Gobiatherium and Arsinoitherium updated with a Meniscotherium Bauplan

Recent housekeeping in the LRT
has finally brought Gobiatherium (Fig 1) and Arsinoitherium (Fig 2)  around for a second look, with more taxa and more experience. Both were modified with updated DGS colors.

Figure 1. Gobiatherium updated on a Meniscotherium (Fig 3) Bauplan. ” data-image-caption=”

Figure 1. Gobiatherium updated on a Meniscotherium (Fig 3) Bauplan.

” data-medium-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/06/gobiatherium-skull588.jpg?w=214″ data-large-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/06/gobiatherium-skull588.jpg?w=584″ tabindex=”0″ role=”button” class=”size-full wp-image-86831″ src=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/06/gobiatherium-skull588.jpg” alt=”Figure 1. Gobiatherium updated on a Meniscotherium (Fig 3) Bauplan. ” width=”584″ height=”819″ />

Figure 1. Gobiatherium updated on a Meniscotherium (Fig 3) Bauplan. The base of the naris was difficult to ascetain without a proper Bauplan.

Their smaller, more plelsiomorphic ancestor,
Meniscotherium (Figs 1, 3) provides the new Bauplan. That lacrimal (tan) overlapping the jugal (cyan) was overlooked earlier, here repaired.

Figure 2. Arsinoitherum updated based on a revised Gobiatherium + Meniscotherium Bauplan. ” data-image-caption=”

Figure 2. Arsinoitherum updated based on a revised Gobiatherium + Meniscotherium Bauplan.

” data-medium-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/06/arsinoitherium588-1.jpg?w=126″ data-large-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/06/arsinoitherium588-1.jpg?w=431″ tabindex=”0″ role=”button” class=”size-full wp-image-86864″ src=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/06/arsinoitherium588-1.jpg” alt=”Figure 2. Arsinoitherum updated based on a revised Gobiatherium + Meniscotherium Bauplan.” width=”584″ height=”1387″ />

Figure 2. Arsinoitherum updated based on a revised Gobiatherium + Meniscotherium Bauplan.

Gobiatherium mirificum
(Osborn and Granger 1932; middle Eocene) is widely considered a distinct type of uintathere, like Uintatherium. Here it nests with Arsinoitherium, another horned herbivore. Gobiatherium has a long wide skull and no horns. Those wide, elevated set of nasals, further expand into horns in Arsinoitherium.

Figure 2. Meniscotherium skull. In this is a smaller predecessor to Astrapotherium note the genesis of maxillary tusks here and then longer dentary when the teeth are matched to occlude correctly. Note the overlapping lacrimal. ” data-image-caption=”

Figure 2. Meniscotherium skull. In this is a smaller predecessor to Astrapotherium note the genesis of maxillary tusks here and then longer dentary when the teeth are matched to occlude correctly. Note the overlapping lacrimal.

” data-medium-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2016/09/meniscotherium588.jpg?w=219″ data-large-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2016/09/meniscotherium588.jpg?w=584″ tabindex=”0″ role=”button” class=”size-full wp-image-61406″ src=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2016/09/meniscotherium588.jpg” alt=”Figure 2. Meniscotherium skull. In this is a smaller predecessor to Astrapotherium note the genesis of maxillary tusks here and then longer dentary when the teeth are matched to occlude correctly. Note the overlapping lacrimal.” width=”584″ height=”799″ />

Figure 3. Meniscotherium skull. In this is a smaller predecessor to Astrapotherium note the genesis of maxillary tusks here and then longer dentary when the teeth are matched to occlude correctly. Note the overlapping lacrimal.

Meniscotherium tapiacitum
(Cope 1874; Williamson and Lucas 1992; Middle Eocene 54-38 mya; 25-50 cm long) nests with Astrapotherium  in a clade near the base of the Condylarthra. Considering the Paleocene date for Astrapotherium, Meniscotherium probably originated earlier, perhaps in the Cretaceous. The incisor canines were reduced here. That happens because fossils are so rare.

Arsinoitherium zitteli
(Beadnell 1902, Figs. 1, 2; late Eocene, early Oligocene, 36-30 mya) was a sister to Gobiatherium and derived from a sister toMeniscotherium. Wikipedia describes Arsinoitherium as, “an extinct genus of paenungulate mammal belonging to the extinct order Embrithopoda. It is related to elephants, sirenians, hyraxes and the extinct desmostylians.” A trait that makes Arsinoitherium distinct is its nearly complete arcade of teeth, none of them tusks, in which the canine is absent (or at least indistinct) and the medial incisor is missing. The premaxilla redevelops an ascending process of the premaxilla, a trait not seen in mammals since their origin in the Triassic.

References
Beadnell HGC 1902. A preliminary note on Arsinoitherium zitteli, Beadnell, from the Upper Eocene strata of Egypt. Public Works Ministry, National Printing Department. Cairo: 1–4.
Chow MM, Chang Y-P, Wang BY and Ting SY 1973. New mammalian genera and species from the Paleocene of Nanhsiung, N. Kwangtung. Vertebrata PalAsiatica 11(1):31-35.
Cope ED 1881. The Condylarthra (Continued). American Naturalist 84;18: 892–906.
Lucas SG 2001. Gobiatherium (Mammalia: Dinocerata) from the Middle Eocene of Asia: Taxonomy and biochronological Significance. Paläontologische Zeitschrift 74 (4): 591–600.
Osborn HF and Granger W 1932. Coryphodonts and uintatheres from the Mongolian expedition of 1930. American Museum Novitates 552:1-16.
Scott WB and Osborn HF 1887. Preliminary Report on the Vertebrate Fossils of the Uinta Formation, Collected by the Princeton Expedition of 1886. Proceedings of the American Philosophical Society 24(126):255-264.
Shelley SL, Williamson TE and Brusatte SL 2018. The osteology of Periptychus carinidens: A robust, ungulate-like placental mammal (Mammalia: Periptychidae) from the Paleocene of North America. PlosOne July 18, 2018. https://doi.org/10.1371/journal.pone.0200132
Williamson TE and Lucas SG 1992. Meniscotherium (Mammalia, “Condylarthra”) from the Palaeocene-Eocene of Westeran North America. New Mexico Museum of Natural Hstory and Science Bulletin 1.

wiki/Periptychus
wiki/Arsinoitherium
wiki/Gobiatherium
wiki/Isectolophus
wiki/Bemalambda