Growth layer patterns in Arctocephalus australis canine teeth: evaluation of techniques for age determination

Molina-Schiller, D.; Pinedo, Maria Cristina

doi:10.5597/lajam00056

Cited by 14 publications

(28 citation statements)

References 17 publications

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“…In general, the evidence for differential expenditure in the sexes seems rather tenuous (Trillmich, 1996). The pronounced sexual dimorphism in skulls of A. australis described here for the populations of Uruguay and Peru corroborates previous studies (Ximenez et al, 1984;Drehmer and Ferigolo, 1996;Brunner, 2000;Molina-Schiller, 2000;Molina-Schiller and Pinedo, 2004b;Sanfelice, 2004). The allometry observed in the ventral view of males and females of A. australis agrees with the results found by Drehmer and Ferigolo (1996) and Molina (2000).…”

Section: Discussionsupporting

confidence: 80%

Size and shape sexual dimorphism in the skull of the South American fur seal, Arctocephalus australis (Zimmermann, 1783) (Carnivora: Otariidae)

Oliveira¹,

Hingst‐Zaher²,

Morgante³

2005

Lat. Am. J. Aquat. Mamm.

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-We present a quantitative analysis of sexual dimorphism in the skull of Arctocephalus australis assessed by traditional and geometric morphometrics. Differences in size and shape of skulls of 386 adult males and females of A. australis from Uruguayan and Peruvian populations were analyzed using 15 linear measurements. These differences were also investigated applying geometric morphometrics techniques to two-dimensional images of 346 skulls in dorsal, ventral and lateral views. Results of traditional and geometric morphometrics revealed pronounced sexual dimorphism in size and shape of the skull for both populations of A. australis. Males are always larger than females, and differences in shape are concentrated mainly in the rostral region. Sexual dimorphism is more accentuated in the Uruguayan population. Differences in size and shape of the skulls between males and females of A. australis can be related to sexual selection, mating system and life history. In A. australis, as well as in other polygynous species, the selective pressures can favor the development of traits that enhance fighting ability in males, such as larger canines, increased rostral and mastoid widths and increased overall body size.Resumo -Apresentamos uma análise quantitativa do dimorfismo sexual craniano de A. australis através de técnicas de morfometria tradicional e geométrica. Diferenças no tamanho e na forma dos crânios de machos e fêmeas de 386 espécimes adultos de A. australis das populações do Uruguai e Peru foram analisadas através de 15 medidas lineares. Estas diferenças também foram investigadas através das técnicas de morfometria geométrica aplicadas a imagens bidimensionais de 346 crânios nas posições dorsal, ventral e lateral. Os resultados tanto da morfometria tradicional quanto da geométrica indicaram a existência de um pronunciado dimorfismo sexual no tamanho e na forma dos crânios de A. australis de ambas as populações. Os crânios dos machos são sempre maiores do que os das fêmeas, e as diferenças na forma estão concentradas principalmente na região rostral. O dimorfismo sexual é mais acentuado na população do Uruguai. As diferenças na forma e no tamanho do crânio entre machos e fêmeas de A. australis podem estar associadas à seleção sexual, sistemas reprodutivos e a história de vida. Em A. australis, assim como em outras espécies poligínicas, as pressões seletivas podem favorecer o desenvolvimento de caracteres que aprimoram as habilidades de luta nos machos, tais como dentes caninos maiores, aumento na largura do rostro e do mastóide, assim como um aumento geral do tamanho do corpo.

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Section: Discussionsupporting

confidence: 80%

Size and shape sexual dimorphism in the skull of the South American fur seal, Arctocephalus australis (Zimmermann, 1783) (Carnivora: Otariidae)

Oliveira¹,

Hingst‐Zaher²,

Morgante³

2005

Lat. Am. J. Aquat. Mamm.

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“…The fact is that the growth of these animals is in part structured by environmental variables, these variables condition modifications that imprint themselves on the dentine and the cement of the animal teeth (Crespo et al, 1994, Grandi et al, 2010. Within this framework, the lines or bands of growth identified in these specimens are generated sequentially and create a development pattern that can be interpreted in terms of the study of a number of interrelated aspects, including among others, the individual's growth and seasonality of death (Crespo, 1988;Grandi et al, 2010;Laws, 1962;Molina-Schiller and Pinedo, 2004;Pretto, 2016;Rosas, Haimovici and Pinedo, 1993;Schiavini, Lima and Batallés, 1992).…”

Section: Materials and Methods: Seasonality Studies Of Death In Pinnimentioning

confidence: 99%

Death seasonality determination from pinnipeds teeth: the Cueva del Negro site case (Argentine Patagonia)

Ambrústolo¹,

Zubimendi²,

Crespo³

2019

Arq

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In this article, we present the first results of the determination of season at death performed over eighteen South American sea lions (Otaria flavescens) teeth recovered at Cueva del Negro site (northern coast of the Santa Cruz Province, Patagonia, Argentina). Age and season of death were determined by growth-layer analysis on sea lion teeth. This analysis allowed us to suggest potential aboriginal hunting strategies regarding the capture of these pinnipeds. Our results indicate that sea lions were hunted between summer and early fall, more precisely between January and April. This would reflect a marked seasonality in relation to sea lion availability, which could be explained in terms of mobility and subsistence strategies of the human groups that inhabited the area. In this sense, our results are discussed taking into consideration paleodietary data and the existing archaeological studies. Determinación de estacionalidad de muerte en dientes de pinnípedos: el caso del sitio Cueva del Negro (Patagonia Argentina) ResumenEn este trabajo se presentan los primeros resultados de los estudios de estacionalidad de muerte obtenidos sobre 18 dientes de pinnípedos (Otaria flavescens) recuperados en el sitio Cueva del Negro (costa norte de la provincia de Santa Cruz, Patagonia Argentina). Los mencionados análisis nos permitieron plantear un potencial patrón de captura de dichas presas y forma de uso de un espacio puntual. Las tendencias preliminares sugieren una explotación de pinnípedos orientada hacia el verano e inicios de otoño, más precisamente entre los meses de enero y abril. Ello reflejaría una marcada estacionalidad en relación con el aprovisionamiento de las presas, lo que podría explicarse en función de las estrategias de movilidad y modo de subsistencia de los grupos humanos que habitaron el área. En este sentido, los resultados se discuten en función de información paleodietaria y los antecedentes arqueológicos disponibles. Keywords Otaria flavescens Seasonality Patagonia Hunter-gatherers Coastal occupations Palabras claveOtaria flavescens Estacionalidad Patagonia Cazadores-recolectores Ocupaciones costeras ISSN 0327-5159 (impresa) / ISSN 1853-8126 (en línea) Arqueología 25(2) mayo-agosto: 247-262 (2019) 248 P. Ambrústolo et al

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“…For this study, only male individuals older than 5 years (sub-adult and adult age classes) were considered, this is because juvenile males have a different diet than the subsequent age classes (Vales et al, 2015). Individual ages were estimated from counts of growth layer groups (GLGs) in the dentine and/or in the cementum of teeth assuming that one GLG is deposited per year (Schiavini et al, 1992;Crespo et al, 1994;Molina-Schiller and Pinedo, 2004). In order to prevent damage to the skulls, a small fragment of maxillo-turbinal bone from the nasal cavity was sampled (Drago et al, 2009), and then stored dry until isotope analysis.…”

Section: Samplingmentioning

confidence: 99%

Long-Term Stability in the Trophic Ecology of a Pelagic Forager Living in a Changing Marine Ecosystem

et al. 2020

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Natural or human-induced environmental changes can modify the structure of ecological communities and thus alter food web interactions. After the collapse of hake stocks (Merluccius hubbsi) provoked by fisheries over the Patagonian shelf in 1997 profound changes have taken place in the community, including long-term dietary shifts in some marine vertebrate predators. Stable carbon (δ 13 C) and nitrogen (δ 15 N) isotope ratios in bone collagen of subadult and adult male South American fur seals (Arctocephalus australis) were measured for the period 1976-2017 to investigate if the changes occurred in the marine community from northern and central Patagonia affected the diet of this predator. Suess corrected δ 13 C values and δ 15 N values in bone collagen of fur seals did not change significantly over the study period. According to this, male fur seals have remained as pelagic foragers without changing their trophic position nor switching their main preys in the Patagonian food web over the last four decades. This longterm stability in the diet of fur seals contrasts with dietary changes reported for benthic foragers in the region. Although long-term diet studies are restricted to a few marine predators in the region, current evidence suggests that benthic-demersal foragers were more prone to dietary shifts than pelagic ones after perturbations that occurred in the marine community of northern and central Patagonia.

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Growth layer patterns in Arctocephalus australis canine teeth: evaluation of techniques for age determination

Cited by 14 publications

References 17 publications

Size and shape sexual dimorphism in the skull of the South American fur seal, Arctocephalus australis (Zimmermann, 1783) (Carnivora: Otariidae)

Size and shape sexual dimorphism in the skull of the South American fur seal, Arctocephalus australis (Zimmermann, 1783) (Carnivora: Otariidae)

Death seasonality determination from pinnipeds teeth: the Cueva del Negro site case (Argentine Patagonia)

Long-Term Stability in the Trophic Ecology of a Pelagic Forager Living in a Changing Marine Ecosystem

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