Weekly Spotlight: Preondactylus

13 03 2010

Good tidings and well-wishes!

As any perusal of Dave Hone’s Archosaur Musings and Mark Witton’s photostream will reveal, few groups of fossilized organisms are as controversial as their beloved pterosaurs. It’s not difficult to understand why, given their notoriously-thin bones and the fact that they relied extensively on delicate and seldomly-preserved soft tissue. Few aspects of pterosaur paleontology, however, have amassed a degree of debate obtained by the subject of the animals’ ancestry. While proto-dinosaurs are well-known and extensively documented, no analagous beasts have been conclusively located for these famed fliers, a situation which is probably due to the factors cited above. Nonetheless, we can infer a reasonable amount of information concerning the early phylogeny of the pterosauria by examining the earliest members of the order, one of the best known of which is the earliest known pterosaur, Preondactylus buffarini of the Italian late Triassic.

In his book “Dinosaurs Of Italy”, Cristiano Dal Sasso writes:

“[The] first individual of Preondactylus (literally ‘finger of Preone’) was the size of a magpie; it had a wingspan of less than 50 centimeters. Subsequently a second, larger individual, with an estimated wingspan of 150 centimeters, represented by three wing phalanges, was discovered in Endenna, in Lombardy [(interestingly, this latter specimen is theorized to actually be a fossilized pellet of bones which had been spat out by a fish that had previously consumed the reptile)]. Preondactylus had triangular teeth with only one cusp each, arranged in a row of alternating long and short points, which do not give a clear idea of the animal’s diet [(though insectivorous and piscivorous diets have been proposed)].”

Additionally, according to Dave Unwin’s “Pterosaurs: From Deep Time”,

Preondactylus was about the size of a pigeon and had numerous well-developed teeth, including several large prey-grabbing fangs at the tip of its jaws. This pterosaur also had a fully developed flight apparatus and was almost certainly a competent flier, although its wings seem to have been relatively shorter than in any other pterosaurs found so far and the tail, unlike those of later rhamphorynchoids, was relatively simple, without the usual stiffening sheath of bony rods.”

Another primitive characteristic possessed by this animal was its relatively long hindlimbs, as evidenced by the following illustration.

It should be noted, however, that Éric Buffetaut and Jean-Michel Mazin have argued that “A re-examination of… this taxon showed that the wing metacarpal and tibia were considerably shorter and the first wing phalanx considerably longer than thought, casting doubt about its basal position within the Pterosauria.” The pair went on to assert that the species is “more derived than anurognathids and Sordes“. Unwin, however, has antithetically claimed that Preondactylus is the most basal pterosaur known to science.

Regardless of one’s personal convictions on the subject of the previous paragraph, it can’t be denied that Preondactylus shared a number of features with fellow Triassic pterosaur Peteinosaurus, which strongly suggests a relatively close kinship. To once again reference “Pterosaurs: From Deep Time”: 

Preondactylus reconstruction, courtesy of the legendary Mark Witton.

Peteinosaurus was in many respects similar, but had the classic stiffened whip-tail of typical rhamphorhynchoids, and, significantly, the dentistry was rather different. Behind the prey-grabbing fangs was a row of tiny, saw-like teeth that probably served to hang onto food items until they could be swallowed.”  

Even if this aspect of Preondactylus‘ phylogeny is relatively unambiguous, this genus and the order in which it taxonomically resides contains no shortage of mysteries to be pursued by the next generation of pterosaur researchers.

May the fossil record continue to enchant us all!

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