Leafy branches of Gangamopteris from the Gzhelian-Asselian of westernmost Gondwana.

FERNÁNDEZ, JOHANA ANTONELLA; CÉSARI, SILVIA NÉLIDA

COMPTES RENDUS PALEVOL

ELSEVIER FRANCE-EDITIONS SCIENTIFIQUES MEDICALES ELSEVIER

Lugar: Paris; Año: 2019 vol. 18 p. 913 - 924

1631-0683

tThe first reconstructions of glossopterids interpreted this Gondwanan group as arborescent,deciduous plants, with leaves and reproductive structures inserted on short shoots, whichwere arranged on long branches. The leaves are its most abundant organ in the fossil record,but they are mainly found isolated. The arrangement of the leaves as terminal whorls ortight spirals has been the most accepted phyllotaxis hypothesis. The few examples of leafimpressions preserved in connection with axes correspond mainly to leaves of GlossopterisBrongniart, and mostly without clear evidence of the type of insertion. Several specimensof Gangamopteris McCoy leaves attached to axes from the Bajo de Véliz Formation (LatestCarboniferous?Earliest Cisuralian) facilitate reconstruction of the foliar arrangement of thegenus, to date known mostly from isolated leaves. The available evidence from the newspecimens confirms a variation from well-spaced to dense helical insertion of the leaveswithout forming true whorls, and discards the early notion that they were mainly clusteredapically on short shoots in a similar manner to the extant Ginkgoales.