Although the araucarians are restricted today to the southern hemisphere, fossil evidence from the Mesozoic demonstrates that they were widespread throughout the world from the Triassic through the Cretaceous. Their present day distribution probably dates back to the Tertiary. Look briefly at the Jurassic Araucaria cone and at the paper by Stockey on the history of the araucarians. These plants are mostly dioecious trees or shrubs with spirally arranged, scalelike, linear or broad leaves. Pollen cones have 2 microsporangia per microsporangium while seed cones have one ovule maturing per ovulate structure that is conelike or modified into several small scales and a subtending bract.
Pollen is saccate.
In contrast to the araucarians, which had a wide distribution in the Mesozoic, the podocarps have always been essentially southern hemisphere plants. Podocarps are first recognized in the Triassic, and become extensive in the Jurassic of Gondwana. Vegetative and reproductive structures referred to the genus Rissikia from Australia and Africa are podocarpaceous, as are several Jurassic forms. Recently a podocarpaceous stem has been described from the Triassic of Antarctica. The Pinaceae are the best known and largest family of extant conifers, and are probably the most familiar to you because they are a predominantly northern hemisphere group well represented in the current flora.