Reptile & Amphibian Forums

not owning any chams with horns (e.g. jackson's) I have often wondered about the reasons for their protuberancies. I am assuming that it is mating related since it is the males who have these (like the higher casque of male veiled's) but why horns? Is it for mating "fights" like horned mammals? Just curious, as I always like to understand adaptations and frankly, I find insects and herps to be much more interesting than mammals!
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Chameleon Help & Resource Info

0.1 Veiled - Luna
1.0 Beardie - Darwin
0.2 felines - Kyndra and Líta
1.0 African Clawed Frog - Skipper
0.3 Mad. Hissers (2 died ;(
0.1 Chilean Rose Hair Tarantula - Rosa Leigh
0.1 Goliath Bird-Eater Tarantula - Natasha

I believe it's for sexual selection. Males with larger bigger horns are more "appealing" to females (and larger males are also healthier and stronger) and I believe it's for male-male encounters during mating season as well. Also, Chamaeleo trioceros sp. aren't very colorful (compared to F. pardalis and others) so maybe during their evolution their degree of horn size compensated for color in attracting females. It's my take on it...
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Experience and appreciate nature's creation.

www.zenexotics.com

I would agree, its for sexual selection. I saw a documentary on africa, and it had a scene of two wild male jacksons fighting in a tree. It was real neat. From what I observed, they try to knock the opponent of the tree. The bigger or stronger male will "lift" the other male with his horns and toss him off the branch. So the bigger the horns, the more power, which means a stronger male.

There's more to itthan that even.

The most dangerous part of chameleon on it's mouth. Even triceratops, which had 4 foot horns, had a more powerfulweapon - it's mouth.

With their jaws, they could cripple and kill another of their kind very quickly. Same goes with chameleons. they have about the most powerful jaws for a lizard of their size(as did triceratops and its relatives).

Veields and panthers will fight to the death sometimes. Horned chameleons will fight, but their horns get in the way of their jaws. The one with the longer horns can keep the other's jaws farther away.

It's not just triocerus - remember, furcifer AND Calumma have similar adaptations - rostral projections, while not true horns, provide the same function. They keep the other guy's jaws away.

Pardalis have short "horns," and seem to rely on color and threat,not pushing and shoving. Same for calyptratus.

That might be the evolutionary reason for the horns showing up in the first place, and for them being useful. Now, I'm sure the females sexual selction has a say in it. If horns are a desireabel trait, then sexual selection may be even more of a factor now than fighting.

I agree with you that their jaws are very powerful but most male-male interactions don't even go as far as actual "fighting" and therefore don't even have the opportunity to use their jaws. Most interactions are intimidation...puffing themselves up to look bigger, gaping, swaying back and forth and positioning themselves to look the biggest. That in itself will make the weaker one withdraw....only if both size each other up and are of equal size and strength will they fight and that is probably less than 10% of the time.
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Experience and appreciate nature's creation.

www.zenexotics.com

I figured it was sexually/mating related, but had also wondered about the furcifer elongated snout, so this makes sense. Since Luna has never bitten me I never think of their bite as being very painful even though I had heard it can be - esp. with the larger species.

So what do veileds do to battle/dissuade another male? Is the casque used in a similar way - cocking head and jabbing or pushing with it? Would make sense (from an evolutionary stand point) for the higher the casque the better the chance of survival. I have also read that the casque adaptation in general is in part to catch water and then run down into the mouth and b/c of veiled's range theirs is larger due to less rain/moisture. Makes sense to me!
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Chameleon Help & Resource Info

0.1 Veiled - Luna
1.0 Beardie - Darwin
0.2 felines - Kyndra and Líta
1.0 African Clawed Frog - Skipper
0.3 Mad. Hissers (2 died ;(
0.1 Chilean Rose Hair Tarantula - Rosa Leigh
0.1 Goliath Bird-Eater Tarantula - Natasha

Nah, no real use for the casque besides display. Anything that seems to be at odds with survival, horns, frills, crests, ornimentation of any sort is almost always attributable to two things : Sex or fighting for Sex.

If they are of no benifit to survival, they must be of a benifit to reproduction.

Veileds probably solve 99% of their territorial disputes by sight - same with panthers. Little guys run away. They learn, too. If they are raised by themselves, they'll charge a male twice their size - they have to get beaten up to know what can happen to them. I've seen it happen.

Horns help with those few disputes that display doesn't solve. Maybe in dense jungle, chameleons get closer than they do in the open areas and forest edges frequented by the large, display species. Coloration would be less effective, and close encounters more liekly...maybe.

But they do bite - hard. Even a female veiled can probably crack a fingernail if they wanted. Usually they don't clamp down, though.