Morphology and Variation in Porpoise (Cetacea: Phocoenidae) Cranial Endocasts
ABSTRACT Evolution of endocranial anatomy in cetaceans is important from the perspective of echolocation ability, intelligence, social structure, and alternate pathways for circulation to the brain. Apart from the importance of studying brain shape and asymmetries as they relate to aspects of behavi...
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crwiley:10.1002/ar.22704 2024-06-02T08:13:15+00:00 Morphology and Variation in Porpoise (Cetacea: Phocoenidae) Cranial Endocasts Racicot, Rachel A. Colbert, Matthew W. 2013 http://dx.doi.org/10.1002/ar.22704 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Far.22704 http://onlinelibrary.wiley.com/wol1/doi/10.1002/ar.22704/fullpdf en eng Wiley http://onlinelibrary.wiley.com/termsAndConditions#vor The Anatomical Record volume 296, issue 6, page 979-992 ISSN 1932-8486 1932-8494 journal-article 2013 crwiley https://doi.org/10.1002/ar.22704 2024-05-03T11:37:05Z ABSTRACT Evolution of endocranial anatomy in cetaceans is important from the perspective of echolocation ability, intelligence, social structure, and alternate pathways for circulation to the brain. Apart from the importance of studying brain shape and asymmetries as they relate to aspects of behavior and intelligence, cranial endocasts can show a close correspondence to the hydrostatic shape of the brain in life, and canals and grooves can preserve features of the circulatory system. Multiple samples are rarely available for studies of individual variation, especially in fossils, thus a first step in quantifying variation and making comparisons with fossils is made possible with CT scans of osteological specimens. This study presents a series of high‐resolution X‐ray CT‐derived cranial endocasts of six extant species of Phocoenidae, a clade including some of the smallest and one of the rarest cetaceans. Degree of gyrification varies interspecifically and intraspecifically, possibly resulting from variation in preservation of the ossified meninges. Computed tomographic data show that visually assessed asymmetry in the cranial endocasts is not correlated with volumetric measurements, but nonetheless may reflect torsion in the skull's shape such that the right cerebral and cerebellar hemispheres extend rostrally and laterally more than the left. Vasculature and canals are similar to other described cetacean species, but the hypophyseal casts are unusual. Similarities between brain shape and volume measurements in the different species can be attributed to paedomorphism and concomitant variation in ecological preferences. This may explain similarities Neophocaena phocaenoides and Phocoena sinus share with the juvenile Phocoena phocoena specimen studied. Anat Rec, 296:979–992, 2013. © 2013 Wiley Periodicals, Inc. Article in Journal/Newspaper Phocoena phocoena Wiley Online Library The Anatomical Record 296 6 979 992 |
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ABSTRACT Evolution of endocranial anatomy in cetaceans is important from the perspective of echolocation ability, intelligence, social structure, and alternate pathways for circulation to the brain. Apart from the importance of studying brain shape and asymmetries as they relate to aspects of behavior and intelligence, cranial endocasts can show a close correspondence to the hydrostatic shape of the brain in life, and canals and grooves can preserve features of the circulatory system. Multiple samples are rarely available for studies of individual variation, especially in fossils, thus a first step in quantifying variation and making comparisons with fossils is made possible with CT scans of osteological specimens. This study presents a series of high‐resolution X‐ray CT‐derived cranial endocasts of six extant species of Phocoenidae, a clade including some of the smallest and one of the rarest cetaceans. Degree of gyrification varies interspecifically and intraspecifically, possibly resulting from variation in preservation of the ossified meninges. Computed tomographic data show that visually assessed asymmetry in the cranial endocasts is not correlated with volumetric measurements, but nonetheless may reflect torsion in the skull's shape such that the right cerebral and cerebellar hemispheres extend rostrally and laterally more than the left. Vasculature and canals are similar to other described cetacean species, but the hypophyseal casts are unusual. Similarities between brain shape and volume measurements in the different species can be attributed to paedomorphism and concomitant variation in ecological preferences. This may explain similarities Neophocaena phocaenoides and Phocoena sinus share with the juvenile Phocoena phocoena specimen studied. Anat Rec, 296:979–992, 2013. © 2013 Wiley Periodicals, Inc. |
format |
Article in Journal/Newspaper |
author |
Racicot, Rachel A. Colbert, Matthew W. |
spellingShingle |
Racicot, Rachel A. Colbert, Matthew W. Morphology and Variation in Porpoise (Cetacea: Phocoenidae) Cranial Endocasts |
author_facet |
Racicot, Rachel A. Colbert, Matthew W. |
author_sort |
Racicot, Rachel A. |
title |
Morphology and Variation in Porpoise (Cetacea: Phocoenidae) Cranial Endocasts |
title_short |
Morphology and Variation in Porpoise (Cetacea: Phocoenidae) Cranial Endocasts |
title_full |
Morphology and Variation in Porpoise (Cetacea: Phocoenidae) Cranial Endocasts |
title_fullStr |
Morphology and Variation in Porpoise (Cetacea: Phocoenidae) Cranial Endocasts |
title_full_unstemmed |
Morphology and Variation in Porpoise (Cetacea: Phocoenidae) Cranial Endocasts |
title_sort |
morphology and variation in porpoise (cetacea: phocoenidae) cranial endocasts |
publisher |
Wiley |
publishDate |
2013 |
url |
http://dx.doi.org/10.1002/ar.22704 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Far.22704 http://onlinelibrary.wiley.com/wol1/doi/10.1002/ar.22704/fullpdf |
genre |
Phocoena phocoena |
genre_facet |
Phocoena phocoena |
op_source |
The Anatomical Record volume 296, issue 6, page 979-992 ISSN 1932-8486 1932-8494 |
op_rights |
http://onlinelibrary.wiley.com/termsAndConditions#vor |
op_doi |
https://doi.org/10.1002/ar.22704 |
container_title |
The Anatomical Record |
container_volume |
296 |
container_issue |
6 |
container_start_page |
979 |
op_container_end_page |
992 |
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1800736686977581056 |