Scuba Pete
Le plongeur avec attitude...
So then... what do you think HAPPENED to all the dinosaurs? You don't think that simply grew into something else?
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Birds from Reptiles?
- Thread starter HelpMe
- Start date
painted wolf
Grey Muzzle
Seyorni- in some places dinos seem to have been having some problems but a new sudy suggests that they were still in thier prime at the time of the extinction event. I'll see if I can find it and post a link to it. We may never know 100% what happined. In North America they were being hit hard by tectonic activity and thus the polution that goes with it. Pandemic can not account for all the dinosaurs... the ones in Australia and South America and Africa were isolated from the rest of the world and Pandemic can not account for them. Nor can it account for all the other things that died in the extinction event. It wasn't just the dinosaurs that died out.
HelpMe- the specimins I'm talking about are 'Willo' a Thescelosaurus who was found with its heart fossilized. 'Skippy' a baby Scipionyx who was preserved with most of internal organs. John Horner has done exencive work on Hadrosuars and the microscopic structure of their bones and thier growth rates. Others such as Phillip Currie have done the same with other groups like Tyrannosaurs. Thanks to mass graves due to volcanic eruptions and floods we have complete herds preserved with whole series of ages from hatchlings to old s. Checking the growth rings on bones will show how quickly they aged and what sort of metabolism they had.
The process to becoming warm blooded probably started with the dinosaurs/pterosaurs last shared ancestors the Ornithodira. They were small animals that were built for fast agile lives. Prior to this you have the split between the dinosaur/pterosaur like animals and the early Crocodilians. Pterosaurs are also thought to have been warm ed due to the presence of fur and thier active flapping flight, wich would have required a hot metablolism to maintain.
willo: http://www.dinoheart.org/insideout/index.html
skippy: http://www.dinodata.net/Dd/Namelist/Tabs/S038.htm
lagosuchus: http://dino.lm.com/images/display.php?id=2232
wa:do
HelpMe- the specimins I'm talking about are 'Willo' a Thescelosaurus who was found with its heart fossilized. 'Skippy' a baby Scipionyx who was preserved with most of internal organs. John Horner has done exencive work on Hadrosuars and the microscopic structure of their bones and thier growth rates. Others such as Phillip Currie have done the same with other groups like Tyrannosaurs. Thanks to mass graves due to volcanic eruptions and floods we have complete herds preserved with whole series of ages from hatchlings to old s. Checking the growth rings on bones will show how quickly they aged and what sort of metabolism they had.
The process to becoming warm blooded probably started with the dinosaurs/pterosaurs last shared ancestors the Ornithodira. They were small animals that were built for fast agile lives. Prior to this you have the split between the dinosaur/pterosaur like animals and the early Crocodilians. Pterosaurs are also thought to have been warm ed due to the presence of fur and thier active flapping flight, wich would have required a hot metablolism to maintain.
willo: http://www.dinoheart.org/insideout/index.html
skippy: http://www.dinodata.net/Dd/Namelist/Tabs/S038.htm
lagosuchus: http://dino.lm.com/images/display.php?id=2232
wa:do
The Voice of Reason
Doctor of Thinkology
And yet, their "design" did not allow them to survive.Seyorni said:
Why would that be?TVOR
painted wolf
Grey Muzzle
first off 'better' is a false idea. Dinosaurs were superbly designed as top animals. They 'ruled' the planet for 250 million years, a far longer dinasty than mammals have thus far mustered.
At the time that dinosaurs became te the world was much different and mammals while successful were not designed for nce.
Mammals still had a semi-sprawling posture wich limited thier speed and manuverablility. They didn't have a metabolism advantage as dinosaurs were warm ed as well. Mammals saught refuge in being quick breeders in the dark places that the then te Reptiles held.
The Dinosaurs were also small, but they had the advantage of a fully upright posture. With their bird-like legs they could run and jump in ways other animals couldn't. They could range far and wide in search of food, water, and mates... something the mammals couldn't do nor could the Reptiles. Their speed and agility let them avoid the much larger predators like Postosuchus (who at the time was the largest land predator on earth) they were also sociable animals and found early on that hunting in groups maximized thier ability to bring down prey. (Ghost ranch for example has hundreds of Celeopysis who died together at a dry waterhole)
Their design eaventually allowed them to become the largest animals that ever lived.
In the end that may have been part of thier downfall... large warmblooded animals require more food and space than small ones. With thier environment in disarray they couldn't do what thier small bird relitives could, fly someplace new to find food. Birds could cover vast areas, small mammals can hibernate as can many reptiles like turtles and crocs. Dinosaurs apparently could not and thus they couldn't simply sleep away the bad times.
The world was going through massive changes. The great shallow central ocean was disapearing, this ocean helped control the environment of North America and other shallow seas were also dissapearing around the world. Volcanism was on the rise at levels rediculously higher than we have now. The Rocky Mountains were thusting up as a chain of Volcanos, some as we all know still active. Imagine nearly all the mountains of the Rockies exploding regularly, from Alaska to California. Similer events were going on all over the world... Europe was riseing up out of the growing Atlantic Ocean and Africa slammed into Asia as did India and Australia and Antartica were ripping apart.
Add on top of this the impact of the ilub asteroid and its amazing that 40% of life on Earth managed to survive.
Small size, the ability to hibernate and high reproductive success are all that kept the few mammals that made it through the K/T extintion from joining the dinosaurs. Remember of the 6 orders of mammals that existed in the time of the dinosaurs only 3 made it though.
Of all the orders of Dinosauria only the two groups of Aves we have today survived.
wa:do
At the time that dinosaurs became te the world was much different and mammals while successful were not designed for nce.
Mammals still had a semi-sprawling posture wich limited thier speed and manuverablility. They didn't have a metabolism advantage as dinosaurs were warm ed as well. Mammals saught refuge in being quick breeders in the dark places that the then te Reptiles held.
The Dinosaurs were also small, but they had the advantage of a fully upright posture. With their bird-like legs they could run and jump in ways other animals couldn't. They could range far and wide in search of food, water, and mates... something the mammals couldn't do nor could the Reptiles. Their speed and agility let them avoid the much larger predators like Postosuchus (who at the time was the largest land predator on earth) they were also sociable animals and found early on that hunting in groups maximized thier ability to bring down prey. (Ghost ranch for example has hundreds of Celeopysis who died together at a dry waterhole)
Their design eaventually allowed them to become the largest animals that ever lived.
In the end that may have been part of thier downfall... large warmblooded animals require more food and space than small ones. With thier environment in disarray they couldn't do what thier small bird relitives could, fly someplace new to find food. Birds could cover vast areas, small mammals can hibernate as can many reptiles like turtles and crocs. Dinosaurs apparently could not and thus they couldn't simply sleep away the bad times.
The world was going through massive changes. The great shallow central ocean was disapearing, this ocean helped control the environment of North America and other shallow seas were also dissapearing around the world. Volcanism was on the rise at levels rediculously higher than we have now. The Rocky Mountains were thusting up as a chain of Volcanos, some as we all know still active. Imagine nearly all the mountains of the Rockies exploding regularly, from Alaska to California. Similer events were going on all over the world... Europe was riseing up out of the growing Atlantic Ocean and Africa slammed into Asia as did India and Australia and Antartica were ripping apart.
Add on top of this the impact of the ilub asteroid and its amazing that 40% of life on Earth managed to survive.
Small size, the ability to hibernate and high reproductive success are all that kept the few mammals that made it through the K/T extintion from joining the dinosaurs. Remember of the 6 orders of mammals that existed in the time of the dinosaurs only 3 made it though.
Of all the orders of Dinosauria only the two groups of Aves we have today survived.
wa:do
The Voice of Reason
Doctor of Thinkology
Why wouldn't it be? If it were "Intelligent", it would seem intelligent to design it to be safe from all vicissitudes - especially when you know all of the vicissitudes that are possible. Why even design the vicissitudes in the first place? What benefit is there in that design?Seyorni said:
TVOR
painted wolf
Grey Muzzle
oh, another bit of behavior that links dinosaurs and birds.
Sleeping posture of the dromeosauridae/troodontidae.
New (2004) species of dinosaur named Mei long (soundly sleeping dragon) was discoverd in China. It was found intact and in a natural sleeping posture. Legs tucked under its body and its head tucked under its wing/arm.
This compliments nicely an earlier find of an Ovaraptor who was found intact sitting on top of her clutch of eggs, arms/wings out to cover them.
Certenly not the behavior of lizards
wa:do
Sleeping posture of the dromeosauridae/troodontidae.
New (2004) species of dinosaur named Mei long (soundly sleeping dragon) was discoverd in China. It was found intact and in a natural sleeping posture. Legs tucked under its body and its head tucked under its wing/arm.
This compliments nicely an earlier find of an Ovaraptor who was found intact sitting on top of her clutch of eggs, arms/wings out to cover them.
Certenly not the behavior of lizards
wa:do
Hazel
Member
Quote from leading evolutionist and world authority on birds Alan Feduccia on the so-called transitional fossil of Archaeopteryx:
"Paleontologists have tried to turn Archaeopteryx into an earth-bound, feathered dinosaur. But it's not. It is a bird, a perching bird. And no amount of "paleobabble" is going to change that."
This specimen has clear fully formed flying feathers including vanes and ventral reinforcing furrows found in the feathers of modern birds. Also the bone structure and same brain has modern birds. Some people claim the fact it had teeth would be evidence enough to place it as a transitional fossil, but this is irrelvent because many extinct birds had teeth while many reptiles then and now do not.
"Paleontologists have tried to turn Archaeopteryx into an earth-bound, feathered dinosaur. But it's not. It is a bird, a perching bird. And no amount of "paleobabble" is going to change that."
This specimen has clear fully formed flying feathers including vanes and ventral reinforcing furrows found in the feathers of modern birds. Also the bone structure and same brain has modern birds. Some people claim the fact it had teeth would be evidence enough to place it as a transitional fossil, but this is irrelvent because many extinct birds had teeth while many reptiles then and now do not.
painted wolf
Grey Muzzle
Actually Archy is quite different from 'perching birds' perching birds have definite adaptations to thier feet and legs that literally force thier feet to grip when at rest. Archy does not have these adaptations.
Archy has many features that dispite Feduccia's clames link it directly with birds. His clames have been refuted by others repeatedly and he has yet to provide an alternitive ancestor that stands up to scruteny.
If it were just the teeth that link Archy he may have a point.
One nice thing about Feduccia is that he is keeping the Paleontologists on thier toes and has, instead of harming the dino-bird link, made them strengthin it by forcing intence study on the subject.
wa:do
Archy has many features that dispite Feduccia's clames link it directly with birds. His clames have been refuted by others repeatedly and he has yet to provide an alternitive ancestor that stands up to scruteny.
If it were just the teeth that link Archy he may have a point.
One nice thing about Feduccia is that he is keeping the Paleontologists on thier toes and has, instead of harming the dino-bird link, made them strengthin it by forcing intence study on the subject.
wa:do
painted wolf
Grey Muzzle
one more piece of evidence linking Dinosaurs and birds.
A new (as yet unidentified) Oviraptorid dinosaur was found with eggs in the pelvic area getting ready to be layed.
The eggs (2) show that dinosaurs layed thier eggs like birds a small number at a time untill clutch size is reached rather than like Crocodylians or reptiles who lay all thier eggs at one time.
However still like Crocs they apeared to have two overies rather than one in birds. One overie appears to likely have been an adaptation to reduce weight makeing long flight easier.
http://www.newscientist.com/article.ns?id=dn7267
http://news.bbc.co.uk/2/hi/science/nature/4446769.stm
wa:do
A new (as yet unidentified) Oviraptorid dinosaur was found with eggs in the pelvic area getting ready to be layed.
The eggs (2) show that dinosaurs layed thier eggs like birds a small number at a time untill clutch size is reached rather than like Crocodylians or reptiles who lay all thier eggs at one time.
However still like Crocs they apeared to have two overies rather than one in birds. One overie appears to likely have been an adaptation to reduce weight makeing long flight easier.
http://www.newscientist.com/article.ns?id=dn7267
http://news.bbc.co.uk/2/hi/science/nature/4446769.stm
wa:do
painted wolf
Grey Muzzle
why thank you... its one of my absolute favorite subjects
I figure that rather than keeping on opening new threads I'd just up-date this one from time to time
wa:do
I figure that rather than keeping on opening new threads I'd just up-date this one from time to time
wa:do
painted wolf
Grey Muzzle
any idea what other lineage?
For quite a while I was unconvinced of the Dino-bird link untill the host of evidence for it began to really pile up eaven in just the past few years.
Feathers really put the iceing on the cake.
wa:do
For quite a while I was unconvinced of the Dino-bird link untill the host of evidence for it began to really pile up eaven in just the past few years.
Feathers really put the iceing on the cake.
wa:do
Dinogrrl
peeb!
Well...I think they shared a common ancestor, but that ancestor may or may not ahve actually been an early dinosaur. If I'm remembering right, Archaeopteryx and Compsognathus were alive at the same time, right? Or am I thinking of another dinosaur?... Anyway, a lot of the bird-like dinosaurs were alive later in the dinosaur's reign, but by then there already were birds flying around. So...it may be a case of convergent evolution or something, or that one branch of maniraptorans 'became' birds a lot sooner than the others.
painted wolf
Grey Muzzle
sorry to get back to you so late..
Yes 'Archy' and 'Compy' were found in the same formation. Both are from the Late Jurassic. However the history of the Ceoleosaurs (Compsognathus' group) goes back a good deal further and we know that they had protofeathers (Sinosauropteryx).
Compy and Archy are so similer in many respects that one of the Archy specimines that was found without any feather impressions was mislabled a Compsognathus for decades.
There is also fragmentary remains of possible Maniraptors from earlier in the Jurassic than Archy, but they are a bit too little to go on for my tastes at the moment.
Sadly the remains of the very bird like dinos that have feather impressions are mostly from well after Archy in the Cretaceous. However the lineages of featherd dinosaurs extend back much farther some into the Early Jurassic/Late Triassic.
Feathers are very tricky to fossilize and need just the right conditions, bone is much more forgiving and preserves better. Thus we end up with more dinosaurs without preserved integument than with.
I do feel however that it is only a matter of time (and admitedly luck) before we find such well preserved examples older than Archaeopteryx.
Incidently seeing that the other closest relations to the Dinosaurs, the Pterosaurs also had insulating covering. However the rules of parsimony indicate that something as complex as a true feather likely would not evolve twice.
It may be that proto-feathers are indeed a basal feature of Dinosaurs. Eoraptor and other early dinosaurs may have been proto-feathered.
wa:do
Yes 'Archy' and 'Compy' were found in the same formation. Both are from the Late Jurassic. However the history of the Ceoleosaurs (Compsognathus' group) goes back a good deal further and we know that they had protofeathers (Sinosauropteryx).
Compy and Archy are so similer in many respects that one of the Archy specimines that was found without any feather impressions was mislabled a Compsognathus for decades.
There is also fragmentary remains of possible Maniraptors from earlier in the Jurassic than Archy, but they are a bit too little to go on for my tastes at the moment.
Sadly the remains of the very bird like dinos that have feather impressions are mostly from well after Archy in the Cretaceous. However the lineages of featherd dinosaurs extend back much farther some into the Early Jurassic/Late Triassic.
Feathers are very tricky to fossilize and need just the right conditions, bone is much more forgiving and preserves better. Thus we end up with more dinosaurs without preserved integument than with.
I do feel however that it is only a matter of time (and admitedly luck) before we find such well preserved examples older than Archaeopteryx.
Incidently seeing that the other closest relations to the Dinosaurs, the Pterosaurs also had insulating covering. However the rules of parsimony indicate that something as complex as a true feather likely would not evolve twice.
It may be that proto-feathers are indeed a basal feature of Dinosaurs. Eoraptor and other early dinosaurs may have been proto-feathered.
wa:do
painted wolf
Grey Muzzle
dreging up an old thread but yet another link between dinosaurs and birds was found...
This time it also helps to distinguish the sex of the dinosaur in question.
Female birds produce a distinctive layer of bone in their legs when they are with eggs. The bone growth is the result of hormones from egg devolpment. The layer is called medullary bone and is found not only in birds but has been found in T.rex. This type of bone is not found in Crocodillians. Because only females produce medullary bone, we now have a way to tell if the T.rex or other theropod dinosaur was a boy or girl and get an estimate of age, based on how much medullary bone is layed down.
more here: http://www.nature.com/news/2005/050531/full/050531-8.html
I wonder if non-avian dinosaurs also produced this type of bone as well or if was a development unique to theropod dinosaurs and birds. :jiggy:
wa:do
This time it also helps to distinguish the sex of the dinosaur in question.
Female birds produce a distinctive layer of bone in their legs when they are with eggs. The bone growth is the result of hormones from egg devolpment. The layer is called medullary bone and is found not only in birds but has been found in T.rex. This type of bone is not found in Crocodillians. Because only females produce medullary bone, we now have a way to tell if the T.rex or other theropod dinosaur was a boy or girl and get an estimate of age, based on how much medullary bone is layed down.
more here: http://www.nature.com/news/2005/050531/full/050531-8.html
I wonder if non-avian dinosaurs also produced this type of bone as well or if was a development unique to theropod dinosaurs and birds. :jiggy:
wa:do