AGATHIS AMBER: A CRETACEOUS INSECT TRAP

The significance of Agathis species that have contributed to Cretaceous amber deposits throughout the world is just being recognized. The use of nuclear magnetic spectroscopy has permitted researchers to identify Agathis as the plant source of Cretaceous amber, which include the Canadian, New Jersey, Alaskan, Burmese and Lebanese deposits as well as samples buried one mile under the Persian Gulf. These latter deposits indicate that Agathis forests could have provided the source plants for crude oil. The widely dispersed Agathis amber sources indicate the extensive range of these ancient araucarians during the Cretaceous and suggest that Agathis was a key species in the vast forests that existed at that time. Not only were the trees important in the ecology of the Cretaceous habitat, but also their resin served as traps for the organisms living there. These amber-embedded invertebrate and plant fossils give us further information about forest life and allow us to reconstruct previously unknown ecosystems. The process from resin to copal to amber can be documented with the New Zealand Kauri pine, Agathis australis. Studies of these processes allow insight into the mechanisms of amber formation in the Cretaceous and show how much resin could have been produced in those ancient forests. This is the only species of Agathis that provided man with a commercial use of its resin. The picturesque history of man’s quest for Agathis resin and copal is well established. During this period, studies on the chemistry and analysis of Agathis resin provided the basis for studies on the preservative qualities of amber. Unfortunately Agathis species today are restricted to relictual populations living at the brink of extinction in a few locations in the southern hemisphere. The various Agathis-derived Cretaceous amber deposits are briefly discussed and significant fossil discoveries noted such as new families of insects, blood-sucking invertebrates that could have fed on dinosaurs, beetles with extra leg joints, earliest appearance of plant families and terrestrial gastropods. Cretaceous amber also has provided us with the earliest records of ecto and endo parasitism of terrestrial animals, including the earliest fossil nematode.