Giant sloths, anteaters and glyptodonts are moon rat descendants in the LRT

Sunday, July 19, 2026 12:22

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In evolution
everything comes from something else via transitional taxa.

In this case,
little moonrats, like Echinosorex (Figs. 1, 2), gave rise to giant sloths, like Megatherium (Fig 2) in the large reptile tree (LRT, 2340 taxa).

On another branch in the LRT moonrats gave rise to tenrecs, pakicetids and odontocetes.

Figure 3. Echinosorex, the extant moonrat, looks like an opossum, but nests with Deinogalerix in the large reptile tree. Both are basal to the sloth, armadillo, anteater clade in the LRT.

Echinosorex gymnura
(Blainville 1838; length to vent up to 40cm, tail up to 30cm) is the extant moonrat, or gymnure, a small omnivore that looks like a small opossum or rat. Here it nests at the base of the tenrec – odontocete clade AND the sloth – armadillo – aardvark – sengi – pangolin clade.

These are all Placentalia 3 taxa in the LRT.
Meanwhile… tree shrews, multituberculates and rodents are all Placentalia 2 taxa in the LRT.
Carnivores, primates and artidodactys are Placentalia 1 taxa in the LRT.

Figure 2. Extant Echinosorex, extinct Deinogalerix and extant Tenrec show the evolution of double-rooted canine-like (in shape and position) premolars to single-rooted even more canine-like premolars. Tenrec is basal to odontocetes, which are also gigantic and derived for a marine niche.

Megatherium americanum
(Cuvier 1796; Pliocene; 6m length) is the largest ground sloth. The medial pedal digits are absent or vestiges. There is little space for an auditory bulla and none was preserved. Metacarpal 4 and metatarsal 4 are the longest.

Figure 3. Megatherium represents one branch of descendants from Echinosorex, the moonrat in figure 1 in the LRT.

Of course,
there are several transitional taxa spanning the gap between Echinosorex (Figs 1, 2) and Megatherium (Figs 3, 4).

Such transitional taxa include Pholidocerus (Fig 7) and Holmesina (Fig 7).

Figure 4. Megatherium the giant sloth. Inserts show the manus and pes. These are former hooves in the ancestral taxon, Barylambda.

Pholidocercus hassiacus
(von Koenigswald & Storch 1983; HLMD Me 7577; Middle Eocene) is a traditional ancestor to hedgehogs, but here bridges the gap from Echinosorex to the larger armadillo, Holmesina (Fig 7). Known from several fossils, Pholidocercus has a long thick tail provided with tall neural spines and deep chevrons. The rostrum is short. Soft tissue is preserved as scales on the head in a helmet-like formation and scales on the tail, a pattern seen in armadillos and glyptodonts.

Figure 7. Tiny pholidocercus is a traditonal extinct hedgehog relative. Earlier it nested with Glyptodon. Now it nests with Holmesina, a large extinct armadillo with an inflexible carapace.

This appears to be a novel hypothesis of interrelationships.
If not, please provide a citation so I can promote it here.

References
de Blainville HMD 1838. C.R. Acad. Sci. Paris, 6: 742.
Cuvier G 1796. Notice sur le squelette d’une très-grande espèce de quadrupède unconnue jusqu’a présent, trouvé a Paraguay, et déposé au cabinet d’histoire
naturelle de Madrid. — Magasin Enciclopedique: ou Journal des Sciences, des Lettres et des Arts 1: 303–310, 2: 227–228; Paris.
von Koenigswald W and Storch Gh 1983. Pholidocercus hassiacus, ein Amphilermuride aus dem Eozan der “Grube Messel” bei Darmstadt (Mammalia: Lipotyphla). Senchenberg Lethaia 64:447–459.

wiki/Moonrat
wiki/Pholidocercus
wiki/Megatherium

Source: https://pterosaurheresies.wordpress.com/2026/07/19/giant-sloths-anteaters-and-glyptodonts-are-moon-rat-descendants-in-the-lrt/