Resumo

BODNAR, Josefina  e  COTUREL, Eliana Paula. El origen y diversificación del crecimiento cambial atípico en plantas fósiles: procesos del desarrollo involucrado. Bol. Soc. Argent. Bot. [online]. 2012, vol.47, n.1-2, pp.33-70. ISSN 1851-2372.

Origin and diversification of atypical cambial growth in fossil plants: developmental processes involved. We found a series of morphologies in the fossil record whose origin can only be inferred by means of ontogenetic studies. Therefore, comprehension of plant developmental processes and their resultant patterns are extremely important in Paleobotany. In this contribution, we exposed the relation between developmental processes and the different patterns observed in fossil plant secondary growth. Polished surfaces, peels and thin slides of silicified trunks belonging to Lycopsida, Sphenopsida, Medullosales, Corystospermales and Cycadales, were studied. We identified a diversity of cambial patterns which can be clustered in two main groups: whirling pattern and cambial variants (e.g. unifacial, radial and tangential fragmentation of vascular elements, polyxyly, inverse orientation and medullary system). The appearance of whirling pattern was related to the origin of the Lygnophyta clade. The cambial variants characterize specific groups and have undergone a significant evolutionary diversification linked with developmental events.

Palavras-chave : Evo-devo; Paleobotany; Cambium; Secondary vascular tissues.

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