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Discussion of everything related to the Theory of Evolution.

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Postby alextemplet » Tue Dec 27, 2005 12:26 am

Excalibur wrote:
Its a well known theory that Dinosaurs existed many millions of years ago, and started to apparently evolve in the Cretaceous (even though the same missing link problem applies here) and were eventually extinct by the Triassic.


Actually, dinosaurs evolved in the Triassic, then went extinct at the end of the Cretaceous. And the missing link problem doesn't apply, since we know that dinosaurs evolved from archosaurs, a group of reptiles also known as the ruling reptiles, which also gave rise to pterosaurs and crocodilians.

The missing link issue is rather a dead horse, since numerous such links have been found and documented for nearly every conceivable lineage. Exact details about the evolution of a lineage are not, and probably never will be, fully known, but that doesn't change the fact that the overall picture is clear. We don't need to know every single early hominid species to see the big picture of how humans evolved from apes. For example, we don't the names of every single ancient Egyptian pharoah, and there are gaps the in the heiroglyphic record. But just because there's gaps doesn't mean the pharoahs never existed, doesn't it?
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Postby Excalibur » Tue Dec 27, 2005 12:57 am

alextemplet wrote:Excalibur wrote:
Its a well known theory that Dinosaurs existed many millions of years ago, and started to apparently evolve in the Cretaceous (even though the same missing link problem applies here) and were eventually extinct by the Triassic.


Actually, dinosaurs evolved in the Triassic, then went extinct at the end of the Cretaceous. And the missing link problem doesn't apply, since we know that dinosaurs evolved from archosaurs, a group of reptiles also known as the ruling reptiles, which also gave rise to pterosaurs and crocodilians.

The missing link issue is rather a dead horse, since numerous such links have been found and documented for nearly every conceivable lineage. Exact details about the evolution of a lineage are not, and probably never will be, fully known, but that doesn't change the fact that the overall picture is clear. We don't need to know every single early hominid species to see the big picture of how humans evolved from apes. For example, we don't the names of every single ancient Egyptian pharoah, and there are gaps the in the heiroglyphic record. But just because there's gaps doesn't mean the pharoahs never existed, doesn't it?


Thanks for correcting me about the Triassic and Cretaceous mix up I made 8)

A recent study has demonstrated that reptiles disappeared and the giant carnivorous dinosaurs replaced them within a period of less than 10,000 years of the Triassic-Jurassic boundary and only 30,000 years after the last Triassic taxa, which were eliminated by a mass extinction event, probably due to an asteroid collision.

The rate of evolution of these dinosaurs is almost beyond belief. Of course, it all fits into one or another of the current evolutionary theories. Maybe we should try to short-circuit a near-earth asteroid to repeat the experiment and see if evolution really works that fast!

And also how can you explain that Scientists have found a dinosaur species, Allosaurus fragilis, dated to have lived in Colorado some 150 million years ago, also lived on the other side of the Atlantic Ocean, in Portugal, at about the same time.

These are only the smallest problems evolution looks at with a grim face, however it seems that we ara still lead to believe all of this is coincidence and actually there is really a logical theory to this problem. What :? this from the theory of evolution who believe in utter blind luck and chance!
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Postby alextemplet » Tue Dec 27, 2005 1:34 am

As I understand it, and correct me if I'm wrong, but no mass extinction occurred at the end of the Triassic, only at the beginning. By the way, the Permian-Triassic extinction is famous for being the largest mass extinction in the history of the earth, but that's a different story.

All of what you say depends on how you classify your fossils. For example, the earliest dinosaurs were certainly not "giant carnivores" in the mold of T. rex, but had much more in common with their archosaur ancestors than with T. rex, who lived at the end of the Cretaceous. The boundary between archosaur and dinosaur is rather difficult to distinguish with absolute certainty. What one scientist calls an early dinosaur, another might call a late archosaur. I'm also skeptical about the "ten thousand years of rapid evolution" that you mention, especially since it's rather difficult to date 250 million year old fossils to an accuracy of only 10,000 years.

Concerning Allosaurus, this is another fuzzy issue when dealing with dinosaurs. Maybe the American and European varieties were the same species, but maybe not. Species within the same genus often have very similar skeletons, and when the skeletons are all that survive it can be very hard to differentiate between closely-related species. For example, a recent issue of debate among paleontologists had been the classification of Tarbosaurus, which was an animal very similar to T. rex that lived in Asia. Some believe Tarbosaurus should be reclassified as another species of Tyranosaurus, and perhaps it should, but my point is that it's hard to say that with any certainty. And even if it was the exact same species of Allosaur, that doesn't seem to matter that much to me. During the Jurassic, when Allosaurus lived, the Atlantic was little more than a large lake. There were only two large continents on earth, one in the north and one in the south, and since both North America and Europe are in the northern half of the world, I can see who Allosaurus might have occurred across the entire range. I believe the names of those two super continents were Gondwonaland and Laurasia, though I can't remember which one was north and which was south. Perhaps someone can enlighten me?
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Postby Excalibur » Tue Dec 27, 2005 2:07 am

alextemplet wrote:As I understand it, and correct me if I'm wrong, but no mass extinction occurred at the end of the Triassic, only at the beginning. By the way, the Permian-Triassic extinction is famous for being the largest mass extinction in the history of the earth, but that's a different story.

All of what you say depends on how you classify your fossils. For example, the earliest dinosaurs were certainly not "giant carnivores" in the mold of T. rex, but had much more in common with their archosaur ancestors than with T. rex, who lived at the end of the Cretaceous. The boundary between archosaur and dinosaur is rather difficult to distinguish with absolute certainty. What one scientist calls an early dinosaur, another might call a late archosaur. I'm also skeptical about the "ten thousand years of rapid evolution" that you mention, especially since it's rather difficult to date 250 million year old fossils to an accuracy of only 10,000 years.

Concerning Allosaurus, this is another fuzzy issue when dealing with dinosaurs. Maybe the American and European varieties were the same species, but maybe not. Species within the same genus often have very similar skeletons, and when the skeletons are all that survive it can be very hard to differentiate between closely-related species. For example, a recent issue of debate among paleontologists had been the classification of Tarbosaurus, which was an animal very similar to T. rex that lived in Asia. Some believe Tarbosaurus should be reclassified as another species of Tyranosaurus, and perhaps it should, but my point is that it's hard to say that with any certainty. And even if it was the exact same species of Allosaur, that doesn't seem to matter that much to me. During the Jurassic, when Allosaurus lived, the Atlantic was little more than a large lake. There were only two large continents on earth, one in the north and one in the south, and since both North America and Europe are in the northern half of the world, I can see who Allosaurus might have occurred across the entire range. I believe the names of those two super continents were Gondwonaland and Laurasia, though I can't remember which one was north and which was south. Perhaps someone can enlighten me?



I was actually referring to the Triassic-Jurassic extinction event which occured at the phanerozoic, and yes there was a significant extinction event!

This event profoundly affected life on Earth wiping out at least half of the species alive.

This event opened an ecological niche allowing the dinosaurs to assume the dominant roles in the Jurassic period.

This event apparently happened in less than 10,000 years and occurred just before Pangaea started to break apart! (Ask your professor about this!)

Correct me if I am wrong but do you know that there are two primary groups of archosaurs.

The Ornithodira which were insignificant during the Middle Triassic but in the Late Triassic radiated as the dinosaurs and pterosaurs.

I find it quite hard to believe that such a radiation could occur in this small amount of time!

I stated quite explicitly that the Allosaurus fragilis actually lived on the OTHER SIDE OF THE ATLANTIC OCEAN, in Portugal instead of Colorado where it was found and dated to have lived at 150 years ago originally.

The new fossil was discovered by palaeontologist Bernardino Perez-Moreno of the Universidad Aut—noma de Madrid and colleagues in 150-million-year-old rock formations in Leira, 155 kilometres north of Lisbon

In fact why don’t you find out about this at Uni, online or look at this journal

Staff writer. 1999. Random Samples. Science 284: 903.

Actually the earliest forms of Archosaurs were thought to have been carnivores, with narrow serrated meat-tearing teeth!

Why dont you watch that programme that comes on the BBC (assuming you live in Britain), I think you would be quite enlightened :wink:
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Postby alextemplet » Tue Dec 27, 2005 5:09 am

I must admit, Excalibur, you have inspired me to read over my sources again, and now I feel prepared to make a few more comments.

First of all, it seems I was mistaken about the late Triassic extinction. After consulting one of my books, I have learned that a mass extinction did indeed occur at the end of the Triassic, and it seems it was this extinction event that allowed dinosaurs to flourish, not unlike how the end of the dinosaurs allowed mammals to triumph. Also, to put the Allosaur matter to rest, it appears that North America and Europe were connected during the Jurassic, so I see no reason why Allosaurus would not occur over such a wide range.

Also, from what I have just read, I can confirm that there were in fact two main groups of archosaurs. One group evolved into crocodilians, while the other into pterosaurs, dinosaurs, and eventually birds. As for the issue of shredding teeth, then if you don't like my T. rex analogy perhaps I should've used Triceratops instead? My point remains the same. The first dinosaurs had more in common with their archosaur ancestors than they did with Triceratops, or if you prefer Parasauralophus? My final point is that the evolutionary ancestry of dinosaurs is fairly well understood.

I must admit that you have inspired me to research and learn more about this topic, and that is something that an anti-evolutionist rarely causes me to do. Of course, most anti-evolutionists are the ultra-religious type I meet at church, who know next to nothing about biology, so I generally don't have to try that hard to defeat their poorly argued attacks on evolution. You, Excalibur, are different, you have presented intelligent arguments and inspired me to learn more. I'm not yet convinced by you, but I do know more than I would had you not raised your objections, and knowledge is always a good thing. For that, I offer you my admiration and respect.
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Postby new_guy » Thu Dec 29, 2005 5:43 pm

.......................

**still trying to figure out what the above users trying to say**
"Aut Ceaser , Aut Nihil." (This is Latin grammar)

"I'll be loquacious allright! I'll loquace like no one ever loquaced before."(This is BAD grammar)
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Postby alextemplet » Sun Jan 01, 2006 3:43 am

I believe I was trying to say, "I like chicken, but I believe I ordered a cheeseburger."

Hehe, only joking! :lol:
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