So, while looking through old JVPs I ran across this oddity. Perhaps it has already been discussed elsewhere. Any dino-guys out there, feel free to chirp in.
[I have to confess, I threw this one together rapidly and I made a mistake. Andrew Farke and Jaime Headden steered me in a better direction. Even so, there’s still something to say here. After further examination, I learned something. And no, I did not misinterpret a tracing earlier. There was no tracing. I was working solely on the tracing by Evans and Reisz (2007.]
Evans and Reisz (2007) took a look at the skull of Lambeosaurus magnicristatus (Fig. 1) and identified the bones and plaster that make up the crest. They put the nasal above and behind the orbit in a narrow strip. That struck me as odd. Odd things make for interesting posts.
The pattern of the bones in the Lambeosaurus crest might be more like this:
The strongest lines in the Lambeosaurus crest might define bone sutures. Or they might represent cracks. Or they might represent bone surface irregularities. I went with sutures. I might be wrong.
The image below of Corythosaurus, Hypacrosaurus and another species of Lambeosaurus (Fig. 3) helps set the possibilities of the extent of the premaxilla and nasal – along with the minor contribution by the prefrontal in the first two taxa.
Overall the broad crest of L. magnicristatus (Figs. 1, 2) appears closer in morphology to that of Corythosaurus (Fig. 3). The premaxilla appears to have three ascending processes in both taxa. The crest is expanded to a larger extent than in the other two. There appears to be a contribution from the prefrontal that Lambeosaurus lambei (Fig. 3) crest does not have.
Here again, I’m stepping out of my comfort zone, but I’m avoiding the temptation of calling the nasal narrow just because L. lambei has a narrow nasal. They are all closely related taxa. I’m probably missing some of the fine points that differentiate them.
Again, sorry for the earlier mistake. It did lead to some interesting study.
We’ll take a look at bones that make up crests soon, as I see similarities here to the pterosaur Tupuxuara (by convergence, of course).
As always, I encourage readers to see specimens, make observations and come to your own conclusions. Test. Test. And test again.
Evidence and support in the form of nexus, pdf and jpeg files will be sent to all who request additional data.
Brink KS, Zelenitsky DK, Evans DC, Therrien F and Horner JR 2011. A sub-adult skull of Hypacrosaurus stebingeri (Ornithischia: Lambeosaurinae): Anatomy and comparison. Historical Biology 23(1):63-72.
Evans DC and Reisz RR 2007. Anatomy and relationships of Lambeosaurus magnicristatus, a crested hadrosaurid dinosaur (Ornithischia) from the Dinosaur Park Formation, Alberta. Journal of Vertebrate Paleontology 27 (2): 373–393.