High Encephalization in a Fossil Rorqual Illuminates Baleen Whale Brain Evolution
Baleen whales are considered underencephalized mammals due to their reduced brain size with respect to their body size (encephalization quotient [EQ] << 1). Despite their low EQ, mysticetes exhibit complex behavioral patterns in terms of motor abilities, vocal repertoire, and cultu...
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crskarger:10.1159/000519852 2024-09-15T17:57:25+00:00 High Encephalization in a Fossil Rorqual Illuminates Baleen Whale Brain Evolution Bisconti, Michelangelo Daniello, Riccardo Damarco, Piero Tartarelli, Giandonato Pavia, Marco Carnevale, Giorgio 2021 http://dx.doi.org/10.1159/000519852 https://www.karger.com/Article/Pdf/519852 en eng S. Karger AG https://www.karger.com/Services/SiteLicenses https://www.karger.com/Services/SiteLicenses Brain, Behavior and Evolution volume 96, issue 2, page 78-90 ISSN 0006-8977 1421-9743 journal-article 2021 crskarger https://doi.org/10.1159/000519852 2024-07-31T04:07:17Z Baleen whales are considered underencephalized mammals due to their reduced brain size with respect to their body size (encephalization quotient [EQ] << 1). Despite their low EQ, mysticetes exhibit complex behavioral patterns in terms of motor abilities, vocal repertoire, and cultural learning. Very scarce information is available about the morphological evolution of the brain in this group; this makes it difficult to investigate the historical changes in brain shape and size in order to relate the origin of the complex mysticete behavioral repertoire to the evolution of specific neural substrates. Here, the first description of the virtual endocast of a fossil balaenopterid species, Marzanoptera tersillae from the Italian Pliocene, reveals an EQ of around 3, which is exceptional for baleen whales. The endocast showed a morphologically different organization of the brain in this fossil whale as the cerebral hemispheres are anteroposteriorly shortened, the cerebellum lacks the posteromedial expansion of the cerebellar hemispheres, and the cerebellar vermis is unusually reduced. The comparative reductions of the cerebral and cerebellar hemispheres suggest that the motor behavior of M. tersillae probably was less sophisticated than that exhibited by the extant rorqual and humpback species. The presence of an EQ value in this fossil species that is around 10 times higher than that of extant mysticetes opens new questions about brain evolution and provides new, invaluable information about the evolutionary path of morphological and size change in the brain of baleen whales. Article in Journal/Newspaper baleen whale baleen whales Karger Brain, Behavior and Evolution 1 13 |
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Baleen whales are considered underencephalized mammals due to their reduced brain size with respect to their body size (encephalization quotient [EQ] << 1). Despite their low EQ, mysticetes exhibit complex behavioral patterns in terms of motor abilities, vocal repertoire, and cultural learning. Very scarce information is available about the morphological evolution of the brain in this group; this makes it difficult to investigate the historical changes in brain shape and size in order to relate the origin of the complex mysticete behavioral repertoire to the evolution of specific neural substrates. Here, the first description of the virtual endocast of a fossil balaenopterid species, Marzanoptera tersillae from the Italian Pliocene, reveals an EQ of around 3, which is exceptional for baleen whales. The endocast showed a morphologically different organization of the brain in this fossil whale as the cerebral hemispheres are anteroposteriorly shortened, the cerebellum lacks the posteromedial expansion of the cerebellar hemispheres, and the cerebellar vermis is unusually reduced. The comparative reductions of the cerebral and cerebellar hemispheres suggest that the motor behavior of M. tersillae probably was less sophisticated than that exhibited by the extant rorqual and humpback species. The presence of an EQ value in this fossil species that is around 10 times higher than that of extant mysticetes opens new questions about brain evolution and provides new, invaluable information about the evolutionary path of morphological and size change in the brain of baleen whales. |
format |
Article in Journal/Newspaper |
author |
Bisconti, Michelangelo Daniello, Riccardo Damarco, Piero Tartarelli, Giandonato Pavia, Marco Carnevale, Giorgio |
spellingShingle |
Bisconti, Michelangelo Daniello, Riccardo Damarco, Piero Tartarelli, Giandonato Pavia, Marco Carnevale, Giorgio High Encephalization in a Fossil Rorqual Illuminates Baleen Whale Brain Evolution |
author_facet |
Bisconti, Michelangelo Daniello, Riccardo Damarco, Piero Tartarelli, Giandonato Pavia, Marco Carnevale, Giorgio |
author_sort |
Bisconti, Michelangelo |
title |
High Encephalization in a Fossil Rorqual Illuminates Baleen Whale Brain Evolution |
title_short |
High Encephalization in a Fossil Rorqual Illuminates Baleen Whale Brain Evolution |
title_full |
High Encephalization in a Fossil Rorqual Illuminates Baleen Whale Brain Evolution |
title_fullStr |
High Encephalization in a Fossil Rorqual Illuminates Baleen Whale Brain Evolution |
title_full_unstemmed |
High Encephalization in a Fossil Rorqual Illuminates Baleen Whale Brain Evolution |
title_sort |
high encephalization in a fossil rorqual illuminates baleen whale brain evolution |
publisher |
S. Karger AG |
publishDate |
2021 |
url |
http://dx.doi.org/10.1159/000519852 https://www.karger.com/Article/Pdf/519852 |
genre |
baleen whale baleen whales |
genre_facet |
baleen whale baleen whales |
op_source |
Brain, Behavior and Evolution volume 96, issue 2, page 78-90 ISSN 0006-8977 1421-9743 |
op_rights |
https://www.karger.com/Services/SiteLicenses https://www.karger.com/Services/SiteLicenses |
op_doi |
https://doi.org/10.1159/000519852 |
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Brain, Behavior and Evolution |
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13 |
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1810433572066033664 |