Thursday 9 January 2014

Agamid Lizard remains from the late Early Pleistocene of Spain.

Western Europe is thought to have had a diverse Squamate (Snake and Lizard) fauna during the Miocene, but to have largely lost this during the cooling climate of the Plio-Pleistocene, during which time Squamate groups are thought to have progressively disappeared. Varanid (Monitor) Lizards, Aniliid (False Coral) Snakes and Elapid Snakes (Cobras and Sea Snakes) are thought to have disappeared about 3.2 million years ago, Geckos, Scolecophidian (Blind or Thread) Snakes, Boas and Oriental Vipers around 2.6 million years ago, Agamid Lizards about 1.8 million years ago and Anguid Lizards (Slowworms) about 1.3 million years ago.

In a forthcoming paper in the journal Acta Palaeontologica Polonica, available online since 13 May 2013, a team of scientists led by Hugues-Alexandre Blain of the Institut Català de Paleoecologia Humana i Evolució Social describe a collection of Agamid Lizard remains from the late Early Pleistocene of the Sierra de Quibas in southeastern Spain.

Blain et al. do not attempt to classify these remains to species level, but are confident that they do belong to Agamid Lizards. They note that this extends the known presence of Agamid Lizards in Western Europe by about 500 000 years, from 1.8 million years ago to around 1.3 million years ago, though also that the area where the remains were found has the warmest climate in Western Europe, so the presence of Agamids later than elsewhere in the region is not greatly surprising.

Agamid Lizard remains from the late early Pleistocene of Sierra de Quibas, Murcia, southeastern Spain. (A) Right maxilla in lateral (A1) and medial (A2) views. (B) Left dentary in lateral (B1) and medial (B2) views. (C) Right dentary in lateral (C1) and medial (C2) views. (D) Trunk vertebra in dorsal (D1), ventral (D2) and posterior (D3) views. (E) Anterior caudal vertebra in dorsal (E1), ventral (E2), anterior (E3), posterior (E4) and left lateral (E5) views. Blain et al. (2013).

Blain et al. also note that a previous find, comprising a single dentary (jawbone) of an Agamid Lizard from Monte Tuttavista on Sardinia was previously considered to be of similar age, but that the dating of this specimen has been called into question, and that a single skeletal element should be treated with caution anyway, as this could possibly be the result of contamination. They contend that the dating of the Sierra de Quibas can be more confidently asserted, and that the larger number of specimens makes the possibility of contamination less likely.

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