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Hautier, Lionel; Weisbecker, Vera; Sánchez-Villagra, Marcelo R.; Goswami, Anjali; Asher, Robert J.
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2010 |
Skeletal development in sloths and the evolution of mammalian vertebral patterning.
Proc. Natl. Acad. Sci. (USA) 107(44): 18903-18908. 4 figs. Nov. 2, 2010.
–P. 18906: {"Short-necked sloths (C[holoepus]. hoffmanni) possess five to six ribless neck vertebrae. Manatees are known to typically possess six ribless neck vertebrae [Buchholtz et al., 2007]. We predict that when data on their axial skeleton ossification sequences are available, they will show one to two cranial-most rib-bearing vertebrae that are developmentally cervical. That is, they will exhibit late ossification of their centra, after that of more distal, rib-bearing vertebrae and coincident with more proximal cervical vertebrae."}
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Hautier, Lionel; Helder Gomes Rodrigues; Sergio Ferreira-Cardoso; Christopher A. Emerling; Marie-Lou Porcher; Robert J. Asher; Roberto Portela Miguez; Frederic Delsuc
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2023a |
From teeth to pad: tooth loss and development of keratinous structures in sirenians.
Proceedings of the Royal Society B. Royal Society Publishing. Org. https://doi.org/10.1098/rspb.2023.1932 Nov. 29, 2023.
–ABSTRACT: Sirenians are a well-known example of morphological adaptation to a shallow-water grazing diet characterized by a modified feeding apparatus and orofacial morphology. Such adaptations were accompanied by an anterior tooth reduction associated with the development of keratinized pads, the evolution of which remains elusive. Among sirenians, the recently extinct Steller's sea cow represents a special case for being completely toothless. Here, we used ?-CT scans of sirenian crania to understand how motor-sensor systems associated with tooth innervation responded to innovations such as keratinized pads and continuous dental replacement. In addition, we surveyed nine genes associated with dental reduction for signatures of loss of function. Our results reveal how patterns of innervation changed with modifications of the dental formula, especially continuous replacement in manatees. Both our morphological and genomic data show that dental development was not completely lost in the edentulous Steller's sea cows. By tracing the phylogenetic history of tooth innervation, we illustrate the role of development in promoting the innervation of keratinized pads, similar to the secondary use of dental canals for innervating neomorphic keratinized structures in other tetrapod groups.
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Hautier, Lionel; Gomes Rodrigues, H,; Ferreira-Cardoso, S,; Emerling, C.A.,; Porcher, M.-L.; Asher, R.; Portela, Miguez R.; Delsuc, F.
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2023b |
From teeth to pad, tooth loss and development of keratinous structures in sirenians. Figshare.
The Royal Society. Collection. https://doi.org/10.6084/m9.figshare.c.6927574.v1 Nov. 13, 2023.
–ABSTRACT-- Sirenians are a well-known example of morphological adaptation to a shallow-water grazing diet characterized by a modified feeding apparatus and orofacial morphology. Such adaptations were accompanied by an anterior tooth reduction associated with the development of keratinized pads, the evolution of which remains elusive. Among sirenians, the recently extinct Steller's sea cow represents a special case for being completely toothless. Here, we used ?-CT scans of sirenian crania to understand how motor-sensor systems associated with tooth innervation responded to innovations such as keratinized pads and continuous dental replacement. In addition, we surveyed nine genes associated with dental reduction for signatures of loss of function. Our results reveal how patterns of innervation changed with modifications of the dental formula, especially continuous replacement in manatees. Both our morphological and genomic data show that dental development was not completely lost in the edentulous Steller's sea cows. By tracing the phylogenetic history of tooth innervation, we illustrate the role of development in promoting the innervation of keratinized pads, similar to the secondary use of dental canals for innervating neomorphic keratinized structures in other tetrapod groups.
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