New ‘rodents and rabbits’ cladogram

Asher et al. 2019
bring us a new phylogenetic + genomic cladogram of rabbits + rodents (clade = Glires) that fails to include taxa recovered by the large reptile tree (LRT, 1552 taxa, subset Fig. 1).

From their abstract:
“Our results support the widely held but poorly tested intuition that fossils resemble the common ancestors shared by living species, and that fossilizable hard tissues (i.e. bones and teeth) help to reconstruct the evolutionary tree of life.”

From their results:
“Our analysis supports Glires and three major clades within crown Rodentia: Sciuromorpha (squirrels and kin), Myomorpha ((beavers + gophers) + mice and kin), and Ctenohystrica (porcupines, chinchillas and kin).”

Figure 1. Subset of the LRT focusing on Glires and subclades within.

Figure 1. Subset of the LRT focusing on Glires and subclades within. This is an older image not updated yet with the dormouse, Eliomys.

The LRT
also supports these divisions. It also supports the basal nesting of ‘Tupaiidae’ relative to Glires. It does not support the inclusion of Primates within Glires, but the two are sister clades within a single clade. The LRT supports the basal nesting of Didelphis relative to Metatheria and Eutheria.

Some oddities in the results of Asher et al. 2019.

  1. Papio, the baboon, nests between Dermoptera (flying lemurs/colugos) and Plesiadapis + lemurs. That’s way too primitive for such a derived monkey.
  2. Rodent-toothed Pleisadapis nests with baboons and lemurs. This is a traditional nesting not recovered by the wider gamut LRT where Plesiadapis nests closer to multituberculates and the aye-aye, Daubentonia.

Asher et al. 2019 included dormice
(Eliomys and kin; Fig. 2), and found them to be rather primitive, closer to squirrels. So Eliomys was added to the LRT and it nested with Mus, the mouse.

Figure 2. Eliomys, the dormouse.

Figure 2. Eliomys, the dormouse.

How to tell a mouse from a dormouse.
The skulls are similar, but different. The dormouse tail is furry, not scaly. Dormice are more arboreal. The dormouse hibernates rather than seeking warm spots. Fossil dormice are found in the Eocene, but their genesis must go back to the Early Jurassic, where multituberculates are found, according to the LRT.


References
Asher RJ, Smith MR, Rankin A and Emry RJ 2019. Congruence, fossil and the evolutionary tree of rodents and lagomorphs. Royal Society Open Science 6:190387. http://dx.doi.org/10.1098/rsos.190387

A tiny Late Jurassic pre-rabbit: Henkelotherium

This earlier tracing and nesting
saw improvement with a higher resolution image.

Figure 1. Henkelotherium, a traditional pantothere, nests as a Late Jurassic pre-rabbit in the LRT.

Figure 1. Henkelotherium, a traditional pantothere, nests as a Late Jurassic pre-rabbit in the LRT. Image about 3.5x life size.

Henkelotherium guimarotae (Krebs 1991; Late Jurassic 150 mya; Figs. 1-3) was traditionally considered a pantothere or eupantothere. Here Henkelotherium nests with rabbits as a Late Jurassic member of the clade Glires. Like its sisters, the manus was small and the pes had long digits with sharp claws. The lumbar region was long and flexible. A tiny taxon, the image below (Fig. 2) is about twice natural size.

Figure 2. Henkelotherium reconstructed from DGS tracings in figure 1. Note the tiny manus and large pes, traits that continue into extant rabbits.

Figure 2. Henkelotherium reconstructed from DGS tracings in figure 1. Note the tiny manus and large pes, traits that continue into extant rabbits. Image about twice life size. What looks like an eye here is just a tracing of bone cracks, probably in the frontal.

Wikipedia reports
“Eupantotheres are derived compared to symmetrodonts in having wider upper than lower teeth (although they still lack the protocone of tribosphenic forms.” The large reptile tree does not recover this clade. Rather the clade Lagomorpha should be extended to include the taxa found here (Fig. 3).

Figure 3. The Lagomorpha clade with the addition of Henkelotherium.

Figure 3. The Lagomorpha clade with the addition of Henkelotherium.

References
Krebs B 1991. Skelett von Henkelotherium guimarotae gen. et sp. nov. (Eupantotheria, Mammalia) aus dem Oberen Jura von Portugal. Berl Geowiss Abh A.: 133:1–110.

wiki/Henkelotherium