The brain endocast of the Canary Islands giant rats (Canariomys, Muridae, Rodentia): paleobiological and evolutionary implications
Vincent, Flavien (Institut Català de Paleontologia Miquel Crusafont)
Souron, Antoine (Centre National de la Recherche Scientifique. Université de Bordeaux)
Casanovas i Vilar, Isaac (Institut Català de Paleontologia Miquel Crusafont)
Gamarra González, Jesús (Institut Català de Paleontologia Miquel Crusafont)
Bertrand, Ornella C. (Institut Català de Paleontologia Miquel Crusafont)

Data:	2025
Resum:	Insular mammal faunas have been the focus of numerous studies in evolutionary biology, specifically regarding the patterns of dwarfism and gigantism. Previous work has shown either increase or decrease in relative brain size in various clades, including elephants, hippos, lagomorphs, bovids, and multituberculates. Decrease in specific senses such as audition and vision were also observed. In this study, we describe the virtual brain endocasts of the giant rats of the Canary Islands, Canariomys bravoi and Canariomys tamarani, and make morphological and quantitative comparisons with 10 extant mainland and insular Murinae. We measured endocranial volumes and the relative sizes of brain regions, including the olfactory bulb and petrosal lobule volumes and the neocortical and paleocortex surface areas. Our results show that intraspecific variation was higher in Ca. bravoi compared to its closest extant relative Arvicanthis niloticus, which supports the idea that phenotypic variability is more prevalent on islands than on the continent. Canariomys tamarani could represent an intermediate form between Arvicanthis and Ca. bravoi, as previously hypothesized. The midbrain exposure in Ca. bravoi is likely a derived feature due to the reduction in the neocortex. The relatively small size of the olfactory bulbs in Canariomys might be related to decreased predation risk. The relatively smaller petrosal lobules in Ca. tamarani and insular extant rodents could have resulted from a shift to slower locomotion compared to their mainland relatives. Overall, we show that, as in the insular lagomorph Nuralagus rex, decrease in various senses has also occurred in rodents living on islands.
Ajuts:	Generalitat de Catalunya 2021/BP-00042 Agencia Estatal de Investigación PID2020-117289GB-I00 Agencia Estatal de Investigación RYC2023-042630-I Generalitat de Catalunya 2021/SGR-00620
Drets:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan es reconegui l'autoria de l'obra original.
Llengua:	Anglès
Document:	Article ; recerca ; Versió publicada
Matèria:	Brain endocast ; Canary islands ; Gigantism ; Insular mammals ; Island effect ; Pleistocene
Publicat a:	Journal of Mammalian Evolution, Vol. 32 (December 2025) , art. 40, ISSN 1573-7055

DOI: 10.1007/s10914-025-09785-0

28 p, 11.8 MB

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