Ultrastructural study of Arcellites humilis Villar de Seoane and Archangelsky, 2008, from the Cretaceous of Patagonia, Argentina - 11/07/13
Abstract |
A scanning and transmission electron microscopy-based ultrastructural study of Arcellites humilis Villar de Seoane and Archangelsky, 2008 , from the Kachaike Formation and Piedra Clavada Formation (Albian-Cenomanian) from several localities in Patagonia (Argentina), is presented in this paper. TEM-photographs of thin-sectioned specimens show a thick spore body wall composed of three layers: a thin and dense exine, an inner granular perine sublayer with irregularly disposed small channels and lacunae, and an outer alveolate perine sublayer with channels perpendicular to the external surface. Transverse sections of the A. humilis wall are compared with fossil and extant species of Marsileaceae. We show that the wall ultrastructure is similar in A. humilis, A. santacrucensis, A. disciformis, A. stellatus and Regnellidium upatoiensis. However, the body wall and acrolamella of A. humilis are more similar to those of R. diphyllum Lindman than to those of the Marsilea L. or Pilularia L. species. Water ferns such as members of the Marsileaceae played an important role in aquatic or semi-aquatic niches in Patagonian Cretaceous floras, suggesting that high humidity and temperature prevailed during the Albian-Cenomanian in this region of Argentina.
Le texte complet de cet article est disponible en PDF.Keywords : Ultrastructure, Megaspores, Marsileaceae, Cretaceous, Patagonia, Argentina
Plan
☆ | Corresponding editor: Marc Philippe. |
Vol 46 - N° 3
P. 243-252 - mai 2013 Retour au numéroBienvenue sur EM-consulte, la référence des professionnels de santé.
L’accès au texte intégral de cet article nécessite un abonnement.
Déjà abonné à cette revue ?