AMBER, THE LOOKING GLASS INTO THE PAST

A variety of techniques are used to reconstruct biodiversity. Techniques using fossil specimens can be employed to reconstruct biodiversity. Techniques such as acetone peels, cat scans and x-rays are also used. Fossils found in amber (fossilized tree sap or resin) really drew my attention, as the degree of preservation is phenomenal.

Amber originated from an extinct tree namely, Hymenaea which was prevalent in an ancient rainforest. Animals, plants and animals became entrapped in this resin leaving us with exquisite detail of what life was like millions of years ago. Amber even provides awesome preservation of internal organs, soft tissue, the last meal of an organism and muscles. Amber is therefore able to explain a lot in terms of evolutionary processes [1].

Most of the inclusions found in amber are those of extinct species [1]. Some rare inclusions are those of lizards, scorpions, mammal hair and blood filled ticks. Seeds, leaves and buds are among those of botanical inclusions. In some rare cases, pollen streams were created as the resin flowed over the flower and the pollen was carried away thus creating a scene so realistic as if the winds were still blowing.

There are various kinds of Amber namely Baltic, Bitterfeld (Saxon), Florissant, Dominican and Lebanese amber. Baltic amber is the most famous dating back to the Early Eocene and Early Oligocene. Baltic amber was formed in the vast forests of Fennoscandia consisting mainly of Arecaceae (palms) and Fagaceae (oaks) and a few conifers. Pinaceae and Cupressaceae were probably the main plants to produce resin. Organisms were entrapped in the resin and fossilization occurred over millions of years under high pressure and anaerobic conditions. The amber was washed into the Baltic Sea where it is still prevalent today [1].

Although amber can be found in the North Sea and the Baltic Sea, it does not compare to the vast amounts found in Sambia that forms part of Russia. About 90% of the world’s extractable amber can be found in the Kaliningrad region of Russia on the Baltic Sea. Amber is collected by using nets that are attached to long poles, or it is raked up between the boulders in shallow waters from boats. Divers also retrieve amber found in deep waters. Extensive mining is presently being undertaken in the search for more amber.

Firstly, I will be looking at bacteria found in Amber. You may ask why bacteria and of what importance are they to us? All organisms contribute to life in some way and provide unique insights that are lost forever if species become extinct [2]. Bacteria are not all bad as they play vital roles in the global ecosystem. The insights from one species could very likely open the doors to new information about past and present evolution.

The oldest bacteria found in Dominican amber are believed to be about 25 to 40 million years old. This evidence came from retrieving and identifying a bacterial spore from the abdominal contents of extinct bees. The bacterium survived for millions of years without air or nutrients. It is able to have long periods of dormancy. Evidence showed that the isolated bacterium actually possessed qualities of an ancient origin. Further investigations gave the indication that the ancient bacterium is very closely related to extant Bacillus sphaericus. Cano claims to have discovered 30 to 40 species of Bacteria. Most are from the genus Bacillus. Some of the organisms from the genus, Bacillus thuringiensis are used for biological control of insects [3].

There is evidence of bacteria in the fossil record. Who would have thought that bacteria could in actual fact leave fossils? The oldest fossils known that are quite similar to cyanobacteria, are about 3.5 billion years old [4]. These are however not found in amber. Because they are the oldest fossils known today they are therefore very important as they can tell us more about our history. Structures called stromatolites come from Cyanobacteria [4]. When these fossil stromalites are carefully sectioned, the discoveries are phenomenal. One is able to observe fossil cyanobacteria and algae with a very high degree of preservation.


The picture above depicts cyanobacterial cells aged at about 1 billion years old. These cells are actually very similar to present day cyanobacteria. This is not only true for an isolated case but many living genera of cyanobacteria can be linked to fossil cyanobacteria. The detail noted in the fossils of this group gives indication of extreme conservation of morphology, more extreme than in other organisms [4].

The record held for the smallest fossils (a few hundred millionths of a meter) are those of magnetobacteria. This group of bacteria actually form nanometer-sized crystals of magnetite (iron oxide) inside their cells. These crystals have been found in rocks aged two billion years old [4].

Secondly, an amazing discovery was made finding a bee embedded in amber aged 100 million years old. This may even be the oldest bee ever discovered. Poinar (2006) says that this discovery “pushes the bee fossil record back about 35 million years”. This bee was found in a mine in northern Myanmar (Burma) by Danforth and Poinar.

Scientists are under the notion that the first appearance of bees was about 120 million years ago. Unfortunately, previous fossil records could only be dated back to 65 million years. There is strong evidence presently indicating a more remote ancestor due to the contributions made by Danforth and Poinar. Their fossil also indicates a link between bees and wasps as wasp traits are prevalent in the fossil found [5].

Learning more about the evolutionary patterns of bees, one is able to relate it to the evolution of flowering plants. This is due to an assumption that bees have always been around facilitating in pollination of plants thus creating a vast number of new species [5].

Many researchers believe that bees originated in the Southern Hemisphere (either South America or Australia) because primitive bees are believed to come from the family, Collectidae. Danforth’s work suggests otherwise indicating the family Mellittidae as the origin. Taking the latter into consideration, it would mean that bees actually have an African origin and could very likely be nearly as old as flowering plants [5]. This would tell us a lot about these plants evolutionary diversification.

Fossils found in amber also portray the social interactions between organisms e.g. mating, commensalism and parasitism, trapping two fossils in one piece of amber [6]. Nematode parasites from the family Mermithidae target ants as their main host group. Baltic amber has captured the attack of a nematode juvenile on a male ant [7]. This information indicates the prevalence of parasitic interactions with ants in the Eocene.

Amber has become very popular in the jewellery industry and I think that human greed for wealth might be the driving force for discovering new and fascinating fossils in their search for amber.

References:

[1] Rossi, W., Kortrba, M., Triebel, D. (2004). A new species of Stigmatomyces from Baltic amber, the first fossil record of Laboulbeniomycetes. The British Mycological Society. 109 (3): 271-274

[2] Kunin, W.E. & Lawton, J.H. (1996). Does biodiversity matter? Evaluating the case for conserving species. In: Biodiversity, a biology of numbers and difference, K.J. Gaston (ed.), Blackwell Science, Oxford, pp. 283—308.

[3] Cano, R.J. & Boruck M.K. (1995). Revival and identification of bacterial spores in 25 to 40 million-year-old Dominican amber. Science. 268(5213): 1060-4

[4] http://www.ucmp.berkeley.edu/bacteria/bacteriafr.html

[5] Poinar, G.O. & Danforth B.N. (2006). A fossil bee from Early Cretaceous Burmese Amber. Science. 314#5799: 614

[6] http://www.iob.org/downloads/1153.pdf

[7] http://journals.cambridge.org/download.php?file=%2FPAR%2FPAR125_05 2FS0031182002002287a.pdf&code=4d0c6b99c0a6540c7fc0936b8a4b398c