The Brain of the Black (Diceros bicornis) and White (Ceratotherium simum) African Rhinoceroses: Morphology and Volumetrics from Magnetic Resonance Imaging

Abstract

The morphology and volumetrics of the understudied brains of two iconic large terrestrial African mammals: the black (Diceros bicornis) and white (Ceratotherium simum) rhinoceroses are described. The black rhinoceros is typically solitary whereas the white rhinoceros is social, and both are members of the Perissodactyl order. Here, we provide descriptions of the surface of the brain of each rhinoceros. For both species, we use magnetic resonance images (MRI) to develop a description of the internal anatomy of the rhinoceros brain and to calculate the volume of the amygdala, cerebellum, corpus callosum, hippocampus, and ventricular system as well as to determine the gyrencephalic index. The morphology of both black and white rhinoceros brains is very similar to each other, although certain minor differences, seemingly related to diet, were noted, and both brains evince the general anatomy of the mammalian brain. The rhinoceros brains display no obvious neuroanatomical specializations in comparison to other mammals previously studied. In addition, the volumetric analyses indicate that the size of the various regions of the rhinoceros brain measured, as well as the extent of gyrification, are what would be predicted for a mammal with their brain mass when compared allometrically to previously published data. We conclude that the brains of the black and white rhinoceros exhibit a typically mammalian organization at a superficial level, but histological studies may reveal specializations of interest in relation to rhinoceros behavior.

Braincase With Natural Endocast of a Juvenile Rhinocerotinae From the Late Middle Pleistocene Site of Melpignano (Apulia, Southern Italy)

“…Therefore, the MPND1083 represents one a few natural brain endocasts described in extinct Rhinocerotinae (Figure 6). MPND1083 consists of a globular telencephalon, free of convolutions with the frontal lobes less expanded than the parietal ones resembling in the general shape those reported on extant Ceratotherium simum and Dicerorhinus sumatrensis (Garrod, 1878;Bhagwandin et al, 2017), whereas it differs from that of Diceros bicornis (Figure 5I). In dorsal view, the brain of the black rhino shows a very rounded shape without the narrowing at the level of the lateral sulcus, which is evident in the other taxa.…”

“…In dorsal view, the brain of the black rhino shows a very rounded shape without the narrowing at the level of the lateral sulcus, which is evident in the other taxa. The different brain morphology of extant D. bicornis and C. simum (Figures 5I,J) has been studied with Magnetic Resonance Imaging by Bhagwandin et al (2017) and related to diet. According to the authors, the shape of the brains reflects the overall architecture of the skulls, which in turn are related to the feeding habits of the two species, browsing for the black rhinoceros and grazing for the white rhinoceros.…”

“…Probably due to technical difficulties in performing CT scans on bulk and large skulls with conventional medical equipment. Consequently, many developmental and morpho-functional aspects of the skull pneumatization and the brain morphology are still almost completely unknown in extinct and extant rhinoceroses (Garrod, 1878;Bhagwandin et al, 2017). The most comprehensive ontogenetic studies on fossil Rhinocerotinae, based on external craniodental features, were conducted on Chilotherium wimani with nine complete skulls from the Late Miocene of China (Deng, 2001b), on Teleoceras major represented by 27 skulls from the Miocene of Nebraska (Hagge, 2010) and probably the largest sample of 399 mandibular fragments and limb bones from a minimum of 42 individuals of C. antiquitatis was reported by Shpansky (2014) from two Late Pleistocene sites in the Tomsk Priob'e area (south-east Western Siberia).…”

Epidermal Keratinocyte Sensing and Processing of Environmental Information Together with the Brain’s Simulation and Prediction Abilities Helped to Enable <i>Homo sapiens’</i> Evolutionary Success

“…These three examples suggest that the combina-M. Denda, S. Nakanishi DOI: 10.4236/aa.2020.101002 24 Advances in Anthropology tion of an exposed, environmentally sensitive skin and a large brain might have played a key role during animal evolution. Several terrestrial mammals are largely hairless, including the hippopotamus, elephant, rhinoceros and naked mole rat, and the hippopotamus and rhinoceros do not have large brains (Lyras, 2018;Bhagwandin et al, 2017). We propose that because these two animals have thick skin, it might have been difficult to construct tightly-organized, arborizing peripheral nerve networks in their skin.…”

The Comparative Neurology of Neocortical Gyration and the Quest for Functional Specialization

“…Along that line, substantial progress is noted in the study of brain structure in gyrencephalic species beyond primates, such as the dromedary (Simon, 1965 ), llama (Welker et al, 1976 ), horse (Cozzi et al, 2014 ), hippopotamus (Butti et al, 2014 ), rhinoceros (Manger, 2011 ; Bhagwandin et al, 2017 ), elephant seal, and sea lion (Sawyer et al, 2016 ; Turner et al, 2017 ), not to mention the extensive literature on proboscidea (Dexler, 1907 ; Jakob, 1909 ; Janssen and Stephan, 1956 ; Haug, 1966 ; Cozzi et al, 2001 ; Shoshani et al, 2006 ; Jacobs et al, 2011 ; Herculano-Houzel et al, 2014 ) and cetacea (Tower, 1954 ; Haug, 1970 ; Walløe et al, 2010 ; Butti et al, 2011 ; Mortensen et al, 2014 ).…”