Dryolestes, a tiny mammal mandible with many molars

Figure 1. Having 7 or 8 molars is very unusual for mammals. So finding a close match for Dryolestes is easy, once you have Docodon and Amphitherium. Dryolestes is the most derived of these three.

Figure 1. Having 7 or 8 molars is very unusual for mammals. So finding a close match for Dryolestes is easy, once you have Docodon and Amphitherium. Late Jurassic Dryolestes is the most derived of these three based on the anterior lean of the coronoid process and the shamrock-shaped molars, reduced from their Middle and Late Jurassic relatives. 

With only the mandible + teeth to work with
(Fig. 1) the data on Dryolestes is too sparse to enter into the LRT, but having 8 molars in the Late Jurassic is atypical enough to make finding a close relative relatively easy—if you have Docodon and Amphitherium (Fig. 1) in your list. The best place to look for tiny Jurassic mammals with so many molars is within the Prototheria (Monotremata), which now includes extant toothless taxa.

Wikipedia offers
a cladogram that nests Dryolestes close to Amphitherium, but the next taxon at the next node is Vincelestes, which has very few molars and large saber teeth and therefore is in no way related. Docodon does not appear on that cladogram. The plasticity of the tooth shapes is quite apparent here. Dryolestes looks like to was more interesting in sieving than in cracking beetle shells. But who knows?

All these taxa have been known for over 150 years. Wikipedia reports, “It has been suggested that this group [Dryolestoidea] is closely related to modern therian mammals.  Dryolestid dentition is thought to resemble the primitive mammalian dentition before the marsupial-eutherian differentiation and dryolestids are candidates to be the last common ancestor of the two mammalian subclasses.”

The burrowing placental, Necrolestes, is listed as a dryolestoid in Wikipedia.

References

wiki/Dryolestes
wiki/Dryolestidae
wiki/Dryolestoidea

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