that the sail was used help heat the blood).

The Dinosaurs are, however, true warm-blooded creatures with fast metabolisms and all that jazz. They were traditionally classed as lizards (hence -sauros) and so were presumed to be cold-blooded. But nowadays Dinosaurs are viewed as warm-blooded (if they ain't warm-blooded they aint dinosaurs).

Foot

[antisocialmunky]

Cold/Warm blooded is a little outdated. Great White sharks are one of many animals that shares traits of both. Really the only difference is one generates it own heat, the other relys on external heat. Great Whites use muscle generated heat to keep its body temperature above the surrounding water's.

Same with dinosaurs. The only ones that are usually considered warm blooded are therapods - evidence isn't particularly supportive of either bloodedness for most dinosaurs.

[Ibrahim]

Cold/Warm blooded is a little outdated. Great White sharks are one of many animals that shares traits of both. Really the only difference is one generates it own heat, the other relys on external heat. Great Whites use muscle generated heat to keep its body temperature above the surrounding water's.

Same with dinosaurs. The only ones that are usually considered warm blooded are therapods - evidence is directly or indirectly supported for endothermy/homoiothermy/I can never remember the diff .

much better. now on with the rest of this post :

correct regarding the classification, metabolism wise; specifically, an animal's metabolism is devided in 3 grades:

ectothermy/endothermy: where the metabolism comes from
Homoiotherm/poikilotherm: the level of variation in an animal's metabolism
bradymetabolic/tachymetabolic: how high or low the resting metabolism is. I can't remember which is which.


as to dinosaur metabolism? what you said is incomplete: its now known that all three were fairly high: high metabolism, low to medium variation, and self generating heat. the reason we know this are as follows:

1)the animals most certainly had 4 chambered hearts; all living archosaurs (Birds and Crocodiles) do as well*. and genetic and embryological research has shown that the Crocodilians were natively warmblooded, then became cold blooded-like the naked Mole rat did. 4 chambered hearts are more powerfull/efficient than 3, so more metabolic energy is available for the dinosaur.

2) knowing what we now know about Sauropod and Theropod anatomy, they also had an avian respiration system-in fact this is the most efficient respiratory system possible. Ornithischains may have had it too, but no hollows in the vertebrae have been found in such animals (that's because in birds, the airsacs are in vertbrae as well as in the body cavity). this doesn't mean that they ornithischians had none: embroyologically, the airsacs in birds at first appear outside the bone, in the chest and abdominal cavity only.

3)its well know that theorpoda, especially Coelurosaurs, had feathers. even T-rex was likely a fuzzy fellow (at least as a hatchling/juvenile; after 1 ton mass, the feathers are no longer needed).

4)growth rates in Dinosaurs were closer to that found in warm blooded than cold blooded animals. that said, it was unusually slow**-closer to marsupial rates of growth than birds or mammals.

5)ecologically, it makes no sense that cold blooded animals would dominate warm blooded animals (in this case dinosaurs suppressed mammals, preventin them from occupying the larger niches). this doesn't even happen today. the only reason Komodo Dragons are dominant in their islands is because there are no warm blooded predators, and the now extinct Megalarnia prisca was rare, slow, and ecologically worthless. cold blooded animals do however have a good hold on semiaquatic environments, but as non-avian dinosaurs were almost totally terrestrial, I only worry about the Komodo.

6) more energy is required for the active, erect legged, bipedal stance of the T-rex or the Coelophysis than being squatted, as in a lizard's case (believe me, erect legs really are energy wasting), and the physics of many dinosaurs-especially the small and the early, are built in a cursorial manner-or great for running and agile moves. Crocodiles are a partial exception.


*However, Crocodiles also have a valve that allows the heart to act as a 3 chambered heart, especially when under water.
**this paper touches on the presence of growth rings as well as fibro-lamellar bone, which collectively indicate this. it also covers more stuff, but I invite you to read it


EDIT: I think the dinosaurian parts ought to be moved to the science forum, in the dinosaur thread.

[WinsingtonIII]

Hahaha and it appears that the thread Ludens created because it started as an off-topic conversation in another thread has now turned into another off-topic conversation about dinosaurs...

I'm not making fun of you guys, I love dinosaurs and I think it's an interesting topic, I just think it's great that this thread that derailed another thread has now been derailed as well. Where will it end?!?

[Ludens]

I think the dinosaurian parts ought to be moved to the science forum, in the dinosaur thread.

It does belong there, but I don't think it necessary unless someone really wants to pursue this "discussion".

[oudysseos]

There is a potentially interesting question as to how the people in EBs time frame viewed progress. Did they conflate successive technological and scientific discoveries with a linear advancement from 'primitive' to 'advanced' societies, as some in this thread have done? Did they have any conception at all of their society changing for the better, and for them to be agents of that change? That last bit is they key element to the modern idea of progress, in my mind. Why should you try and stop global warming, for instance, unless you want the future to be better than today? Did people in the Hellenistic era think that way? Or was it all apres moi le deluge?

One thing to look at would be the literary corpus of the time. This is almost all backwards-looking: Vergil wrote about Aneas from ca. 1,000 years before his own time. Appolonius of Rhodes wrote about Jason and the Argonauts from even further back. It was reasonably common for Roman aristocrats to write plays (Julius Caesar did so, although it was suppressed by Augustus), the themes of which were almost always taken from older Greek literature - and people like Plautus made careers out of rewriting the Greek classics in Latin.

So one possible conclusion is that the people who read and wrote books did not look to the future for anything. There is no 'science fiction' of people imaging what the world would be like in a technologically advanced future (Plato's Republic isn't so much about an alternative future as it is about an alternative past).

On the other hand, Aristotle is famous for his system of how types of governments can regress from a good example to a bad one: Monarchy becomes Tyranny, Democracy becomes Demagogy, and so on. The concepts needed for thinking in terms of 'progress' are inherent in that system - but I do not recall anyone saying, "O.K., we start out with Oligarchy and end up with Capitalist Democracies and MacDonalds."

In our own time, the idea of the whole world progressing towards being American-style Democracies is losing validity, although you still hear a great deal of cliched rhetoric in political circles. The economic troubles of the past few years have made capitalism look a little rusty as well- but just look back to the political dialogs of the 30s - as far as they were concerned, capitalism and democracy were gone with the dinosaurs. Who were warm blooded.

Personally, I think that a lot depends on what happens in the next 100 years, which I think will be a hard time for humanity. As global warming puts more and more people under strain, political unrest is sure to follow - the entire population of Florida, for example, will have to be relocated eventually, as will large parts of LA. Do you want them? But the economic consequences go way beyond that kind of immediate cause-and-effect. Currently, the lifestyle of 'The West' is predicated on the cheap labour, costs and resources of the Third World (just look at the labels on your stuff sometime). Never mind if child workers in Bangladesh were to get pissed off at working themselves to a shoeless death in a cesspit just so you can have a new pair of Nikes every few months - if climate change destroys the countries that provide us with the slave labour that makes our lives possible, our own economies will regress to a much lower level. Without the money to pay for CERN or LHC projects, scientific progress will also slow. I think we are headed for a period very similar to that of the fall of the Roman empire.