Triassic gastric pellet semi-reconstructed, better this time…

A while back
Dalla Vecchia, Wild and Muscio (1989) described a small pellet (MFSN 1891, Fig. 1) of Late Triassic bones from the Dolomia di Forni Formation of Firuli (NE Italy) as a small jumble of pterosaur bones. They tentatively referred it to Preondactylus, the only pterosaur known at the time from that formation. This was an early work for all three paleontologists.

Following the original paper
Earlier I attempted a reconstruction of the elements based on the pterosaur model. I recognized then that it didn’t turn out too well. I was working from the original drawings. Now new data has been published and a new hypothesis has been put forth that makes much more sense.

Figure 1. Several views of the Triassic gastric pellet formerly considered pterosaurian, but now considered langobaridsaurian. Elements from a surface photo, a microCT scan of the opposite side still buried in matrix, and DGS colors. Not all bones have been colored here.

Figure 1. Several views of the Triassic gastric pellet formerly considered pterosaurian, but now considered langobaridsaurian. Elements from a surface photo, a microCT scan of the opposite side still buried in matrix, and DGS colors. Not all bones have been colored here, but employed colors are assembled in figure 2. The long cervical at upper left is 1 cm long. So is the scale bar. The pellet is about 5 cm wide.

Recently 
Holdago et al. (2015) redescribed the pellet in much greater detail using microCT acquisition. They concluded “The best candidate for the pellet is not a pterosaur, but a protorosaurian like Langobardisaurus.  Therefore, the skeletal remains could belong to a still unknown small reptile with procoelous dorsal vertebrae, rather elongate and probably procoelous cervical vertebrae with low neural arch and spine, filiform cervical ribs, at least some dicephalous dorsal ribs, elongated and hollow limb bones, and no osteoderms.”

They did not attempt a reconstruction,
so I do so here (Fig. 2) following the hypothesis that the elements belong to a langobardisaur (contra Holdgago, et al., not a protorosaur but a tritosaur lepidosaur).

Figure 2. The elements of MFSN 1891 assembled to form a langobardisaur in a bipedal pose.

Figure 2. The elements of MFSN 1891 assembled to form a langobardisaur in a bipedal pose. Some langobardisaurs have a very long neck, slender limbs and a short tail. Lots of guesswork here.

Lots of guesswork here. 
Everything is tentative. The toes could be ribs. Lots of slivers and scraps left over. More complete langobardisaurs (Fig. 3) have 8 cervicals, but they are related to tanystropheids, with 13 cervicals. Renesto et al. (2002) considered langobardisaurs as likely facultative bipeds in the manner of the many extant facultative bipedal lizards, all with sprawling hind limbs.

Langobardisaurus tonneloi reconstructed. Note the cosesaur-like pectoral girdle.

Figure 3. Langobardisaurus tonneloi reconstructed. Note the cosesaur-like pectoral girdle.

MFSN 1891 needs to be dissembled
in high resolution, then reassembled like a puzzle. I’d like to help if possible. Here (Fig. 2) is a first draft lo rez example leading to others of greater detail in the future. Worthwhile taking another look at the pes (Fig. 3) which greatly resembles a basal pterosaur pes with that elongate p5.1. It resembles a pterosaur pes because these two taxa are related (Peters 2000).

Figure 6. Click to view full scale on a 72 dpi screen. Tanystrachelos compared to the gastric pellet lepidosaur.

Figure 4. Click to view full scale on a 72 dpi screen. Tanystrachelos compared to the gastric pellet lepidosaur. The large hemal arches on the gastric pellet are the genesis of the paddle-like hemal arches on Tanytrachelos and Tanystropheus.

Compared to the tritosaur Tanytrachelos (Fig. 4)
the gastric pellet reptile has a similar number of cervicals, but longer limbs and longer cervicals. Are we seeing the origin of Tanystropheus (Fig. 5) here? Or a hatchling? The large hemal arches appear to have homologs in Tanytrachelos and Tanystropheus.

Tanystropheus and kin going back to Huehuecuetzpalli.

Figure 5. Tanystropheus and kin going back to Huehuecuetzpalli. Two scales here, one yellow, one white.

Then we have Fuyuanssaurus, 
a tiny tanystropheid (Fig. 6) about twice the size of the gastric pellet reptile. Unfortunately we don’t know if it was long-legged or not. Notably the skull elements of Fuyuansaurus, which we looked at earlier here were all quite slender. This is the model we should use for the gastric pellet lizard until data suggests another model.

Figure 2. Click to enlarge. Reconstruction of Fuyuanasaurus. Fraser et al. identified a strange circular object as the pubis, but no sister taxa have a circular pubis. Here it is tentatively ID'd as an egg because a standard pubis is found nearby.

Figure 6. Click to enlarge. Reconstruction of Fuyuanasaurus. Fraser et al. identified a strange circular object as the pubis, but no sister taxa have a circular pubis. Here it is tentatively ID’d as an egg because a standard pubis is found nearby.

References
Dalla Vecchia FM, Wild R and Muscio G 1989. Pterosaur remains in a gastric pellet from Upper Triassic (Norian) of Rio Seazza valley (Udine, Italy). Gortania 10: 121–132.
Holgado B, Dalla Vecchia FM, Fortuny J, Bernardini F and Tuniz C 2015. A Reappraisal of the Purported Gastric Pellet with Pterosaurian Bones from the Upper Triassic of Italy. PLoS ONE 10(11): e0141275. doi:10.1371/journal.pone.0141275
Peters D 2000. A Redescription of Four Prolacertiform Genera and Implications for Pterosaur Phylogenesis. Rivista Italiana di Paleontologia e Stratigrafia 106 (3): 293–336.
Renesto S, Dalla Vecchia FM, Peters D. 2002. Morphological evidence for bipedalism in the Late Triassic prolacertiform reptile Langobardisaurus. In: Gudo M, Gutmann M, Scholz J, editors. Concepts of functionalengineering and constructional morphology: biomechanical approaches on fossil and recent organisms. Senckenb Lethaea 82(1): 95–106.

 

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