The Triassic Pterosaur Gastric Pellet – Reconstructed

This is the first in a series of Triassic pterosaur enigmas.

Figure 1 From Dalla Vecchia et al. 1983. Original identification of the pterosaur pellet elements. Scale bar = 1 cm.

Figure 1 From Dalla Vecchia et al. 1983. Original identification of the pterosaur pellet elements. Scale bar = 1 cm. Slightly distorted to match the published photograph. cV= caudal vertebra. Cv = cervical vertebra.

An odd jumble of Triassic bones was identified by Dalla Vecchia, Muscio and Wild (1983) as the remains of Preondactylus (Fig. 2), one of the few Triassic pterosaurs known at that time, in a gastric pellet (aka: vomited bones). The problem is, if you put the bones, as originally identified, on a reconstruction of Preondactylus, you’ll find a few matches and several mismatches (Fig. 1).

Figure 1. The major bones of the Triassic gastric pellet placed upon the skeleton of Preondactylus, a contemporary pterosaur. Note the several mismatches.

Figure 2. The major bones of the Triassic gastric pellet placed upon the skeleton of Preondactylus, a contemporary pterosaur. Note the several mismatches.

Generally the wing finger elements are too gracile and so is the femur. The dorsals are a bit too long and metacarpal 4, the base of the wing, is not quite large enough.

Putting the originally traced bones together in a different, yet still Triassic way, yields a pre- or proto-pterosaur with some resemblance to Longisquama. Now the more gracile and possibly much shorter wings make some sort of sense, because this was not a flyer, but a running flapper and a glider at best. Of course, in this case, I was able to draw the imagined parts “to fit.”

Freddy Mercury put it best, “Is this the real life? Is this just fantasy?”

Figure 2. With so few bones, and so few of those complete, you can rebuild the gastric pellet into a pre- or proto- pterosaur, something like Longisquama.

Figure 3. With so few bones, and so few of those complete, you can rebuild the gastric pellet bone tracings of Dalla Vecchia et al. into a pre- or proto- pterosaur, something like Longisquama. Now the femur becomes a distal humerus. What was a metatarsal becomes a metacarpal similar in size and thickness to metacarpal 4. The large dorsals are a good fit as Longisquama had a long torso. Minimizing the amount of bone lost from each of the wing/finger phalanges yields a much shorter wing, like Longisquama. Black wiry shapes are completely imagined, as is most of the rest of this restoration. The actual animal shape may never be adequately known.

Wouldn’t it be exciting if the gastric pellet, now known for over 30 years, turned out to be an example of a transitional/basal taxon? Odd that only segments of all four wing phalanges would be preserved.

After producing these images I learned the pellet is under study once again. Hopefully those studies will help resolve this mystery.

When I ran the published images through DGS I was able to identify many other bones and create another much more complete reconstruction that also made sense. It was standard basal pterosaur. But then, the data I was using was poor at best.

Given the mishmash of the in situ fossil, the poor quality of my data and the detailed new study of the gastric pellet specimen to come, I hesitate putting it out early. I will say that the originally identified ‘palatine’ and ‘pterygoid’ are probably the first two dorsal ribs, which were more robust than the others, as in other pterosaurs. And several more ribs are present, which were generally overlooked in the original tracing (Fig. 1).

References
Dalla Vecchia FM, Muscio G and Wild R 1983. Pterosaur remains in a gastric pellet from the Upper Triassic (Norian) of Rio Seazza Valley (Udine, Italy). Gortania – Atti Museo Friul. Storia Naturale 10(88):121-132.

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