FaunaBgirl
New Member
Does anybody know if they have found any dinosaurs to have shooting tongues like our chameleons today?
Dinosaurs with shooting tongues?
- Thread starter FaunaBgirl
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Eric Adrignola
Avid Member
There are some fossil animals with similar adaptations, but no dinosaurs that I know of.
Of course, the bones of the hyoid are not very large, and probably do not fossilize well. It'd be hard to know for sure.
My understanding is that fossil evidence shows they had (in general, for therapods - the meat eaters) rather stiff, short tongues. Chameleons' tongue structure is so highly specialized, it's not something you can miss if you've got all the bones to work with.
With small animals, that's usually the problem - little bones in little animals do not fossilize well except under ideal situations.
I'm pretty sure large marine mosasaurs had a secondary set of jaws inside the main ones. What purpose they served, we can't know for sure. I've heard some palentologists suggest that they shot out like the jaws of the "aliens" from the alien movies. I kinda think a simpler explaination is better.
There are a few other animals wich seem like they lived like chameleons. One creature that the "birds are NOT decended from dinosaurs!!!" crowd adores is an example. It is a lizard-looking thing with grasping feet and a long neck. The animal seems to have long, sail-like scales on its back(visual display, like our lizards have). People want to believe they're feathers - so that this is the bird ancestor. They don't look like feathers to me.
That's besides the point... the thing looks like it pulled it's head back in an "S" and snapped it forward quickly to grab prey. Ambush predator.
Kinda cool.
Of course, the bones of the hyoid are not very large, and probably do not fossilize well. It'd be hard to know for sure.
My understanding is that fossil evidence shows they had (in general, for therapods - the meat eaters) rather stiff, short tongues. Chameleons' tongue structure is so highly specialized, it's not something you can miss if you've got all the bones to work with.
With small animals, that's usually the problem - little bones in little animals do not fossilize well except under ideal situations.
I'm pretty sure large marine mosasaurs had a secondary set of jaws inside the main ones. What purpose they served, we can't know for sure. I've heard some palentologists suggest that they shot out like the jaws of the "aliens" from the alien movies. I kinda think a simpler explaination is better.
There are a few other animals wich seem like they lived like chameleons. One creature that the "birds are NOT decended from dinosaurs!!!" crowd adores is an example. It is a lizard-looking thing with grasping feet and a long neck. The animal seems to have long, sail-like scales on its back(visual display, like our lizards have). People want to believe they're feathers - so that this is the bird ancestor. They don't look like feathers to me.
That's besides the point... the thing looks like it pulled it's head back in an "S" and snapped it forward quickly to grab prey. Ambush predator.
Kinda cool.
THECHAMMAN
Established Member
im pretty sure cuttlefish shoot their mouth out and catch crabs and that stuff. it looked like a cham tongue, but with a mouth at the end of it.
Chris Anderson
Dr. House of Chameleons
Eric, I'm curious if you're referring to fossils of extinct chameleons or if you're talking about other organisms with particularly similar adaptations. Out of curiosity, do you have any more specific details? I'm aware of fossil chameleons but don't know of any other fossilized organisms showing a similar tongue projection system. People might find this article, which includes photos of a fossilized chameleon skull, interesting: http://www.jstor.org/pss/1565027
You're referring to pharyngeal jaws which actually are not quite as rare as people might expect. A number of living fish species actually have pharyngeal teeth and jaws. Here is an article on Moray Eels which have them: http://news.nationalgeographic.com/news/2007/09/070905-eel-jaw.html
Cuttlefish and squid don't shoot their mouth out but rather project out their tentacles. This mechanism is actually very different from chameleons and is more similar to how our tongue or an elephants trunk works. Its called a muscular hydrostat. In these systems, there aren't any bones for the muscles to act against to cause conformational changes but rather, muscles are arranged to act on each other to cause the changes.
To be more specific (and I'll warn everyone it may be more detail then you care to read), in the squid tentacles, there are longitudinal muscles extending the length of the tentacles and circular muscles which wrap around them. Since muscles have to maintain a constant volume, when the longitudinal muscles contract, the tentacle shortens and fattens. When the circular muscles contract around the longitudinal muscles, they force the longitudinal muscles to lengthen at high speeds.
Chameleons are different because they have a circular muscle (the accelerator muscle) that is wrapped around a parallel sided, rod shaped bone called the entoglossus. As the accelerator muscle contracts around the entoglossus, it lengthens so as to maintain its constant volume and tongue projection occurs as the muscle extends over the tapered tip of the entoglossus. Its somewhat like squeezing a watermelon seed. Now, there are additional things at work in the system as well (collagen fiber sheaths that act as an elastic storage mechanism), but that is just a basic rundown of how it works.
Some Salamanders actually project their tongues as well, very similar to chameleons, only their tongue mechanism is exactly the opposite. Rather then shooting their accelerator muscle and tongue pad and leaving the bone behind, in salamanders, the accelerator muscle stays behind and the bone is fired with the tongue pad. There are a number of high speed videos of salamander tongue projection at this link: http://www.autodax.net/feedingmovieindex.html These are videos were taken by my adviser that I work under here at USF (Stephen Deban). He specializes in tongue projection in salamanders and I'm in the lab working on tongue projection in chameleons.
Anyway, I'm sure that was more detail then people really cared for but this is specifically what I do so I had to chime in.
Chris
Sepioteuthis
New Member
It's appreciated, Chris!
Since cephalopods is what I used to work on, I'll take the opportunity to elaborate on this. (not that anything that Chris wrote about these guys is wrong)
Cephalopods are cuttlefish, squid, octopus and sepiolids. Cephalopods belong to the order of the mollusks. Other mollusks are snails, slugs and bevalves.
Cephalopod means head-foot. They are called this because their arms are attached to the head.
A cephalopod's mouth is in the center if the arms and looks like an upsidedown parrot beak with inside it a radula. For those of you that have seen a snail clean the inside of a fishtank; that little rasp that scraps the algae of the glass is the radula. Cephalopods use them to drill holes in or chew pieces off shells and exoskeletons (crabs, shrimp ect).
Cuttlefish, squid and sepiolids have, in addition to their 8 normal arms, 2 tentacles. These tentacles are rolled up in a pouch under the beak (cuttlefish) or in front of the mouth (squid, sepiolids). Unlike the arms, tentacles only have suckers on the tips. These much longer tentacles are used to catch prey.
For more information on cephalopods visit http://www.thecephalopodpage.org/
Didn't mean to turn this into a biology class, but I just thought it was worth while to elaborate a little.
- Suzanne
Eric Adrignola
Avid Member
Nope Chris - I wasn't talking about projectile tongues. I was a bit ambiguous - I was nto referring to the tongue, but to the method of hunting.
http://en.wikipedia.org/wiki/Longisquama
Some scientists had thought it had a long neck, and hunted like a chameleon - only with a neck like a crane or heron, instead of a projectile tongue.
From the looks of things, these assumptions were a bit premature. I can't find any recent finding that support the idea that the thing had a long neck at all!
Feduccia was a big pusher of this thing being a bird-ancestor (hates dinosaurs... plus he's at UNC chapel hill... so go figure! hehe). He was pushign it so hard, I think a lot of the early ideas about it were suspect - including it's proposed chameleon-like hunting adaptations.
As far as other animals with similar hunting methods, cephalopods are the neatest and most far along, mantids, dragonfly larvae, some fish... some turtles like the matamata, some spiders... some of the coolest animals. I'm pretty sure chameleons are the only one (fossil record and all) with a similar mechanisim. Other herps just flap their tongues out.
http://en.wikipedia.org/wiki/Longisquama
Some scientists had thought it had a long neck, and hunted like a chameleon - only with a neck like a crane or heron, instead of a projectile tongue.
From the looks of things, these assumptions were a bit premature. I can't find any recent finding that support the idea that the thing had a long neck at all!
Feduccia was a big pusher of this thing being a bird-ancestor (hates dinosaurs... plus he's at UNC chapel hill... so go figure! hehe). He was pushign it so hard, I think a lot of the early ideas about it were suspect - including it's proposed chameleon-like hunting adaptations.
As far as other animals with similar hunting methods, cephalopods are the neatest and most far along, mantids, dragonfly larvae, some fish... some turtles like the matamata, some spiders... some of the coolest animals. I'm pretty sure chameleons are the only one (fossil record and all) with a similar mechanisim. Other herps just flap their tongues out.
THECHAMMAN
Established Member
i have now been learned. thanks for that tid bit of info and for correcting my error.
