Guest shallowman Posted February 5, 2004 Posted February 5, 2004 Okay, I've always wondered.... 1. Why have large animals (like all them Super-sized dino's) all given way to smaller ones. 2. How could animals of this size have supported themselves against both the weight and in terms of getting enough calories --heck, they'd have to eat all day and night. It may sound stupid (I've been called worse) but I always wondered if gravity has not been constant thru the earth's history. Didn't they say that they found evidence of water being deposited on earth on a daily basis from space (I think they mentioned cometary debris). What if, over the millions of years, earth has been bombarded with water that has increased the gravitational constant (non-constant?). Just wondering.... shallowman
Cap'n Refsmmat Posted February 5, 2004 Posted February 5, 2004 1: Large ones must be cold blooded, a warm blooded animal must have a HUGE heart to manage. Cold blooded animals require less energy to sustain themselves. 2: Yes, they did probably eat a lot. But have you heard about how a gator can eat one meal every few months? Slow metabolisms! Water would not increase the constant, it would make earth more massive, increasing the force of gravity.
Guest shallowman Posted February 5, 2004 Posted February 5, 2004 Hmmm... 1. True about the metabolism thingie, but I still have a hard time imagining a beast of that size physically operating -- 2. One meal per week but that doesn't hold true for herbivores, does it? 3. By gravitational constant I mean accelleration due to earth's gravity. That's what I mean, more earth-mass means more gravity, means that things are heavier, therefore, larger animals have a harder time doin' stuff. I've also heard scientists reason that the large animals were possible due to thier hollow bones (like birds), but a 30 ft animal still packs a lot of beef if you ask me... shallowman
Radical Edward Posted February 5, 2004 Posted February 5, 2004 isn't the blue whale the largest animal ever?
mossoi Posted February 5, 2004 Posted February 5, 2004 The blue whale has no problem with it's weight because it effectively floats in the water and it eats ALL day getting through huge quantities of plankton. The dino's didn't need to eat that much because they were cold blooded. A grazing lizard doesn't need to eat as much as a grazing mammal.
aman Posted February 5, 2004 Posted February 5, 2004 If size was dependent on food available and energy used to get it we can understand the blue whale as a maximum for mammals but there is a source of food, bacteria on the bottom of the ocean that is so abundant that I would imagine there may be a lifeform down there that is also very very large. If it was cold blooded and ate bottom bacteria it would have the potential to grow large and live long. I find it hard to believe that all this food source is available and we haven't really discovered any major harvestor animals. Maybe tommorrow. Just aman
Aegir Posted February 5, 2004 Posted February 5, 2004 aman said:If it was cold blooded and ate bottom bacteria it would have the potential to grow large and live long. I don't think cold blooded and living on the bottome of the ocean would go well together...
-Demosthenes- Posted February 5, 2004 Posted February 5, 2004 A cold blooded animal couldn't withstand the temperature changes in the ocean. What about the less oxygen? There has been less and less oxygen for the last millions of years. Bigger animals could handle it so they died out.
Sayonara Posted February 5, 2004 Posted February 5, 2004 Aegir said in post # : I don't think cold blooded and living on the bottome of the ocean would go well together... There aren't a great deal of warm blooded species down there.
-Demosthenes- Posted February 5, 2004 Posted February 5, 2004 I guess they can move around, huh. If they're cold they can move to a warmer place, and visa versa.
mossoi Posted February 5, 2004 Posted February 5, 2004 I'm not sure the amount of oxygen in the atmosphere is a factor.
-Demosthenes- Posted February 16, 2004 Posted February 16, 2004 Theres been less and less oxygen in the atnosphere for millions of years, scientists have found this out by analyzing the air traped in amber(solidified tree sap). It only makes sense that they are related.
Cap'n Refsmmat Posted February 17, 2004 Posted February 17, 2004 -Demosthenes- said in post #9 :A cold blooded animal couldn't withstand the temperature changes in the ocean. Says who? Adapt your internal organs to perform at low temp! Plus, the temp at the bottom of the ocean is a nearly a constant, because so little happens to change it. A large animal well adapted could be HUGE , and from readings from microphones at the bottom of the ocean, there's a lot of big stuff we don't know about.
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