The succession of Cessaniti encompasses a transgressive (Tortonian) – regressive (Messinian) cycle. A rich fossil record come from the Unit 2 (according to the stratigraphy by Gramigna et al., 2008), made up by grey sandstones containing a fully marine fauna, with extremely abundant echinoids, abundant sirenians (Metaxytherium serresii; Carone & Domning, 2007, Carone et al., 2013) and rare continental mammals (Ferretti et al., 2003, Gramigna, 2008, Marra et al., 2011). Nine sperm whale teeth coming from Unit 2 have been tentatively attributed to Scaldicetus sp. by Carone (2010), according to the several species often referred to this genus based even on a single tooth. However, recent studies evidenced the weak diagnostic significance of teeth and, when found isolated, they have generally been referred to indeterminate physeteroids (Bianucci & Landini, 2006). The same approach is here proposed to describe and determine the teeth from Cessaniti, which unlikely the common occurrences, were not isolated but originally associated to remains of one skull and/or mandible now unfortunately lost. The teeth are robust and fusiform, from circular to elliptical in cross section, with a relatively short enamelled crown and open pulp cavity. The apical wear varies from weak to strong and the distal portion of the root is marked by weak occlusal wear facets due to the opposite teeth. The presence of enamel is a plesiomorphic character that permits to exclude the appurtenance of these teeth to the Physeteridae + Kogiidae crown group. The occlusal wear indicates that there were functional teeth both in lower and upper jaw, suggesting that this sperm whale had a raptorial feeding behavior. The open pulp cavity and the relatively reduced wear remind an immature animal. The size of the Cessaniti teeth is intermediated between the one of Zygophyseter and Acrophyseter, significantly smaller than Livyatan. Considering the body length estimations of Zygophyseter and Acrophyseter, we can speculate a moderately large size (ca 5 m) for the Cessaniti sperm whale. Such a predator could have fed on the small (ca 2.2 m) sirenian Metaxitherium serresii, whose remains frequently occur at Cessaniti. Tooth marks on sirenian ribs have been hitherto attributed to sharks (Sorce, 2010). The discovery of more complete specimens of this sperm whale from Cessaniti beds could better support these preliminary considerations.

Sperm whale teeth from the late miocene of cessaniti (Southern italy)

MARRA, Antonella Cinzia
Primo
;
2016-01-01

Abstract

The succession of Cessaniti encompasses a transgressive (Tortonian) – regressive (Messinian) cycle. A rich fossil record come from the Unit 2 (according to the stratigraphy by Gramigna et al., 2008), made up by grey sandstones containing a fully marine fauna, with extremely abundant echinoids, abundant sirenians (Metaxytherium serresii; Carone & Domning, 2007, Carone et al., 2013) and rare continental mammals (Ferretti et al., 2003, Gramigna, 2008, Marra et al., 2011). Nine sperm whale teeth coming from Unit 2 have been tentatively attributed to Scaldicetus sp. by Carone (2010), according to the several species often referred to this genus based even on a single tooth. However, recent studies evidenced the weak diagnostic significance of teeth and, when found isolated, they have generally been referred to indeterminate physeteroids (Bianucci & Landini, 2006). The same approach is here proposed to describe and determine the teeth from Cessaniti, which unlikely the common occurrences, were not isolated but originally associated to remains of one skull and/or mandible now unfortunately lost. The teeth are robust and fusiform, from circular to elliptical in cross section, with a relatively short enamelled crown and open pulp cavity. The apical wear varies from weak to strong and the distal portion of the root is marked by weak occlusal wear facets due to the opposite teeth. The presence of enamel is a plesiomorphic character that permits to exclude the appurtenance of these teeth to the Physeteridae + Kogiidae crown group. The occlusal wear indicates that there were functional teeth both in lower and upper jaw, suggesting that this sperm whale had a raptorial feeding behavior. The open pulp cavity and the relatively reduced wear remind an immature animal. The size of the Cessaniti teeth is intermediated between the one of Zygophyseter and Acrophyseter, significantly smaller than Livyatan. Considering the body length estimations of Zygophyseter and Acrophyseter, we can speculate a moderately large size (ca 5 m) for the Cessaniti sperm whale. Such a predator could have fed on the small (ca 2.2 m) sirenian Metaxitherium serresii, whose remains frequently occur at Cessaniti. Tooth marks on sirenian ribs have been hitherto attributed to sharks (Sorce, 2010). The discovery of more complete specimens of this sperm whale from Cessaniti beds could better support these preliminary considerations.
2016
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11570/3109457
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