Both Ectocion taxa are now marsupials in the LRT

These two taxa,
both referred to Ectocion (Fig 1), did not fit well among the placentals. Among the marsupials they found a good match close to another narrow-skulled taxon, Eolophiodon (Fig 1). You’ll note the large orbit and short rostrum, traits typical of neotony apparent in the smaller two taxa.

Ectocion cedrus and Ectocion ralstonensis now nest with similar marsupials in the LRT (Fig 2).

Figure 1. The two Ectocion taxa in the LRT updated with new DGS colors here. ” data-image-caption=”

Figure 1. The two Ectocion taxa in the LRT updated with new DGS colors here.

” data-medium-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/06/ectocion-ralstonensis588.jpg?w=300″ data-large-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/06/ectocion-ralstonensis588.jpg?w=584″ tabindex=”0″ role=”button” class=”size-full wp-image-87077″ src=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/06/ectocion-ralstonensis588.jpg” alt=”Figure 1. The two Ectocion taxa in the LRT updated with new DGS colors here. ” width=”584″ height=”234″ />

Figure 1. The two Ectocion taxa in the LRT updated with new DGS colors and restorations here. Note the narrow morphology of both taxa.

According to Wikipedia – Ectocion
“Ectocion (sometimes Ectocyon) is an extinct genus of placental mammals of the family Phenacodontidae. It reached 6 to 12 kg and was similar in size and morphology to Copecion. Both these herbivorous ungulates likely occupied similar ecological niches.”

Adding taxa and changing scores based on a more parsimonious Bauplan changed these former phenacodontids into lophiodontids. As long-time readers know, several marsupial clades converge with placental clades (eg Creodonta and Carnivora). This is yet another instance of marsupial- placental convergence.

Figure 2. The two Ectocions join these narrow-skull lophiodons in the LRT, here shown to scale. ” data-image-caption=”

Figure 2. The two Ectocions join these narrow-skull lophiodons in the LRT, here shown to scale.

” data-medium-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/06/litolophus_danjiangia588-1.jpg?w=126″ data-large-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/06/litolophus_danjiangia588-1.jpg?w=429″ tabindex=”0″ role=”button” class=”size-full wp-image-87078″ src=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/06/litolophus_danjiangia588-1.jpg” alt=”Figure 2. The two Ectocions join these narrow-skull lophiodons in the LRT, here shown to scale. ” width=”584″ height=”1394″ />

Figure 2. The two Ectocions join these narrow-skull lophiodons in the LRT, here shown to scale.

Ectocion ralstonensis
(Cope 1882 a, e, Granger 1915; Late Paleocene; 11 cm skull length) is generally considered a member of the Phenacodontidae, like Phenacodus, but here nests It nests close to Eolophiodon in the Marsupialia in the LRT.

Ectocion cedrus
(Cope 1882a, e, Thewissen 1990; UM 86155; Paleocene, 50mya) This genus is known from a fragmentary skull and several partial skeletons. The dental morphology is lophodont with a narrow rostrum. It nests close to Eolophiodon in the LRT.

You might remember
earlier the LRT moved Lophiodon and relatives (Fig 2) to the Marsupialia.

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

References
Cope ED 1882a. Contributions to the history of the Vertebrata of the lower Eocene of Wyoming and New Mexico, made during 1881. Proceedings of the American Philosophical Society: 139-197.
Cope ED 1882e. Note on Eocene Mammalia. American Naturalist 16:522.
Filhol H 1881. Etude sur les mammifères fossiles de Ronzon (Haute-Loire). Bibliothèque Ecole des Hautes Etudes. Section Sciences Naturelles, Masson éd. (Paris), T. 24, art. 4: 1-270, 26 pl.
Finarelli JA 2008. A Total Evidence Phylogeny of the Arctoidea (Carnivora: Mammalia): Relationships Among Basal Taxa. Journal of Mammalian Evolution. 15(4): 231–259.
Granger W 1915. A revision of the lower Wasatch and Wind River faunas, Part III: Order Condylarthra, families Phenacodontidae and Meniscotheriidae. Bulletin of the American Museum of Natural History 34:329-361.
Thewissen JGM 1990. Evolution of Paleocene and Eocene phenacodontidae (Mammalia, Condylarthra). University of Michigan Papers on Paleontology 29:1-107.

wiki/Ectocion

Lophiodon revisited: now a marsupial close to Paedotherium