Connections: Big lemurs and bigger oreodonts
Here
in the large reptile tree (LRT, 2338 taxa) big extinct Madagascar lemurs, like Megaladapis, now evolve into hoofed oreodonts, like Brachycrus (Fig 1). Transitional taxa still include the artiodactyl with thumbs, Agriochoerus latifrons (Fig 1). Much smaller Notharctus (Fig 1) is another extinct lemur basal to Megaladapis, bats, monkeys, apes and humans.
So, it’s that close. Basal primates are basal to artiodactyls (including blue whales) in the LRT where taxon exclusion is minimized by adding taxa.
Figure 1. The primate lemur, Megaladapis, is basal to Agriochoerus latifrons and Brachycrus, an oreodont.
” data-medium-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/03/brachycrus_laticeps_mooki_skull588.jpg?w=146″ data-large-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/03/brachycrus_laticeps_mooki_skull588.jpg?w=498″ class=”size-full wp-image-92138″ src=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/03/brachycrus_laticeps_mooki_skull588.jpg” alt=”Figure 1. The primate lemur, Megaladapis, is basal to Agriochoerus latifrons and Brachycrus, an oreodont. ” width=”584″ height=”1201″ srcset=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/03/brachycrus_laticeps_mooki_skull588.jpg?w=584&h=1201 584w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/03/brachycrus_laticeps_mooki_skull588.jpg?w=73&h=150 73w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/03/brachycrus_laticeps_mooki_skull588.jpg?w=146&h=300 146w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/03/brachycrus_laticeps_mooki_skull588.jpg 588w” sizes=”(max-width: 584px) 100vw, 584px” />
Figure 1. The primate lemur, Megaladapis, is basal to Agriochoerus latifrons and Brachycrus, an oreodont. Leptauchenia and Sespia are also oreodonts. Note the postorbital bar on Brachycrus. Now that’s a homolog trait with primates, not a convergent trait. Hope you can see the family resemblance when all put together.
Megaladapis insignis
(Major 1894, up to 1.5m in length) is the extinct koala lemur from Madagascar. The arms were longer than the legs. The snout remains unknown. Only three molars were present. Here it nests between Notharctus and the rest of the primates and the rest of the Artiodactyla.
Brachycrus laticeps
(originally Merycochoerus Douglass 1900; CM796; Miocene, 14mya; 1m long) was considered an North American oreodont with a tapir-like trunk and deep jaws, but here nests with South American Astrapotherium.
(Major 1894, up to 1.5m in length) is the extinct koala lemur from Madagascar. The arms were longer than the legs. The snout remains unknown. Only three molars were present. Here it nests between Notharctus and the rest of the primates and the rest of the Artiodactyla. ” data-image-caption=”
Figure 2. Brachycurus, in turn, is basal to Astrapontus and Astrapotherium in the LRT. Look how far primates have evolved – in the other direction.
” data-medium-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/03/astrapotherium.astraponotus.skull_.jpg?w=111″ data-large-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/03/astrapotherium.astraponotus.skull_.jpg?w=380″ class=”size-full wp-image-92143″ src=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/03/astrapotherium.astraponotus.skull_.jpg” alt=”Megaladapis insignis(Major 1894, up to 1.5m in length) is the extinct koala lemur from Madagascar. The arms were longer than the legs. The snout remains unknown. Only three molars were present. Here it nests between Notharctus and the rest of the primates and the rest of the Artiodactyla.” width=”584″ height=”1573″ srcset=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/03/astrapotherium.astraponotus.skull_.jpg?w=584&h=1573 584w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/03/astrapotherium.astraponotus.skull_.jpg?w=56&h=150 56w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/03/astrapotherium.astraponotus.skull_.jpg?w=111&h=300 111w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/03/astrapotherium.astraponotus.skull_.jpg 588w” sizes=”(max-width: 584px) 100vw, 584px” />
Figure 2. Brachycurus, in turn, is basal to Astrapontus and Astrapotherium in the LRT. Look how far primates have evolved – in the other direction.
This appears to be a novel hypothesis of interrelationships.
If not, please provide a citation so I can promote it here.
This expands on an earlier post on Agriochoerus latifrons.
References
Douglass E 1900.New species of Merycochoerus in Montana. Part I. American Journal of Science 10(60):428-438.
Major CIF 1894. On Megaladapis madagascariensis, an Extinct Gigantic Lemuroid from Madagascar; with Remarks on the Associated Fauna, and on Its Geological Age. Philosophical Transactions of the Royal Society B: Biological Sciences. 185: 15–38.
Major CIF 1900. Extinct Mammalia from Madagascar. I. Megaladapis insignis, sp. N. Philosophical Transactions of the Royal Society B: Biological Sciences. 193 (185–193): 47–50.
wiki/Notharctus
wiki/Megaladapis
wki/Astrapotherium
wiki/Brachycrus
wiki/Astraponotus
Source: https://pterosaurheresies.wordpress.com/2025/03/28/connections-big-lemurs-and-bigger-oreodonts/
