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| Amphimoschus, autopodial morphology and palaeoecological implications in Sánchez, Cantalapiedra, DeMiguel, Azanza, Strani et Morales, 2024. Art by Flavia Strani. |
Abstract
Here we present the first description of the postcranial skeleton of Amphimoschus, an enigmatic hornless ruminant known from the late Early to the late Middle Miocene of Eurasia (c. 17.5–13.8 Ma). This new fossil material that includes several elements of the appendicular skeleton comes from the French sites of Pontlevoy (MN5), Aérotrain (MN4), and Artenay (MN4). The postcranial skeleton of Amphimoschus is relevant to determine its phylogenetic affinities within the Pecora and to better understand the evolution of cervoids, the pecoran ruminants more closely related to deer. Our total-evidence tip-dating phylogenetic analysis recovers three well-supported main lineages of crown pecorans (Giraffomorpha, Bovidomorpha and Cervidomorpha) and places Amphimoschus as a basal member of a monophyletic Cervoidea. Thus, we reject the recent assignment of Amphimoschus to the Bovoidea, and confirm the presence of hornless forms at the base of the cervoid clade. We define the Cervoidea as the least inclusive clade of crown pecorans including Amphimoschus and the Cervidae. We also define the Cervidomorpha as the least inclusive clade of crown pecorans containing Namibiomeryx and the Cervidae. Cervidomorphs were relatively successful in the Miocene, spreading through Africa, Eurasia and North America during the Early–Middle Miocene. Amphimoschus xishuiensis Y.-K. Li et al., 2021 is recovered here as the closest sister group to the Bovidae and hence cannot be considered to belong to the genus Amphimoschus. We erect for it the new genus Dimidiomeryx. Our topology adds complexity to the recently revamped hypothesis based on molecular data regarding the single origin of the cranial appendages in pecoran ruminants. Amphimoschus probably had a sitatunga-like lifestyle, sporting sprawling-out fingers with very long third phalanges, long limbs and a general configuration of the appendicular skeleton that probably allowed it to live in swampy/semiaquatic environments.
Keywords: body size, Cervoidea, headgear, Ruminantia, phylogeny, Miocene
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| Amphimoschus, autopodial morphology and palaeoecological implications. A, composite articulated right anterior autopodium of Amphimoschus from Artenay (right digit mirrored from the single preserved one) showing the c. 34° angle formed by Amphimoschus digits (similar to extant Moschus), with digits in neutral articulation position and the collateral ligaments (marked in green) showing the vector of their action (green arrows); B, reconstruction of an adult male Amphimoschus in its postulated habitat; C, detail of Amphimoschus left manus and right pes showing the elongated sitatunga-like main hooves and the flat stance of the digits III–IV against the ground. Art by Flavia Strani. |
Israel M. Sánchez, Juan L. Cantalapiedra, Daniel DeMiguel, Beatriz Azanza, Flavia Strani and Jorge Morales. 2024. The Postcranial Skeleton of Amphimoschus Bourgeois, 1873 (Cetartiodactyla, Ruminantia, Pecora) sheds light on Its Phylogeny and the Evolution of the clade Cervoidea. Journal of Systematic Palaeontology. 22(1); 2386020. DOI: doi.org/10.1080/14772019.2024.2386020
