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New Insights into Howler Monkey Vocal Tract Anatomy via 3‐Dimensional Imaging Technology
Author(s) -
Shearer Brian,
Halenar Lauren,
Pagano Anthony,
Reidenberg Joy,
Laitman Jeffrey
Publication year - 2015
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.29.1_supplement.867.8
Subject(s) - anatomy , primate , hyoid bone , biology , geology , paleontology
The howler monkey (Primates: Alouatta ) has one of the most highly derived hyolaryngeal morphologies of any living group. The laryngeal cartilages are greatly enlarged (and sometimes ossified) while the bulbous, pneumatized hyoid bone is hypothesized to act as a resonating chamber for their distinctive vocalizations. With these specializations, howlers can produce the loudest call of any land animal: a low pitched, high volume howl that can reach an upper limit of 140 decibels and be heard five kilometers away. However, the functional morphology of this vocalization is not well understood, particularly due to a lack of research concerning the airflow and spaces in the hyolaryngeal complex. In this study we examine Alouatta hyolaryngleal anatomy using computed tomography and magnetic resonance imaging to elucidate the functional aspects of howler monkey vocal tract anatomy. Our three‐dimensional reconstructions of these air spaces in adult howler specimens corroborate early hypotheses for the function of some hyolaryngeal structures and provides additional clarity on the exact location and function of extra‐laryngeal structures. We propose a mechanism for the path of airflow through the hyolaryngeal air spaces that may facilitate re‐breathing, and allow for use of the hyoid by which Alouatta may modulate the volume of its calls without changing frequency.