Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 2 de 2
Filtrar
Mais filtros

Base de dados
País/Região como assunto
Ano de publicação
Tipo de documento
Intervalo de ano de publicação
1.
Science ; 374(6573): eabj8723, 2021 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-34882454

RESUMO

Sibert and Rubin (Reports, 4 June 2021, p. 1105) report an early Miocene extinction in pelagic sharks based on the loss of shark denticle diversity in two widely separated deep-sea sediment cores. We assert that the pattern observed is not a consequence of extinction but results from shifting species ranges induced by global current reorganization.


Assuntos
Tubarões , Animais
2.
PLoS One ; 5(5): e10552, 2010 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-20479893

RESUMO

BACKGROUND: As we know from modern species, nursery areas are essential shark habitats for vulnerable young. Nurseries are typically highly productive, shallow-water habitats that are characterized by the presence of juveniles and neonates. It has been suggested that in these areas, sharks can find ample food resources and protection from predators. Based on the fossil record, we know that the extinct Carcharocles megalodon was the biggest shark that ever lived. Previous proposed paleo-nursery areas for this species were based on the anecdotal presence of juvenile fossil teeth accompanied by fossil marine mammals. We now present the first definitive evidence of ancient nurseries for C. megalodon from the late Miocene of Panama, about 10 million years ago. METHODOLOGY/PRINCIPAL FINDINGS: We collected and measured fossil shark teeth of C. megalodon, within the highly productive, shallow marine Gatun Formation from the Miocene of Panama. Surprisingly, and in contrast to other fossil accumulations, the majority of the teeth from Gatun are very small. Here we compare the tooth sizes from the Gatun with specimens from different, but analogous localities. In addition we calculate the total length of the individuals found in Gatun. These comparisons and estimates suggest that the small size of Gatun's C. megalodon is neither related to a small population of this species nor the tooth position within the jaw. Thus, the individuals from Gatun were mostly juveniles and neonates, with estimated body lengths between 2 and 10.5 meters. CONCLUSIONS/SIGNIFICANCE: We propose that the Miocene Gatun Formation represents the first documented paleo-nursery area for C. megalodon from the Neotropics, and one of the few recorded in the fossil record for an extinct selachian. We therefore show that sharks have used nursery areas at least for 10 millions of years as an adaptive strategy during their life histories.


Assuntos
Ecossistema , Extinção Biológica , Tubarões/fisiologia , Animais , Fósseis , Geografia , Estágios do Ciclo de Vida , Modelos Biológicos , Panamá , Tubarões/anatomia & histologia , Tubarões/crescimento & desenvolvimento , Fatores de Tempo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA