THE STUDY OF AMBER PIECES WITH SEVERAL
INCLUSIONS INSIDE

 

Laima Vaiciulyte,

Palanga amber museum (Lithuania)

 

The fauna, flora and ecological conditions of the ancient Baltic amber forest have been the object of study for more than a century from quite different scientific points of view. A good summary of nearly one hundred and fifty years of scientific research on Baltic amber flora and fauna has been published by Larsson S. G. (Larsson S. G. 1978). In this monograph he tried to overview all groups of flora and fauna from Baltic amber and attempted to group them according to their living environments and biology. Later, a short summary of amber trees biotopes was done by Katinas V. (Katinas V. 1983). More detailed overview of inclusions from amber was published by Poinar G. O. (Poinar Jr. G. O. 1992). A controversial picture of amber forest has been presented by Lourenco W. R. and Weitschat W. (Lourenco W. R., Weitschat W. 1996). There they explained why a fossil scorpion Palaeochylas balticus (which has closest recent living relatives in the tropical forests of South-East Asia, North Australia, Indo-Malayan region and some parts of Africa) might live in usually judged as subtropical or even Palaearctic or Nearctic (Ander K., 1942) climate of today amber forests. Baltic amber forest was immense, covering large areas of what is now Scandinavia and northern Europe almost to the Urals (Poinar G. O., 1992, p. 265).

In my work I will classify amber pieces with groups of inclusions inside (with more than seven inclusions) into three groups, using a modified system of Larsson S. G., in order to find out which part of the amber tree particular piece of amber with inclusions has come from.

Materials and methods

About 3000 pieces with inclusions from Palanga amber museum were investigated, from which only 100 pieces of amber with inclusions had more than seven inclusions inside. Those were examined more detailed by binocular microscope. Systematic position was determinate till the level of families. Generally, in Baltic amber from Palanga amber museum amber contains 1.3 inclusions per piece. The biggest one examined by me has 95 specimens of different inclusions inside.

Description of zones

A vertical layering can be observed in an amber forest. Conditions of light and humidity in this forest must have varied from the base of a tree to the treetops. There can be separated three zones in the amber forest: “Sciara” zone, the tree-trunk zone and the crown of a tree zone.

“Sciara” zone

Among the amber fossils, there is large number of one biological type from that animal life which has been widely distributed in the forest floor. This is the type of animal, which lives larval live in rotting vegetation and adult's existence free in the vegetation of the forest undergrowth. The most characteristic representatives are Diptera Sciaridae - fungus gnats. Others, belonging to this wet, filled with mold-forming plant material were Diptera Mycetophilidae, part of Diptera Chironomidae, etc. Moss, liverwort, lichen, fungi were abundant in this zone. (Katinas V. 1983, p.20-21).

The fauna of moss and bark with a great variety of groups also could be found there.

Diptera from families Sciaridae, Mycetophilidae preferred wet, shadowed undergrowth. Part of representatives from families Empididae, Dolichopodidae hunted on them. Collembola, Acarina, Pseudoscorpiones, Coleoptera Carabidae, Silphidae, Embioptera, Dermatptera belonge to this zone. Blatoides, Myriopoda, Formicidae were found here.

The tree trunk zone

The fauna has been of a different type of this shadowed, partly sunny, less humid region.Mostly of Diptera were hound there. Part of them was caught while resting, part of them while feeding. This is the zone, which has contained many spiders, Diptera Ceratopogonidae, Diptera Empididae, Diptera Rhagionidae (Larsson S. G. 1978, p. 182). The hidden fauna of tree trunks (Coleoptera Buprestidae, Anobiidae, Mycetophagidae) belonged to this level.

The fauna of the crown of the amber trees (tree crown zone).

Fossils, which with certainty must have originated from the crown of the amber trees, are unknown. Only some good fliers seed and leave eaters, or nectar seekers may have belonged to it. They were Apoides (bees), Diptera Tabanidae, Syrphidae, part of Curculionidae (weevils).

 

Results

Several examples are presented here.

Amber piece No. ED 159 containing 20 inclusions and a piece of a lizard skin. In this piece 55% of the fauna are from the “Sciara” zone, 35 % - from the tree trunk zone and 10 % - from an undetermined location (undeterminated larva, Diptera Brachycera). The formation of such piece might take place on the “Sciara” zone. The part of a lizard skin also pointed to this.

Piece of amber Ap. 14597, contains 95 inclusions in it. 61 of them are Acarina - mites. 73 % of a fauna in this piece belong to “Sciara” zone.

Piece of amber Ap. 14580 contains 29 inclusions in it. 44 % of fauna belong to “Sciara” zone, 38 % of them belong to tree trunk zone, and 18 % are remnants and inclusions without clear location.

From the study of 100 specimen of amber pieces with several inclusions, 50 % of them probably had been formed in the “Sciara” zone, 40 % - in the tree - trunk zone, 2 % - in the tree - crown zone and 8 % belonging equally to “Sciara” and the tree trunk zones.

 

Conclusions

Pieces of amber with several inclusions inside are quite rare. Most of amber with inclusions was formed in the lower part of an amber tree, in so-called “Sciara” zone.

Some elements in amber pieces determined as from the “Sciara” zone, are from the tree trunk zone. It proves the flow of a resin downwards, catching on its way bits of fauna and flora from the different vertical levels. The biggest excretion of a resin took place in the tree trunk zone. There were no strong boundaries between vertical levels. In order to receive more information, systematic determination must be more detailed, to the level of genus or species.

 

References

Ander K. Die Insectenfauna des Baltischen Bernstein nebst damit verknupften zoogeographischen problemen. - 1942, Lunds. Univ. Aarskr. n. f. p. 85.

Larsson S. G. Baltic amber - a Palaeobiological study. - 1978, Entomonograph, vol. 1. Scandinavian Science Press Ltd., Klampenborg, Denmark.

Lourenco W. R., Weitschat W. More than 120 years after its description, the enigmatic status of the genus of the Baltic amber scorpion “Tityus eogenus” MENGE, 1869 can finally be clarified. - 1996, Mitt. Geol.-Palaont. Inst. Univ. Hamburg. Heft 79, s. 183-193.

Katinas V. Baltijos gintaras. - 1983, Vilnius, Mokslas. P. 19-46.

Poinar Jr. G. O. Life in amber. - 1992, Stanford University Press, California. P.68-241.

 

Prepared by: Vaiciulyte L. The study of amber pieces with several inclusions inside // Baltic Amber / edited by Adomas Butrimas. - Vilnius: Publishing Office of Vilnius 

Academy of Fine Arts, 2001. P. 41-42.