Preondactylus skeleton model on a tree

Rummaging through my file cabinets,
I ran across some Polaroid photos of a wire and putty model of Preondactylus (Figs. 1, 2) I made decades ago and mounted to a backyard branch. Note the sprawling femora, a lepidosaur trait.

Figure 1. Years ago, back in the days of Polaroid cameras, I built this to scale model of Preondactylus, mounted it on a tree branch and took its picture.

Figure 1. Years ago, back in the days of Polaroid cameras, I built this to scale model of Preondactylus, mounted it on a tree branch and took its picture.

Preondactylus bufarinii (Wild 1984, Dalla Vecchia 1998; Norian, Late Triassic, ~205 mya) was considered by Unwin (2003) to be the most basal pterosaur. It is not. Derived from a sister to the Italian specimen of AustriadactylusPreondactylus phylogenetically preceded Dimorphodon. Distinct from Austriadactylus, the skull of Preondactylus was lower and narrower with a larger antorbital fenestra completely posterior to the naris. The cervicals were shorter, the caudals more robust. The scapula and coracoid were more robust and straighter. The sternum was much larger. The humerus was anteriorly concave. The ulna and radius were shorter. The pelvis and pes were relatively longer. Pedal digit IV was shorter and V was longer. The metatarsals were longer than the pedal digits and IV was shorter than III.

Figure 2. At the time I thought I would use this photo of Preondactylus for a basis for an illustration with all the problems of perspective worked out.

Figure 2. At the time I thought I would use this photo of Preondactylus for a basis for an illustration with all the problems of perspective worked out. This is literally a ventral view.

Contra traditional pterosaur paleontologists,
who readily admit they have no idea which taxa are proximal outgroups to Pterosauria, basal pterosaurs, like Late Triassic Preondactylus and their fenestrasaur ancestors, were bipedal. Even so they continued to use their long, sharp-clawed free fingers to cling to trees like this (Figs. 1, 2).

Note the digitigrade pedes in this basal pterosaur,
distinct from the flat-footed beachcombers that made most of the tracks. By the way, we have tracks of digitigrade anurognathid pterosaurs (Peters 2011) derived from digitigrade dimorphodontids, like Preondactylus.

Earlier
here, here and here we looked at other ways pterosaurs could stand on and hold on to tree branches. Two of the many ways we know pterosaurs are lepidosaurs are the elongate manual digit 1 and the elongate pedal digit 5, neither of which appear in archosaurs, both of which appear in tritosaur lepidosaurs.

References
Peters D 2000a. Description and Interpretation of Interphalangeal Lines in Tetrapods. Ichnos, 7: 11-41.
Peters  D 2000b. A redescription of four prolacertiform genera and implications for pterosaur phylogenesis. Rivista Italiana di Paleontologia e Stratigrafia 106: 293-336
Peters D 2002. A New Model for the Evolution of the Pterosaur Wing – with a twist.
Historical Biology 15: 277-301.
Peters D 2007. The origin and radiation of the Pterosauria. Flugsaurier. The Wellnhofer Pterosaur Meeting, Munich 27.
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
Wild R 1984. A new pterosaur (Reptilia, Pterosauria) from the Upper Triassic (Norian) of Friuli, Italy, Gortiana — Atti Museo Friuliano di Storia Naturale 5:45-62.

wiki/Preondactylus

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