Allometry of the postnatal cranial ontogeny and sexual dimorphism in Otaria byronia (Otariidae)

Tarnawski, Bárbara Alejandra; Cassini, Guillermo Hernán; Flores, David A.

doi:10.1007/s13364-012-0124-7

Cited by 28 publications

(35 citation statements)

References 54 publications

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“…Indeed, the youngest female of our sample exhibit lesser CS than the youngest males analyzed. These results suggest that sexual dimorphism in skull shape is size-related, as has been reported in other mammals (e.g., Cardini and Elton, 2008;Flores and Casinos, 2011;Tarnawski et al, 2014aTarnawski et al, , 2014b, although, as a general trend, favoring males.…”

Section: Sexual Dimorphismsupporting

confidence: 82%

“…4) derives in an amount of the available space for the accommodation of the temporalis. This character seems to be common in mammals (and perhaps a plesiomorphic condition), as was detected in the ontogeny of several groups of marine and terrestrial mammals (e.g., Segura and Prevosti, 2012;Flores et al, 2013;Segura et al, 2013;Tarnawski et al, 2014aTarnawski et al, , 2014b. Although the longer rostrum suggests a decreasing of the mechanical advantages at the tip (Preuschoft and Witzel, 2002;Segura and Prevosti, 2012;Segura et al, 2013), its length, associated with a well-developed temporal musculature, also implies a gain in mouth-closing speed at the tip, making prey catch function in adults more efficient.…”

Section: Ontogenetic Changesmentioning

confidence: 76%

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Ontogenetic development and sexual dimorphism of franciscana dolphin skull: A 3D geometric morphometric approach

Castillo

Flores

Cappozzo

2014

Journal of Morphology

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The aim of this work was to study the postnatal ontogenetic development of Pontoporia blainvillei skull, identifying major changes on shape, and relating them to relevant factors in the life history of the species. We analyzed a complete ontogenetic series (73♂, 83♀) with three-dimensional geometric morphometric techniques. Immature dolphins showed a very well-developed braincase and a poorly developed rostrum, and the principal postnatal changes affected the rostrum and the temporal fossa, both structures implied functionally to the feeding apparatus, thus suggesting a specialized mode for catch fast prey in P. blainvillei. Osseous elements associated with sound production were already well developed on immature dolphins, suggesting the importance of this apparatus since the beginning of postnatal life. Sexual dimorphism was detected on both shape and size variables. Females were bigger than males, in accordance with previous studies. Shape differences between sexes were found on the posterior part of premaxillaries and external bony nares (P < 0.01), suggesting that this sexual dimorphism is related to differences on vocalization capabilities.

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Section: Sexual Dimorphismsupporting

confidence: 82%

Section: Ontogenetic Changesmentioning

confidence: 76%

Ontogenetic development and sexual dimorphism of franciscana dolphin skull: A 3D geometric morphometric approach

Castillo

Flores

Cappozzo

2014

Journal of Morphology

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“…12) to describe skull components in all specimens of the ontogenetic series. The craniomandibular dimensions analyzed here, partially overlap with those considered in other morphometric studies of mammalian skulls (Abdala et al 2001;Giannini et al 2004Giannini et al , 2010Cassini et al 2012Cassini et al , 2015Flores et al 2013;Tarnawski et al 2014aTarnawski et al ,b, 2015. To estimate growth trends, we used multivariate analyses based on the generalized allometry equation originally proposed by Jolicoeur (1963).…”

Section: Quantitative (Allometric) Analysissupporting

confidence: 61%

“…; Tarnawski et al. ,b, ). To estimate growth trends, we used multivariate analyses based on the generalized allometry equation originally proposed by Jolicoeur ().…”

Section: Methodsmentioning

confidence: 98%

Comparative cranial ontogeny of Tapirus (Mammalia: Perissodactyla: Tapiridae)

Moyano

Giannini

2017

Journal of Anatomy

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Skull morphology in tapirs is particularly interesting due to the presence of a proboscis with important trophic, sensory and behavioral functions. Several studies have dealt with tapir skull osteology but chiefly in a comparative framework between fossil and recent species of tapirs. Only one study examined an aspect of cranial ontogeny, development of the sagittal crest (Holbrook. J Zool Soc Lond 2002; 256; 215). Our goal is to describe in detail the morphological changes that occur during the postnatal ontogeny of the skull in two representative tapir species, Tapirus terrestris and Tapirus indicus, and to explore possible functional consequences of their developmental trajectories. We compared qualitative features of the skull on a growth series of 46 specimens of T. terrestris ordered on the basis of the sequence of eruption and tooth wear, dividing the sample into three age classes: class Y (very young juvenile), class J (from young juvenile to young adult) and class A (full and old adult). The qualitative morphological analysis consisted of describing changes in the series in each skull bone and major skull structure, including the type and degree of transformation (e.g. appearance, fusion) of cranial features (e.g. processes, foramina) and articulations (sutures, synchondroses, and synovial joints). We then measured 23 cranial variables in 46 specimens of T. terrestris that included the entire ontogenetic series from newborn to old adults. We applied statistical multivariate techniques to describe allometric growth, and compared the results with the allometric trends calculated for a sample of 25 specimens of T. indicus. Results show that the skull structure was largely conserved throughout the postnatal ontogeny in T. terrestris, so class Y was remarkably similar to class A in overall shape, with the most significant changes localized in the masticatory apparatus, specifically the maxillary tuber as a support of the large-sized permanent postcanine dentition, and correlated changes in diastemata, mandibular body, and sagittal and nuchal crests. In the nasal region, ontogenetic remodeling affected the space for the meatal diverticulum and the surfaces for the origin of the proboscis musculature. Overall, ontogenetic trajectories exhibited more negative allometric components in T. indicus than in T. terrestris, and they shared 47.83% of allometric trends. Tapirus indicus differed most significantly from T. terrestris in the allometry of postcanine toothrows, diastemata and mandibular body. Thus, some allometric trends seem to be highly conserved among the species studied, and the changes observed showed a strong functional and likely adaptive basis in this lineage of ungulates.

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“…Growth in cranial size is often found to be the primary way to increase bite force across ontogeny (La Croix et al ., 2011b; Santana and Miller, 2016; Law et al ., 2016b; Ginot et al ., 2020). However, many carnivorans also exhibit significant cranial shape changes across ontogeny such as the development of the sagittal and nuchal crests (Tanner et al ., 2010; La Croix et al ., 2011a; Tarnawski et al ., 2013; Tarnawski et al ., 2015). Although these developmental changes are often viewed to increase jaw muscle size by increasing muscle attachment sites on the skull (Radinsky, 1981a; Radinsky, 1981b), how they actually relate to ontogenetic increases in bite force are rarely quantified in mammals.…”

Section: Introductionmentioning

confidence: 99%

Sex‐specific ontogenetic patterns of cranial morphology, theoretical bite force, and underlying jaw musculature in fishers and American martens

Law

2020

Journal of Anatomy

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The carnivoran cranium undergoes tremendous growth in size and development of shape to process prey as adults and, importantly, these ontogenetic processes can also differ between the sexes. How these ontogenetic changes in morphology actually relate to the underlying jaw musculature and overall bite performance has rarely been investigated. In this study, I examined sex‐specific ontogenetic changes in cranial morphology, jaw adductor muscles, and theoretical bite force between subadults and adults in the fisher (Pekania pennanti) and American marten (Martes americana). I found evidence that cranial size alone does not completely explain ontogenetic increases in bite forces as found in other mammalian species. Instead, cranial shape development also drives ontogenetic increases in relative bite force by broadening the zygomatic arches and enlargement of the sagittal crest, both of which enable relatively larger jaw adductor muscles to attach. In contrast, examination of sexual dimorphism within each age‐class revealed that cranial shape dimorphism did not translate to dimorphism in either size‐corrected bite forces or size‐corrected physiological cross‐sectional area of the jaw adductor muscles. These results reveal that morphological size and shape variation can have different influences on bite performance depending on the level of intraspecific variation that is examined (i.e. ontogenetic versus sexual dimorphism).

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Allometry of the postnatal cranial ontogeny and sexual dimorphism in Otaria byronia (Otariidae)

Cited by 28 publications

References 54 publications

Ontogenetic development and sexual dimorphism of franciscana dolphin skull: A 3D geometric morphometric approach

Ontogenetic development and sexual dimorphism of franciscana dolphin skull: A 3D geometric morphometric approach

Comparative cranial ontogeny of Tapirus (Mammalia: Perissodactyla: Tapiridae)

Sex‐specific ontogenetic patterns of cranial morphology, theoretical bite force, and underlying jaw musculature in fishers and American martens

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