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Beatty, Brian Lee; Vitkovski, Taisia; Lambert, Olivier; Macrini, Thomas E.
(detail)
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2012 |
Osteological associations with unique tooth development in manatees (Trichechidae, Sirenia): a detailed look at modern Trichechus and a review of the fossil record.
Anat. Rec. 295: 1504-1512. 4 figs. https://doi.org/10.1002/ar.22525
–ABSTRACT--Modern manatees have a unique type of tooth development, continually forming identical new molars in the posterior end of each quadrant of their mouths, and then progressively moving teeth anteriorly, only to reabsorb roots and spit out worn crowns. This process is not only developmentally complex, but requires space in the oral cavity that imposes its own limitations on other uses of that space. To gain a clearer understanding of the anatomical constraints on the evolution of this unique developmental process, we identified the specialized craniodental features in modern Trichechus that permit this specialization using visual observation and CT. Furthermore, to better understand the evolution of these traits, we review the fossil record of trichechids for these traits, including CT analysis of the skull of Miosiren kocki, a possible early member of the family from the Early Miocene of Belgium.
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Orihuela, Johanset; Viñola López, Lázaro W.; Macrini, Thomas E.
(detail)
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2019 |
First cranial endocasts of early Miocene sirenians (Dugongidae) from the West Indies.
Jour. Vert. Pal. 39(2): e1584565. .2 tabs. 10 figs.. DOI: 10.1080/02724634.2019.1584565 Publ. online May 3, 2019;
–ABSTRACT: We report and describe the first sirenian endocranial casts from the West Indies based on three specimens collected from two quarries of the upper Oligocene–lower Miocene Colón Formation, in the province of Matanzas, western Cuba. We assign them to Dugongidae incertae sedis, based on a phylogenetic analysis of fossil and extant sirenians. Thus, these new specimens provide a unique opportunity to describe the endocranial neuroanatomy of this family. The endocasts are suggestive of dugongids with limited vision and olfaction, based on the diminished olfactory and optic nerves. Additionally, we provide a geological reinterpretation of the Colón Formation and its paleoecological setting. Altogether, these data provide further insight into the diversity and evolution of sirenians, especially Caribbean dugongs.
RESUMEN: Se describen los primeros moldes endocraniales de sirénido hasta ahora reportados de las Antillas. Los tres especímenes que reportamos provienen de dos canteras con afloramientos de la Formación Colón, en la provincia de Matanzas, Cuba. Esta formación se considera de edad Oligoceno tardío a Mioceno temprano, pero nosotros asignamos los moldes al Mioceno temprano. Conjuntamente, proveemos una lista de caracteres y un análisis filogenético que puede ayudar aclarar su posición sistemática. Por falta de material comparativo, los moldes endocranianos no se pudieron atribuir a una especie, y por ende los asignamos a la familia Dugongidae incertae sedis, por su posición en el árbol filogenético. Estos especímenes permiten un acercamiento a la historia, diversidad y evolución de los sirénidos, y en especial de los dugongídos en el neógeno caribeño.
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Bibliography and Index of the Sirenia and Desmostylia 