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segunda-feira, 14 de março de 2011

Evolução 223: Tarsius sirindhornae

Cientistas descobriram uma nova espécie fóssil de társio em jazidas tailandesas do Mioceno Médio, batizada de Tarsius sirindhornae.


A new Middle Miocene tarsier from Thailand and the reconstruction of its orbital morphology using a geometric–morphometric method
  1. Yaowalak Chaimanee1,2,*,
  2. Renaud Lebrun3,
  3. Chotima Yamee1 and
  4. Jean-Jacques Jaeger2

+ Author Affiliations

  1. 1Palaeontology Section, Department of Mineral Resources, Rama VI Road, Bangkok 10400, Thailand
  2. 2IPHEP: Institut International de Paléoprimatologie et Paléontologie Humaine, Éolution et Paleoenvironments, CNRS UMR 6046-Université de Poitiers, 40 Avenue du Recteur Pineau, 86022 Poitiers, France
  3. 3Anthropological Institute, University of Zürich, Zürich, Switzerland
  1. *Author for correspondence (yaowalak@dmr.go.th).

Abstract

Tarsius is an extant genus of primates endemic to the islands of Southeast Asia that is characterized by enormously enlarged orbits reflecting its nocturnal activity pattern. Tarsiers play a pivotal role in reconstructing primate phylogeny, because they appear to comprise, along with Anthropoidea, one of only two extant haplorhine clades. Their fossils are extremely rare. Here, we describe a new species of Tarsius from the Middle Miocene of Thailand. We reconstructed aspects of its orbital morphology using a geometric–morphometric method. The result shows that the new species of Tarsius had a very large orbit (falling within the range of variation of modern Tarsius) with a high degree of frontation and a low degree of convergence. Its relatively divergent lower premolar roots suggest a longer mesial tooth row and therefore a longer muzzle than in extant species. The new species documents a previous unknown Miocene group of Tarsius, indicating greater taxonomic diversity and morphological complexity during tarsier evolution. The current restriction of tarsiers to offshore islands in Southeast Asia appears to be a relatively recent phenomenon.

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