The palate and occiput of Daemonosaurus

Daemonosaurus, a basal phytodinosaur, was published in two lateral views, left and right with bones partly disarticulated (Fig. 1). Not readily apparent, some palatal and occipital bones are also visible. I ignored those earlier, but add them here (Fig. 2). This is made doubly difficult because sister taxa palate data is scarce.

Figure 1. Daemonosaurus with bones colored here. The right side of the skull is flipped. Color shapes correspond to color shapes in figure 2. Click to enlarge.

Figure 1. Daemonosaurus with bones colored here. The right side of the skull is flipped. Color shapes correspond to color shapes in figure 2. Click to enlarge. Note the rotation of the T-shaped quadratojugal. If you see any errors here, please advise with data.

Using DGS
the colors traced here (Fig. 1) are restored to their in vivo places (Fig. 2). Notably this is quite a tall and narrow skull, as in Heterodontosaurus.  Note the relatively short mandible (overbite) — unless you add a mandible tip. Luckily such a tip is apparent just beyond that anterovental break in the matrix in the upper image of figure 1 (Fig. 3). Without some sort of addition, the mandible is way too short relative to the rostrum.

Figure 2 Daemonosaurus skull in 4 views. The new reconstruction is narrower than previously with a new descending pterygoid flange and very few other refinements. The jaw is shorter. The dentary fang(s) appear to slip into that pmx/mx notch as in Heterodontosaurus. A small comb-like dentary tip appears to be a precursor for the predentary found in ornithischians. If this is an artifact, please provide data. Gray areas are unknown.

Figure 2 Daemonosaurus skull in 4 views. The new reconstruction is narrower than previously with a new descending pterygoid flange and very few other refinements. The jaw is shorter. The dentary fang(s) appear to slip into that pmx/mx notch as in Heterodontosaurus. A small comb-like dentary tip appears to be a precursor for the predentary found in ornithischians. If this is an artifact, please provide data. Gray areas are unknown.

The proto-predentary
of Daemonosaurus is here (Fig. 3). It extends the mandibles to their proper length (Fig. 2). As a phytodinosaur, Daemonosaurus might have used its long premaxillary teeth to comb vegetation to remove the greenery while leaving the stems.

Several basal sauropodomorphs also had an overbite. So an overbite is not an autapomorphy at this node. Even with the addition of a predentary, Daemonosaurus also had a short mandible (Fig. 2).

The proto-predentary extends the mandibles to their proper length.

Figure 3. The proto-predentary extends the mandibles to their proper length. Several basal sauropodomorphs also have an overbite. So an overbite is not an autapomorphy at this node.

Figure 4. Overall the skull of Dryosaurus is similar to that of Daemonosaurus, but has no premaxillary teeth, has a distinct predentary, and develops a palpebral.

Figure 4. Overall the skull of Dryosaurus is similar to that of Daemonosaurus, but has no premaxillary teeth, has a distinct predentary, and develops a palpebral.

It’s worth taking a look at another, more distant sister, Dryosaurus (Fig. 4), another phytodinosaur that provides clues to the architecture of the palate of Daemonosaurus. Perhaps Dryosaurus gives us further clues to the unknown post-crania of Daemonosaurus.

References
Sues H-D, Nesbitt SJ, Berman DS and Henrici AC 2011. A late-surviving basal theropod dinosaur from the latest Triassic of North America. Proceedings of the Royal Society Bpublished online

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