Revisiting the Dendromaia tiny den-mate

Earlier I attempted a tracing of the 2cm skull of the Dendromaia (Maddin et al. 2020; Figs. 1–3) small den-mate using a low resolution image. That didn’t work out well due to using only one plate and misinterpreting the subtle grays in the photo. Even so, oddly enough, the error-filled scoring nested the small skull close to the same taxa that Maddin et al. nested the specimen.

As you might remember,
the much larger den-mate nested in the large reptile tree (LRT, 1628+ taxa) with Acleistorhinus and other skull-only taxa between the more complete Casea, Eocasea and Eunotosaurus taxa. The large den-mate was probably an herbivore based on phylogenetic bracketing. The tiny den-mate was a likely insectivore.

Today
with higher resolution images of the part and counterpart mated together in Photoshop layers (Fig. 1), the skull of the small den-mate is re-traced and reconstructed in much greater detail. (Still far from perfect.) The resulting plate and counter plate preserve the palate and the mandibles respectively in ventral view. Dorsal sutures are unknown.

Figure 1. The small den mate assigned to the genus Dendromaia traced using DGS methods and reconstructed in figure 2.

Figure 1. The small den-mate assigned to the genus Dendromaia traced using DGS methods and reconstructed in figure 2. Details are difficult to interpret. As before, this is a best guess based on current data.

Details are still difficult to interpret.
As before, this is a best guess based on current data. Now the small Late Carboniferous den-mate nests between two other much larger skull taxa both assigned to the genus Varanosaurus, known from Early Permian skeletons. So the small den-mate must be congeneric with Varanosaurus. The small size of the small den-mate is probably due to its young ontogenetic age.

These taxa are basal synapsids (in the lineage of humans), not protodiapsids.

Figure 3. The small den mate nests between these two specimens assigned to Varanosaurus.

Figure 2. The small den-mate nests between these two specimens assigned to Varanosaurus.

Morphologically flat skulls,
like those in Varanosaurus (Fig. 2) and the small den-mate (Fig. 3), tend to fossilize in dorsal or palatal view (Fig. 1). The shape of the mandible informs the reconstructed width of the skull. The dorsal sutures are best guesses based on phylogenetic bracketing.

Figure 3. Reconstruction of the small den mate based on DGS tracings in figure 1.

Figure 3. Reconstruction of the small den-mate based on DGS tracings in figure 1.

The number of mistakes I’ve made
and corrected over the last eight years is now deep into six figures. These corrections are just the latest set to get corrected. Few other workers are attempting to identify bones to this degree on such tiny specimens. There’s no blueprint for this. Everyone who attempts such tracings are on their own. You might try practicing on some roadkill for starters.


References
Maddin HC, Mann A and Hebert B 2020. Varanopid from the Carboniferous of Nova Scotia reveals evidence of parental care in amniotes. Nature ecology & evolution 4:50–56.

wiki/Varanosaurus
wiki/Dendromaia (not yet posted)

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