Azdarchid pterosaurs as terrestrial stalkers? (Again?)

Witton and Naish 2015
once again conclude that terrestrial foraging remains the most parsimonious habit for azhdarchid pterosaurs. (Didn’t we see this earlier in Witton and Naish 2008?) There’s nothing new here. The two professors have put forth the same lame hypothesis seven years later with no apologies for the former and no improvements in the latter.

Unfortunately for Witton and Naish
the best modern analogs, birds that most closely resemble azhdarchid pterosaurs, are all shallow water waders (Fig. 3). That fact/observation has not changed in seven years. To make matters worse, and for reasons known only to themselves, Witton and Naish have set up a straw dog, the pelican for their foil.

Straw dog = In business, something (an idea, or plan, usually) set up to be knocked down. It’s the dangerous philosophy of presenting one mediocre idea, so that the listener will make the choice of the better idea which follows.

Foil = a character who contrasts with another character (usually the protagonist) in order to highlight particular qualities of the other character.

No one thinks azhdarchids resemble pelicans!
What were Witton and Naish thinking?? The key word ‘pelican” is found thirty times in their paper prior to the references. The word “stork” is found nine times. The word ‘hornbill” is found three times. The word “heron” is not found.

Figure 1. Witton and Naish 2015 azhdarchid based on a chimaera of pterosaurs including Zhejiangopterus juvenile for the skull.

Figure 1. Witton and Naish 2015 azhdarchid based on a chimaera of pterosaurs including using a Zhejiangopterus juvenile for the skull. Juvenile skulls are fine because pterosaurs develop isometrically according to ReptileEvolution.com. But Witton and Naish don’t see it that way. They think juvenile pterosaurs have large eyes and a short rostrum, like archosaurs. So, are they straddling the fence? Being hypocritical? Or taking their first steps out of the dark side?

There is no denying
that long-legged, long-necked, long-billed azhdarchid pterosaurs (Figs. 1, 2) most closely resemble today’s similarly built wading storks and herons (Fig. 3). And yet Witton and Naish don’t quite see it that way. Yes, they report that azhdarchid traits were “stork-like.” But, oddly they choose the one stork that does not have an elongate neck, the Marabous stork (Fig. 4, which often wades). SO… they also add in the ground hornbill, which does not wade because it does not have extra-long legs nor an extra-long neck.

Earlier (in 2013) we noted that hornbills most closely resemble similarly short-legged germanodactylids…something that was overlooked by Witton and Naish in 2008 and ignored in 2015.

Figure 1. Click to enlarge. There are several specimens of Zhejiangopterus. The two pictured in figure 2 are the two smallest above at left. Also shown is a hypothetical hatchling, 1/8 the size of the largest specimen.

Figure 2. Click to enlarge. There are several specimens of Zhejiangopterus. The two pictured in figure 2 are the two smallest above at left. Also shown is a hypothetical hatchling, 1/8 the size of the largest specimen.

Once again we trot out
the Zhejiangopterus azhdarchid ontogeny series (Fig. 2) demonstrating isometric growth, but Witton and Naish don’t subscribed to isometry, but rather to allometry. Perhaps hypocritically, and without comment, Witton and Naish used the giant skull of a small juvenile Zhejiangopterus and placed it on the body of an adult specimen. Why didn’t they elongate the rostrum and reduce the orbit to follow their “pterosaurs as archosaurs” hypothesis? They should have, but they didn’t. Actually, I’m glad they did not elongate the rostrum of the juvenile when they put it on the adult body. Apparently Witton and Naish hopped the fence and embraced the hypothesis that was otherwise only found at ReptileEvoluton.com and hoped to that nobody would notice.

As Pterosaur Heresies readers all know…
Pterosaurs, like other lepidosaurs, develop isometrically. Archosaurs go through a short nose “cute” phase known as allometry. You’ll see such short-nosed juvenile pterosaurs throughout the illustrations of Witton, but this is no paradigm shift for him.

The bird genera
that Witton and Naish consider effective analogues for ground-feeding azhdarchids, are the large African stork, Leptoptilos and the ground hornbill, Bucorvus (Fig. 4). I can’t imagine that anyone else agrees, especially when you have better analogs in the saddle-bill stork (Fig. 3), all ready to Google under the keyword, “stork.”

Figure 3. In my opinion this saddle-bill stork wading in water appears to be the bird closest to azhdarchid morphology and, for that matter, niche.

Figure 3. In my opinion this saddle-bill stork wading in water appears to be the bird closest to azhdarchid morphology and, for that matter, niche.

Oddly
Witton and Naish avoid the herons completely. Sure they have a smaller skull, but herons do have a long neck lacking in the birds that Witton and Naish prefer. You just don’t get both huge skull and a long neck in modern birds, otherwise we would note them as modern analogs. Wading azhdarchids were illustrated here in prior blogs.

Figure 4. Two herons, a Marabou stork and a ground hornbill, which is of these birds, the least like an azdarchid. Perhaps that is why one was not pictured in Witton and Naish 2015, despite the manuscript.

Figure 4. Two herons, a Marabou stork and a ground hornbill, which is of these birds, the least like an azdarchid. Perhaps that is why one was not pictured in Witton and Naish 2015, despite the manuscript.

Unfortunately
Witton and Naish still do not indicate the slightest interest in azhdarchid origins (Fig 5). The large pterosaur tree demonstrates their origins in tiny taxa of similar shape. That long neck developed early in their tiny ancestry and was maintained throughout.

Azhdarchids and Obama

Figure 5. Click to enlarge. Here’s the 6 foot 1 inch President of the USA alongside several azhdarchids and their predecessors. Most were knee high. The earliest examples were cuff high. The tallest was twice as tall as our President. This image replaces an earlier one in which a smaller specimen of Zhejiangopterus was used.

 

Heron damage from spearing a fish

Figure x. Heron damage from spearing a fish. Perhaps this was the preferred technique for the sharp billed germanodactylids, including the nyctosaurs and pterandontids.

A Weapon? Sure!
Witton and Naish describe the use of the long sharp rostrum as a weapon capable of inflicting deep wounds. We looked at that earlier with a photo of a fish after a heron stab.

When you read about Witton and Naish
disrespecting ReptileEvolution.com, remember that they wrote and published two identical papers that overlooked the obvious. They set up a straw dog where one was neither needed nor warranted. They created a chimaera reconstruction. And finally, after blackwashing my work at ReptileEvolution.com, they embraced the use of a juvenile skull on an adult pterosaur.

Perhaps there is still hope
for those two professors! Wonder how they’ll try to backpedal this?

References
Witton MP and Naish D 2008. A Reappraisal of Azhdarchid Pterosaur Functional Morphology and Paleoecology. PLoS ONE 3(5): e2271. doi:10.1371/journal.pone.0002271
Witton MP and Naish D 2015. Azhdarchid pterosaurs: water-trawling pelican mimics
or “terrestrial stalkers”? Acta Palaeontologica Polonica 60 (3): 651–660.

Advertisements

2 thoughts on “Azdarchid pterosaurs as terrestrial stalkers? (Again?)

  1. Well, Witton and Naish don´t support the methodology of representing drawings or silhouettes as real bones. So, they are not hypocritical. They shows a explicative diagram that represents the concept derived from the REAL bones. I see that you confuse the factual reality with the visual representation, so you think that the Azdarchid diagram confirms your ideas.

  2. I would agree with you if Witton and Naish reported first hand observation of the pertinent skeletal elements. However, like me, it appears they had access only to the paper and its published photos. I encourage you to read the paper itself. You’ll see that the only complete skull is quite small.

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 )

Twitter picture

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

Facebook photo

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

Google+ photo

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

Connecting to %s