AMBER - Inclusions and the world of amber

One must remember that the resin acted as a trap for everything that it came in contact with. Overall, it can be stated that what is most often found in Baltic amber are smaller animals of about 1 to 5 mm, often with wings or animals that lived in or on the bark of the tree. Anything above this size belongs among the less frequent inclusions. We know that this is not because the larger animals were necessarily rarer in the primeval forest, but because, among other things, due to the consistency of the resin, they probably had an easier time pulling free. Likewise, we also have a greater knowledge of the animals and plants that lived on or in the immediate vicinity of the resin-producing trees than the animals and plants that lived in other areas of the forest as they were rarely caught in the resin. There are several factors that have an impact on what was captured in the resin, and therefore the inclusions in amber do not necessarily give the complete picture of life in the primeval forest, but still provide a highly detailed insight.

Picture: Otto Frello, 'Oksbølbilledet' / The Baltic amber forest

The inclusions that are frequent in one type of amber certainly do not have to be frequent in another type of amber. For example, enclosed feathers, snails, lizards and scorpions are far more common in Burmese amber than in Baltic or Dominican amber - but do not get me wrong, they are still rare in Burmese amber. Due to the fact that something like age and climate were different, as the types of resins were liquid, then there will also be a big difference in the inclusions, which ones you find and how often you find them in the amber.

When you are lucky enough to find an inclusions in Baltic amber, mosquitoes and flies are by far the most common along with something like aphids, ants and wasps. Beetles are also frequently found in amber and among them you will most often find the beetles that live in the bark of the tree. In addition, something like spiders and mites are frequent, while whole plants and flowers are generally quite rare. Among the botanical inclusions, however, it should be emphasized that small plant hairs (trichomes) from the flowers of oak trees (sometimes also called star hairs) are extremely frequent in Baltic amber. These small plant hairs cover the flowers of the oak tree in the spring and in the early summer period. Due to the high frequency of these plant hairs in Baltic amber, researchers believe that the production of resin must have been particularly high during this very period. Among the rarest inclusions in Baltic amber are i.a. lizards, ticks, scorpions, dragonflies, blood-sucking mosquitoes, fungi, snails, worms, insects that live their whole lives in water and bird feathers. Occasionally, hairs from the mammals of the Baltic primeval forest are also found, but no other remains have yet been found in amber from the mammals that lived in the primeval forest.

Picture: Piece of Baltic amber whit a huge pseudoscorpion, midge and a weevil

Over time, conifers have been the primary suppliers of the resin that has hardened and turned into amber, but there are also examples of amber derived from deciduous trees. Here, for example, the Dominican amber can be mentioned.

It is certain that it was conifers that produced the largest amount of the resin that became the Baltic amber, but which conifers are still up for debate. Based on the remains of wood found in Baltic amber, it was decided in 1845 that the tree must be an extinct tree from the pine family and named Pinus succinifera (Goeppert & Berendt, 1845). Using an infrared spectral analysis, it was discovered in 1969 that the Baltic amber was most reminiscent of resin from the tree Agathis australis, which today only grows in New Zealand. This opened the eyes of researchers to the fact that it was not necessarily a tree from the pine genus. Subsequently, researchers have also suggested cedar or a tree from the genus of parasol trees. So based on the morphological studies, it suggests that it is a tree from the genus of pine, but with the help of modern technology it immediately becomes more obscure.

In recent times, findings of pollen in amber have also been included, which had not previously been included in the studies. These results indicate that it is most likely one or more different trees from the pine genus that have produced the resin that became the Baltic amber. But whether we will ever find the final answer to exactly which tree or trees that certainly supplied the resin is probably uncertain.

Picture: Otto Frello, 'Oksbølbilledet' / The Baltic amber forest

The primeval forest that produced the resin that has since become what we call the Baltic amber grew in northern Europe 34-48 million years ago. More precisely, the primeval forest was located in Fennoscandinavia, ie in the area where, among other places, Norway, Sweden, Finland and the Baltic Sea are located today. In addition, the primeval forest stretched into Russia - possibly all the way to the Ural Mountains and then to the south down into i.a. Poland.

In the old primeval forest it was peaceful - the days passed, the century became millennia. But nothing lasts. Millions of years of peace were broken. The giant conifers, the creators of the Baltic amber, as well as most of the life in the primeval forest reached its demise about 34 million years ago. It was the climate that changed. What became the downfall of the primeval forest set in motion the long journey of the Baltic amber.

Millions of years of production, thousands of tons of resin, were carried from north to south by an extensive river system. Large amounts of resin were deposited in the area we today call the Gdansk Gulf. Almost all the Baltic amber we find today is not found where the forest grew, but where the rivers glaciers and meltwater have led it.

Deeply buried, the Baltic amber lay in its new deposit and due to the passage of time and a strong pressure from the surroundings, its chemical composition changed slowly. The sun took its orbits across the sky, species arose and perished, millions of years passed. Most of the Baltic amber lay undisturbed for the changing times, while only smaller quantities were washed out into Europe via rivers.

A new climate change was to seriously tear the Baltic amber loose from its rest. We are now well over 2 million years back in time, and the glacial glaciers are plowing over northern Europe. Glaciers and meltwater rivers initiated the journey of the Baltic amber again and through several ice ages it was carried out into Europe. Today one can find the Baltic amber as far away as in Holland and on the English east coast. Due to the meltwater rivers, the amber was deposited in certain soil layers along with other material of similar density.

These soil layers are called 'amber stick layers'. The 'amber stick layer' is typically a thin layer consisting of sand, gravel, small pieces of wood and amber. 'Amber stick layers' are found throughout Northern Europe - both on land and in water. The largest deposits on land are found i.a. in the Kaliningrad Region, Poland, Lithuania and northern Germany.

In Denmark, the 'amber stick layer' is found especially in West and North Jutland and also in North Zealand. In addition, there are large deposits of amber throughout the Baltic Sea and the North Sea, where large storms tear it loose from the seabed and lead it towards the shores.

Back then 34 million years ago when the climate changed. The temperature dropped and it led to the primeval forest finally. The large conifers that produced the resin that turned into amber perished along with many other of the primeval forest's animals and plants. Some species were adapted to the cooler climate, and their descendants can still be found in some areas of where the primeval forest once lay, while many of the subtropical and tropical species that lived in the primeval forest migrated toward warmer areas to the east and south. The descendants of these we find today in i.a. Southeast Asia and Africa. Due to enclosures in the amber, we know that the climate and life in the old primeval forest has been markedly different from the climate we have today at the same latitudes.

Thanks to these millions of years old time-traveling animals and plants that we find in amber, we can tell the story of this primeval forest and thus better understand how the earth and life have evolved. Imagine - without the amber to encapsulate them, this whole world would be forgotten.

The map: Paleogeographic map of Europe during the early to middle Eocene. Yellow areas indicate the position of the present-day amber Lagerstätten at Bitterfeld, Gdansk and Rovno. Made by Jason A. Dunlop, Ulrich Kotthoff, Jörg U. Hammel, Jennifer Ahrens, Danilo Harms. Source

All life is part of evolution. What we must not forget is that animals and plants are many hundreds of millions of years old and what we find in amber is, if you look at the big picture, relatively new in evolutionary development. The inclusions found in Baltic amber, for example, are only 34-48 million years old. It is not much seen in light of the fact that the oldest insects on earth are about 400 million years old and the oldest plants are more than 420 million years old.

In short, evolution can be seen as a force that is slowly changing everything living here on earth. This ‘force’ pushes life in a direction towards greater diversity, as each organism constantly adapts and specializes in different niches, which over time will also change. In this way, new organisms will emerge and life on earth will change.

Many of the overall 'forms' that living organisms have proved to be 'functioning' at an early stage, have been able to last for many millions of years - in some cases hundreds of millions of years.

All the beetles belong to an order. An order consists of several families, which are subsequently divided into genera and species. The beetle order is about 300 million years old and the overall ‘shape’ that they developed at the time still holds. If you take a quick look at fossil beetles, it may seem that they have not changed, but if you study them in more detail, it can be stated that they have. Thanks to fossils, we can observe that new families, genera and species have emerged and become extinct in step with life and the earth's evolution. Most of the beetle families we find today are extremely old. Therefore, we have also found in beetles in virtually all types of amber in which we have found inclusions.

At first glance, it may seem that the animals and plants we find in amber have not evolved, as they may resemble those we see today, but if you study them more closely, it can be stated that it is only the overall forms that recur. What is particularly exciting about studying the inclusions in amber is both the study of the individual species, but equally the composition of organisms in the primeval forest.

If the species in amber belong to an genera that today live in tropical regions, we can state that there must have been similar conditions at the time where the amber was liquid. If you find families or generas in amber, where living species from the family have a special biology, then you can theorize about whether this special biology must also have existed in the time where the species in amber lived.

Since we know the requirements of living animals and plants, we can use that information to recreate the old primeval forest. Although the animals and plants found in amber are extinct species, the water strider in amber will also be dependent on water and the termite attached to subtropical and tropical areas. Due to an extensive knowledge of living animals and plants and the growing study of inclusions in amber, we can recreate and better understand the world that existed millions of years ago and also gain insight into how life has evolved on earth through millions of years.