The ethmoidal region of the skull of Ptilocercus lowii (Ptilocercidae, Scandentia, Mammalia) – a contribution to the reconstruction of the cranial morphotype of primates

I. Ruf, S. Janßen, U. Zeller
2015 Primate Biology  
<p><strong>Abstract.</strong> The ethmoidal region of the skull houses one of the most important sense organs of mammals, the sense of smell. Investigation of the ontogeny and comparative anatomy of internal nasal structures of the macrosmatic order Scandentia is a significant contribution to the understanding of the morphotype of Scandentia with potential implications for our understanding of the primate nasal morphological pattern. For the first time perinatal and adult stages of
more » ... ges of <i>Ptilocercus lowii</i> and selected <i>Tupaia</i> species were investigated by serial histological sections and high-resolution computed tomography (μCT), respectively. Scandentia show a very common olfactory turbinal pattern of small mammals in having two frontoturbinals, three ethmoturbinals, and one interturbinal between the first and second ethmoturbinal. This indicates a moderately developed sense of smell (moderately macrosmatic). The observed septoturbinal is probably an apomorphic character of Scandentia. A general growth in length occurs during postnatal ontogeny; thus the adult ethmoidal region is proportionally longer compared to the rest of the skull. Throughout ontogeny <i>Ptilocercus</i> has a proportionally longer nasal cavity than <i>Tupaia</i>. Major differences exist between <i>Ptilocercus</i> and <i>Tupaia</i> in regard to the proportions of the nasal cavity which correlate with the position of the orbits. Compared to <i>Tupaia</i>, <i>Ptilocercus</i> shows more anteriorly oriented orbits and has a proportionally longer nasal capsule than <i>Tupaia</i> and based on anatomy probably a higher level of olfactory discrimination. Furthermore, <i>Ptilocercus</i> has a platybasic skull base that resembles a derived feature of Ptilocercidae. In contrast, <i>Tupaia</i> has a distinct septum interorbitale leading to a tropibasic skull, a pattern that is a plesiomorphic character of Tupaiidae and Scandentia in general. This finding helps us to understand the septum interorbitale pattern in Primates. Our results indicate that differences among the investigated Scandentia species are correlated with adaptations to foraging and behavioural biology.</p>
doi:10.5194/pb-2-89-2015 fatcat:iinwdyqxejg2rno36v2kesd4ju