Anurognathus had a longer neck

Döderlein's first reconstruction of Anurognathus. He mistook the premaxilla for the maxilla. The neck is short.

Figure 1. Click to enlarge.

Earlier reconstructions
of the holotype of Anurognathus gave it the shortest neck of all pterosaurs. In Döderlein’s (1923) first reconstruction of Anurognathus (Fig.1), he reconstructed the neck only according to the visible elements and each element appears to be short. We’ve been reconstructing Anurognathus with a short neck ever since, with one curious exception, the ‘Walking with Dinosaurs’ version seen here.

By the way
Döderlein’s (1923) also mistook the premaxilla for the maxilla and therefore had to imagine the snout tip based on other pterosaurs all with a longer snout. IMHO that’s more than reasonable given what was known at the time.

Döderlein also illustrated four wing phalanges. Modern workers like Bennett (2007) find only three wing phalanges, chiefly based on the related SMNS specimen, which Bennett considered congeneric. Here that specimen is called the flat-head pterosaur, and the fourth wing phalanges remain largely buried in the matrix.

Back to the Neck Problem:
Now that we know of several anurognathids (Fig. 7), we know that no sister taxa had such a short neck, even the other so-called Anurognathus, the flat-head pterosaur. So, I wondered if maybe we got it wrong. Maybe half the neck of Anurognathus is hidden beneath the matrix (Fig. 2). The rest of the skeleton is more or less articulated. Maybe the difficult to see back half of the skull is still attached to the invisible top half of the neck. That’s why it was worth taking another look at this specimen.

Figure 2. Click to enlarge. DGS tracing of Anurognathus ammonia. Note the placement of the lacrimals in the skull, behind the large antorbital fenestra. That is not the orbit. The small jugal (bright light blue) also indicates the placement of the small orbit in the back half of the skull, as in all other anurognathids. Also note the disappearance of the cervicals beneath the matrix. That may be an embryo by the tail. More on that tomorrow.

Figure 2. Click to enlarge. DGS tracing of Anurognathus ammonia. Note the placement of the lacrimals in the skull, behind the large antorbital fenestra. That is not the orbit. The small jugal (bright light blue) also indicates the placement of the small orbit in the back half of the skull, as in all other anurognathids. Also note the disappearance of the cervicals beneath the matrix. That may be an embryo by the tail. More on that tomorrow.

Like everyone else,
I had problems understanding Anurognathus. Some of the bones are bones. Others are impressions. Some, I think, are buried just beneath the matrix. I think at least part of the neck was buried beneath the matrix. It’s not crystal clear, otherwise this problem would have been at first reading. I’m not sure how long the anterior elements were. They may have been shorter if the skull is indeed disarticulated from the neck. But the skull may remain articulated. The torso/neck/skull proportions match sister taxa better when the neck is as shown (Figs. 6, 7).

Anurognathus neck in situ.

Figure 3. Anurognathus neck in situ.

Here’s the neck, the old interpretation (Fig. 4) and the new interpretation (Fig. 5). I think we were all taken in by the tonal change in the matrix.

Anurognathus neck, old interpretation of short cervicals.

Figure 4. Anurognathus neck, old interpretation of short cervicals based on tonal changes.

Anurognathus neck, new interpretation in which cervical 4 dives beneath the matrix.

Figure 5. Anurognathus neck, new interpretation in which cervical 4 dives beneath the matrix and a hypothetical continuation of the cervical series meets the back of the skull.

The new reconstruction
makes more sense (Fig. 2) in that it is more like that of its sisters. Maybe the neck is a little too long. We’ll never know until we see beneath the matrix.

Figure 6. The new reconstruction of Anurognathus with its new, longer neck, more like that of its sisters. The exact length of the neck remains unknown because cervicals 1-3 and part of 4 are buried. Here the neck is relatively slightly longer than those of its sisters. The embryo is one-sixth the size of the adult.

Figure 6. The new reconstruction of Anurognathus with its new, longer neck, more like that of its sisters. The exact length of the neck remains unknown because cervicals 1-3 and part of 4 are buried. Here the neck is relatively slightly longer than those of its sisters.

The longer neck may correspond to the long tibia of this taxon. Other pterosaurs with long legs, like no. 42, have a longer neck despite their tiny size.

All known anurognathids (in black) and their ancestors in gray).

Figure 7. Click to enlarge. All known anurognathids (in black) and their ancestors in gray).

We will look at the skull and embryo details in future posts.

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.

References
Bennett SC 2007. A second specimen of the pterosaur Anurognathus ammoni. Paläontologische Zeitschrift 81(4):376-398.
Bennett SC 2008. Morphological evolution of the wing of pterosaurs: myology and function. Zitteliana B28: 127-141.
Döderlain L 1923Anurognathus ammoni, ein neuer Flugsaurier. Sitzungsberichte der Königlich Bayerischen Akademie der Wissenschaten, zu München, Mathematischen-physikalischen Klasse: 117-164.
Elgin RA, Hone DWE and Frey E 2011. The extent of the pterosaur flight membrane. Acta Palaeontologica Polonica doi: 10.4202/app.2009.0145 online pdf
Peters D 2001. A New Model for the Evolution of the Pterosaur Wing – with a twist. Historical Biology 15:277–301.

wiki/Anurognathus

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