Bennett’s (2013) Revision of Pterodactylus – part 1

Chris Bennett’s pubs on pteros have been less than regular lately.
And what he has published on has been widely accepted, but largely off the mark (see below). So it is with tepid interest that we take a look at his latest paper (Bennett 2013), New information on body size and cranial display structures of Pterodactylus antiquus, with a revision of the genus.”

In short, Bennett is a lumper, to the extreme.
He lumped tiny pterosaurs, like n9 and n31 (in the Wellnhofer 1970 catalog) under Germanodactylus. He’s lumped Rhamphorynchus under one species as a growth series (Bennett 1995). He lumped nearly all Pteranodon together (other than P. sternbergi) Bennett 1991, 1992, 1994  2001).

Here Bennett (2013, Fig. 1) lumps several Pterodactylus together in a growth series based on the hypothesis of allometry (shape changes) during ontogeny, a concept with no evidence when one considers the morphology of pterosaur embryos. Virtually identical to adults, pterosaur embryos demonstrate isometric growth during ontogeny, a process that goes back to their basal lizard precursor Huehuecuetzpalli based on observations made by Reynoso (1998), and further demonstrated by the  growth series in the azhdarchid, Zhejiangopterus.

What Bennett fails to understand is the only way to arrive at large pterosaurs, like derived crested Pteranodon, is to evolve them from small pterosaurs (Fig. 2) like basal crestless Pteranodon and certain Germanodactylus. This he would discover through phylogenetic analysis and by creating reconstructions (Fig. 2). Even so his own bone length analysis (Fig. 1) points in that direction. This is also how you get large Pterodactylus specimens, like the old P. longicollum (now Ardeadactylus).

Even so, the concept of generic lumping is not necessarily a bad thing. We’ve been doing it for two hundred years with pterosaurs. But we have to figure out where to draw the lines (as discussed earlier) and the only way to do that is phylogenetically, which Bennett is loath to do. There’s no phylogenetic analysis in Bennett (2013), only a chart of skull and post-cranial bone lengths (Fig. 1) demonstrating ontogeny in Bennnett’s mind, evolution in mine (Fig. 2). Note Bennett’s chart does not indicate variation on foot bone morphology, which Peters (2011) found to be notable throughout the clade, even within the genus Pterodactylus (here, here and here for starters). Bennett’s chart includes 12 variables. A good phylogenetic analysis will include over a hundred and fifty before the returns start to flatten out.

Bennett (2013) is also loath to create scaled reconstructions (Fig. 2), which generally tell the tale at first glance better than bone lengths.

Chart from Bennett 2013 of skull and post-cranial bone lengths

Figure 1. Chart from Bennett 2013 of skull and post-cranial bone lengths for putative Solnhofen Pterodactylus specimens identified in Wellnhofer 1970. A few are identified on the chart with callouts. Bennett says these are allometric growth charts. I say this is how you evolve a large Pterodactylus, since embryos demonstrate isometric growth (they are nearly identical to parents in proportion). TM 10341 is a tiny pterosaur related to Dorygnathus, for instance. BSP AS I 739 is the holotype of Pterodactylus. Ardeactylus (n58 of Wellnhofer 1970 and JME-SOS 2428, the flightless pterosaur, n57 are not shown here.

Bennett (2013) includes several putative Pterodactylus (like TM 10341) that nest elsewhere, as recovered by phylogenetic analysis and graphically shown here (Fig. 2).

Many of the specimens previously referred to the wastebasket taxon, Pterodactylus. Some belong. Some do not.

Figure 2. Click to enlarge. Many of the specimens previously referred to the wastebasket taxon, Pterodactylus. Some belong. Some do not. All to scale. Red boxes highlight taxa discussed here. TM10341 is in the upper left hand corner. It is derived from Dorygnathus and leads to azhdarchids.

We’ll continue this tomorrow, introducing the cast of characters in Bennett’s (2013) study (boxed in red, Fig. 2), plus the new one.

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. 

Reference
Bennett SC 1991. Morphology of the Late Cretaceous Pterosaur Pteranodon and Systematics of the Pterodactyloidea. [Volumes I & II]. Ph.D. thesis, University of Kansas, University Microfilms International/ProQuest.
Bennett SC 1992. Sexual dimorphism of Pteranodon and other pterosaurs, with comments on cranial crests. Journal of Vertebrate Paleontology 12: 422–434.
Bennett SC 1994. Taxonomy and systematics of the Late Cretaceous pterosaur Pteranodon (Pterosauria, Pterodactyloidea). Occassional Papers of the Natural History Museum University of Kansas 169: 1–70.
Bennett SC 2001. The osteology and functional morphology of the Late Cretaceous pterosaur Pteranodon. Part I. General description of osteology. Palaeontographica, Abteilung A, 260: 1–112. Part II. Functional morphology. Palaeontographica, Abteilung A, 260: 113–153
Bennett SC 1995. A statistical study of Rhamphorhynchus from the Solnhofen limestone of Germany: year classes of a single large species. Journal of Paleontology 69, 569–580.
Bennett  SC (2012) [2013] New information on body size and cranial display structures of Pterodactylus antiquus, with a revision of the genus. Paläontologische Zeitschrift (advance online publication) doi: 10.1007/s12542-012-0159-8
http://link.springer.com/article/10.1007/s12542-012-0159-8
Peters D 2011. A Catalog of Pterosaur Pedes for Trackmaker Identification. Ichnos 18(2):114-141. http://dx.doi.org/10.1080/10420940.2011.573605
Wellnhofer P 1970. Die Pterodactyloidea (Pterosauria) der Oberjura-Plattenkalke Süddeutschlands. Abhandlungen der Bayerischen Akademie der Wissenschaften, N.F., Munich 141: 1-133.

1 thought on “Bennett’s (2013) Revision of Pterodactylus – part 1

  1. Pingback: DinoAstur - » Ardeadactylus, nuevo nombre para Pterodactylus longicollum

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