Zarafasaura – a short-faced plesiosaur

A recent paper (Lomax and Wahl 2013) introduced us to a more complete specimen (WDC CMC-01) of Zarafasaura, a short-faced elasmosaurid plesiosaur previously known from isolated material. The specimen (Figs. 1, 2) includes a nearly complete skull and numerous postcranial elements including limbs, pectoral and pelvic material, and vertebrae.

Figure 1. Zarafasaura, the short-faced plesiosaur.

Figure 1. Zarafasaura, the short-faced plesiosaur.

Lomax and Wahl report, “Due to the nature of the original preservation and subsequent reconstruction  of the skull, certain cranial features such as sutures and individual bones are difficult to distinguish with certainty.” The skull (Fig. 1) is from Lomax and Wahl. The tracings without black outlines (Fig.1), and some with outlines, were restored based on close taxa.

The shortening of the rostrum and the elongation of the upper temporal fenestra make this genus distinct and attest to larger jaw muscles for stronger bites. The teeth are correspondingly robust.

Binocular vision appears likely, at least over a narrow range of overlap medially. For an elasmosaurid the neck was relatively short, the dorsal ribs were not so wide and the paddles were large indeed. It all seems to add up to an aggressive and lethal underwater predator.

The internal naris question
Earlier we looked at plesiosaur nostrils, examining the idea that the internal nares were possibly covered by soft tissue and an alternate internal naris developed at the pterygoid. Here this appears to be a very interesting possibility, but the “stoppers” are still the incredibly small external nares, too small to breathe through. Better, perhaps, that this large, long-necked plesiosaur breathed through its mouth. Moreover, it’s hard to imagine that lips could seal off the air-filled tooth-lined mouth and so divert air only through the internal nares. Instead, underwater, plesiosaurs would have been good bubble-makers, letting air escape between their teeth – if they did that.

Zarafasaura reconstructed.

Figure 2. Zarafasaura reconstructed. The high neural spines provide large anchors for strong torso muscles. The paddles are relatively large for an elasmosaurid and the ribs indicate the torso was no particularly flattened.

Reference
Lomax DR and Wahl WR 2013. A new specimen of the elasmosaurid plesiosaur Zarafasaura oceanis from the Upper Cretaceous (Maastrichtian) of Morocco. Paludicola 9 (2): 97-109.

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