‘Aerodactylus’ nests with Pterodactylus antiquus. It’s not a new genus.

A recent online paper in PLOS by Vidovic and Martill (2014) proposed that the BSP AS V 29a/b specimen (n15 in the Wellnhofer 1970 catalog, Figs. 1-5) formerly attributed to Pterodactylus scolopaciceps (Meyer 1860) was actually more closely related to Cycnorhamphus. They gave it a new name, “Aerodactylus.

I know this sounds technical. I’ll make it simple with pictures and links.

From their abstract:
A cladistic analysis demonstrates that Aerodactylus is distinct from Pterodactylus, but close to Cycnorhamphus Seeley, 1870, Ardeadactylus Bennett, 2013a and Aurorazhdarcho Frey, Meyer and Tischlinger, 2011, consequently we erect the inclusive taxon Aurorazhdarchidae for their reception.

BSP AV S 29a/b, formerly attributed to Pterodactylus, Vidovic and Martill rename Aerodactylus. Scale bar = 2cm.

Figure 1. BSP AV S 29a/b, formerly attributed to Pterodactylus, Vidovic and Martill rename Aerodactylus. Scale bar = 2cm. Upper image distorted to match lower image. Looks like it is swimming or walking.

The BSP specimen is gorgeous and complete.
It looks like quadrupedal in situ (Fig. 1). I’m happy to take this opportunity to finally create a reconstruction (Fig. 5) and add it to the large pterosaur tree (not updated yet), especially considering the current drama brought on by this change of genus.

Unfortunately,
my results do not support the Vidovic and Martill (2014) results. In the large pterosaur tree BSP AS V 29a/b is recovered as a sister to the original pterosaur, the first one ever described, Pterodactylus antiquus (Figs. 3, 4).

The authors also have the traditional mindset, falsified several times recently.
From their abstract:
“The majority of pterosaur species from the Solnhofen Limestone, including P. scolopaciceps are represented by juveniles. Consequently, specimens can appear remarkably similar due to juvenile characteristics detracting from taxonomic differences that are exaggerated in later ontogeny.”

The authors fail to recognize the several juveniles that are not morphologically different than adults here, here, here and here, along with the three embryos that are not different from adults here, here and here.

Okay, so let’s take a look at the contenders.
Vidovic and Martill (2014) nested BSP AS V 29 a/b with the their purported cycnorhampid Gladocephaloideus (Fig. 2, and why was it not mentioned in the abstract?)

Here three pterosaurs considered sisters by Vidovic and Martill 2014 are shown to scale. In the large pterosaur tree, these taxa do NOT nest together. It is clear to see they are not closely related.

Figure 2. Click to enlarge. Here three pterosaurs considered sisters by Vidovic and Martill 2014 are shown to scale. In the large pterosaur tree, these taxa do NOT nest together. It is clear to see they are not closely related. These specimens show variety, not similarity.

In Evolution
there is supposed to be a gradual change from one taxon to another. Sister taxa should share a long list of traits. Here (Fig. 2) they don’t.

Here are the competing contenders
It turns out that this Pterodactylus, BSP AS V 29a/b, really IS a Pterodactylus. It shares many more traits with its sisters (Fig. 3).

Figure 3. Click to enlarge. The large pterosaur tree nests these three taxa together. So this Pterodactylus really is a Pterodactylus.

Figure 3. Click to enlarge. The large pterosaur tree nests these three taxa together. So this Pterodactylus really is a Pterodactylus, just a distinct species. These specimens show similarity, with a little variety.

What a mess!
And why? What was it about this very run-of-the-mill pterosaur made anyone think it was anything but what it is, a Pterodactylus.

Figure 4. Subset of the large pterosaur tree, with the BSP specimen added.

Figure 4. Subset of the large pterosaur tree, with the BSP AS V 29a/b specimen added.

Re: Gladocephaloideus, Ardeadactylus and Aurorazhdarcho
In the large pterosaur tree, Gladocephaloideus nests with Gegepterus within the Ctenochasmatoidea.

Ardeadactylus nests with Huanhepterus and other proto-azhdarchids. Pterodactylus longicollum is not related, but nests on the other side of the Pterodactylus antiquus holotype (Fig. 4). Yes, this genus generally gets bigger as members become more derived.

Aurorazhdarcho nests with Eoazhdarcho and Eopteranodon at the base of Nyctosaurus + Pteranodon.

So none of these taxa are really related to one another.

Getting back to the juvenile problem
Vidovic and Martill (2014) considered the SMF R 4072 specimen to be a juvenile Pterodactylus. However in phylogenetic analysis, it nests at the base of Germanodactylus. The fear of adding tiny Solnhofen specimens to phylogenetic analysis is unwarranted. A tree that includes them has been on the web for three years. And juvenile pterosaurs identical to parents are well known, but ignored.

The authors had direct access to the specimens and I did not. 
I hope you see that direct access to the specimens is no guarantee of validity. Conversely, lack of direct access to the specimens is no hinderance to critical observation.

The authors thanked, Chris Bennett (Fort Hayes), David Hone (London), and Dino Frey (Karlsruhe) ‘for the useful comments made during the project.’ And this is why I have trouble getting pterosaur papers published.

I hope now you can appreciate when I say the world of pterosaur study is like a funhouse mirror where everything is distorted and, in this case at worst, makes no sense, yet is supported by professional workers.

And let’s leave on a good note

Figure 5. Pterodactylus specimen BSP AS V 29a/b reconstructed. Soft tissue shows where the naris opens.

Figure 5. Pterodactylus specimen BSP AS V 29a/b reconstructed. Soft tissue shows where the naris opens. Presumeably the small hole at the front of the antorbital fenestra. But there is a larger hole further back! This specimen has the usual wingtip claw, fifth toe claw and fifth manual digit. It may also have a few more ribs than usual, which might go along with the smaller pelvis.

BSP AS V 29 a/b is a premiere specimen.
It looked so much like other Pterodactylus ()Fig. 3) that I ignored it until now. A bit of soft tissue fills most of the antorbital fenestra leaving a small hole up front (the naris?) and a larger hole further back. The sternum is smaller relative to the humerus than in other Pterodactylus specimens. The twin teeth at the mandible tips are easy to see. These fuse to become one sharp tooth in germanodactylids and their descendants. There is nothing about this specimen that says it is anything but a Pterodactylus.

After this paper, Hermann von Meyer must be rolling over in his grave.

References
Vidovic SU and Martill DM 2014. Pterodactylus scolopaciceps Meyer, 1860 (Pterosauria, Pterodactyloidea) from the Upper Jurassic of Bavaria, Germany: The Problem of Cryptic Pterosaur Taxa in Early Ontogeny. PLoS ONE 9(10): e110646. doi:10.1371/journal.pone.0110646

 

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2 thoughts on “‘Aerodactylus’ nests with Pterodactylus antiquus. It’s not a new genus.

  1. The term ‘reject’ is generally used in academic publications, which this is not. But as you intimate, the new names don’t make sense when the taxa are properly nested. Use what makes sense to you.

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