A recent paper by described a new multituberculate, Litovoi. The authors also produced a cladogram of multituberculates (Fig. 1).
Long have I wondered
which taxa were considered outgroups for the multituberculates in modern paleo-thinking. Thanks to Csiki-Sava et al. now we know they nested Haramiyavia as the outgroup (Figs. 1, 2).
Or is that solution possible
only due to taxon exclusion?
the large reptile tree (LRT, 1201 taxa) nested multis with rodents and plesiadapids (Fig. 2). Haramiyavia nested far distant, as a pre-mammal, not far from Pachygenelus. While the .nex files include all the details, the illustration of skulls (Fiji. 3) compares the two hypotheses of relationships.
Taking the skulls from Figure 2
(Fig. 3) one can compare the traditional hypothesis of multituberculate origins with that recovered by the LRT, offering a sort of short hand of all the data scores. One should appear to demonstrate a gradual accumulation of traits. The other should appear to not do so well. Which outgroup lineage appears to have more multituberculate traits in your judgement?
The closest living relative of long extinct multituberculates,
according to the LRT is Daubentonia, the aye-aye (Figs. 4, 5), once considered a lemur-like primate, but here nesting with extinct Carpolestes and the multis. No other primate, living or extinct (Plesiadapis is also a rodent relative in the LRT), has such a suite of bony traits, including those very large, rodent-like (due to homology) incisors.
According to Wikipedia
“The multituberculates existed for about 166 or 183 million years, and are often considered the most successful, diversified, and long-lasting mammals in natural history. They first appeared in the Jurassic, or perhaps even the Triassic, survived the mass extinction in the Cretaceous, and became extinct in the early Oligocene epoch, some 35 million years ago. The oldest known species in the group is Indobaatar zofiae from the Jurassic of India, some 183 million years ago, and the youngest are two species, Ectypodus lovei and an unnamed possible neoplagiaulacid, from the late Eocene/Oligocene Medicine Pole Hills deposits of North Dakota. If gondwanatheres are multituberculates (all tested taxa are not in the LRT), then the clade might have survived even longer into the Colhuehuapian Miocene in South America, in the form of Patagonia peregrine.”
Employing taxon inclusion,
the LRT presents a heretical and more parsimonious hypothesis of multituberculate origins (Figs 2, 3) that tests Haramiyavia and over 1000 other possible candidates.
To test this hypothesis,
simply add the above suggested relevant taxa to your favorite wide gamut phylogenetic analysis and run. Let me know if your analysis then confirms the LRT—or do you find yet another origin/set of outgroups for the multituberculates? Haramiyavia has very few multi traits, far fewer than rodents and Daubentonia.
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