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Communication Dans Un Congrès Année : 2020

Adaptation of vision to depth in shrimps from the Late Cretaceous of Lebanon

Denis Audo
Norbert Winkler
  • Fonction : Auteur

Résumé

Exceptionally preserved fossil fishes from Leba-non have been reported from Lebanon since, at least, the 13th century. These fishes come from Cenomanian and Santonian outcrops (Fossil-La-gerstätten) with exquisitely preserved fossils (articulated, with soft parts), which also yield a very diverse fauna of crustaceans. Among crus-taceans, Dendrobranchiata shrimps are among the most abundant, and those from the Santo-nian of Sahel Alma often possess unusually bi-lobed eyes. Systematic investigations show that shrimps with bilobed eyes often belong to dis-tinct families, and their closest relatives from the Late Jurassic of Solnhofen and from extant faunas have subspheric eyes (the usual shape for most shrimps). The bilobed eyes seem therefore to be specific to the shrimps of Sahel Alma. Observa-tions of the ommatidia of a particularly well-pre-served specimen show the eyes were probably well-suited for low light conditions (reflective su-perposition optics). We also observe specializa-tion of certain areas of the eye with larger om-matidia on the anterior lobe than the posterior lobe, suggesting that the anterior lobe, pointing downward, perhaps had an increased sensitivity and the posterior lobe a slightly higher resolu-tion. These shrimps with bilobed eyes are a re-markable case of convergent evolution, proba-bly linked to the regional tectonically controlled increase in depth during the Late Cretaceous
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Dates et versions

hal-02963618 , version 1 (13-10-2020)

Identifiants

  • HAL Id : hal-02963618 , version 1

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Denis Audo, Norbert Winkler, Sylvain Charbonnier. Adaptation of vision to depth in shrimps from the Late Cretaceous of Lebanon. 2nd Palaeontological Virtual Congress, May 2020, Valencia (Virtual ), Spain. ⟨hal-02963618⟩
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