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On the vestibular labyrinth of Brachiosaurus brancai.
J Vestib Res. 2005; 15(2):65-71.JV

Abstract

The extensive remains of large sauropods, excavated in the Upper Jurassic layers of the Tendaguru region of Tanzania, East Africa by Janensch [15], include an intact fossil cast of a vestibular labyrinth and an endocast of the large Brachiosaurus brancai. The approximately 150 million year old labyrinth cast demonstrates clearly a form and organisation congruent in detail to those of extant vertebrate species. Besides the near-orthogonal arrangement of semicircular canals (SCCs), the superior and inferior branches of the vestibulo-acoustic nerve, the endolymphatic duct, the oval and round windows, and the cochlea can be identified. The orientation of the labyrinth in the temporal bone is also equivalent to that of many extant vertebrates. Furthermore, the existence of the twelve cranial nerves can be identified from the endocast. The present study was initiated after the photogrammetric measurement of the skeleton volume of B. brancai [13] yielded a realistic estimate of body mass (74.42 metric tons). Dimensional analysis shows that body mass and average SCC dimensions of B. brancai generally fit with the allometric relationship found in previous studies of extant species. However, the anterior SCC is significantly larger than the allometric relationship would predict. This would indicate greater sensitivity, supporting the idea that the behavioural repertoire must have included much slower pitch movements of the head. These slower movements would most likely have involved flexion of the neck, rather than head pitching about the atlas joint. Pursuing the relationship between body mass and SCC dimensions further, the SCC frequency response is estimated by scaling up from the SCC dimensions of the rhesus monkey; this yields a range between 0.008-26 Hz, approximately one octave lower than for humans.

Authors+Show Affiliations

Clarke AH
ENT Department, Campus Benjamin Franklin, Charité Medical School, Berlin, Germany. andrew.clarke@charite.de

MeSH

AnimalsBiophysical PhenomenaBiophysicsBody WeightDinosaursEar, InnerImage Processing, Computer-AssistedMacaca mulattaMammalsSkull

Pub Type(s)

Journal Article

Language

eng

PubMed ID

15951620

Citation

Clarke, A H.. "On the Vestibular Labyrinth of Brachiosaurus Brancai." Journal of Vestibular Research : Equilibrium & Orientation, vol. 15, no. 2, 2005, pp. 65-71.
Clarke AH. On the vestibular labyrinth of Brachiosaurus brancai. J Vestib Res. 2005;15(2):65-71.
Clarke, A. H. (2005). On the vestibular labyrinth of Brachiosaurus brancai. Journal of Vestibular Research : Equilibrium & Orientation, 15(2), 65-71.
Clarke AH. On the Vestibular Labyrinth of Brachiosaurus Brancai. J Vestib Res. 2005;15(2):65-71. PubMed PMID: 15951620.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - On the vestibular labyrinth of Brachiosaurus brancai. A1 - Clarke,A H, PY - 2005/6/14/pubmed PY - 2005/9/28/medline PY - 2005/6/14/entrez SP - 65 EP - 71 JF - Journal of vestibular research : equilibrium & orientation JO - J Vestib Res VL - 15 IS - 2 N2 - The extensive remains of large sauropods, excavated in the Upper Jurassic layers of the Tendaguru region of Tanzania, East Africa by Janensch [15], include an intact fossil cast of a vestibular labyrinth and an endocast of the large Brachiosaurus brancai. The approximately 150 million year old labyrinth cast demonstrates clearly a form and organisation congruent in detail to those of extant vertebrate species. Besides the near-orthogonal arrangement of semicircular canals (SCCs), the superior and inferior branches of the vestibulo-acoustic nerve, the endolymphatic duct, the oval and round windows, and the cochlea can be identified. The orientation of the labyrinth in the temporal bone is also equivalent to that of many extant vertebrates. Furthermore, the existence of the twelve cranial nerves can be identified from the endocast. The present study was initiated after the photogrammetric measurement of the skeleton volume of B. brancai [13] yielded a realistic estimate of body mass (74.42 metric tons). Dimensional analysis shows that body mass and average SCC dimensions of B. brancai generally fit with the allometric relationship found in previous studies of extant species. However, the anterior SCC is significantly larger than the allometric relationship would predict. This would indicate greater sensitivity, supporting the idea that the behavioural repertoire must have included much slower pitch movements of the head. These slower movements would most likely have involved flexion of the neck, rather than head pitching about the atlas joint. Pursuing the relationship between body mass and SCC dimensions further, the SCC frequency response is estimated by scaling up from the SCC dimensions of the rhesus monkey; this yields a range between 0.008-26 Hz, approximately one octave lower than for humans. SN - 0957-4271 UR - https://www.unboundmedicine.com/medline/citation/15951620/On_the_vestibular_labyrinth_of_Brachiosaurus_brancai_ DB - PRIME DP - Unbound Medicine ER -