Morphology of the Nasal Capsule of Primates—With Special Reference to Daubentonia and Homo

Abstract

Primitive mammals are considered macrosmatic. They have very large and complicated nasal capsules, nasal cavities with extensive olfactory epithelia, and relatively large olfactory bulbs. The complicated structures of the nasal capsule follow a relatively conservative "bauplan," which is normally easy to see in earlier fetal stages; especially in altricial taxa it differentiates well into postnatal life. As anteriormost part of the chondrocranium, the nasal capsule is at first cartilaginous. Most of it ossifies endochondrally, but "appositional bone" ("Zuwachsknochen") is also common. Many fetal structures become resorbed. Together, all surviving bone structures form the ethmoid bone, but cartilages of the external nose and of the vomeronasal complex can persist throughout life. We describe in detail the anatomy of Daubentonia madagascariensis based on a fetal stage (41 mm HL) and an adult skull was analyzed by mCT. We found that the nasal capsule of this species is by far the most complicated one of all extant Primates. We also describe older fetuses of Homo sapiens (35 and 63 mm HL) as representative of a derived primate. The most significant feature of man-and probably of all anthropoids-is the complete loss of the recessus frontoturbinalis and its associated structures. It can be demonstrated that the evolutionary reductions within the primate Abbreviations used: ahy 5 ala hypochiasmatica; ane 5 apertura nasi externa; aor 5 ala orbitalis; at 5 atrioturbinale; az 5 arcus zygomaticus; bol 5 bulbus olfactorius; cat 5 concha atrioturbinalis; cdnp 5 cartilago ductus nasopalatini; cna 5 cupula nasi anterior; cnp 5 cupula nasi posterior; con 5 commissura orbitonasalis; cpa 5 cartilago paraseptalis anterior; cpal 5 cartilago palatina; cse 5 concha septalis; css 5 cartilago supraseptalis; ctu 5 cartilago tubaria; dI 5 deciduous incisor; dni 5 ductus nasi inferior; dnl 5 ductus nasolacrimalis; dnp 5 ductus nasopalatinus (Steno); dvn 5 ductus vomeronasalis; et 5 ethmoturbinale; et a 5 ethmoturbinale lamina anterior; et p 5 ethmoturbinale lamina posterior; fop 5 foramen opticum; fr 5 frontale; ft 5 frontoturbinale; gnl 5 glandula nasi lateralis; hmx 5 hiatus maxillaris; it 5 interturbinale; ju 5 jugale; la 5 lacrimale; lcr 5 lamina cribrosa; lh 5 lamina horizontalis; hsl 5 hiatus semilunaris; lor 5 lamina orbitalis; lsc 5 lamina semicircularis; lta 5 lamina transversalis anterior; lte 5 lamina terminalis; ltp 5 lamina transversalis posterior; ltr 5 lamina trabecularis; mt (mat) 5 marginoturbinale; met 5 mesethmoid; mx 5 maxillare; mxt 5 maxilloturbinale; na 5 nasale; nph 5 ductus nasopharyngeus; nt (nat) 5 nasoturbinale; nop 5 nervus opticus; osp 5 orbitosphenoid; ovn 5 organon vomeronasale (Jacobson); pal 5 palatinum; pao 5 planum antorbitale; pas 5 processus alaris superior; pet 5 processus ethmoidalis orbitosphenoidei; pmp 5 processus maxillaris posterior; pmx 5 praemaxillare; pna 5 paries nasi; ppp 5 processus paraseptalis posterius; ppt 5 processus pterygoideus; prl 5 prominentia lateralis; psp 5 praespheno...

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

“…Our new findings on the investigated Scandentia support earlier observations on Tupaia that the nasal cavity of Scandentia is well-developed and clearly indicates macrosmatic sense, the ability of high olfactory performance (Spatz, 1964;Zeller, 1987;Smith et al, 2014b). Macrosmatic ability is a plesiomorphic mammalian character (see Maier and Ruf, 2014), and many of the here described characters and ontogenetic transformations are correlated with this feature and represent plesiomorphic states for the clade Scan-dentia (Zeller, 1986b(Zeller, , 1987Maier and Ruf, 2014;Ruf, 2004Ruf, , 2014.…”

“…Primates, another striking example, show the evolutionary tendency to highly reduce number and complexity of turbinals due to adaptations to an arboreal life along with stereoscopic vision. Thus, not only is olfaction less important in haplorhine primates but also the enlarged eyes and rostrally oriented orbits are conflicting with the posterior nasal capsule in terms of the demand for space (Maier, 1983;Maier and Ruf, 2014). However, Scandentia have an elaborated ethmoidal region with well-developed olfactory turbinals which is obviously not in spatial conflict with the enlarged eyes (Smith et al, 2014b).…”

“…Thus we can confidently conclude that two frontoturbinals, and three ethmoturbinals plus one interturbinal represent the morphotype of Scandentia. This pattern is also observed in many small-sized mammals but especially in members of the Euarchontoglires like many leporids, rodents, and Dermoptera (Paulli, 1900c;Voit, 1909;Frick and Heckmann, 1955;Zeller, 1987;Ruf, 2004Ruf, , 2014Maier and Ruf, 2014). Therefore the ethmoidal pattern of Scandentia may represent the plesiomorphic ground plan pattern (sensu Hennig, 1950) of Euarchontoglires and at least a more general pattern of placental mammals.…”

“…Adult specimens can now be investigated to elucidate the three-dimensional architecture of the internal nasal structures (e.g. Clifford and Witmer, 2004;Rowe et al, 2005;Van Valkenburgh et al, 2004, 2011Craven et al, 2007Craven et al, , 2010Macrini, 2012;Maier and Ruf, 2014;Ruf, 2014). A recently published supplement to The Anatomical Record is an outcome of a symposium dealing with the vertebrate nose that took place at the 10th International Congress of Vertebrate Morphology in Barcelona in 2013 and demonstrates the renaissance of research on the ethmoidal region especially in primates (see Van Valkenburgh et al, 2014a).…”

The influence of nasal airflow on respiratory and olfactory epithelial distribution in felids

“…Our measurement of the fronto-ethmoturbinal complex includes all larger and smaller turbinals of the ethmoid bone (i.e. combined surface area of the ethmoturbinals, interturbinals and frontoturbinals as defined by Maier, 1993;Smith et al, 2007b;Maier and Ruf, 2014). The perimeter of non-sensory epithelium for each section was determined by subtracting OE perimeter from total septal and turbinal perimeters.…”