Virtual brain endocasts of the palaeanodont Metacheiromys marshi and the neurosensory evolution of early Pholidotamorpha
Cabasés Bru, Eduard (Institut Català de Paleontologia Miquel Crusafont)
Moya-Costa, Raquel (Institut Català de Paleontologia Miquel Crusafont)
Wible, John (Carnegie Museum of Natural History. Section of Mammals)
Brusatte, Stephen L. (Carnegie Museum of Natural History. Section of Mammals)
Bertrand, Ornella C. (Institut Català de Paleontologia Miquel Crusafont)

Data:	2026
Resum:	Palaeanodonts are extinct placental mammals exhibiting myrmecophagous and fossorial adaptations. They have been viewed as the sister group to Pholidota (pangolins), which is the sister-clade to Carnivora within Ferae. Palaeanodonts display morphological features that are similar to those in pangolins and xenarthrans, which are likely related to their specialized ecological niche. Therefore, it has been challenging to decipher whether shared features are synapomorphies or convergences. Here, we describe in detail the brain virtual endocast anatomy of the middle Eocene palaeanodont Metacheiromys marshi and make morphological and quantitative comparisons with two extant African pangolins, Smutsia gigantea and Phataginus tricuspis. We found several differences between the fossil and extant taxa including in the olfactory bulbs, the cerebellum, and the venous and arterial systems. However, we propose an anatomical feature as a possible synapomorphy uniting palaeanodonts and pangolins in Pholidotamorpha: the presence of a well-developed orbital gyrus and a presylvian sulcus. These correlated features are present in some other groups but are likely derived traits acquired independently, for example in xenarthrans. In terms of the behavioural ecology of M. marshi and pangolins, we suggest that reduced olfaction and eye movement control is likely linked to fossoriality or slow arboreality as previously proposed for rodents. The expansion of the orbital gyrus of the neocortex is proposed to be related to the evolution of myrmecophagy and the emergence of a protrusile tongue in early Pholidotamorpha, acquired convergently in giant anteaters. Overall, this work provides a novel perspective on the evolution of palaeanodonts and pangolins and presents new hypotheses related to the impact of ecological adaptations on the brain evolution of mammals.
Ajuts:	European Commission 792611 European Commission 756226 Generalitat de Catalunya 2021/BP-00042 Generalitat de Catalunya 2021/SGR-00620 Ministerio de Ciencia, Innovación y Universidades RYC2023-042630-I Ministerio de Ciencia, Innovación y Universidades PID2024-160207NB-I00 Ministerio de Ciencia e Innovación PID2020-117289GBI00
Drets:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, i la comunicació pública de l'obra, sempre que no sigui amb finalitats comercials, i sempre que es reconegui l'autoria de l'obra original. No es permet la creació d'obres derivades.
Llengua:	Anglès
Document:	Article ; recerca ; Versió publicada
Publicat a:	Journal of Anatomy, April 2026, ISSN 1469-7580

DOI: 10.1111/joa.70142

26 p, 8.9 MB

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