This will sound like a dumbass question, so let me give it some context. A student of mine recently offered some arguments to prove that the Bible is literally true. He offered, for example, that reptiles never stop growing their entire lives, and since early humans lived for hundreds of years, so might have reptiles, hence dinosaurs.
I don’t buy it (I hope that would go without saying…), but as I had never heard this reptile factoid, all I could say was, “I have never heard that reptile factoid.” In the interest of pure truth, let me formally ask: do reptiles never stop growing their entire lives? I have heard a similar and (to me) more credible story about fish, where size is a function of food supply and volume of container, but I don’t even know if that’s true.
Anyway, reptiles? Unlimited growth potential? Help me out.
A great number of ectothermic animals do continue some growth throughout their lives. However, there is still a maximum size that any species attains. If the dinosaurs (many of which were as small as chickens) were simply lizards grown large, why do we not have fossils of the same species at all different sizes? We have found very few pre-adult dinosaur fossils (which would be expected if dinosaurs spent a relatively short portion of their life as children, then a large portion of their life as specific-sized adults). We do not find 3 foot, 5 foot, 7 foot, 9 foot, . . . 20 foot long Triceratops fossils. We have a very few hatchlings and several hundred 20 foot specimens.
A sidelight to the point the student raised is that evidence for continued growth is one of the points of evidence that paleontologists wrangle over in the attempt to discover whether dinosaurs were ectothermic (cold-blooded) or endothermic (warm blooded). There is conflicting evidence for both points of view, and it has been suggested that our ecto-/endo- categories could be too limited and that dinosaurs managed to have traits of both.
However, no one who has studied dinosaurs has come to the conclusion that they achieved their enormous size simply by living a long time.
I’m not sure how that would be an argument against evolution, in any event. We do not find large mammals in the same strata as dinosaurs. We have a fairly clear record of dinosaur development. Even if the dinosaurs did achieve their large size simply by not dying for a long time, that does nothing to refute the tremendous amount of evidence regarding evolution.
Thoughtful answer, tomndebb, and about what I was looking for. Thanks. As to your last point…
As it happens, he wasn’t using that particular factoid to refute evolution per se, but was instead trying to date the universe at less than 6,000 years old. The big reptile theory basically allows for the coexistence of Dinos and Humans, and so allows for a much younger Earth. Sort of. I guess. He had other, less coherent arguments against evolution, mostly revolving around the fact that humans are waaaaay cooler than other animals. Go humans! Yeah!
I’ve heard that one too. I always accepted it at face value, but then I’ve never had a theological/scientific argument that hinged on it, either. If I found myself in such an argument, I’d probably look it up before using it.
Someone asks the same question of Scientfic American, and frustratingly, it isn’t really answered, but this is offered:
From Compton’s Encyclopedia: " Some reptiles may reach adult size in a year or less, while others, like turtles and crocodiles, may continue to grow for as long as they live."
So lifelong growth is neither unique to, nor universal among, reptiles.
Of course, it ignores that we never find dinosaur fossils in the same geological strata as humans–or any pre-humanoid primates. “Ah! But the dinosaurs were simply heavier and got buried deeper in the mud during the Great Flood.” (Which explains why we have found clutches of dinosaur eggs in the fossil record–after the turbulence of the flood, they all just sank into the same place at the same time.)
A good resource for a lot of these sorts of claims is at http://talkorigins.org
I was surprised to not find anything specifically on the ectothermic/growth-throughout-life argument, this morning, but I did not spend a lot of time looking.
A good jumping-off point is the FAQS page at http://talkorigins.org/origins/faqs-qa.html
which answers the “general” Creationist objections against Evolution by providing a link to a page dealing with each separate issue in depth.