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1) I doubt I have shared this in the Org. but apart from the Middle Ages, I am very keen on the Mezoic Period i.e. the dinosaurs. I really enjoyed the three films of Jurassic Park (esp. the 2nd one) and this was a good demonstration why some dreams should never come to reality. Yet, do you think it is technically possible to make the big mistake to revive the dinosaurs?
2) This thread can be used to discuss anything you wish about dinosaurs.
What do you believe led to their extinction? I know the asteroid causing it, but I assume their are other theories out there as well.
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Originally Posted by Ichigo
Well, I think the dinosaurs were quite resilient so a single factor could not bring to their extinction. I think the vulcanic activity, the poisonous sulphur fumes and the asteroid: they all brought about their exticntion. In fact, even that was not enough in relative terms since for a shord period after that the birds, a close relatives of the dinos, managed to dominate the world for a limited period of time. The mammals were faster to adapt to the new conditions. Why the mammals were thriving was the big question. I have always wondered if being a dominating species weakens your surviving ability or it has something to do with the egg shell...
There's a few theories floating about that the Dinosaurs were actually extinct before the Asteroid, since they can't seem to find in Mineral Tables any record that the Dinosaurs died out en-mass. I don't really know whether that's true or not, but I thought it was interesting to hear that.
Just use some large lizard's egg cell, and insert dino's DNA..... now we can clone them.... but I think the scientists wass too scared....:laugh4:
I don't think it's possible to bring them back. There just isn't enough DNA(if at all) for that.
but isaw them do it in jurassic park must be true!!!!11
It's all too old by this point, even the "preserved" blood they found within Mosquitoes flash preserved in Amber (ala Jurassic Park) is worthless, the iron in the blood was sure to take care of that. Had we only progressed to the point we are now, a few million years ago, we might have had better luck. :shrug:Quote:
Originally Posted by Ibn-Khaldun
Most of the dinosaurs died in the flood 4,000 years ago, except some dragons and the Loch Ness monster.
It's hard to tell what the future brings. Maybe we will be able to design our own "dinosaurs" from scratch, or maybe we come up with something else really clever that will make us capable of bringing them back no matter the state of the fossil DNA.
Rhyfelwyr is, of course, correct.
On a more serious note though... I find it fascinating that the dinosaurs got so totaly wiped out. Specially since birds and mammals obviosly survived (along with other species).
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Originally Posted by Viking
It would have to come from Mitochondrial DNA preserved in Fossilized Bone Marrow. Even though it would be useless, they may be able to replicate it, of course that brings a whole other book of problems with it...
I talk with the Pathologist at the Crime Lab, way too often.
I actually have just what you need hanging on my neck, a ancient mosquito TRAPPED in barn. You will find a lot of these in Denmark.
Well, big creatures need a lot of oxygen to survive. When the meteor hit, the air had less of it, and they got slower and easier to catch. :clown:Quote:
Originally Posted by Kadagar_AV
Did birds exist? I'm not certain. The bottom line is, larger creatures are generally more adapted to a particular enviroment, and are more vulnerable to changes. Presumably, smaller dinosaurs simply evolved into other reptiles, or mammals and birds. Global temperatures also probably dropped due to the debris in the atmosphere, which isn't exactly good for cold-blooded animals. Us humans can go most places, and are hard to exterminate.
Well, one problem would be the issue of so many dinosaurs being over-specialized. Examples- the giant sauropods(Brachiosaurus, etc...), the over-sized carnivores(T-rex, etc...), the oversized sea life(giant sharks, icthyosaurus, etc...). Even the "not as specialized" creatures like the duck bills were still very large and required a lot of food to eat. All it takes is something(like an asteroid :juggle2:) to kick out a few links in the food chain and the whole thing would teeter over like a giant game of real life Jinga. Ignoring, of course, the enormous environmental impact such an impact would cause. Look at creatures like the Saber toothed tiger, giant sloth, and dire wolves that all consumed too much food to be able to sustain quick alterations in food supply. Over-specialization can lead a species to the top of a food chain for a while, but it also makes it less adaptable to change and more likely to go extinct in a period of turmoil.
1-it is, but not the way Michael Chrichton envisioned it; the best way is via genetic engineering of avian dinosaurs (i.e birds) , and even then you can only recreate, with the limited technology we have, dinosaurs long or near the avian branch.Quote:
Originally Posted by Stephen Asen
2-thanks.:2thumbsup:
much better.Quote:
Originally Posted by Kadagar_AV
there are almost 10,000 species of them alive today. of course they are now known as "birds", but they are in fact highly derived theropodan dinosaurs. If anyone wants to know how that is the case, look for theprof1988 ( a good friend of mine on YT), or Albukhshi (me! :beam:); we both talk alot about bird/dinosaur relationships. or you can always grab a good book on the subject (my recommendation is "glorified dinosaurs" by Luis Chiappe.
N.B: when I mention dinosaurs from now on in a capacity seperate from birds, assume non-avian dinosaurs.
well, the asteroid alomst certainly didn't do it-at least not completely; if it had, the Amphibians would have had it; they are very susceptable to extreme climate change, as brought about by the meteorite; and the acid rain that would ineviteably result from the impact in the long run, coupled with the sun being blotted out, would have killed them dead. there is little to no evidence of Amphibians undergoing mass extinctions in that timeperiod, so the killer(s) was gradual. and that also measn that the meteor was not as deadly as originally thought. at best, it was a coup de grace. at worst, the dinosaurs were already extinct by then.Quote:
Originally Posted by Csargo
you have to look at the fossils (dinosaur and non dinosaur alike) from the maastrichtian (the last subperiod of the Cretaceous), and see the species diversity, specimens per species, and of course, the climate and geography of the planet 65.5 MYA, then compare to the Campanian, the subperiod preceding it. only then can we know for sure; but from the initial research, it seems that the extinctions of the latest cretaceous took millions of years to accomplish.
I recommend you read Dinosaur heresies by Dr.Robert T. Bakker-his book is in simple english, and it give the "disease" theory of the extinction; its not simply disease doing it, but a series of factors tied in with the paleogeography of the late cretaceous.
yes and no; yes, Oxygen levels in the mesazoic were higher than today, but they didn't go down to levels lower than that in the mesozoic till after the dinosaurs kicked it; nor is the current O2 level lethal to large animals; Blue whales breathe air, and they weigh 200 Tons.Quote:
Originally Posted by A very super market
in fact, the meteorite wouldn't have had any permanent effect on the atmosphere, and only a smallish mount would be reacted, producing NO2 and NO3 (and perhaps SO2); all these produce the acid rain I mentioned above. the first chemical iirc also would have turned the sky reddish brown
and the part about smaller dinosaurs evolving in to mammals and "reptiles" was simply the most laugheable explanation I have ever seen-no offense, but it is simply ridiculous. I have never heard of this from any creadible evolutionary/paleobiological scientist, or any students of such, including myself (remember? I mentioned I'm stdying to be a paleontologist).
@ everybody: this is why people need to be taught evolution properly in schools:
there is no way in hell a dinosaur van evolve in "reptiles"(by that I assume you mean squamates: lizards), nor can they evolve in mammals-both cases would in fact defy evolution, as mammals and squamates are on two seperate branches of the evolutionary tree. and besides, mammals have existed sice the late triassic, and reptiles since the permian (omniotic animals have existed since the Carboniferous; reptile IMHO=diapsids+euryapsids, the latter being just derived diapsids (e.g plesiosaurs). and while some coelurosaur theorpods did indeed evolve into birds, this had occured long before the mass extinction.Quote:
Presumably, smaller dinosaurs simply evolved into other reptiles, or mammals and birds
and no, dinosaurs were/are currently not cold blooded. Ignore anything from Spotila et al. or Ruben et al.
Did birds exsist? they were around for 150 million years, having diverged from the Maniraptorans in the late jurassic, so of course they existed. modern birds however are ~100 MYA (I could be off, but I know they are From the mid-cretaceous).
first off, Ichthyosaurs and Sharks are not dinosaurs; your comment makes it sound as if they are.Quote:
Originally Posted by Yaseikhaan
second, Ichthyosaurs died out around 30 million years before the KT event; and giant sharks are a feature of the Cenozoic, not the Cretaceous or the Mesozoic in general.
third: correct on specialization, but most dinosaurs in the late cretaceous were not that specialized (compared to spinosaurs, dicraeosaurs, and others, all of which were long gone by the maastrichtian), nor were they overly large by dinosaur standards. However, they were indeed starting to get bigger again, after having shrunk a bit in the Campanian. a good example is the replacement of 30ft, 2-3 ton Albertosaurus, Gorgosaurus, and Daspletosaurus with Tyrannosarus, a 40 foot, 6 ton animal. a more accurate description is that the dinosaurs, by growing larger (almost certainly in response to Climate change-IIRC is was becoming more seasonal and cooler towards the end, which favors large animals. the reason why would take another post :clown:), were setting themselves up for extinction due to other factors, specialization aside. I'll discuss this in a moment.
In fact, specialization has doesn't necessarily have anything to do with the size-though size can be a specialization. spcialization has more to do with the specific niche the animal occupies. Sinze may contribute to the specialized status, but not on its own. the Cheetah for example is not a very large predator by serengeti standards, but it is the most specialized. It deals with ultra fast prey in quiet and flat environments. the elephant on the other hand, is the largest animal, but oddly not as specialized: they'll eat leaves, bark, and even grass on occasion-though trees are best for their dentition..large size in fact can destroy a lineage simply because reproduction and life cycle rates go down, and when it does, it leaves the population vulnerable to sudden events that can wipe out the young/a considerable proportion of the breeding population, whereby destroying remarkeably easily the ability of the population to carry on.
thus large size,
So overall, Stephen Asen is quite close to the mark, though not necessarily the right combo: its most likely the case that no one factor did the dinosaurs in, but a series of ignominious circumstances did them in.
The clown is there for a reason Ibrahim, but you are forgiven for not knowing the glory of Jack Chick
didn't notice. my bad.Quote:
Originally Posted by A Very Super Market
but you should have put a clown on the second one too.
well, I suppose this is an example of Poe's law striking again:wall:
:bow: :bow: :bow:
Well, after reading your first post in the thread, I can only say, "Ibrahim, make another post, please." (Whenever you dig some leisure time, of course.)
:beam: :yes: :bow:
well, somebody finally did it; for the first time in history, the color of a dinosaur is known with a certain level of confidence; this is a redering of sinosauropteryx prima, as based on a paper recently published in Nature by Fucheng Zhang et.al, 2010, regarding the animal's coloration. apparently, some pigmentation was fossilized in the fur/feather coat, revealing a surprisingly colorful animal. thanks must be given to the person who drew this, since he did an excellent job depicting it.
Spoiler Alert, click show to read:
any opinions?
Wow... I am in a way surprised and in a way not. I've grown with the idea of the dinosaurs as overed with scales animals. On the other hand, having in mind their relation with the birds, I expected a diversity of colours. ~:)
I think we should accept many of these animals had something between feather and scales on them. I still think there were dinosaurs covered with scales and of course others with furs. The same can be said about warm/cold blooded question, perhaps.
Btw, what is the chance for the T-rex of having a fur like this? Apart from being bipedal there is not much in common between his skull and that of a chicken... Personally, I think that T-rex looked like a huge bipedal reptile (scales dominating over the fur/feather though I would not be surprised if they is some fur/feather). I feel slightly incompetent to judge whether it was cold or warm-blooded. Warm-blood makes him closer to the birds and would make him and active hunter but being a cold-blood would make him more resistant to hunger and the harsh environment of the Cretaceous. His giant size also favours the second since the later species of the mammals and the terror birds never reached the size of the dynasaurs. Tail is also absent from the typical birds. I tend to think that the birds are simply one of the branches of a larger family of warm-blooded dinosaurs whilst others were cold blooded (but it is hard to say the ratio between the warm and cold blood dinos, I think).
In short, I opne the debate what is the image and the blood for the bigger dinos like T-Rex and some other gigantic carnivores and herbivores from... say, the Cretaceous?
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Originally Posted by Prince Cobra
well, you need experience in dinosaur anatomy before deciding that. just looking at a chicken and a T-rex side by side isn'tenough. a T-rex's skull is very similar to a birds, once you look carefully: both have antiorbital fenestra,a sclerotic ring in both (none have been found in T-rex, but the ring is rarely preserved, and as other relative were found with them, its likey and birds usually have them); both are diapsid, poposses a mandibular fenestra, etc.
the postcranial skeleton shows FAR more similarities: the presence of a furcula (wishbone), the tridactyl foot structure, reduction in digit numbers, penumaticized bones, a process on the humerus (found in all dinosaurs), etc.
as to whether Tyrannosauroids had feathers: well, it really depends on the size of the animal: a fossil tyrannosauroid, Dilong, was about 5.5-6 ft, and it was found with feathers. surviving skin impressions of Albertasaurus, a very close relative to T-rex that was 30 ft long, show only scales. the descrepency is due to the fact that as the animal's size increases, the animal is less able to shed heat (surface/volume ratio goes down), thus natural selection favors the secondary loss of feathers in the larger forms. consequently, T-rex, at least as an adult, had scales, not feathers. it also means that T-rex was almost certainly* "warm blooded".
also, T-rex is a coelurosaur: its thus actually FAR closer to birds than to crocodiles. though its actually pretty basal by coelurosaur standards: Dromeosaurs and troodonts are even closer, with over 30 different basic traits being shared with the birds. (fused sternum, uncinate processes, wing feathers, semilunate carpals, and a list of other traits I can't be arsed to remember).
*as in 99.999% certain
EDIT: its highly unlikely any dinosaur was truly ectothermic; and as far a I know, all papers that supposedly "prove" ectothermy are either outdated, or, if they come from John Ruben, pretty much full of it.
Ibrahim, how does the warm blood affect the behaviour of the dynosaurs? For me this means a constant need to eat (especially for the carnivorous species)... It's not like the snake: you catch a big prey, eat it and then you can wait for the next meal a looong time...
warm bloodedness simply means, as you say, a higher metaolic rate. this means that the animal waill be active throughout the day, hunting, mating, etc.
this has a far greater advantage than any disadvantage: the animal can regularly, and constantly find food, mate, defend its territy, etc, since the animal no longer needs to bask in the sun or hide in the shade as much. that was the edge archosaurs (like dinosaurus), and later mammals, had over everything else.