The extinction of Neanderthals and the emergence of the Upper Paleolithic in Portugal

Este trabalho foi apresentado no âmbito de Provas de Agregação na área de Arqueologia. Estas provas académicas, constituídas por 3 fases, são de carácter público. Para cada fase existe um arguente, sendo as fases, respectivamente, a discussão do currículo do candidato, a análise de um relatório de uma disciplina do ensino universitário e uma lição-síntese, seguida de discussão. Esta última prova consiste numa apresentação de uma hora de um tema à escolha e, como parte constituinte das Provas de Agregação, pode ser pensada de duas formas essencialmente opostas: uma de entre as várias lições do programa da disciplina apresentado no relatório acima mencionado, fazendo por isso a descrição de uma qualquer parte do conteúdo desse mesmo programa; ou, pelo contrário, respeitar o título da prova e fazer-se uma verdadeira lição síntese, de carácter inédito.

Status and the potential for extinction of the largetooth sawfish Pristis pristis in the Atlantic Ocean

1. Sawfishes currently are among the most threatened elasmobranchs in the world. Only two species inhabit Atlantic waters: the largetooth sawfish (Pristis pristis) and the smalltooth sawfish (Pristis pectinata), both having suffered dramatic declines in their ranges. 2. The goal of this study was to evaluate the status of P. pristis in the Atlantic, and estimate local extinction risk based on historical and recent occurrence records. In order to accomplish these goals, a thorough search for historical and recent records of P. pristis in the Atlantic was conducted, by reviewing scientific and popular literature, museum specimens, and contacting regional scientists from the species’ historical range. 3. In total, 801 P. pristis records (1830–2009) document its occurrence in four major regions in the Atlantic: USA (n =41), Mexico and Central America (n =535), South America (n=162), and West Africa (n =48). Locality data were not available for 15 records. 4. Historical abundance centres were the Colorado-San Juan River system in Nicaragua and Costa Rica (and secondarily Lake Izabal of Guatemala), the Amazon estuary, and coastal Guinea-Bissau. 5. Currently, the species faces drastic depletion throughout its entire former range and centres of abundance. It appears to have been extirpated from several areas. The probability of extinction was highest in the USA, northern South America (Colombia to Guyane), and southern West Africa (Cameroon to Namibia). 6. Currently, the Amazon estuary appears to have the highest remaining abundance of P. pristis in the Atlantic, followed by the Colorado–San Juan River system in Nicaragua and Costa Rica and the Bissagos Archipelago in Guinea Bissau. Therefore the protection of these populations is crucial for the preservation and recovery of the species.