How Experts Have Disfigured Pterosaurs – part 2

Anurognathus by Mark Witton following the reconstruction by Chris Bennett (2007) that is different in all respects from all other pterosaurs.

Figure 1. Anurognathus by Mark Witton following the reconstruction by Chris Bennett (2007) that is different in all respects from all other anurognathid pterosaurs (fig. 2). You don’t see pedal digit 5 because it extends, full length, to frame the uropatagium (or connect to the main wing membrane) in this interpretation. Note also the lack of distal wing phalanges, m4.4 and m4.5 (the ungual) when other anurognathids have these.

Yesterday we discussed some of the disfiguring ways in which pterosaurs have been reconstructed and restored by pterosaur experts Mark Witton and David Unwin, mostly by the way they moved the bones into odd configurations, especially to demonstrate pterosaur walking. Today we’ll talk about misinterpretations of pterosaur fossils and how those bad images have propagated themselves through the Internet.

Bennett’s 2007 Anurognathus (Figs. 1, 2), which is more accurately called the flat-head anurognathid (Fig. 2), is a prime example of misinterpretation that fails all tests for validity (see more here). More worrisome, Bennett’s interpretation has become widely adopted by artists, some having a PhD in paleontology, without testing (performing their own skull tracings) or criticism (the morphology is way different than in related taxa (Fig. 2), but then who knows that? No one else has attempted anurognathid skull tracings and reconstructions but yours truly and maybe Döderlein and Wellnhofer on a very limited basis.

It’s bad enough when one scientist on a bender (Fig. 2), promotes this, but when others, (Fig. 1) follow, then we’ve got widespread madness. As you can see (fig. 2) Bennett’s interpretation bears no resemblance to the other anurognathids, all of which have a large naris, large antoribital fenestra, eyes in the back half of the skull and a narrow skull between the upper temporal fenestrae. Bennett (2007) promoted the idea that anurognathids had but three wing phalanges. However, more derived anurognathids, like Jeholopterus, also have a manual 4.4 and 4.5 (the ungual). So, why are these data ignored?

Figure 2. Anurognathid skulls in phylogenetic order.

Figure 2. Anurognathid skulls in phylogenetic order.

Note that in every case (fig. 2), but the Bennett (2007) reconstruction (on gray field), the nares are large, the antorbital fenestra is larger, the orbit is in the back half of the skull (even if it extends slightly into the front half) and, although you can’t see it from these angles, the parietal is narrow between the upper temporal fenestrae, as in most other reptiles with upper temporal fenestrae and all squamates close to pterosaurs. Most of Bennett’s 2007 other mistakes are listed and rectified here.

Santanadactylus hand and fingers

Figure 3. Click to enlarge. Santanadactylus hand with metacarpals preserved at a 45 degree angle to the anterior face of metacarpal 4.

Bennett (2008) is also the author of the hypothesis on pterosaur origins who suggested the palms of pre-pterosaurs supinated, finger 5 disappeared, finger 4 hyper-hyper-extended until it became able to fold against the back of the metacarpus, metacarpals 1-3 migrated as a unit to the former palmar now anterior face of metacarpal 4, and the wing ungual was lost because it would have otherwise caught on nearby trees (Figs 3,4). All this in an effort to avoid having to acknowledge that Cosesaurus and Longisquama may have had something to do with the origin of pterosaurs. He also studied a ornithocheirid metacarpus (Fig. 3) in which mc1-3 were preserved at a 45 degree angle, which Bennett assumed meant they had detached themselves from mc4 (fig. 4). Actually they had been raised like a drawbridge by currents following the removal of the large extensor tendon. So Bennett completely misunderstand pterosaur basics like this and promotes such misinformation.

Pterosaur finger orientation in lateral view

Figure 4. Pterosaur finger orientation in lateral view, the two hypotheses. There’s no room for a giant extensor tendon in the Bennett model that many experts seem to prefer. When the experts  acting as manuscript referees hold such bad hypotheses, its no wonder competing hypotheses don’t get published.

Such disfigurement leads to odd configurations, like upside-down fingers illustrated by Bennett (1991) here (fig. 5).

Bad Pteranodon reconstruction from Bennett 1991, 2000 in which the fingers faced palmar side up and the elbow bent at an impossible angle with regard to the shoulder joint.

Figure 5. Bad Pteranodon reconstruction from Bennett 1991, 2000 in which the fingers faced palmar side up and the elbow bent at an impossible angle with regard to the shoulder joint. Unwin (2005) replaced the skull and flipped the hand.

Sometimes it just takes a more careful examination of the evidence.
Paleontologists have a lot to deal with (students, grant writing, trips to foreign lands, etc.). Like all of us, sometimes they overlook the little things, especially when the paradigm says those little things should not be there. Often their cartoonish tracings reflect the interest they show in their subjects. Refusing to study in detail the overlapping bones of a crushed specimen had led to bad reconstructions, with an example here.

Conventional wing shape in pterosaurs supported by Unwin, Elgin, Hone, Bennett, Wilkinson, Frey and others vs heretical wing shape supported by Peters and Conway.

Figure 6. Above: Conventional wing shape in pterosaurs supported by Unwin, Elgin, Hone, Bennett, Wilkinson, Frey and others vs heretical wing shape supported by Peters and Conway. All the evidence from smaller pterosaurs supports the lower wing and uropatagium shape. And doggone it! It just makes sense not to overextend the elbow, not to miss align the femoral head axis with the acetabulum, not to extend the fingers palmar side anteriorly and not to put the pteroid pointing forward in the sesamoid cup of the medial metacarpal. See what a beautiful and functional wing you get when you follow anatomical rules!

Finally there’s the old wing shape problem
Wilkenson (2007, fig. 6) and others support a deep chord wing membrane attached to the ankles. Here the hand is also palmar side anterior while flying. And the elbow is overextended. This is an embarrassing reconstruction when ALL the evidence demonstrates a narrow-at-the-elbow narrow chord wing shape NOT attached to the ankle. The fingers are palmar side ventral while flying. And the elbow does not overextend, but is angled close to a right angle, as in birds and bats. A narrow chord wing membrane prevents the sort of wing folding with wing drooping that has ruined hundreds of artist reconstructions, IMAX films and Jurassic Park III ptero reconstructions.

That’s why the Pterosaur Heresies and ReptileEvolution.com present evidence when we depart from conventional thinking — especially when conventional thinking departs from logical thinking, precise observation, reconstruction and phylogenetic analysis.

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 1923
Anurognathus 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
Ji S-A and Ji Q 1998. A New Fossil Pterosaur (Rhamphorhynchoidea) from Liaoning. Jiangsu Geology 4: 199-206.
Peters D 2001. 
A New Model for the Evolution of the Pterosaur Wing – with a twist. Historical Biology 15:277–301.
Wilkinson MT 2007. Sailing the skies: the improbable aeronautical success of the pterosaurs. The Journal of Experimental Biology 210, 1663-1671. pdf

wiki/Anurognathus

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.