Olfactory fossa of Tremacebus harringtoni (platyrrhini, early Miocene, Sacanana, Argentina): Implications for activity pattern

CT imaging was undertaken on the skull of ∼ 20‐Myr‐old Miocene Tremacebus harringtoni. Here we report our observations on the relative size of the olfactory fossa and its implications for the behavior of Tremacebus. The endocranial surface of Tremacebus is incomplete, making precise estimate of brai...

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Bibliographic Details
Published in:The Anatomical record 2004-11, Vol.281A (1), p.1157-1172
Main Authors: Kay, Richard F., Campbell, Victoria M., Rossie, James B., Colbert, Matthew W., Rowe, Tim B.
Format: Article
Language:English
Subjects:
Adaptation, Physiological - physiology
Animals
Anthropoidea
Aotus
Argentina
Behavior, Animal - physiology
Brain - anatomy & histology
Brain - physiology
Callicebus
Cebidae - anatomy & histology
Cebidae - physiology
Cebus
Circadian Rhythm - physiology
Fossils
Miocene
nocturnality
olfaction
Olfactory Bulb - anatomy & histology
Olfactory Bulb - physiology
Paleontology
Phylogeny
Platyrrhini
Primates
Skull - anatomy & histology
Skull - diagnostic imaging
Skull - physiology
Smell - physiology
Species Specificity
Tomography, X-Ray Computed
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Summary:CT imaging was undertaken on the skull of ∼ 20‐Myr‐old Miocene Tremacebus harringtoni. Here we report our observations on the relative size of the olfactory fossa and its implications for the behavior of Tremacebus. The endocranial surface of Tremacebus is incomplete, making precise estimate of brain size and olfactory fossa size imprecise. However, olfactory fossa breadth and maximum endocranial breadth measured from CT images of one catarrhine species and eight platyrrhine species for which volumes of the olfactory bulb and brain are known show that the osteological proxies give a reasonably accurate indication of relative olfactory bulb size. Nocturnal Aotus has the largest relative olfactory fossa breadth and the largest olfactory bulb volume compared to brain volume among extant anthropoids. Tremacebus had a much smaller olfactory fossa breadth and, by inference, bulb volume—within the range of our sample of diurnal anthropoids. Variations in the relative size of the olfactory bulbs in platyrrhines appear to relate to the importance of olfaction in daily behaviors. Aotus has the largest olfactory bulbs among platyrrhines and relies more on olfactory cues when foraging than Cebus, Callicebus, or Saguinus. As in other examples of nocturnal versus diurnal primates, nocturnality may have been the environmental factor that selected for this difference in Aotus, although communication and other behaviors are also likely to select for olfactory variation in diurnal anthropoids. Considering the olfactory fossa size of Tremacebus, olfactory ability of this Miocene monkey was probably not as sensitive as in Aotus and counts against the hypothesis that Tremacebus was nocturnal. This finding accords well with previous observations that the orbits of Tremacebus are not as large as nocturnal Aotus. © 2004 Wiley‐Liss, Inc.
ISSN:1552-4884
0003-276X
1552-4892
1097-0185
DOI:10.1002/ar.a.20121