Anthracobune and Cambaytherium move closer to Phenacodus

Housekeeping continues
in the large reptile tree (LRT, 2338 taxa). Now the anthracobunids, Anthracobune and Cambaytherium (Figs 1–2) nest with Phenacodus among the pantodonts basal to elephants and sloths.

Figure 1. Anthracobune and Cambaytherium to scale with Phenacodus and Ectocion cedrus. ” data-image-caption=”

Figure 1. Anthracobune and Cambaytherium to scale with Phenacodus and Ectocion cedrus.

” data-medium-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/09/anthracobune588.jpg?w=300″ data-large-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/09/anthracobune588.jpg?w=584″ class=”size-full wp-image-94642″ src=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/09/anthracobune588.jpg” alt=”Figure 1. Anthracobune and Cambaytherium to scale with Phenacodus and Ectocion cedrus. ” width=”584″ height=”572″ srcset=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/09/anthracobune588.jpg?w=584&h=572 584w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/09/anthracobune588.jpg?w=150&h=147 150w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/09/anthracobune588.jpg?w=300&h=294 300w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/09/anthracobune588.jpg 588w” sizes=”(max-width: 584px) 100vw, 584px” />

Figure 1. Anthracobune and Cambaytherium to scale with Phenacodus and Ectocion cedrus.

Fanged Ectocion cedrus
(Fig 1) is also part of this clade and likely the basal member because it was smaller = phylogenetic miniiaturuzation and shared several traits with the proximal outgroup taxon, the massive herbivore, Coryphodon.

Figure 2. The manus and pes of Phenacodus compared to the partial manus of Cambaytherium. ” data-image-caption=”

Figure 2. The manus and pes of Phenacodus compared to the partial manus of Cambaytherium.

” data-medium-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/09/cambaytherium-phenacodus_manus.pes588.jpg?w=184″ data-large-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/09/cambaytherium-phenacodus_manus.pes588.jpg?w=584″ class=”size-full wp-image-94643″ src=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/09/cambaytherium-phenacodus_manus.pes588.jpg” alt=”Figure 2. The manus and pes of Phenacodus compared to the partial manus of Cambaytherium. ” width=”584″ height=”954″ srcset=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/09/cambaytherium-phenacodus_manus.pes588.jpg?w=584&h=954 584w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/09/cambaytherium-phenacodus_manus.pes588.jpg?w=92&h=150 92w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/09/cambaytherium-phenacodus_manus.pes588.jpg?w=184&h=300 184w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/09/cambaytherium-phenacodus_manus.pes588.jpg 588w” sizes=”(max-width: 584px) 100vw, 584px” />

Figure 2. The manus and pes of Phenacodus compared to the partial manus of Cambaytherium.

Cambaytherium thewissi 
(Rose et al. 2014; Eocene, 55 mya; 45-75 lbs) was originally considered a basal perissodactyl, but nests here between Anthracobune and Phenacodus. The posterior mandible has a long retroarticular process as in Anthracobune. Cambaytherium was found on the marine coastline of island India, close to where pakicetid aand archaeocete whales were convergently evolving from terrestrial tenrec ancestors.

Anthracobune pinfoldi
(Pilgrim 1940; Kumar 1991, middle Eocene, size of a small tapir) The anthracobunids were originally considered proboscideans, like Elephas. Cooper et al. 2014 nested them with perissodactyls. Here Anthracobune nests with the Phenacodus basal to elephants. Anthracobunids have small and simple upper and lower incisors and relatively small canines. The naris opens dorsally signaling an aquatic niche or a flexible proboscis. The retroarticular process is the largest among all mammals.

Apologies for not getting this right the first, second or third times.

References
Cooper LN, Seiffert ER, Clementz M, Madar SI, Bajpai S, Hussain ST, Thewissen JGM 2014. Anthracobunids from the Middle Eocene of India and Pakistan Are Stem Perissodactyls. PLoS ONE. 9 (10): e109232. doi:10.1371/journal.pone.0109232. PMID 25295875.
Kumar K 1991. Anthracobune aijiensis nov. sp. (Mammalia: Proboscidea) from the Subathu Formation, Eocene from NW Himalaya, India”. Geobios. 24 (2): 221–39. doi:10.1016/s0016-6995(91)80010-w. OCLC 4656806310.
Leidy J 1850. [Abstract of remarks made before a meeting of the Academy of Natural Sciences of Philadelphia, December 17th, 1850]. Proceedings of the Academy of Natural Sciences of Philadelphia 5(1):121-122.
Pilgrim GE 1940. Middle Eocene mammals from north-west Pakistan. Proceedings of the Zoological Society. B. London. 110: 127–152.
Rose, KD et al. (8 other authors) 2014. Early Eocene fossils suggest that the mammalian order Perissodactyla originated in India. Nature Communications. 5 (5570). doi:10.1038/ncomms6570.
Rose KD et al, 2020. Anatomy, Relationships, and Paleobiology of Cambaytherium (Mammalia, Perissodactylamorpha, Anthracobunia) from the lower Eocene of western India, Journal of Vertebrate Paleontology (2020). DOI: 10.1080/02724634.2020.1761370

wiki/Cambaytherium
wiki/Anthracobune