On the genus Tomaxellia (Coniferae) from the Lower Cretaceous of Patagonia (Argentina) and its male and female cones

Abstract

This paper reports the organic attachment of male and female cones to twigs previously described as Tomaxellia biforme Archangelsky. The male cones produce Classopollis pollen, while the scales of the female StIWCtWeS are comparable to the Rhaeto-Liassic northern genus Cheirolepidium. A new interpretation of the possible femqle cone of Cheirolepidium is presented, based on the new evidence now available with the knowledge of Tomaxeellia cones. Other female cones found in Mesozoic formations may be comparable to some extent with Tomaxellia, such as Indostrobus (Cretaceous of India) or Paruraucaria (Jurassic of Argentina), and they may be grouped in the family Cheirolepidiaceaa. Comparisons with older conifer genera with known female cones are also included (Voltziaceae). Some morphological changes of the female cones, which probably took place during the Mesozoic (in these particular groups) are also inferred.