Stegosaurs are, understandably, famous for their combination of spike and bony plates that give them a distinctive profile even when compared to other dinosaurs. However in addition to these more obvious bits of armour (and let’s face it, some of them are really obvious) is the gular armour. For those not familiar, the former word refers to the throat (most often used by me at least when talking about the gular pouches of various pterosaurs) and as you can see here this armour is a series of tiny bony ossicles that lie almost like chainmail around the throat and base of the neck (here in Stegosaurus). To my knowledge these are pretty rare in stegosaurs and I can easily imagine that they fall away or simply don’t preserve given their small size.
10 Responses to “Gular armour”
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Dave Hone's Archosaur Musings 
Wow, I didn’t know about that. Are there are other dinosaurs apart from Stegosaurs that have it?
I’m not sure there’s any record of it outside of Stegosaurus to be honest, but then my knowledge of the stegosaur fossil record is not great. I don’t think any other clade has them though.
This has been known for some time. Given the increasing lengths of stegosaur necks by the late Jurassic, and the fact that plates protected only their dorsal surfaces, throat armor isn’t surprising. We may expect it in Miragaia (=Dacentrurus?). But basically stegosaurs placed more reliance (than ankylosaurs) on keeping the anterior out of harm’s way than on withstanding attack.
Is that on display at the Smithsonian?
Nope, yet another photo from Japan.
I don’t know the stego-literature that well. The most complete Stegosaurus specimens show this. However, until Ken Carpenter did his new mount at the Denver Museum back in the 1990s, museums were unable to put them in the life-position mounts. Unfortunately, life position mounts hold a great influence over how people (scientists and the public alike) perceive the whole animal, and these osteoderms went unappreciated.
This patch of ossicles is part of the reason that I suggested a head-up-look-backwards defense posture for Kentrosaurus.
http://palaeo-electronica.org/2011_2/255/index.html
Stegosaurus maybe famous, but this throat isn’t common knowledge. Come to think of it, I don’t remember seeing any artists draw a Stegosaurus with it.
Since the plates are so thin and apparently well endowed with blood vessels, I don’t think they would work as “defense” but for display as in I’m too big for you to attack. The throat ossicles also seem too puny for defense, perhaps they assisted in swelling the neck up to make it look thicker.
I think the real defense was in the tail and since most of it’s weight pivoted over the hind legs and it’s forelimbs sprawled out, the animal could turn quickly to keep it’s rear toward it’s attacker.
A very interesting beast Stegosaurus.
Of course the main defense was the caudal spikes, brought to bear by rapid turning if necessary. And yes, the plates functioned mainly just as “show.” (Reminds me of soviet military designers–“appearance is more important than substance.”) Still, Carpenter noted that an allosaur took a piece out of a plate, which suggests it got in the way of an attacker who otherwise would’ve hit flesh. Also, if you look at the small cervical plates of Miragaia (=Dacentrurus?) they do seem to inhibit attack, since they could injure the upper jaw of a theropod which attempted to bite the neck (while armor, if present, protected the ventral surface–or perhaps, made the neck too thick for a theropod to encompass with its jaws).