The SMNS flathead anurognathid skull: bone by bone

Two recent blog posts by J. Headden, illustrations by M. Witton and various other odd reconstructions of the skull of the SMNS anurognathid (Bennett 2007), the flathead pterosaur, prompted today’s post. I realize I have not provided sufficient clear imagery and so, here it is (in rollover images or see below).

You’re looking at what appears to be a complete skull crushed ventrally with all parts intact and articulated. That is not the case. If so, you’d end up with a monster bearing little resemblance to other anurognathids and other pterosaurs in general (aka Bennett’s reconstruction, fig. 6 left). There was some shifting during taphonomy as will be made clear in the following photos. Reconstructing the parts produces a very nice anurognathid sharing most traits with other anurognathids (fig. 6 right), but the skull has a flatter morphology.


Figure 1. Skull of the flathead pterosaur. Some of the bones are orange. Others are tan. Still others, perhaps just the shapes they left, are white, as in the apparent fenestra in the top of the skull, which is nevertheless, divided medially. 

I realize the bones I found in this specimen are difficult to see. So today I present some of them as well as I possibly can (see figs. below). You can (and I encourage you to) use a rollover on the reptile evolution page on the flathead anurognathid here.

Bennett (2007) described this specimen and created reconstructions (fig. 6) in which his giant scleral ring was in the anterior half of the skull, the antorbital fenestra was relegated to a tiny zone bounded by bones he claimed he never found and the skull roof was as wide as any turtle’s with widely separated upper temporal fenestrae. Such a reconstruction is at odds with all other pterosaur skulls. Recall that Bennett also invoked the idea that the very wide frontal bones of the SMNS specimen were decayed centrally, providing windows to whatever bones were beneath them. Not so. His frontal bones are composed laterally on the left by a dorsal lacrimal piece (fig. 5) and medially by the narrow nasals (fig. 3). That’s a large corner of an ectopalatine seen through the bones.

SMNS-anurognathus maxillae

Figure 2. SMNS-anurognathus maxillae and teeth. The slender ascending process is broken in both cases. Note Bennett’s proposed “sclerotic ring” continues far beyond the confines of the skull. 

SMNS anurognathid sclerotic rings. They are small in the back half of the skull. Those are the narrow nasals between them.

Figure 3. SMNS anurognathid sclerotic rings. They are small in the back half of the skull. Those are the narrow nasals between them. All of these traits match those of other anurognathids. 

The SMNS anurognathid ascending process only of the premaxillae and frontals.

Figure 4. The SMNS anurognathid ascending process only of the premaxillae and frontals. Compare the frontals to the sclerotic rings (fig. 3), which nest within them.

SMNS anurognathus occiput and lacrimals. Note the extreme width of the occiput. This alone tells you the general shape of the skull, flatter than in other pterosaurs.

Figure 5. SMNS anurognathus occiput and lacrimals. Note the extreme width of the occiput. This alone tells you the general shape of the skull, flatter than in other pterosaurs. The fragile left lacrimal is broken into three parts. The right one has the sinuous shape that provides room for the dorsally bulging eyeballs (see fig. 6).

If you still can’t see the imagery I indicate above, please visit these rollover images. That way you won’t have to shift back and forth to compare images. You can also see the palate and other bones on the same web page.

Using DGS (digital graphic segregation, I was able to find symmetrical pairs for every bone in the skull, despite the layering of cranial bones atop displaced facial and palatal bones. All the bones, even those of the palate, resemble those in other anurognathid palates. Moreover, in the case of the SMNS anurognathid the palatal elements criss-cross and reinforce each other, providing maximum strength with minimum weight. The same cannot be said of the Bennett reconstruction.

anuroSMNSskull588

Figure 6. The SMNS anurognathus. On the left as Bennett (2007) reconstructed it identifying the left maxilla has a giant sclerotic ring (ignoring the teeth). Bennett’s palate does not resemble those of other anurognathids. On the right is the more accurate reconstruction based on DGS. Click for more information.

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.

Reference
Bennett SC 2007. A second specimen of the pterosaur Anurognathus ammoni. Paläontologische Zeitschrift 81(4):376-398.

5 thoughts on “The SMNS flathead anurognathid skull: bone by bone

  1. Your reconstruction DOES, indeed, depend on your completely unreliable, and unsupported interpretations, your counting of pixels as shapes, based on the resolution of the material. It’s ludicrous. Moreover, the “flat-head”edness of your reconstruction has no basis in fact: I can just as easily vault the orbit in one reconstruction as the other, the shape of the antorbital region — just as it is in Dimorphodon macronyx, which you argued on my blog was a better model for the skull shape and positional identification.

    No part of your reconstruction has been verified, and your identifications require a cheesey, and unreliable method (“DGS”) which is subject to pariedolia, and which you’ve never subjected . Indeed, where Bennett found frontals and parietals, and rostrally rotated supraoccipital bone of the occiput (due to crushing), you seem to find nothing BUT all of the intra-orbital bones, complete scleral rings where Bennett identified just frontals, and which seem to conform to the typical shape of frontals (slightly L-shaped, orbital margin inclined rostrally, concave, with transverse process for the postorbital). Indeed, it takes a mind more willing to be “radical” to over-interpret the pixels to find shapes that aren’t there, or use distortions of the bones picked up by lighting artefacts and crushing to find anything but the shapes Bennett sees. Do not mistake me in this, Dave, but I see not a glimmer of truth in your interpretation and will not until you can set up a scientifically testable DGS method that also supports your conclusions.

  2. Check out my work with Romeriscus, Jeholopterus, etc. to see further examples of DGS. Evidently you are refusing to see what is there and believing in what is not there, does not match other taxa, etc. The flathead pterosaur is a simple distortion in 3D space of the Dimorphodon skull. The Bennett skull is not.

  3. Your “work” confuses several issues of taphonomy. I will take some time to prepare the remaining perspectives of the cranial reconstruction; in that time, I will prepare a response and show you have a skull like Bennett’s and mine ends up like the preserved skull above. It will NOT pretend that pixel artefacts on the plate are special, hidden bones or ephemera from which one can draw broad conclusions. Instead, I will use basic assumptions about bone shape and structure, and taphonomy. You won’t agree with my interpretation, and will continue to hold to THIS interpretation, including the vague little doodads everywhere, and we won’t get anywhere, but I will be able to show OTHER people how taphonomy works. And that’s the only reason I will be responsing further on this subject.

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