Saturday, February 23, 2008

Introducing Nyctosaurus

Well, here it is, ladies and germs: The first sketch I have accepted as "good" from the last two weeks of trying to knock out a Nyctosaurus for the art show. Previous efforts have been cave paintings by comparison. I will be painting Nyctosaurus on a large canvas for The Archosauria, and it will be accompanied by a rhamphorhynchoid of undetermined identity.
The original specimens of Nyctosaurus, described in 1958, lacked any kind of headcrest. Marsh allied Nyctosaurus with Pteranodon, but more complete skeletons, described and drawn by Williston in 1902, suggested that Nyctosaurus belonged in a family of its own. For one thing, the "naked lizard" is significantly smaller than Pteranodon, having a wingspan of less than ten feet. Additionally, Nyctosaurus has just three wing phalanges instead of the usual four. Stranger still, this Lower Cretaceous pterosaur has lost all of its non-wing digits (I-III). Because Nyctosaurus could not have spent its entire life on the wing, I have restored it with a fleshy pad capping the main joint of the wing finger.
The crestless Nyctosaurus existed until 2003, when two new specimens were discovered with giant reindeer antlers sticking out of their noggins. Marsh and Williston's crestless forms were probably sexually immature, and, like so many pterosaurs, the crest likely had a display function. Other possibilities exist, I suppose. Perhaps Nyctosaurus grew the crest annually, like modern deer do, but the lack of a rugose surface on the skullcap of the original Nyctosaurus material scratches that out. It's also possible that, like Pteranodon, Nyctosaurus was sexually dimorphic, and only one sex had the crest. This intruiging possibility cannot be adequately tested do to the scant remains of this "naked lizard."
Nyctosaurus has also been regaled to a more basal place on the pterodactyloid family tree. In their recent description of Nemicolopterus, Wang et al. (2008) placed Nyctosauridae as the basalmost clade within the Dsungaripteroidea.
Nyctosaurus is among my very favorite pterosaurs, and I'd like to do it proud. If there are any criticisms out there (Head too big? Legs too long? Crest too short?), I'd be happy to hear them!


Cameron McCormick said...

As Mark Witton discusses, the rami/projections are of equal sized and often reconstructed far undersized. Here's the fossil.

Traumador said...

That's an awesome picture! Wish I could draw that good.

You must love Prehistoric Park than. They've got Nyctosaurs in the China episode (the best of the series... well apart from the T-Rex one :p )... if you haven't seen it I'll have to burn you a copy (as I assume that'll be due to Alaska isolation).

Nathan said...

I thought that stuff looked a bit stunted, vs, Mark Witton's illos.

Here's where I am compelled again to raise the notion that at least some crests (not necessarily this one!) must have been useful, physically. A big crest would have lent the whole head a very high rotational moment of inertia at (proportionally) very little cost in extra weight. That, in turn, would alter the force budget through the neck, turning what would, in a bird, be a strong bending moment into a compressive force. That, in turn, might actually rescue the notion of these things snatching victims from the ground or water on the wing.

I'll yield to Colin Palmer on the plausibility of such a notion.

Christopher said...

Some points on the accuracy of the reconstruction: First, the wing metacarpal is huge in Nyctosaurus, so long in fact that Nyctosaurus would be standing nearly completely upright when on the ground. Second, the pteroid does not ever, ever, ever!!!! EVER!!!! stick out like that. For one thing even with Willson et als carpus articulation scenario its impossible for the pteroid of Nyctosaurus stick out like that given that the articular end is bent at 90 degrees from the main shaft/body of the pteroid. But that is a moot point given Christopher Bennett has firmly put their scenario out of its missery. The pteroid of Nyctosaurus is also quite a bit larger than you show, Nyctosaurus acctually has one of the largest pteroids of all. Third, no dew claw on metatarsal 5, this was in all likelyhood bound in the flesh of the foot. Fouth, the femur and tiba are both way too long for Nyctosaurus. Fith, the fossils are rather ambiguous as to the actual length of the antlers branches, but they probably were much longer. That photo is a cast with lots of reconstruction, the actual fossil is messier.

As an aside, do you use skeletals as a reference base? Your accuracy would improve light years. Here are a couple that I recomend:

Chris Bennett's original:

And John Conway's excellent skeletal of both specimens: He has taken some liberties in reconstructing the crests. They are not entirely complete and unambiguous in the fossil and the sail is purely conjectural and quite unlikely (but does appear to function quite well theoretically) but otherwise John's skeletal is the best you'll find.

Also, I have the relevant papers if you're interested