Pterodactylus? Or Not?

Pterodactylus with hair in life pose, preparing to take off.

Figure 1. Pterodactylus with hair in life pose, preparing to take off.

Lots of Pterosaurs Have Fallen Into This Taxonomic Wastebasket Since 1812
The genus Pterodactylus (Cuvier 1809, Sömmerring 1812, BSP Nr. AS I 739No. 4 of Wellnhofer 1970) was the first name assigned to any pterosaur. Unfortunately, in the early days of discovery many pterosaurs, no matter how distinct, were labeled “Pterodactylus.” In paleo circles genera like this come to be known as “wastebasket” taxa because many scientists throw just about anything in there. Many of these early misidentifications were later corrected as distinct morphologies were observed and reported.

But not all…

Dr. Wellnhofer’s Contribution
Dr. Peter Wellnhofer (1970) produced a large report devoted to all the “pterodactyloids” of the Solnhofen. The majority of taxa he likewise considered “Pterodactylus” despite a wide range of morphologies (Figure 2). Some of these Wellnhofer considered juveniles of larger taxa because they had a shorter rostrum, larger eyes and a smaller overall size that echoed the allometric growth patterns seen in birds, mammals and crocodilians. Others, like the flightless Sos 2428 were considered “variations” of existing species, like P. longicollum.

Granted, Wellenhofer’s report did precede the advent of computer-assisted phylogenetic analysis. His report also preceded the discovery of pterosaur embryos that demonstrate the isometric growth patterns of pterosaurs that are also seen in certain lizards, like Huehuecuetzpalli. Even so, the variety seen in the various specimens attributed to Pterodactylus (see below) should have tipped someone off that there was more to this purported genus than previously reported.

But where to draw the lines?

Bennett’s Mistake
Dr. S. Chris Bennett (1996) used statistics to lump Germanodactylus in with certain Pterodactylus species. This is understandable in light of the fact that the holotype of the mislabeled P. kochi (no. 23 see below) is indeed a sister to G. rhamphastinus, but its not Pterodactylus. Bennett (2002) renounced his own hypothesis as “overzealous.”

The New Tree
Subsequent cladistic analysis (see below) of the Pterosauria has validated many of Dr. Wellnhofer’s assignments, but several specimens turned out to be nested far from the holotype of Pterodactylus. The chart below shows several taxa that have been correctly and incorrectly referred to Pterodactylus, all to the same scale and in phylogenetic order.

The Pterodactylus lineage and mislabeled specimens formerly attributed to this "wastebasket" genus

Figure 2. Click to enlarge. The Pterodactylus lineage and mislabeled specimens formerly attributed to this "wastebasket" genus

Is Ningchengopterus Really Just a Basal Pterodactylus?
Depends on where you draw the line. The large analysis provided an entry taxon, Ningchengopterus, into the genus Pterodactylus and the analysis documented a phylogenetic lineage that showed a gradual size increase terminating with the large P. longicollum. Two giant neck cervicals hint that the so-called “Santanadactylus” brasilensis GIUA M 4895 (Buisonjé 1980) gives every indication that it may be a several times larger and later Pterodactylus descendant.

Just Because They Sorta Looked Like Pterodactylus Doesn’t Mean They Actually Were Pterodactylus.
Several of the specimens formerly attributed to Pterodactylus were actually transitional taxa of reduced size in other lineages. It’s rather amazing how many of them do indeed converge on the morphology of Pterodactylus. Only a computer-assisted analysis enables one to sort through all the convergence. Finger and toe phalangeal proportions helped to segregate the various clades from one another. One line of pseudo-pterodactylids led from Dorygnathus to Huanhepterus and azhdarchids. Another led to ctenochasmatids. A third led from Scaphognathus to Cycnorhamphus and ornithocheirids. A fourth led to Pterodactylus. A fifth led to Germanodactylus and a sixth far removed from all the others led to Nyctosaurus and the more stork-like Eopteranodon and Eoazhdarcho.

Pterodactylus micronyx?
The holotype ELTE V 256, the “Pester” specimen is a pre-ctenochasmatid.

Pterodactylus kochi?
The holotype  B St ASXIX 3 (plate) SMF No. R 404 (counterplate), No. 23 of Wellnhofer 1970) is a pre-germanodactylid.

Pterodactylus spectabilis?
The holotype (TM 10341, no. 1 of Wellnhofer 1970) is a pre-azhdarchid.

 

Pterosaur family tree

Figure 3. Click to enlarge. The pterosaur family tree.

No Prior Published Analyses Uncovered These Relationships
All prior published analyses used only one or two Pterodactylus specimens, completely overlooking the variety in this wastebasket that needed sorting out. In this case, more taxa provided greater resolution and solved the mysteries and mismatches that have attended those prior attempts.  While I was able to go visit a large number of these specimens, most of the data used in this study was from photographs and the literature, validating, once again, the use of a large database, reconstructions and DGS (Digital Graphic Segregation).

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 1996.  Year-classes of pterosaurs from the Solnhofen Limestone of Germany: taxonomic and systematic implications. Journal of Vertebrate Paleontology, 16:432- 444.
Bennett, SC 2002.  Soft tissue preservation of the cranial crest of the pterosaurGermanodactylus from Solnhofen. Journal of Vertebrate Paleontology, 22:43-48.
Collini CA 1784. 
Sur quelques Zoolithes du Cabinet d’Histoire naturelle de S. A. S. E. Palatine & de Bavière, à Mannheim. Acta Theodoro-Palatinae Mannheim 5 Pars Physica, 58–103.
Cuvier G 1801. [Reptile volant]. In: Extrait d’un ouvrage sur les espèces de quadrupèdes dont on a trouvé les ossemens dans l’intérieur de la terre. Journal de Physique, de Chimie et d’Histoire Naturelle 52: 253–267.
Cuvier G 1809. Mémoire sur le squelette fossile d’un reptile volant des environs d’Aichstedt, que quelques naturalistes ont pris pour un oiseau, et dont nous formons un genre de Sauriens, sous le nom de Petro-Dactyle. Annales du Muséum national d’Histoire Naturelle, Paris 13: 424–437.
de Buisonjé PH 1980. Santandactylus brasilensis nov. gen. nov. sp., a long necked, large pterosaurier from the Aptian of Brasil. II. Proceedings of the Koninklijke Nederlandse Akademie van Wetenchappen B 83(2): 158–172.
von Soemmering ST 1812. Über einen Ornithocephalus. Denkschriften der Akademie der Wissenschaften München, Mathematischen-physikalischen Classe 3: 89-158.
Wellnhofer P 1970. 
Die Pterodactyloidea (Pterosauria) der Oberjura-Plattenkalke Süddeutschlands. Abhandlungen der Bayerischen Akademie der Wissenschaften, N.F., Munich 141: 1-133.

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