DarkSun
:eltiT
Why am I getting a mental image of some random German guy in a thunderstorm saying:
"LIve! Live! Nyahahahahahahaha!"
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Questions about Evolution?
- Thread starter painted wolf
- Start date
Why am I getting a mental image of some random German guy in a thunderstorm saying:
"LIve! Live! Nyahahahahahahaha!"
painted wolf
Grey Muzzle
Perhaps we need to split this discussion into it's own thread?
Evolution of the impossible? perhaps....
wa:do
Evolution of the impossible? perhaps....
wa:do
rojse
RF Addict
I keep on thinking of Igor's from Discworld: "My mathther wath a great man, but had hith occathional idiothyncrathieth."
painted wolf
Grey Muzzle
There is quite a lot of evidence for high metabolism in dinosaurs. The three best reasons:
1) growth rates.... dinosaurs lived fast and died young. All dinosaurs grew up quickly and died in relatively short spans of time. A Hadrosaur for example, would go from a hatchling 14 inches long to an adult 30 feet long in just a decade or so... then dead by 30 years old.
(they would start reproducing while still growing up... the ultimate teenage parents.)
The giant sauropods got to full size in as little as 10 to 15 years!
* We know this from studying what are called LAG's (lines of arrested growth) which are layers of bone laid down annually in many animals.
2) Bone structure... Dinosaurs have bones filled with vascular cavities to allow blood vessels to run through the bone. The sheer number of these cavities are like those of mammals and birds (lots and lots of them) and unlike crocs and reptiles (very few of them).
3) Feathers... Insulating body features like true feathers and proto-feathers on many dinosaurs indicates that they may have been trying to maintian a consistant body temp.
There are other areas of evidence... much of it varied in it's iffyness... such as predator/prey ratios.
wa:do
Storm
ThrUU the Looking Glass
LOL, I need that in dummy-speak. High metabolism = warm blooded?
And relatively short lifespans are typical of warm blooded creatures? Why?
OK, that I get.
How could such ratios constitute evidence of warm blood?
Thank you!
Autodidact
Intentionally Blank
Okay, another random question, but...
How long do you think it would take for a plant to evolve in such a way that it would develop animal-like abilities as years and generations progress? Would it be possible?
I want some walking trees like the ones from Lord of the Rings.
It's not like plants aren't doing quite well right now.
painted wolf
Grey Muzzle
It's a bit more accurate. "Warm-blooded" is actually not a very good way to describe things.
There are several ways to maintain a steady internal temperature. Tuna and some Sharks for example are 'warm blooded' due to high activity and specializations of their circulatory system that keep their blood picking up heat from their muscles and running it to their brains.
Leatherback sea turtles maintain a body temperature higher than their northern ocean environment simply by being very large.
Also not all 'warm-blooded' animals have the same range of metabolism... Some mammals need to bask in the sun to raise their body temperatures in the mornings and their overall body temperature can flux by more than ten degrees during a 24 hour period.
It's not so much the short life as the super fast growth. In order to grow that fast you need a really kicking metabolism... you have to eat a lot and convert it quickly into your own mass.
In some of these cases we are talking about more than doubling-tripling your size every year!
As far as I know only whales can compete with that level of growth today.
Reptiles have lower metabolisms... they need less food, but they also grow less quickly, sometimes growing through their whole lives.
High metabolism animals need a lot of food... if the predator is 'warm blooded' then they need access to more prey than a 'cold-blooded' predator. (as much as ten times as much).
The classic example is one gazelle can feed one lion for a day or it can feed ten crocs for the same day.
If you're environment has say, ten predators for every hundred prey animals, then you likely have cold blooded predators.... if you have one predator for every hundred prey animals you likely have a warm blooded predator. (I'm fudging the numbers but you get the idea.)
The problem comes with sampling techniques... the complexity of food webs and so on. It can be easy to fiddle the numbers unwittingly especially in small samples over limited areas.
wa:do
painted wolf
Grey Muzzle
Variation on Homo....
wa:do
wa:do
DarkSun
:eltiT
nonbeliever_92
Well-Known Member
Alceste
Vagabond
OK, I've got a question. I found a bunch of ammonite pieces over the weekend, and was looking the critter up to try to get a sense of what piece goes where. There are striated patterns - like puzzle pieces - that some of the folks I went fossil-hunting with called "growth plates" covering some of the pieces, while others were smooth, irridescent and shiny all over. The "growth plates" are only visible where the shell has weathered off. I've always assumed an ammonite was like a kind of snail, but this doesn't make any sense in the light of the bits I've got. What are the "growth plates" part of, if not the shell? And are there any living relatives or descendents of these things - or evolutionary branches that departed before ammonite evolved but ended up as something else? Anything else with that bizarre puzzle pattern? Any other beaked and tentacled monsters like the below? Also, how do they know about the tentacles?
painted wolf
Grey Muzzle
While they have no descendants the modern cephalopods (squid, octopi) are their closes living cousins... the Nautilus is more distantly related, but visually it looks closest to the ammonites.
It's mostly comparative anatomy that lets us know what they looked like... Few fossils preserve much soft tissue... mostly ink glands and stomachs and the like.
The patterns on the shell are unique to each species and help paleontologists identify them... along with shell shape, which could get quite unusual. Your image looks to me like the outside of the ammonites shell.
Living Nautilus
variations on Ammonite shells:
wa:do
Autodidact
Intentionally Blank
The hardest thing I've found for me to grasp about the grand ToE is that it's so gradual, how/whether we know that there has been enough time to account for the enormous diversity of species? Is there math on this? Do biologists have a way to estimate how long it should have taken for all these complex species to have evolved in less than 4 billion years? An equation taking into account some kind of average rate of speciation or something?
Jose Fly
Fisker of men
As far as I know, that would be somewhat difficult. Just looking at the literature covering rates of speciation shows a lot of diverse viewpoints. You also have to factor in extinctions--including mass extinctions--and subsequent adaptive radiation events, founder events (e.g. settling of islands), cumulative effects, co-dependent effects (sometimes new species create new niches to be filled), and a host of other factors I'm probably not even aware of.
Plus, it's been estimated that about 99% of the life that's existed on earth has gone extinct, and via the fossil record we're only aware of ~3-5% of those extinct species. Heck, we're still discovering new extant species!
Also, keep in mind that the first ~2 billion years of the earth's history was devoted to unicellular evolution (which is why ID creationists' marveling at the complexity of cells is somewhat uninformed/misleading). That cuts down the time that was needed to generate actual multicellular, metazoan life quite a bit.
As one biologist put it (can't remember who)...It's a lot easier to evolve a human given a cell, than it is to evolve a cell.
Plus, it's been estimated that about 99% of the life that's existed on earth has gone extinct, and via the fossil record we're only aware of ~3-5% of those extinct species. Heck, we're still discovering new extant species!
Also, keep in mind that the first ~2 billion years of the earth's history was devoted to unicellular evolution (which is why ID creationists' marveling at the complexity of cells is somewhat uninformed/misleading). That cuts down the time that was needed to generate actual multicellular, metazoan life quite a bit.
As one biologist put it (can't remember who)...It's a lot easier to evolve a human given a cell, than it is to evolve a cell.