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Dilophosaur Venom?
Topic Started: Aug 25 2011, 01:15 PM (3,218 Views)
Scrublord
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Or maybe it just didn't hunt large prey. Think about it-- those crests were very delicate, and would likely be damaged in a battle with a similar-sized dinosaur. More likely, dilophosaurs preyed on animals small enough to swallow whole, so they didn't need the powerful jaws of larger theropods.
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T.Neo
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Anyone ever considered that part of their diet may have been fish?

See the notch in the Spinosaurus jaw:

Spoiler: click to toggle


And also somewhat in the crocodile jaw:

Spoiler: click to toggle


Maybe that would explain the jaws being "flimsy" in comparison to other theropods?
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lamna
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I was that on Wikipedia when I was checking, sounds plausible. Probably more likely than venom.
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Are nipples or genitals necessary, lamna?
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TAXESbutNano
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THAT IS THE BEST IDEA EVER.
Seriously. We can have a whole population of Dilo fanboys when we tell them it's just like Spino!
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trex841
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so that would be 2 jp dinos that turned out to be fish eaters...intresting.
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TAXESbutNano
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Dilophosaurus is too epic to be the litte weird thingy.
By the way, would anyone do a biological comparison between the Primal Carnage Dilo and the little weird thingy?
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Empyreon
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Are you plausible?

T.Neo
 
Anyone ever considered that part of their diet may have been fish?

Y'know, I hadn't thought of that... It makes sense.
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food for thought
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Carlos
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Quote:
 
Also the venom glands in lizards are seated deep within lips which is doubtful dinosaurs ever had given the phylogenetic bracket and how archosaurs develop beaked forms at the drop of hat which suggests what they had covering their mouth margins wasn't the same thing as what lepidosaurs have.


Birds have lips. They're pushed back by the rhamphoteca. Notosuchians also had lips, so the absence of lips in crocodyllians seems unique to them, so archosaurs as a whole probably started as lipped. In addition, some squamates have beak like structures, so rhamphotecae can theoretically evolve easily in lipped sauropsids.
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trex841
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hold the phone...dinosaurs (might of) had lips?
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Dracontes
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@Empyreon: A few pertinent posts for the Dinosaur Mailing List Archives, http://dml.cmnh.org :
http://dml.cmnh.org/1994Jul/msg00168.html
http://dml.cmnh.org/1996Jul/msg00130.html
http://dml.cmnh.org/2001Jul/msg00164.html (this one gets a bit technical but the gist is that some times it's better to bend than break)
Well, JP's dinosaurs were never intended to be more accurate than needed for the plot. Uh... Which is "not particularly". As the novel has it, there were so many genetic inputs to reconstruct the "dinosaurs" that it's no wonder that some (or all) got off the assembly line a bit wonky ;)

@Watcher in the Puddle: In recent years, scientists found a more inclusive clade of venom-producing squamates, http://en.wikipedia.org/wiki/Toxicofera , which oddly enough includes varanids. I also remember a documentary hosted by Brady Barr where he tangled with Komodos and got some of the lizard's drool in his mouth and reported the latter feeling numb after a relatively short while which is consistent with venom.
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@lamna: Actually the 2nd, 3rd and 4th maxillary teeth are long enough that they would be right at the level of the bottom of the lower jaw when the mouth was closed, give or take soft tissue, so these would comply with the somewhat fuzzy definition of "saber-tooth".

@Nanotyranus & El Squibbonator: I can add that the notch probably helped the animal keep its grip on an item of prey once it latched onto it. Think of it as a slot where a neck or head could be fitted and the teeth of the lower jaw clamping only so much on the pertinent vital areas were helped by the prey's struggles.

EDIT:
@JohnFaa:I'm going to need a citation with that if you wouldn't mind.
Edited by Dracontes, Aug 26 2011, 06:34 PM.
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Carlos
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In regards to notosuchians, it is generally agreed by most people interested in biology. Notosuchus, for example, has been proven in a recent paper to have a trunk.

For lips in dinosaurs, seek no other than the Californian Condor and similar New World vultures, which have quite evident squamate style lips on un-beaked areas of the jaws.

For beaked squamates, there's one genus of sea snake with turtle like beaked jaws. I think it appeared in Life in Cold Blood.
Edited by Carlos, Aug 26 2011, 06:53 PM.
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Dracontes
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JohnFaa
Aug 26 2011, 06:51 PM
In regards to notosuchians, it is generally agreed by most people interested in biology. Notosuchus, for example, has been proven in a recent paper to have a trunk.

For lips in dinosaurs, seek no other than the Californian Condor and similar New World vultures, which have quite evident squamate style lips on un-beaked areas of the jaws.

For beaked squamates, there's one genus of sea snake with turtle like beaked jaws. I think it appeared in Life in Cold Blood.
I've read the pertinent parts of Fiorelli (2008) and most of the discussion on facial musculature for Notosuchus seems unwarranted.
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Crocodiles have no nasal septa too which makes the assumption of a short trunk a little less certain. Comparing with pecaries http://www.flickr.com/photos/jbyoder/4118638192/ one sees that the notosuchian's snout is far more bony than the presence of a trunk would imply. I myself think the overbite of Notosuchus' bony snout could have the function Fiorelli et al. infers for a putative fleshy extension, with the nostrils recessed in the narial opening. Fiorelli (2008) makes no effort to invalidate the notion that the skull ornamentation is produced by interaction with large scales or a relatively continuous keratinous surface. I grant that the animal could have had ornithischian-style cheeks but mammalian-style oral musculature isn't particularly parsimonious.

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That on the condor isn't a squamate-style lip to me, as the wide squamate lips occlude to some extent when the mouth is closed. In the condor the thin lip margins slide past each other as in other carnivorous theropods.

You mean these guys?
http://na.oceana.org/en/explore/creatures/turtle-headed-sea-snake
http://www.arkive.org/beaked-sea-snake/enhydrina-schistosa/image-G52862.html
That's not a beak in the slightest: just enlarged scales around the mouth. Come to think of it a pretty solid reason why squamates can't have beaks is that the beaks we know are large thick continuously growing scales which couldn't develop in an animal that sheds its skin periodically.

Uh... Preemptive apologies for being a complete bore with this but I like my speculation with a heavy side of facts ;)
Edited by Dracontes, Aug 27 2011, 07:14 AM.
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Carlos
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I did know that crocodyllians in general have no nasal septum, but I was under the impression that the "evidence" for the trunk was due to the presence of specialised neurovascular foramina. Then again, I have no read the paper.

Fair enough, although at least avian jaws are clearly more fleshy than crocodyllian ones. Whereas crocodiles have the skin pratically attached directly to the skull, you can clearly see that the skin on New World vultures and pigeons is more loose, allowing for the presence of cheeks in the Californian Condor, as you can see.

The sea snake in Life in Cold Blood was an Emydocephalus sea snake, which from the looks do appear to have either a rhamphoteca or a very similar structure.
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Empyreon
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Are you plausible?

Thanks for those links, Dracontes. I like facts and sources too, and don't find them boring at all.
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Dracontes
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I linked to the paper on my previous post ^_^
The skin around the mouth is still living and subjected by its use to a lot of wear and tear so it pays to have sufficient blood supply and innervation so injuries are avoided and if they happen quickly dealt with and thus less crippling in the long run. That's off the top of my head and while it doesn't invalidate per se the the notion of crocodilian fleshy lips, when it's coupled with the current bracket and the tentative nature of Fiorelli et al.'s remarks I'm not convinced.

True, I agree. But I wouldn't go to the extent of giving Paulian lips to my dinosaurs. Just sayin'...

From what I've seen of Emydocephalus on a cursory image search, it's a passing resemblance. Cool pointy rostral scale on the male though.

Now that I've completely derailed the thread let's get it back on track ;)

Venomous dinosaurs are a tough proposition: the only thing I can think of is your basic ectopic expression of poison genes in saliva and subsequent release provoked by biting down on prey. The problem I assume exists with archosaurs is that due to their water-saving adaptations and their snaggle-tooth maws they've substantially reduced their salivary glands. It's true that there are birds doing interesting things with their saliva, http://www.earthlife.net/birds/digestion.html (see third paragraph) and it seems there's a venomous archosauriform, http://appstate.academia.edu/AndrewHeckert/Papers/389410/Grooves_to_tubes_Evolution_of_the_venom_delivery_system_in_a_Late_Triassic_reptile_
Edited by Dracontes, Aug 27 2011, 03:59 PM.
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