Two chalicotheres transitional to the rest of the perissodactyls in the LRT

Short one today,
as Grangeria enters the the large reptile tree (LRT, 2322 taxa) alongside a previously unrecognized sister to the even stranger Litolophus (Fig 1) that has been bounding around the LRT.

Earlier I reported,
“too little is known of Grangeria gobiensis to score it in the LRT. The line drawing Colbert made of the skull (Fig 1) appears to be complete, but it is a chimaera created from several specimens of various sizes.”

This time
I’m taking a measured chance and following Colbert’s drawing. A fragile postorbital bar created by the postfrontal is added based on broken scraps (Fig 2) and phylogenetic bracketing.

If this is a mistake, it won’t be for the first time and corrections will be made.

Figure 1. Updated image of tested chalicotheres, now re-including high-crested Litolophus, perhaps with an overlooked post-orbital bar. ” data-image-caption=”

Figure 1. Updated image of tested chalicotheres, now re-including high-crested Litolophus, perhaps with an overlooked post-orbital bar.

” data-medium-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/07/diadiaphorus_procavia_skulls588-1.jpg?w=137″ data-large-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/07/diadiaphorus_procavia_skulls588-1.jpg?w=469″ tabindex=”0″ role=”button” class=”size-full wp-image-87722″ src=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/07/diadiaphorus_procavia_skulls588-1.jpg” alt=”Figure 1. Updated image of tested chalicotheres, now re-including high-crested Litolophus, perhaps with an overlooked post-orbital bar.” width=”584″ height=”1275″ />

Figure 1. Updated image of tested chalicotheres, now re-including high-crested Litolophus, perhaps with an overlooked post-orbital bar. The presence of canine fangs mark these two taxa as primitive. Procavia and Diadiaphorus have lost these canines.

Where did that postorbital bar
come from? Perhaps from overlooked broken and taphonomically shifted pieces that still remain in the skull (Fig 2) here identified by DGS colors.

Figure 2. Litolophus skull. Colors added here. Postorbital bar restored in frame 2. ” data-image-caption=”

Figure 2. Litolophus skull. Colors added here. Postorbital bar restored in frame 2.

” data-medium-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/07/litolophus-skull588.gif?w=196″ data-large-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/07/litolophus-skull588.gif?w=584″ tabindex=”0″ role=”button” class=”size-full wp-image-87725″ src=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/07/litolophus-skull588.gif” alt=”Figure 2. Litolophus skull. Colors added here. Postorbital bar restored in frame 2.” width=”584″ height=”892″ />

Figure 2. Litolophus skull. Colors added here. Postorbital bar restored in frame 2 from loose parts.

Grangeria gobiensis
(Colbert 1934) is known from crushed materials of several individuals of various sizes. The incisors are large, as in Procavia (Fig 1). The manus and pes are transitional to derived chalicotheres. The generic name is shared with a plant.

Litolophus gobiensis
(Radinsky 1964b, Bai, Wang and Meng 2010, 2011; Early Eocene) is traditionally considered a basal chalicothere with a slender premaxilla that curves ventrally and a tall parietal. In the LRT this taxon is transitional from chalicotheres to the rest of the perissodactyls. The hooves were small and round, not large and sharp.

Figure 4. Dorcatherium skulls. Compare this basal artiodactyl to chalicotheres in figure 1. ” data-image-caption=”

Figure 4. Dorcatherium skulls. Compare this basal artiodactyl to chalicotheres in figure 1.

” data-medium-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/07/dorcatherium_naui-skull588.jpg?w=236″ data-large-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/07/dorcatherium_naui-skull588.jpg?w=584″ tabindex=”0″ role=”button” class=”size-full wp-image-87731″ src=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/07/dorcatherium_naui-skull588.jpg” alt=”Figure 4. Dorcatherium skulls. Compare this basal artiodactyl to chalicotheres in figure 1. ” width=”584″ height=”741″ />

Figure 3. Dorcatherium skulls. Compare this basal artiodactyl to chalicotheres in figure 1.

These two taxa presently nest
between other chalicotheres and the rest of the Perissodactylia, including tapirs, rhinos and horses, all derived from an ancestor that was a last common ancestor to the rock hyrax (Procavia) and Grangeria, not far from Dorcatherium (Fig 3) nesting at the base of the non-swine Artiodactyla in the LRT.

Which reminds me… we haven’t looked at Dorcatherium yet.

References
Ameghino F 1887. Reports of the Princeton University Expeditions to Patagonia, 1896-1899. J. B. Hatcher in charge. 338pp.
Bai B, Wang Y-Q and Meng J 2010. New craniodental materials of Litolophus gobiensis (Perissodactyla, “Eomoropidae”) from Inner Mongolia, China, and phylogenetic analyses of Eocene chalicotheres. American Museum Novitates 3688: 27pp.
Bai B, Wang Y-Q and Meng J 2010. Early Eocene chalicothere Litolophus with hoof-like unguals. Journal of Vertebrate Paleontology 31(6):1387-1391.
Colbert EH 1934. Chalicotheres from Mongolia and China in the American Museum. Bulletin of the American Museum of Natural History 67: 353–387.
Hatcher JB and Scott WB 1910. Reports of the Princeton University Expeditions to Patagonia 7(1-3):
Holbrook LT Lucas SG and Emry RJ 2004. Skulls of the Eocene Perissodactyls (Mammalia) Homogalax and Isectolophus. Journal of Vertebrate Paleontology 24. (4) 951-956.
Pallas PS 1766. Miscellanea zoologica. AP van Cleef, La Haye, 224 pp.
Radinsky LB 1964b. Notes on Eocene and Oligocene fossil localities in Inner Mongolia.
American Museum Novitates 2180: 1–11.

wiki/Procavia
wiki/Diadiaphorus
wiki/Chalicotheriidae
wiki/Chalicotherium
wiki/Moropus
wik/Anisodon
wiki/Dorcatherium

Grangeria gobiensis links the extant rock hyrax to extinct chalicotheres