In this Blog I’ll describe how biomaterials including animal and plant fossils are included and preserved in amber formed from tree resin, which by its stickiness can entrap objects which contact its surface as shown in Figure . With further addition of the resin the object is sealed within the resin and out of the surrounding biotic environment. With the passing of geological time amber forms from the resin and encloses the organism as described in the legend of Figure 1-[Ref1,2].
In the environment external to the tree in which the amber forms, oxidation and temperature extremes and biotic factors such as bacteria and scavengers accelerate decomposition of an organism; instead the environment within the tree resin capturing the organism provides protection against the biotic environment, allowing the preservation processes to proceed to fossilization. Following entrapment of the organism within the resin, the continuing loss of volatile oils called olio-resins from the resin, which continues through evaporation, coupled with polymerization reactions of terpenoids to form a large network of molecules and other organic compounds result in the formation of amber with time. Under conditions that are not extreme, the amber is impervious to the outside environment and shields the fossilized material during its preservation. Studies of factors affecting preservation have shown that the type of tree resin, hence its chemistry and possible chemical attack on the material, the degree of dehydration, and activity of gut microorganisms are some major factors affecting the preservation of soft tissues of organisms[Ref16,17].
Gallery of Some Fossils Preserved in Amber
Some of the most extraordinary discovered fossils range from insects to plants and animals preserved in amber. —“[Ref3]. To illustrate, a Gallery of some unusual, and representative preserved fossils which I found very interesting are shown beautifully in the following figures.
Biomaterials Found Preserved in Amber
Preserved biomaterials range from biochemicals to fossilized cells, tissues, and entire organisms. Representative examples of these preserved biomaterials are presented below in TABLES I, II, III, and IV.
None of the structural biomolecules of animal and plant life forms are preserved intact in amber. Instead chemical reactions acting on the chitin within the cuticle of arthropods and within the cell walls of fungi and plants, and on the proteins within feathers, cuticle, and soft tissues of animals, respectively form polysaccharides and amino acids as summarized and referenced in TABLE –. Of pigmented biomolecules red hemeporphyrins and melanin are preserved as seen in the table while carotenoids are not.
Recovery of geologically ancient DNA would be of immense value to biology.
However, according to the paper by Hebsgaard, et al[Ref18], the authenticity of the reports of the presence of DNA being found preserved in amber, References 12,16,17,19,23,24 in the paper, is questionable. As stated in the paper by Hebsgaard et al in Box 2 of their paper, “It is concerning that all claims published to date on DNA surviving over geological time spans have not followed the most fundamental of these authentication criteria.”
Biochemicals which have been found in amber are summarized in TABLE I. Examples of preserved bio-materials ranging from bio-chemicals are described with illustrated references in TABLE I, and from tissues to organisms are described in the text and summarized with illustrated references in TABLE II, and in TABLE & III.
TABLE I . SOME EXAMPLES OF BIOMOLECULES FOUND PRESERVED IN AMBER
GEOLOGICAL AGE (Million-years-ago)
β-1,3 and β- 1,4-linked polysaccharides
Cretaceous, 138-66 Mya
Cretaceous extending into Eocene, 99-44 Tertiary – Creataceous 130-40 Mya
Eocene, 66-23 Mya
Cells and both soft and hard tissues are found preserved in amber as shown in TABLE II.
TABLE II. EXAMPLES OF ANIMAL AND PLANT CELLS AND TISSUES PRESERVED IN AMBER
Flight Muscle, fibers and mitochondria
Miocene 23-5 Mya
Neural, axons & glial cells
Oligocene 34-23 Mya
Plate1, Figures 5 & 6
Eye, Lens, pigment cells, crystalline cone
Eocene, 45 Mya
Cockroach, Beetle, Grass-hopper
Cretaceous, ~130 Mya
*Cuticle & soft tissues in sections
Blood, Red Blood Cells
Oligocene, 30-15 Mya
Cretaceous, ~ 105 Mya
Miocene, ~20 Mya
Figures 1, S1 & S2
Eocene, ~45 Mya
Figures 1 & 2
Cretaceous. ~98 Mya
Figures 1 & 2
*Images obtained by micro CT scanning.
Some animals from the Cretaceous Era into the Miocene Era found preserved in amber are presented in TABLE III.
TABLE III. SOME ANIMALS FOUND PRESERVED IN AMBER
GEOLOGICAL AGE (MILLION YEARS AGO)
FIGURE NUMBER IN REFERENCE/ NUMBERS OF FIGURES
k-one figure., l-one figure
Some plants living from the Cretaceous Era into the Eocene Era found preserved in amber are presented in TAVLE IV.