Anomodont tree problems

We still need to add more taxa to our matrices.

Figure 1. Cisneros et al. 2015 cladogram nesting Tiarajudens and Anomolocephalus as basal anomodonts. This is odd because both are quite derived.

Figure 1. Cisneros et al. 2015 cladogram nesting Tiarajudens and Anomolocephalus as basal anomodonts. This is odd because both are quite derived.

 

Figure 2. Cladogram of taxa listed by Cisneros et al. but using the Peters 2015 matrix.

Figure 2. Cladogram of taxa listed by Cisneros et al. but using the Peters 2015 matrix.

Case in point:
Cisneros et al. 2015, is a recent paper on Tiarajudens (Fig. 4) behavior. Their cladogram (Fig. 1) does not match a larger study (Fig. 2) with regard to the way they ordered basal therapsids.

Two problems right at the start:
Everyone knows Dimetrodon is not basal to therapsids. It is far too derived. No basal therapsid has dorsal spines.

There’s a body of work that demonstrates that Tetraceratops is not a basal therapsid. Again, it is too derived, too bizarre, too different — and it does not nest with synapsids!  In the large reptile tree it nests with Tseajaia. Actual basal therapsids include Cutleria and Biarmosuchus, which Cisneros et al. did use. Even so, they missed several taxa listed here (Fig. 3). Every taxon counts and adds value to the tree.

Adding taxa is a chore.
So, is that why paleontologists don’t like to add any more than they have to? It seems they often ask a grad student to do the work, and they’re new at it! They’re not experts until after they’ve done their studies. Workers can always reference the large reptile tree (Fig. 3). It works in whole or in part.

Figure 3. Where Tiarajudens and Anomocephalus nest as a subset of the large reptile tree.

Figure 3. Where Tiarajudens and Anomocephalus nest as a subset of the large reptile tree. Here they nest as derived taxa, not basal taxa. They did not produce descendants.

Anomocephalus and Tiarajudens
are giant, terrestrial dromasaurs, a clade of otherwise small, long-tailed, arboreal anomodonts. Giant dromasaurs converge with dicynodonts in several regards (short toes, tusks, size). Perhaps that leads to confusion generally.

Figure 4. Dromasaurs to scale. Tiarajudens and Anomocephalus are giant terrestrial dromasaurs.

Figure 4. Dromasaurs to scale. Tiarajudens and Anomocephalus are giant terrestrial dromasaurs. The pmx/ms suture IMHO probably includes four teeth, like Suminia.

BTW
Biseridens
has nothing to do with basal anomondonts. It’s a derived dinocephalian (Fig. 3) when more taxa are added. Let’s get that straight, too.

References
Cisneros JC, Abdala F, Jashashvili T, de Oliveira Bueno A and Dentzien-Dias P 2015. Tiarajudens eccentricus and Anomocephalus africanus, two bizarre anomodonts (Synapsida, Therapsida) with dental occlusion from the Permian of Gondwana.

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