TY - JOUR
T1 - Homology of the "ethmoid complex" of tyrannosaurids and its implications for the reconstruction of the olfactory apparatus of non-avian theropods
AU - Ali, Farheen
AU - Zelenitsky, Darla K.
AU - Therrien, François
AU - Weishampel, David B.
N1 - Funding Information:
Thanks are extended to Thomas Carr (Carthage College), Larry Witmer (Ohio University College of Osteopathic Medicine), Chris Brochu (University of Iowa), and Richard Zusi (National Museum of Natural History) for advice during the course of this project. We also are grateful to Yubin Li (University of Calgary) for technical assistance and to Apostolos Kantzas (University of Calgary) for allowing free access to a CT-scanner. DKZ was supported by the Alberta Ingenuity Fellowship Fund and the Killam Fellowship Fund. FT was supported by a Natural Sciences and Engineering Research Council of Canada Postdoctoral Fellowship. Part of this project was conducted in the context of the senior author’s Master’s degree.
PY - 2008/3/12
Y1 - 2008/3/12
N2 - The "ethmoid complex" is an enigmatic element of the anterior portion of the braincase first described in Tyrannosaurus rex in 1912, which has since been recognized in many non-avian theropods. Because the "ethmoid complex" is a landmark for the reconstruction of the olfactory apparatus of non-avian theropods, we clarify the homology of this structure among archosaurs. The "ethmoid complex" consists of a trough-shaped element that is attached to an anteriorly-located median septum capped by a dorsal plate. Based on anatomical comparisons with the olfactory region of extant birds and crocodylians, the components of the "ethmoid complex" are shown to have cartilaginous or osteological homologues among extant archosaurs: the trough is homologous to the anterior portion of the planum supraseptale of crocodylians and embryonic birds, whereas the median septum and overlying dorsal plate are homologous to the avian mesethmoid and to the nasal septum and tectum nasi of crocodylians. Based on the location and ossification of olfactory region structures in non-avian theropods, the most appropriate terms for elements of the "ethmoid complex" are the sphenethmoid for the trough and the mesethmoid for the median septum and dorsal plate. The olfactory bulbs of nonavian theropods were housed within the sphenethmoid, which restricted the maximum size of the olfactory bulbs to a size smaller than the cerebral hemispheres.
AB - The "ethmoid complex" is an enigmatic element of the anterior portion of the braincase first described in Tyrannosaurus rex in 1912, which has since been recognized in many non-avian theropods. Because the "ethmoid complex" is a landmark for the reconstruction of the olfactory apparatus of non-avian theropods, we clarify the homology of this structure among archosaurs. The "ethmoid complex" consists of a trough-shaped element that is attached to an anteriorly-located median septum capped by a dorsal plate. Based on anatomical comparisons with the olfactory region of extant birds and crocodylians, the components of the "ethmoid complex" are shown to have cartilaginous or osteological homologues among extant archosaurs: the trough is homologous to the anterior portion of the planum supraseptale of crocodylians and embryonic birds, whereas the median septum and overlying dorsal plate are homologous to the avian mesethmoid and to the nasal septum and tectum nasi of crocodylians. Based on the location and ossification of olfactory region structures in non-avian theropods, the most appropriate terms for elements of the "ethmoid complex" are the sphenethmoid for the trough and the mesethmoid for the median septum and dorsal plate. The olfactory bulbs of nonavian theropods were housed within the sphenethmoid, which restricted the maximum size of the olfactory bulbs to a size smaller than the cerebral hemispheres.
UR - http://www.scopus.com/inward/record.url?scp=42149088870&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=42149088870&partnerID=8YFLogxK
U2 - 10.1671/0272-4634(2008)28[123:HOTECO]2.0.CO;2
DO - 10.1671/0272-4634(2008)28[123:HOTECO]2.0.CO;2
M3 - Article
AN - SCOPUS:42149088870
SN - 0272-4634
VL - 28
SP - 123
EP - 133
JO - Journal of Vertebrate Paleontology
JF - Journal of Vertebrate Paleontology
IS - 1
ER -