Also, still breaking from the next post on oviraptorosaur diet (which will concern the group commonly referred to as “caenagnathids,” but also some outlying taxa and oddities involved). This will begin a series that will allow me to show off technical illustrations I’ve produced over the years (some for papers, some not). We’ll see what people make of them.
The shapes of the rhamphothecal coverings of oviraptorid beaks is a topic that has elicited very little scientific discussion. It is therefore interesting that when the topic has come up, simple arguments are fairly easy to come by, and they fly in the face of conventional illustration. Here is something I threw together a while back to describe a potential rhamphothecal arrangement for oviraptorids (every single taxon shown is a member of Oviraptoridae –and note how each one is so very different from one another in cranial and crest shape!).
Spurred on by Matt Martyniuk of DinoGoss, whose post on the description of a new oviraptorid, Banji [1] (not shown above) led into a thesis that has so far fallen under the radar by University of Oslo PhD candidate Stig Jansen [2].
[1] Xu X. & Han F.-l. 2010. A new oviraptorid dinosaur (Theropoda: Oviraptorosauria) from the Upper Cretaceous of China. Vertebrata PalAsiatica 48(1):11-18.
[2] Jansen, S. O. K. 2008. Beak morphology in oviraptorids, based on extant turtles. MSc Thesis, Universitetet i Oslo [Norway].
Jaime A. Headden
The Bite Stuff 
I felt Jansen’s approach was very weak. I’ll be interested to see when it comes out, but it relies too much on superficial bone anatomy without considering microanatomical surfaces for the attachment of keratin and soft tissues, I would have liked to have seen a more aggressive study. This work doesn’t really meet the bar for what should be standards of inferring nonbony skin structures in fossil sauropsids.
It’s great that he shows in turtles how the shape of the bony structure influences the shape of the beak, but it needed to be taken more aggressively.
Incidentally, the paper about beaks in ornithomimids and birds wasn’t written by Jansen, it was written by Espen Knutsen. The final paragraph of that thesis reads:
“I suggest that future studies in this area should put a greater emphasis on histology to see whether the bone-structure in the area covered by ramphotheca shows any anomaly compared to the rest of the skull (especially in the junction from cover to non-cover). Histological examination of the foramina in birds with comparisons to ornithomimids (and other theropods) might also reveal if they are connected to keratin growth-zones, or if they can throw light on the type of sensory papillae present.”
Neither thesis tackles the issue of what’s going on at a less than superficial level. The methods used in both papers doesn’t really help clarify the extent of the beak in either extinct taxa.
Until someone rolls up their sleaves and starts looking at the snouts of oviraptorosaurs and ornithomimids on a microanatomical level, either through high-res X-ray CT or histology, and compares the data collected to that of living birds, turtles and other beaked vertebrates, we’re not going to even begin to really understand what’s going on here.
Also, other workers have basically already started doing this-i.e. looking at microanatomy of dermal skull bones and finding ramifications for the extent/type of skin structures present over those bones. The bar is set high,if the work isn’t done to meet a good understanding of what’s really happening at the interface of hard and soft tissues, then any assumptions about the extent of keratins is just arm waving.
Oh, I get it. I wasn’t buying the argument. The illustration by itself is not science, and it follows only avian and testudinine patterns without assessing the comparative anatomy involved. That said, I have a much more precise model in mind when it comes to comparison to birds now, but turtles are more difficult because the margins of the rhamphotheca is not always apparent except on a skinned skull.
Jansen’s model also wanted to follow the form of avian jaws closely, but in some birds, especially those with a hooked beak, the rhamphotheca diverges from the underlying bone structure by a decent deal. The illustration is fairly inaccurate with what I would argue these days, especially in that the extent of the crests are much more likely to be close to the bone, albeit thicker, while the extent of the keratin tissue would have been less extensive. I look forward to updating it more scientifically in the future.
Great diagram. Where does the name “Mitrata” come from? And what’s the story with that specimen, is anybody working on describing it?
“Mitrata” is my name for a type of oviraptorid that has so far been in private hands; a specimen is purportedly in an institution for the sake of describing it (I think it’s the Carnegie), and from what I’ve seen it doesn’t differ that much from this specimen (based on a cast, but on first-hand examination at least, produced through Gaston Design). “Mitrata” refers to the miter-like crest, and this is allusive to the headwear worn by some Taoist and Buddhist priests.
About 10 years ago, I read an essay by someone- I think it was Toby White- arguing that even the short-skulled oviraptorosaurs should be restored with much longer beaks that do not match the contours of the skull. It doesn’t seem to be online now, but does anyone have a response to it? The reconstruction was quite different the ones presented here.
I don’t recall this. Toby’s posts on the DML through searches don’t seem to pull it up. I recall a lot of discussion on the extent or even presence of rhamphotheca on toothed animals, but that’s probably less relevant. A lot of what I want to do to answer the question Jansen attempts to answer requires a lot of research, but it’s fairly easy to answer:
If beaks follow rules, examination of beaked animals should reveal them. If so, then the average shape and rules in birds, turtles, etc. should apply to oviraptorosaurs. As such, it should also apply to other taxa which rhamphotheca for the same reasons, and thus we can use those models to “control” the expectation from birds.
Jansen started at birds, but I want to go further, because this impacts dicynodonts, ornithischians, the beaked crocs, etc.
As I said previously, to understand how this works in extinct taxa, we have to understand how it works in extant taxa. Witmer Lab students (such as the new PhD Tobin Hieronymous) have begun to take on the type of work required to address these problems. We can’t just look at the gross morphology, we need to look at the microanatomy of these surfaces and compare them to a wide pool of other beaked vertebrates.
Nick
While I agree when dealing with a full understanding of the structure of the underlying bone, it should be noted that the full range of structural bone underlying keratinized surfaces in extant taxa (birds, mammals, crocs, lizards, etc.) allows us at least some superficial data and thus the ability to make hypothetical arguments by which testing can prove or disprove. It DOES look like there are superficial aspects to the argument about extent and shape in rhamphotheca, but there are also occasional features of the keratin that do not correspond to the underlying bone, such as wrinkled beaks in some spheniscids, so that I can easily make the statement “The shape of the beak in birds conforms to the shape of the underlying bone,” and prove this wrong (this is especially important for assessing parrot bills and the hollowed casques of cassowaries (which are different from those of hornbills).
I have an image of an oviraptorosaur skull that I cannot identify. Here is a link to the image: https://commons.wikimedia.org/wiki/File:Shot_inside_Museu_Blau_velociraptor.jpg, although I am certain it is not a Velociraptor. My closest guess is that it is Khaan, but that is probably way off. What is your opinion?
It’s hard to tell from this perspective what that is. The front of the snout looks reconstructed, even if there seems to be actual material present in other portions. It might be a plaster and paint model only, a skull mock-up.
Another needing assistance Jaime. https://commons.wikimedia.org/wiki/File:Oviraptor_philoceratops.JPG states that it is Oviraptor which I seriously doubt, but apparently the skeleton is based on an non-existent taxon. Since you have, like above, much more knowledge about oviraptorosaurs than I, and know more about how much material than I, could you clarify which taxon it represents, or if it is completely made up? Thanks.
The mount is based on a partial skeleton which doesn’t include a head. Much of the skeleton, and all of the skull, are reconstructed. The skull is pure fantasy, only loosely being based on an actual — or any — oviraptorid skull. It’s what you would make if you had the IDEA of an oviraptorid skull, but had barely ever seen one or knew how they were put together. The holotype specimen of Oviraptor philoceratops, AMNH FABR 6517, doesn’t preserve femora or pubes, yet this specimen demonstrates they are cast from actual, broken, specimens.