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HalfMooner
Dingaling
Philippines
15831 Posts |
Posted - 02/20/2008 : 05:48:38 [Permalink]
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Gotta love 'em.
In my mind, one of the best things about frogs is that they are so damned funny! Such big mouths, silly expressions, pop-eyes, and tailless, hairless bodies that are so much like parodies of humans. I never had a single negative thought about a frog, aside from a time or two when a hellish chorus of them kept me awake and I was wishing for hand grenades.
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“Biology is just physics that has begun to smell bad.” —HalfMooner
Here's a link to Moonscape News, and one to its Archive. |
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Dave W.
Info Junkie
USA
26022 Posts |
Posted - 02/20/2008 : 07:20:18 [Permalink]
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| filthy, our search does work, really. But you needed to spell "rhapsody" incorrectly in order to find it. (I searched for "frogs" and it was fourth in the results.) |
- Dave W. (Private Msg, EMail)
Evidently, I rock!
Why not question something for a change?
Visit Dave's Psoriasis Info, too. |
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filthy
SFN Die Hard
USA
14408 Posts |
 Posted - 02/20/2008 : 07:51:12 [Permalink]
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Originally posted by Dave W.
filthy, our search does work, really. But you needed to spell "rhapsody" incorrectly in order to find it. (I searched for "frogs" and it was fourth in the results.)
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Speling, speling... 'Tis the bane of my existaence. Thanks Dave!
So, here it is:
Our story begins a long, long time ago, some 345 million years ago, or there abouts; way back in the upper Devonian when certain species of air-breathing, lobe-finned fishes, the Rhipidistians, began to experiment with scrabbling about in the aquatic plant growth along the edges of the shallow, lakes and estuaries of the times. Eventually, many of them came ashore, but it was a fumbling start on becoming terrestrial, for even such as Icthyostega, one of the most important, known transitional species of the times, would have been a clumsy, full-time land-dweller at best.
Sorry that some of the illustrations no longer work but some of the ones that do are lovely.
Enjoy!
Oh, and I know that I made the link with Dave's repitious, but, eh... 
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"What luck for rulers that men do not think." -- Adolf Hitler (1889 - 1945)
"If only we could impeach on the basis of criminal stupidity, 90% of the Rethuglicans and half of the Democrats would be thrown out of office." ~~ P.Z. Myres
"The default position of human nature is to punch the other guy in the face and take his stuff." ~~ Dude
Brother Boot Knife of Warm Humanitarianism,
and Crypto-Communist! 
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chaloobi
SFN Regular
1620 Posts |
Posted - 02/20/2008 : 09:28:25 [Permalink]
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Originally posted by filthy
...the Cretatious, wherein 'most everything except mammals was bigger & better... |
Why is that? Not the mammal part but the bigger and better part. |
-Chaloobi
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filthy
SFN Die Hard
USA
14408 Posts |
 Posted - 02/20/2008 : 11:52:14 [Permalink]
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Originally posted by chaloobi
Originally posted by filthy
...the Cretatious, wherein 'most everything except mammals was bigger & better... |
Why is that? Not the mammal part but the bigger and better part.
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Merely a paraphrased figure of speech. But lots of vertibrates were indeed a lot bigger, and as for the 'better' part, well, I would find those vertibrates a lot more interesting than what I'm currently used to -- from a circumspect distance, of course.
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"What luck for rulers that men do not think." -- Adolf Hitler (1889 - 1945)
"If only we could impeach on the basis of criminal stupidity, 90% of the Rethuglicans and half of the Democrats would be thrown out of office." ~~ P.Z. Myres
"The default position of human nature is to punch the other guy in the face and take his stuff." ~~ Dude
Brother Boot Knife of Warm Humanitarianism,
and Crypto-Communist!
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chaloobi
SFN Regular
1620 Posts |
Posted - 02/21/2008 : 06:14:09 [Permalink]
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Originally posted by filthy
Originally posted by chaloobi
Originally posted by filthy
...the Cretatious, wherein 'most everything except mammals was bigger & better... |
Why is that? Not the mammal part but the bigger and better part.
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Merely a paraphrased figure of speech. But lots of vertibrates were indeed a lot bigger, and as for the 'better' part, well, I would find those vertibrates a lot more interesting than what I'm currently used to -- from a circumspect distance, of course.
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I meant why were animals apparently so much larger up until 65 million years ago? Yeah, we had some big mammals through the last glacial period but nothing like the big saurapods and so on. Really, there's two questions that might have the same answer:
#1. Why did some dinosaurs get so freakin' big?
#2. Why did post CT boundary animals never get that big again? (excepting whales of course)
I'm under the impression that pre-CT the world was much warmer than it is today - as in there were no ice caps and winter didn't cool the weather enough to bring snow. That's a big difference.... |
-Chaloobi
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filthy
SFN Die Hard
USA
14408 Posts |
 Posted - 02/21/2008 : 07:28:36 [Permalink]
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Originally posted by chaloobi
Originally posted by filthy
Originally posted by chaloobi
Originally posted by filthy
...the Cretatious, wherein 'most everything except mammals was bigger & better... |
Why is that? Not the mammal part but the bigger and better part.
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Merely a paraphrased figure of speech. But lots of vertibrates were indeed a lot bigger, and as for the 'better' part, well, I would find those vertibrates a lot more interesting than what I'm currently used to -- from a circumspect distance, of course.
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I meant why were animals apparently so much larger up until 65 million years ago? Yeah, we had some big mammals through the last glacial period but nothing like the big saurapods and so on. Really, there's two questions that might have the same answer:
#1. Why did some dinosaurs get so freakin' big?
#2. Why did post CT boundary animals never get that big again? (excepting whales of course)
I'm under the impression that pre-CT the world was much warmer than it is today - as in there were no ice caps and winter didn't cool the weather enough to bring snow. That's a big difference....
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Y'know, that's a damned good question and one I've never given much consideration. As I recall reading, the earth was considerably warmer and the oxygen content of the atmosphere was somewhat higher, but that alone wouldn't explain it. And of course, the KT Event caused great changes in both, especally in climate. In all truth, I dunno.
Perhaps evolution simply favored size in some genera (not all that many dinos were humongous) due to their feeding environment. T. rex, I am convinced, was as much of a scavenger as a predator and size would be of an advantage when opening and/or defending a large carcass. It might be considered that such as the Ceretopsians were huge simply because it is harder to kill a big one than a little one.
But the genes were in play clear back in the Permian & before. Many of the Synapsids were very large and some of the amphibians -- forget it! By the Mid-Triassic size again mattered with Allosarus and Stegosarus, and the Apatasaurs among others, growing to great sizes and apparently, very quickly. The vegetarians had virtually unlimited forage, providing virtually unlimited fodder for the predators.
There are also breeding strategies & displays to consider. Some of these in modern reptiles are quite remarkable and with avians, often spectacular. These too, can modify an organism's form.
All of that is off the top of my head. Again, I dunno and your guess is at least as good as mine.
Food for thought -- thanks 'loobi!
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"What luck for rulers that men do not think." -- Adolf Hitler (1889 - 1945)
"If only we could impeach on the basis of criminal stupidity, 90% of the Rethuglicans and half of the Democrats would be thrown out of office." ~~ P.Z. Myres
"The default position of human nature is to punch the other guy in the face and take his stuff." ~~ Dude
Brother Boot Knife of Warm Humanitarianism,
and Crypto-Communist!
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leoofno
Skeptic Friend
USA
346 Posts |
Posted - 02/21/2008 : 07:54:03 [Permalink]
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Originally posted by chaloobi
Originally posted by filthy
Originally posted by chaloobi
Originally posted by filthy
...the Cretatious, wherein 'most everything except mammals was bigger & better... |
Why is that? Not the mammal part but the bigger and better part.
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Merely a paraphrased figure of speech. But lots of vertibrates were indeed a lot bigger, and as for the 'better' part, well, I would find those vertibrates a lot more interesting than what I'm currently used to -- from a circumspect distance, of course.
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I meant why were animals apparently so much larger up until 65 million years ago? Yeah, we had some big mammals through the last glacial period but nothing like the big saurapods and so on. Really, there's two questions that might have the same answer:
#1. Why did some dinosaurs get so freakin' big?
#2. Why did post CT boundary animals never get that big again? (excepting whales of course)
I'm under the impression that pre-CT the world was much warmer than it is today - as in there were no ice caps and winter didn't cool the weather enough to bring snow. That's a big difference....
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I seem to recall that it was the result of the close-to-Earth orbit of Jupiter at the time. It reduced the net gravitational pull and allowed the development of the gigantic animals in the distant past. 
Or so said Ted Holden back in the day when I read talk.origins. Interesting guy. |
"If you're not terrified, you're not paying attention." Eric Alterman
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Kil
Evil Skeptic
USA
13477 Posts |
 Posted - 02/21/2008 : 09:35:35 [Permalink]
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Many years ago, I was told by a science teacher that a very large size in some dinosaurs would give it and advantage, as a cold blooded creature, due to reduced heat loss based on its size. And while that might be true to some extent, it doesn't come close to the advantages of endothermy, or warm bloodedness as way to keep warm and keep a large body moving, as later thinking suggests.
With regard to any size advantage (and therefore as an explanation for large sized animals) the old idea seems to have been replaced by some very convincing arguments for warm bloodedness. Unfortunately, this does not exactly shed a whole lot of light on exactly why some of these animals were so big. But because scientists did run cold bloodedness up the flagpole as an explanation for size; I think the following is interesting.
Were Dinosaurs Endotherms or Ectotherms?
Evidence for Ectothermy
Approaching the subject from a new position, unaffected by the beliefs of those earlier palaeontologists, we must look for evidence for cold-blood.
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Saurian Skeleton Structure - Dinosaurs had fairly lizard-like skeletons; lizards are cold-blooded.
* Descended from Reptiles - Reptiles are cold-blooded, so dinosaurs are likely to be cold-blooded as well.
*Gigantothermy - The huge size of the animals is explained as being necessary in order to maintain constant activity by reducing heat loss. The volume of an animal increases much more than its surface area when it is made larger so heat loss would be reduced.
Evidence for Endothermy
#8721; Size - In exact opposition to gigantothermy it can be demonstrated that size is unhelpful for cold-blooded animals. In order to move a massive body for a prolonged period of time great strength is required. This can be seen in many modern terrestrial mammals but not in any cold-blooded animals. It is possible to demonstrate that cold-blood is only possible up to a certain size in purely terrestrial animals, something the size of the Diplodocus3 is clearly past that limit.
#8721; Bone Structure - It is possible to note significant differences in microscopic bone structure between warm-blooded and cold-blooded animals. Dinosaur bone clearly shows a warm-blooded structure. This appears much stronger evidence than the mere overall design of the bone and effectively refutes the structure argument for ectothermy.
#8721; Predator/Prey Ratios - If animals are warm-blooded then there is a large amount of prey biomass required per kilogram of predator biomass in order to support a stable population. If they are cold-blooded then the amount required is far less. Fossil discoveries point to a ratio of about 50 tonnes of prey biomass per tonne of predator biomass. This is what we would expect of warm-blooded animals.
Dynamic Body Structure
Stance - Dinosaurs stood erect, not sprawled like lizards. This stance is seen in warm-blooded animals only.
Form - Some dinosaurs have forms extremely reminiscent of fast ground birds, in fact Dromiceiomimus4 was built to a faster design than an ostrich. If we make the reasonable assumption that the form fulfilled the same function in both animals then Dromiceiomimus must have been capable of speeds approaching 60 miles per hour. Replace the warm-blooded animal with a cold-blooded one and those long, powerful legs would have propelled the animal at a less impressive four miles per hour. Moreover it would have had to sit down to rest every hundred yards or so! Obviously the animal must have been warm-blooded.
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Insulation - It is now clear that at least some dinosaurs, and some pterosaurs, were insulated. Insulation is a hazard in cold-blooded animals but a benefit in warm-blooded animals, mammals use fur or blubber, birds use feathers. |
Uncertainty may make you uncomfortable. Certainty makes you ridiculous.
Why not question something for a change?
Genetic Literacy Project |
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H. Humbert
SFN Die Hard
USA
4574 Posts |
Posted - 02/21/2008 : 10:09:08 [Permalink]
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Kil, conversely, I remember hearing that it was unlikely the larger dinosaurs were warm-blooded because they wouldn't be able to dissipate heat quickly enough. It's that surface area to mass thing again. Elephants have large ears that act as radiators to help regulate their body temperature. So sauropods likely either spent a lot of time in water or they weren't fully warm-blooded. It's my understanding that there are a range of metabolisms from completely cold-blooded to completely warm-blooded.
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"A man is his own easiest dupe, for what he wishes to be true he generally believes to be true." --Demosthenes
"The first principle is that you must not fool yourself - and you are the easiest person to fool." --Richard P. Feynman
"Face facts with dignity." --found inside a fortune cookie |
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chaloobi
SFN Regular
1620 Posts |
Posted - 02/21/2008 : 10:51:37 [Permalink]
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As a side note, the time period this newly discovered dinosaur is said to have lived caught my attention. Apparently Emma nor Mathew did their fact checking/editing very well.
China says finds fossil of new dinosaur species
BEIJING (Reuters) - Scientists have found the fossil of a new herbivorous dinosaur species that stood five meters (5.5 yards) high and lived 60 million years ago, the official Xinhua agency reported on Thursday.
The large long-necked sauropod, which was found in Eastern Zhejiang province and has not yet been named, was around 15 meters long, the report quoted a museum curator as saying.
In 1977, a 22-meter-long dinosaur was unearthed in the same province, and last year scientists announced they had identified another fossil found there as a new species.
China makes regular finds of rare fossils, which are sometimes smuggled out of the country to be sold for large sums.
Australia recently handed back to Beijing a 100-million-year-old haul of dinosaur eggs that had been illegally taken abroad.
(Reporting by Emma Graham-Harrison; Editing by Mathew Veedon)
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http://news.yahoo.com/s/nm/20080221/sc_nm/china_dinosaur_dc_1 |
-Chaloobi
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| Edited by - chaloobi on 02/21/2008 10:52:21 |
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filthy
SFN Die Hard
USA
14408 Posts |
Posted - 02/21/2008 : 12:12:30 [Permalink]
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Why not endothermic? It has been discovered that some modern sharks, notably the Great White and the Atlantic Mako are. I think that it would be a safe bet that C. megalodon was, as well as many other species of highly active fish of the past & present. And just because some large dinosaurs might have been endothermic should not be taken to mean that they all might have been as well. I would think that most of the quadrupedal grazer/browsers, and even the more sedentary species of bipeds, would have been exothermic. This argument has been on-going since the mid-1800s.
There are ways to shed body heat, notably panting or spending the off-hours soaking in a pond or at least laying in the shade. And the big carnivores could have been nocturnal, and in my opinion, probably were.
Another question is: exactly how bulky were they -- big & fat or lean & mean? Looking at modern predators, I tend to favor the latter. And if so, they could get rid of excess heat a little easier.
Unfortunately, while the fossils tell us something about their habits, it's not really very much. Nor do they tell us exactly the degree (heh) that they might have been endothermic.
Again, I dunno nor probably ever will. 
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"What luck for rulers that men do not think." -- Adolf Hitler (1889 - 1945)
"If only we could impeach on the basis of criminal stupidity, 90% of the Rethuglicans and half of the Democrats would be thrown out of office." ~~ P.Z. Myres
"The default position of human nature is to punch the other guy in the face and take his stuff." ~~ Dude
Brother Boot Knife of Warm Humanitarianism,
and Crypto-Communist!
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| Edited by - filthy on 02/21/2008 12:27:04 |
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BigPapaSmurf
SFN Die Hard
3192 Posts |
Posted - 02/21/2008 : 12:50:05 [Permalink]
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| About the size issue, one point I thought of was that when dinos evoloved Pangea was in full effect, by 65Million YA it was mostly broken up. Also dinos had more time to evolve and did not have humans to deal with who try their hardest to kill off every large animal, either by killing its food or a more diect method. Evidence shows that all of the largest animals in temperate NA were wiped out shortly after the arrivial of humans. However it may be that the dino period was less prone to sudden ice ages, which no doubt take their toll on larger creatures which are natually smaller in numbers. |
"...things I have neither seen nor experienced nor heard tell of from anybody else; things, what is more, that do not in fact exist and could not ever exist at all. So my readers must not believe a word I say." -Lucian on his book True History
"...They accept such things on faith alone, without any evidence. So if a fraudulent and cunning person who knows how to take advantage of a situation comes among them, he can make himself rich in a short time." -Lucian critical of early Christians c.166 AD From his book, De Morte Peregrini |
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BigPapaSmurf
SFN Die Hard
3192 Posts |
Posted - 02/21/2008 : 12:54:10 [Permalink]
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and another thing,
It may be that dino bones were more suitable to evolving largeness than mammals or others. We assume that exoskeltons can only reach a certain size, perhaps we cant get big either. Only the bouyancy of water has made mega-sized mammals as far as I know, mammoths are almost there but we put a stop to their reign of terror, once and for all!*
Cloners must be stopped! |
"...things I have neither seen nor experienced nor heard tell of from anybody else; things, what is more, that do not in fact exist and could not ever exist at all. So my readers must not believe a word I say." -Lucian on his book True History
"...They accept such things on faith alone, without any evidence. So if a fraudulent and cunning person who knows how to take advantage of a situation comes among them, he can make himself rich in a short time." -Lucian critical of early Christians c.166 AD From his book, De Morte Peregrini |
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chaloobi
SFN Regular
1620 Posts |
Posted - 02/22/2008 : 06:24:13 [Permalink]
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Originally posted by BigPapaSmurf
About the size issue, one point I thought of was that when dinos evoloved Pangea was in full effect, by 65Million YA it was mostly broken up. Also dinos had more time to evolve and did not have humans to deal with who try their hardest to kill off every large animal, either by killing its food or a more diect method. Evidence shows that all of the largest animals in temperate NA were wiped out shortly after the arrivial of humans. However it may be that the dino period was less prone to sudden ice ages, which no doubt take their toll on larger creatures which are natually smaller in numbers.
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A few comments....
I don't know for sure, but I don't believe there were any ice ages during the period the dinos were around. I believe the world was all around much warmer, there not even being ice caps. In geologist speak, we're currently in an Ice Age right now, this current balmy climate being the short warm period interuption of the much longer glaciated period (12k warm years vs. 100k glaciated years for at least the last half million years) where the Northern Hemisphere is largely iced over. Odd to think the entire recorded history of humanity has taken place in a climatological exception rather than the rule.
Regarding animal size, I recall from my college ecology class some years ago the theory that larger animals tend to be found in colder environments, hence all the mega mammals coming out of the last glacial period. The theory is their size allows them to deal with the cold better, which makes the whole big dinosaur question more puzzling since it was apparently quite a bit warmer back then. Likely there's some fundamental metabolic difference between mammals and dinosaurs, like the discussion about warm/cold bloodedness above. (Note, I challenged that cold climate - big animal theory in class discussion because it didn't fit well with the big animals found in South Asia and Africa where it's warm all the time, but whatever....)
I've also recently read a dissent argument to the humans killed the mega-fauna argument. I think that was in SciAm in the last six months or so, but I don't recall the specifics. Strange though that the mammoths died globally due to human over-hunting but the African and Asian elephants managed to survive just fine. Why would that be? There has to be other factors. |
-Chaloobi
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| Edited by - chaloobi on 02/22/2008 06:46:04 |
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Beelzebufo ampinga
