As typical, there’s a wiki for that.
Darren Garrison:
So we know it didn’t get the worm, then.
What I want to know is how the amber bit off a piece of dinosaur tail. Or how something else managed to bite off and discard a piece of dinosaur tail in such a way that it just ever so conveinetly fell into a convenient blob of pine resin.
I mean, dinosaur tails are usually attached to dinosaurs. What happened to the rest of it? It’s not like losing your boots in quicksand. Blobs of pine resin are sticky but you can usually continue forward motion with pine resin stuck to you, you don’t have to chew off your tail in order to make your escape, right?
There are any number of possibilities. Maybe something ate the rest of if and dropped the tail where it happened to land in resin.
Actually, one of the genes triggering eye development is so highly conserved that the mouse gene can substitute for a defective gene in the fruit fly (eyeless/small eyes/aniridia). This point to a common ancestral organ to both insect and vertebrate eyes.
To answer the question of how many times that eyes have evolved, you have to first answer “what is an eye?” (And I feel kinda like I need to shave my head and put on a saffron robe before writing that sentence.) The evidence today suggests that photoreceptors evolved once, and ways to squeeze more useful information out of those photoreceptors (such as putting them in an indentation, mostly covering that indentation, sticking a lens over the open part of the cover) happened multiple times and is is an “evolutionary easy” form of convergence. So if you call a patch of photorecptors an eye, you can say that eyes evolved once. If your definition needs eyes to have more elaborate structures, you can say that eyes evolved multiple times. (In honor of the two levels of complexity, a succinct link and a more elaborate one.)
Gecko tails drop off, to let Mr Gecko escape.
Maybe some dinos could do the trick.
Crocodilians and testudines are more closely related to dinosaurs than lizards; can any of them regrow tails? If not, then it’s unlikely.
Yeah, that’s why I specifically said that imaging eyes had evolved multiple times. I’m not going to get into the question of just what an “eye” is, but I feel pretty comfortable on the question of what an “imaging eye” is.
Back to the amberized tail, it’s also possible that the entire dinosaur died (of whatever), and its corpse fell onto the edge of a patch of resin, such that its tail was in and the rest of it was out. With time, the tail got fully encased, and the portion that was outside the amber rotted away or got mangled by some scavenger or something.
Time travelers.
It was time travelers.
I’m waiting for a water bottle cap to be found in amber.
There could be another chunk of amber waiting to be found (or already in someone’s collection) that contains more of the tail. The amber-producing trees of the past seem to have been pretty leaky (there are actual mines for amber) and chunks can get pretty big.
And now, an ammonite shell preserved in amber. Sadly, no soft tissue preservation, which would have been a huge deal.
I missed this thread the first time. Just read the linked NYT article and am chuffed to discover that there is an expert in prehistoric amber working in our local museum.
Small amber Dino-tails, largest T-rex.
My first thought was Amber is fossilized tree resin. How the HELL does an undersea creature like an ammonite get trapped in amber?.
From the linked article:
That’s a pretty impressive series of unlikely events. A blob of thick resin has to fall from a coastal tree into the water, remain cohesive and not break up on its way to the bottom, then envelop a bunch of stuff, including the small ammonite before it gets so encrusted with shell fragments and beach sand that it isn’t capable of sticking to anything, then avoid currents and waves and the like so it doesn’t get pounded into oblivion. I can envision a tree overhanging a swamp or a salty inlet, maybe, where there’s no more than tidal motion to contend with. But it still seems like a weird and relatively rare scenario.
I thought the amber fell onto a beach, where it covered the shell and terrestrial creatures.
Yeah. Let me just say I’m glad my pet parrots are all under a foot tall and weigh ounces instead of being 6-8 feet tall and weighing a lot. Instead of them calling me for food they’d be hunting me for food.
Birds: Small. Cute. Feathery. Horny. Vicious. They didn’t survive 100 million years by being nice…
I’m just going to point out that modern aviform dinosaurs continue to have scales on their lower legs and feet. So almost certainly yes, feathers scales and both.
In that case it still has to avoid being broken up by the pounding of waves repeatedly on the beach*. It’s still, to my mind, a pretty unlikely scenario. Unless the trees are really thick on the beach and dripping resin everywhere.
*The tree has to be close to the water line, or else the ammonite shell doesn’t get deposited where it can get resin dripped on it. And don’t suggest it’s dropped there by some scavenger – in order for us to have a specimen come down to us, the likelihood of an amber-trapped ammonite is probably a pretty likely scenario.
Err… yes and no.
As others have mentioned, the photoreceptor portion might have evolved only once and the multiple types of eyes arose from different ways of getting more information out of them, such as pits, cephalapod and tetrapod eyes have retinas flipped in relation to each other (and it’s the cephalopods - octopuses and squids - who have the better version), compound vs. single camera eyes, multiple ways of constructing compound eyes, and tribolites had crystalline lens no other type of animal ever did.
So, first define what you mean by “eye” and “vision”. But regardless, once you get past “photoreceptor pigments” there are more than three.
By the way, isn’t this how the monster got started in the 1961 Danish-American film Reptilicus? With a preserved dinosaur tail being dug up, which the scientists then used to recover the original animal by regenerating it from its tail?
http://www.monstershack.net/sp/index.php/reptilicus-1961/
Does anyone know where that amber-preserved tail is now? I hope it’s not soaking in a nutrient bath.