Microsyops and the Plesiadapiformes

Today’s three taxa,
Microsyops, Ignacius and Palaechthon (Fig 1), traditionally have been assigned to the clade Plesiadapiformes, anchored by Plesiadapis.

According to Wikipedia – Plesiadapiformes,
“Plesiadapiformes is an extinct basal pan-primates group, as sister to the rest of the pan-primates. The pan-primates together with the Dermoptera form the Primatomorpha. Purgatorius may not be a primate as an extinct sister to the rest of the Dermoptera or a separate, more basal stem pan-primate branch.”

In the LRT all four taxa above do nest together,
but within Glires, the gnawing clade, not within or just outside Primates (including bats and dermopterans).

Primates and their ancestors never had oversize incisors with a toothless diastema. Those are traits that developed in the clade, Glires, beginning tentatively with tree shrews, like Tupaia and Ptilocercus.

Let’s stop the myth that pre-primates had buck teeth.

Figure 1. Microsyops, Plesiadapis, Daubentonia, Carpolestes and kin in the LRT to scale. ” data-image-caption=”

Figure 1. Microsyops, Plesiadapis, Daubentonia, Carpolestes and kin in the LRT to scale.

” data-medium-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/07/microsyops-plesiadapis-ignacius588-1.jpg?w=101″ data-large-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/07/microsyops-plesiadapis-ignacius588-1.jpg?w=343″ tabindex=”0″ role=”button” class=”size-full wp-image-87487″ src=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/07/microsyops-plesiadapis-ignacius588-1.jpg” alt=”Figure 1. Microsyops, Plesiadapis, Daubentonia, Carpolestes and kin in the LRT to scale.” width=”584″ height=”1742″ />

Figure 1. Microsyops, Plesiadapis, Daubentonia, Carpolestes and kin in the LRT to scale.

According to Wikipedia – Microsyops,
“Some authors argue that microsyopids are plesiadapiforms while others suggest a dermopteran grouping. However, the overall relationship between plesiadiforms and other living and fossil members of Euarchontoglires has been disputed. In a cladistic analysis including postcranial, cranial, and dental characteristics by Bloch et al. (2007), microsyopids were found to be plesiadapiforms more distantly related to euprimates than plesiadapoids or paromomyoids, and without any special relationship to dermopterans. However, while analyses support a euarchontan grouping, specific relationships of microsyopids to other plesiadapiforms, euprimates, scandentia, and dermoptera remain unresolved.^[11] Microsyopids are generally thought to be euarchontans, and some researchers consider them to be stem primates.”

In the LRT (Fig 2) Microsyops (Fig 1) nests between tree shrews and aye-ayes (Daubentonia, Fig 1) and likely had an Early to Mid-Jurassic origin based on the chronology of  the multituberculate, Megaconus (Fig 1).

Figure 2. Subset of the LRT focusing on Scandentia and Glires. Dark red are taxa illustrated in figure 1. ” data-image-caption=”

Figure 2. Subset of the LRT focusing on Scandentia and Glires. Dark red are taxa illustrated in figure 1.

” data-medium-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/07/glires_2024cladogram588.jpg?w=121″ data-large-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/07/glires_2024cladogram588.jpg?w=415″ tabindex=”0″ role=”button” class=”size-full wp-image-87397″ src=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/07/glires_2024cladogram588.jpg” alt=”Figure 2. Subset of the LRT focusing on Scandentia and Glires. Dark red are taxa illustrated in figure 1. ” width=”584″ height=”1442″ />

Figure 2. Subset of the LRT focusing on Scandentia and Glires. Dark red are taxa illustrated in figure 1.

Microsyops annectens
(Leidy 1872; Marsh 1872; Silcox, Bloch, Boyer and Houd 2010; Middle Eocene) is a traditional plesiadapiform. Here it nests with Palaechthon at the base of the gnawing clade, Glires, derived from basalmost tree shrews. So that puts the genesis of this genus back to the Middle Jurassic or earlier.

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

References
Bloch JI, Fishe DC, Rose KD and Gingerich PD 2001. Stratocladistic analysis of Paleocene Carpolestidae (Mammalia, Plesiadapiformes) with description of a new late Tiffanian genus. Journal of Vertebrate Paleontology. 21 (1): 119–131.
Bloch JI and Boyer DM 2006. Grasping primate origins. Science 298:1606-1610.
Gervais P 1877. Enumeration de quelques ossements d’animaux vertebres recueillis aux environ de Reims par M. Lemoine. Journal de Zoologie (Paris) 6:74–79.
Gingerich PD 1976. Cranial Anatomy and Evolution of Early Tertiary Plesiadapidae (Mammalia, Primates). Papers on Paleontology, Museum of Paleontology, The University of Michigan. 1-141. online pdf
Leidy J 1872. Remarks on fossils from Wyoming: Proceedings of the Academy of Natural Sciences, Philadelphia 1872: 19–21.
Marsh OC 1872. Preliminary description of new Tertiary Mammals. Parts I– IV: American Journal of Science 4: 122–128, 202–224.
Matthew WD and Grange W 1921. New genera of Paleocene mammals. American Museum Novitates 13:1-7.
Silcox MT, Gunnelll GF and Bloch JI 2020. Cranial anatomy of Microsyops annectens (Microsyopidae, Euarchonta, Mammalia) from the middle Eocene of Northwestern Wyoming. Journal of Paleontology, 28pp. 0022-3360/20/1937-2337
doi: 10.1017/jpa.2020.24

wiki/Plesiadapis
fossilworks/Ignacius
wiki/Plesiadapiformes
wiki/Microsyops
wiki/Glires