A Miopetaurista (Rodentia, Sciuridae) cranium from the Middle Miocene of Bavaria (Germany) and brain evolution in flying squirrels
Grau-Camats, Montserrat (Institut Català de Paleontologia Miquel Crusafont)
Bertrand, Ornella C. (University of Edinburgh. School of GeoSciences)
Prieto, Jérôme (Ludwig-Maximillians-Universität München. Department für Geo- und Umweltwissenschaften)
López-Torres, Sergi (New York Consortium in Evolutionary Primatology (USA))
Silcox, Mary T. (University of Toronto Scarborough. Department of Anthropology)
Casanovas i Vilar, Isaac (Institut Català de Paleontologia Miquel Crusafont)

Data:	2022
Resum:	Flying squirrels (Sciurinae, Pteromyini) are the most successful group of gliding mammals. However, their fossil record mostly consists of isolated dental remains that provide very limited insights into their palaeobiology and evolution. The first skeleton of a fossil flying squirrel, belonging to the species Miopetaurista neogrivensis, has been described only recently. It presents all the diagnostic gliding-related postcranial features of its extant relatives and shows that this group has undergone very little morphological change for almost 12 myr. However, the associated cranium is badly crushed, and particular details of the cranial morphology cannot be described. Here, we describe a well-preserved cranium of the closely related Miopetaurista crusafonti from 12. 5-12. 0 Ma from Bavaria (Germany). Its cranial morphology is found to be almost identical to extant large flying squirrels, even in details such as the position of the foramina. The virtual endocast also shows close affinities to living large flying squirrels in morphology and in the relative volume of different brain regions, showing diagnostic features such as the size reduction of petrosal lobules and olfactory bulbs. However, the encephalization quotient (EQ) and neocortical ratio are lower than observed in extant flying squirrels. EQ is known to increase through time in squirrels, but might also be related to locomotion, given that arboreal and gliding squirrels display higher EQs than terrestrial ones. Because Miopetaurista was certainly a glider, its comparatively lower EQ and neocortical size support the existence of an independent trend of increasing EQ and neocortical complexity in this flying squirrel subclade.
Ajuts:	Agencia Estatal de Investigación PID2020-117289GB-I00 Agencia Estatal de Investigación CGL2016-76431-P Agencia Estatal de Investigación CGL2017-82654-P European Commission 792611 Ministerio de Economía y Competitividad RYC-2013-12470 Agència de Gestió d'Ajuts Universitaris i de Recerca 2017/SGR-116
Nota:	Altres ajuts: CERCA Programme/Generalitat de Catalunya
Drets:	Tots els drets reservats.
Llengua:	Anglès
Document:	Article ; recerca ; Versió acceptada per publicar
Matèria:	Rodentia ; Sciuridae ; Pteromyini ; Cranial morphology ; Endocast ; Encephalization quotient
Publicat a:	Papers in Palaeontology, Vol. 8, Issue 4 (July-August 2022) , art. e1454, ISSN 2056-2802

DOI: 10.1002/spp2.1454

Postprint 65 p, 2.2 MB

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