The Southern Hemisphere conifer family Araucariaceae contains three extant genera: Araucaria, Agathis and the recently described Wollemia. While the distribution of these taxa is restricted today, they were much more widespread in the past. The genus Araucaria was the most widespread and is well known from both the Northern and Southern Hemispheres. Well-preserved seed cones of Araucaria occur in the Jurassic Cerro Cuadrado petrified forest of Patagonia, two localities in the UK, several localities on Hokkaido, Japan and Saghalien, and most recently from the Jurassic Morrison Formation of Utah. While earlier data seemed to indicate that the Section Bunya of the genus Araucaria was the most common fossil type, new records show that by the Jurassic in the Northern Hemisphere there was a generalized araucarian type with several distinct species. Nearly all of these cones show evidence of embryo structure in the permineralized seeds. Some cones, however, are immature and reveal the remains of free nuclear megagametophytes. The characteristic wavy nucellar apex in the fossil forms indicates a similar pollination mechanism in all of these fossil araucarians similar to that reported for living Agathis australis. In addition to the distinct nucellar structure, fossil pollen tubes indicate that like extant araucarians pollen landed on the nucellus and scale tip, branching after penetration of the nucellar tip, growing next to the megagametophyte prior to penetration of the archegonium. Seed cone and embryo structure indicate that seed germination was epigeal like that seen in Agathis, and Araucaria Section Eutacta. Embryos had two cotyledons in all the fossil forms examined with structure similar to those of Agathis rather than the four cotyledons seen in Section Euctacta species. Evidence of regeneration after fire damage can be seen in the araucarian fossils from Argentina, Japan and Saghalien from the presence of what are probably aerial lignotubers.

Key words: Agathis, Araucaria, conifers, fossil, pollen tubes, reproductive biology