Australia: The Land Where Time Began

A biography of the Australian continent 


The origin and relationships of the Podocarpaceae are uncertain. according to cladograms constructed by Miller (1988), Podocarpaceae and Cephalotaxaceae occur near each other consistently. In Triassic deposits from Madagascar, South Africa, Australia,  and Antarctica (Townrow, 1967b), the presence of Rissikia indicates that the family had already arisen by start of the Mesozoic (Miller, 1988). Nothodacrium (Townrow, 1667b) and Mataia (Townrow, 1667a), from the Jurassic, are believed to probably be podocarps, though their relationships to modern taxa is uncertain (Stockey, 1990).

There are 18 extant genera with more than 150 species in this family, of which the genus Podocarpus has more than half of all species, the next largest being Dacrydium with 16 species. Of these species, 6 are now present in Australia, mostly species being restricted to Tasmania and northeast Queensland.

Extinct genera of Australian podocarps, such as the Early Cretaceous Bellarinea barklyi,  from Victoria, were prominent in the Early Cretaceous (Drinnan & Chambers, 1986). At this time the pollen record is more useful, allowing the documentation in the fossil record of Dacrycarpus, Dacrydium and Podocarpus, all extant genera from the pollen record in the Antarctic-Australia rift valley (Dettmann & Jarzen, 1990). From this it has been found that in southern Australia Dacrycarpus pollen is present in deposits from the Late Cretaceous to the Pliocene, making it the earliest known record of this pollen type. The earliest known macrofossils of Dacrycarpus were reported from the Indian Jurassic (Florin, 1940). It has been suggested that it is very unlikely that the earlier pollen that had been defined as Dacrycarpus pollen (Dettmann & Jarzen, 1990), was actually produced  by Dacrycarpus, as pollen of this type is produced by a number of extant genera. A pollen morphotype that has been associated with fossils designated as Lygistepollenites, that was widespread in deposits from the Late Cretaceous of southern Gondwana, is consistent with living Dacrydium. The earliest occurrence known of this pollen, in the Coniacian-Santonian, is found in southern Australia and Antarctic Peninsula.

In New Zealand, a Dacrydium pollen type consistent with modern genera, such as Halocarpus, that is similar to Podocarpus pollen, has counterparts in Jurassic deposits.

Sources & Further reading

  1. Hill, Robert S., (ed.), 1994, History of the Australian Vegetation, Cambridge University Press. 
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