Tetrapodophis, the four-legged snake – part 3

Just a little more to add
to what was already said about Tetrapodophis ( Martill, Tischlinger and Longrich 2015)  earlier here and here. Today we’ll show DGS tracings of the pectoral girdle (impression only, Fig. 1), manus, pelvis and pes.

Figure 1. Tetrapodophis pectoral region. The tips of the anterior ribs and the pectoral girdle were preserved as faint impressions traced here.

Figure 1. Tetrapodophis pectoral region. The tips of the anterior ribs and the pectoral girdle were preserved as faint impressions traced here. Purple is clavicle. Yellow/green is interclavicle

What does that say about Tetrapodophis
that the forelimbs were ossified (Fig. 1), but the pectoral girdle was not ? The scapula, coracoid, clavicle and interclavicle are not mentioned in the text. Nor are they mentioned by their absence. Are they in the counter plate? I was able to trace colors over possible impressions of the pectoral elements and distal anterior ribs in the plate. But nothing is clear here.

Figure 2. Tetrapodophis manus.

Figure 2. Tetrapodophis manus extends beneath the ribs. Not sure what is happening under there, but the reconstruction (at right) is a best guess. The metacarpals are very short. The proximal phalanges are very long.

The manus of Tetrapodophis
is somewhat obscured beneath a few ribs (Fig. 2), but the reconstruction suggests a pattern of long proximal phalanges, short metacarpals and large claws (unguals).

Figure 2. The hind limbs of Tetrapodophis, here colorized to differentiate the digits (in which all phalanges are fused) from the metatarsals.

Figure 3. The hind limbs of Tetrapodophis, here colorized to differentiate the digits (in which all phalanges are fused) from the metatarsals. At upper right is the reconstructed pelvis. Metatarsals in purple. Distal tarsals in red. 

The pelvis is preserved
along with the hind limbs (Fig. 3). Interesting that the pedal phalanges are all fused together within the five digits. Tetrapods don’t do this very often, if at all. But this is what happens prior to disappearance. The metatarsals were very short, not much longer than the distal tarsals.

References
Martill DM, Tischlinger H and Longrich NR 2015. A four-legged snake from the Early Cretaceous of Gondwana. Science 349 (6246): 416-419. DOI: 10.1126/science.aaa9208x

 

 

 

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