Did Theropods have Poisonous Saliva?

[ningishzida]

This came up in a "Toy" thread, where it was out of place, so thought I would begin a topic about it here.

As most people here know, 'typical' theropods have teeth almost identical to monitor lizards, and these lizards have virulent bacteria and enyzymes that act as a kind of "venom".

This is how a komodo dragon can prey upon massive water buffalos ten times their mass.

This seems a logical explanation of how much smaller theropods could subdue larger sauropods, just bite them and let them weaken from the bacteria.

But the reason this works for komodo dragons is because they have LIPS. This keeps the bacteria- laden saliva in their mouths where the bacteria can breed.

But if dinos had no lips, their mouths would be dry like a crocodile, and there would be virtually no bacteria.

This is yet another reason why theropods had lips.

[[][][]cordylus[][][]]

Sure, I believe that. Some certainly would have been "cleaner" than others. LIke one that hunted fresh, live prey over one that ate putrid carcasses.

[arioch]

I don´t think so. Poisonous bite, or bacteria is an alternative when the predator jaws isn´t enough strong, or they lack the anatomy adaptations needed to grab the prey or kill it fast. This is the case of Komodos. But theropods, with their big slicing teeth who works wonders, and bipedal condition had enough weapons to kill effectively and relatively fast medium and large prey, or chase them when the prey attempt to flee. Nature doesnt develop such resources if theres no need of it.

[[][][]cordylus[][][]]

Some dinosaurs did have weak bites though. (For example) Dilophosaurus was one of those. But then again, it was the biggest predator of it's time... I don't know. :-P

[arioch]

All the theropods bites were relatively weak, they used more the slicing teeth and the neck muscles to rip the flesh, falling like a hatchet with the mouth full open (pretty similar to Smilodon, another carnivore with weak jaws, with the exception he used the fangs to stab). Maybe dilopho was an exception, who knows, his teeths were more weak than usual . But in fact, his potential prey was quite small...

[[][][]cordylus[][][]]

All of their bites were weak? How do you know this? ;D

And the tyrannosaurs didn't have weak bites.

[arioch]

Yeahh...man, i left out tyrannosaurids, give me a break ;D. There´s no need to mention they were radicallly different to the other giant theropods.

For example, we know the bite strenght of allosaur thanks to biomechanics. And trust me, there was nothing impressive, less than 10 times weaker than an alligator. And allos had one of the more strong jaws within theropoda, apart from tyrannosaurid....

But, i repeat, carnosaurs (and maybe megalosauridae too) had strong muscles in neck and shoulders to balance this apparent weakness. Bakker´s theory about allosauroidea hunt methods fits perfectly.

[therizinosaurus]

Very interesting, I first read about this in Dinosaurs and Other Mesozoic Reptiles of California:
dml.cmnh.org/2002Aug/msg00551.html

[sbell]

Monitor lizards (as well as iguanids and all snakes, to some extent) actually contain venom in their saliva. The bite of the Komodo is as dangerous for the venom as the infection. Oh, and the blood loss of the giant lizard head taking a bite.

And I've seen skulls of Komodos--their teeth are more like over-sized snake teeth than like rex, or even dromaeosaur, teeth.

[arioch]

Jan 18, 2009 17:48:35 GMT sbell said:

And I've seen skulls of Komodos--their teeth are more like over-sized snake teeth than like rex, or even dromaeosaur, teeth.

And so? could komodos crush bones or inmobilize their prey?

[sbell]

Jan 18, 2009 18:20:16 GMT arioch said:

Jan 18, 2009 17:48:35 GMT sbell said:

And I've seen skulls of Komodos--their teeth are more like over-sized snake teeth than like rex, or even dromaeosaur, teeth.

And so? could komodos crush bones or inmobilize their prey?

If I had to guess--there would be no bone crushing. The skull just didn't seem that heavy. I guess it would be different if it had been attached to a live lizard...

But it was clearly a bite-hold-and-rip animal. I am guessing that only small or fractured bones would get eaten.

[arioch]

I mean , were you trying to stablish an analogy with theropods by the teeth proportion of Komodo dragon? your statement was like: "komodos teeth are proportionally bigger than rexes and raptor ones. So, if they have bacteria in it, big theropods, being reptiles, may had too". Or maybe is my mistake.

However, assuming that there existed venom in carnosaurs... How fast a beast like, for example, an Argetinosaurus, even a young one, could die by the infection? days? i think the simple bleeding could take it down faster than that. Same with multiton ornithopods or tyreophors...and most of them couldn´t easily outrun theropods, unlike deers outrun Komodos (and thats why the venom is useful).

[tomhet]

Jan 18, 2009 18:58:34 GMT arioch said:

I mean , were you trying to stablish an analogy with theropods by the teeth proportion of Komodo dragon? your statement was like: "komodos teeth are proportionally bigger than rexes and raptor ones. So, if they have bacteria in it, big theropods, being reptiles, may had too". Or maybe is my mistake.

I think he said exactly the opposite.

[sbell]

Jan 18, 2009 18:58:34 GMT arioch said:

I mean , were you trying to stablish an analogy with theropods by the teeth proportion of Komodo dragon? your statement was like: "komodos teeth are proportionally bigger than rexes and raptor ones. So, if they have bacteria in it, big theropods, being reptiles, may had too". Or maybe is my mistake.

However, assuming that there existed venom in carnosaurs... How fast a beast like, for example, an Argetinosaurus, even a young one, could die by the infection? days? i think the simple bleeding could take it down faster than that. Same with multiton ornithopods or tyreophors...and most of them couldn´t easily outrun theropods, unlike deers outrun Komodos (and thats why the venom is useful).

I was just comparing general shape--the teeth are very different, and so the function would be at some level different.

But I do expect that bleeding from a wound inflicted by a rex (or large monitor) would have faster effect than any but the most powerful venoms. Shock is a great killer.

[arioch]

Then it was my mistake. Forget it.

Yes, having power to pulverize bones, the venom in saliva sounds like a joke ;D (though all is possible). On the other hand, we can expect some especulation in dromaeosaurids and other carnivorous theropods.

[tetonbabydoll]

I don't see why a poisonous dino is out of the question. It has been a weapon and defense of choice since life began. Certain small herbivors may have been poisonous too, to avoid being preyed upon, ( and therefor, maybe brightly colored ). Though, I don't see how any of this may be proved, one way or another.

[arioch]

Nothing is out of the question (Mind you, even platypus are venomous...and its a mammal!...well , kinda)...but as i said, venom exists in certain animal to cover some weakness, and i don´t see where is the weakness of bipedal ( that means in the worst case, not precisely slow) predators with big mouths with serrated teeth.

[stoneage]

Jan 19, 2009 1:24:41 GMT @tetonbabydoll said:

I don't see why a poisonous dino is out of the question. It has been a weapon and defense of choice since life began. Certain small herbivors may have been poisonous too, to avoid being preyed upon, ( and therefor, maybe brightly colored ). Though, I don't see how any of this may be proved, one way or another.

Name a poisonous herbivore!

[stoneage]

I know of know poisonous crocodiles or birds that are predators who bite, There are some birds that are poisonous to eat but all are small. Large predators that live active lifes have no need for poison. The biggest snakes are not poisonous but are constrictors. There is no evidence that large dinosaurs were poisonous in any way! ;D

[sbell]

Jan 19, 2009 1:45:23 GMT arioch said:

Nothing is out of the question (Mind you, even platypus are venomous...and its a mammal!...well , kinda)...but as i said, venom exists in certain animal to cover some weakness, and i don´t see where is the weakness of bipedal ( that means in the worst case, not precisely slow) predators with big mouths with serrated teeth.

What do you mean? IT produces young for its young, ergo it must be a mammal. And everyone forgets red-tooth shrews, which are also venomous.

Jan 19, 2009 2:04:08 GMT stoneage said:

Jan 19, 2009 1:24:41 GMT @tetonbabydoll said:

I don't see why a poisonous dino is out of the question. It has been a weapon and defense of choice since life began. Certain small herbivors may have been poisonous too, to avoid being preyed upon, ( and therefor, maybe brightly colored ). Though, I don't see how any of this may be proved, one way or another.

Name a poisonous herbivore!

As in, a mammal one? Or any venomous (ie injecting poison) herbivore? The first one that comes to mind is green iguanas--it may be weak, but it's there. And there are several fish that I believe are venomous--loricariids, for example--that may have venom. But true, there aren't as many. Maybe if we get into arthropods.

Jan 19, 2009 2:13:38 GMT stoneage said:

I know of know poisonous crocodiles or birds that are predators who bite, There are some birds that are poisonous to eat but all are small. Large predators that live active lifes have no need for poison. The biggest snakes are not poisonous but are constrictors. There is no evidence that large dinosaurs were poisonous in any way! ;D

Like with iguanas/varanids, all snakes apparently have a venom of some kind, it just isn't well-developed (or well-injected) in most species. Somewhere around here, I posted the reference before.

I also posited a question that never got a response from anyone--1) varanids + iguanids are considered to share a common ancestor, and are the lizards with venom (I believe the heloderms fall nearby as well).

2)The snakes are understood to share a common ancestor with varanids/iguanids. All have at least a weak venom.

For a great, simplified cladogram of the relationships, the first page on this PDF is good:
www.venomdoc.com/downloads/2005_BGF_Nature_squamate_venom.pdf

3)The mosasaurs are understood to have evolved from within either the varanid or snake line (most likely the former)--in other words, within the clade known to contain venomous squamates.

The question--is it possible that mosasaurs, as a relic of their genetic ancestry, may have been mildly venomous? Or extremely venomous, really.