Fossils are records left over from ancient life and are evidence of the existence of ancient creatures. Fossils in English evolved from the Latin fossilis, which originally means " underground excavation to obtain ".
When I saw fossils in the museum, there were always people who had this doubt: Is this true? Some people also picked up fake fossils of fish-meshed beads in the wild, but treasured them and regarded them as treasures.
real and fake fossils, you can't tell the difference between them!
Now, let’s take a look at which real fossils are and which fake fossils are. Who are the real fossils in
?
Fossils are naturally formed, and are preserved in the strata, relics, active relics, and residual organic molecules . Fossils can be divided into three types: solid fossils, remains fossils, and chemical fossils.
Figure 1 Fossil classification (Picture source: homemade by the author)
Most of the fossils we see on a daily basis are solid fossils, and solid fossils can be divided into three categories: Hardware storage , Software storage , mold cast fossil . When it comes to fossils, the first thing we think of is the Hard body preservation that is preserved by hardware, such as biological bone fossils, plant fossils, etc.
Figure 2 Hardware preservation (Gu's Little Thieves Dragon) (Picture source: Chinese Animal Museum) Some of the physical fossils of
are quite special. They are not hard stones, but preserve the soft tissue of organisms , such as amber fossils, mammoth in the permafrost layer of , etc. These are also fossils, and are solid fossils preserved by software (Soft tissue preservation).
Figure 3 Software preservation (mammoth fossil) (Picture source: documentary "Waking the Baby Mammoth")
molded fossils (Molds and Casts) are also hard stones, but because the bones of paleontology are decomposed, they are not preserved, and only the marks of organisms are preserved .
Figure 4 Molded fossils (coral impression) (Picture source: provided by the author)
Let’s talk about the second major category: Trace fossils (Trace fossils). The most typical remains fossil is footprint fossil . In addition, egg fossils, feces fossils, biological caves, drilled fossils, etc. are also relics fossils.
The third largest fossil is chemical fossil, which is the organic residue of paleontology , including paleo DNA, paleoprotein, coal, petroleum, etc. The formation conditions of
fossils are very harsh, so only a small number of prehistoric life can form fossils. According to paleontologists, fossils preserved in sedimentary records on Earth may be less than 1% of the prehistoric biosphere .
Figure 5 The formation process of fossils (Picture source: homemade by the author)
Are the fossils in the museum really real fossils?
In museums, we often see two kinds of fossil exhibits: one is a stone slab that is flat (Figure 6), and the other is a fossil skeleton like a sculpture (Figure 7). This three-dimensional fossil specimen is called shelf fossil or shelf specimen .
Figure 6 Liudaowan Urumqi salamander fossil (Picture source: Chinese Ancient Zodiac Museum)
Figure 7 Xu's Lufeng Dragon Shelf Fossil (Picture source: Chinese Ancient Zodiac Museum)
Fossils will appear. These two states are mainly related to the burial conditions of fossils . If the paleoorganisms are preserved in very delicate sediments, they are compacted very seriously after diagenesis, and the fossils will look like a stone slab. For example, the fossils produced by the Rehe Biota in western Liaoning and the Sorenhofen Biota in Germany look like a stone slab.
If the sediments buried in paleoorganisms are slightly thicker, the compaction will not be that severe after diagenesis. The fossils will generally be more three-dimensional, and after restoration, they can generally be made into shelf fossils.Secondly, this difference is also related to the size of paleontology and bones and whether the shell is filled with minerals in time.
Because fossils are inevitably missing and damaged during the natural preservation process, the fossils unearthed are incomplete in themselves. When displaying fossil specimens, the museum will take into account the display effect and other issues, refer to the bone fossils of the same species that have been discovered, bond the broken bones, and complement the missing bone fossils with gypsum, pulp or plastic. Shelves fossil specimens such as
will still be called complete skeleton fossils when displayed. If there are too few skeleton fossils, they will not be made into shelves displays. Simply put, the fossils that are made into shelves in the museum are usually real fossils . (We can talk about it in more detail later)
Of course, there is indeed a paleobi skeleton model that looks very similar to the shelf fossils in the museum's exhibits, and there is no real fossil in the model, either.
is actually very easy to distinguish between the shelf fossils and the skeleton model. For shelf fossils, the steel frame that supports will be exposed to the outside to prevent damage to the fossils. vertebrae will be fixed to the steel frame by a steel clamp, and the limbs will generally be wrapped with flat steel bars and fixed to the supporting steel frame. For skeleton models, the support steel frame is generally inside the skeleton model.
Figure 8 Model without external steel brackets (left) Fossils with external steel brackets (right) (Picture source: provided by the author)
is not a real fossil, it is a real and fake fossil
There are some structures or rocks in the wild, which are often mistaken for fossils. For example, tree branch stones, ginger stones , chert tuberculosis, spherical weathered rocks, etc., their causes are not related to organisms. These minerals and rocks are collectively called pseudofossils .
There is a general idea that people who lack knowledge about related knowledge. Artificial things are fake, and natural things are real. Therefore, many people will think that this is "real" after picking up fake fossils. We can joke that this is a "true and fake fossil".
This reminded me of an interesting story. At that time, Fu Sinian and Zheng Zhenduo were both directors of the research institute. Fu Sinian was the director of the chief, "Director Fu" and Zheng Zhenduo was the deputy director, "Director Zheng Zheng".
Next, we will list some common false fossils.
. branch stone
branch stone, also known as mould tree stone in ancient China, is often mistaken for plant fossils. Because tree branch stones are mistaken for plant fossils so many times that it has become the most typical representative of fake fossils.
The rock surface of the branch stone has marks similar to Orchidite dendritic films or mosses, algae and other lower plants, but non-plant remains . The cause is that after dissolves groundwater such as iron and manganese flows into the cracks of the rock, the pressure decreases, and the dissolved minerals precipitate on the surface of the rock, resulting in dyeing.
Figure 9 Branch stone (Picture source: provided by the author)
. Flint tuberculosis
chert is a siliceous rock. Flint tuberculosis is generally seen in the nodule, strip or lens-like shape, and is usually present in the carbonate formation, with limestone and dolomite the most common. Because it often appears in sedimentary rocks , special-shaped flint nodules are also mistaken for real fossils.
Figure 10 Flint nodules (Image source: https://www.sandatlas.org)
. Spherical weathered rocks
Spherical weathering is a phenomenon of rock crushing, which is common in granite , basalt , and sandstone. The rock peels off from the surface and inside in a spherical shape, and the edges gradually become rounded. For example, granite joint development divides the rock mass into many rock blocks. Due to sharp changes in temperature, the inside and various minerals of the rock blocks expand and contract unevenly, causing cracks and continuous breakage of the rock blocks on the surface, and the rock blocks gradually become spherical.After the spherical weathered debris material is peeled off, the remaining spherical rock blocks are called stone egg .
Sometimes the surface of a spherical and weathered rock looks like a trace of a cracked egg, so some people mistakenly regard stone eggs as egg fossils.
Figure 11 Spherical weathering (Picture source: provided by the author)
. Ginger stone
Ginger stone is also called Ginger stone . It is a calcium loess nodule in clay strata. It is named after it is just because its shape is relatively special and resembles ginger. It is a calcium mineral insoluble in water during the migration of rock weathered minerals, which are enriched by leaching water and gelling in underground. Some ginger stones of special shapes will also be regarded as fossils of paleontology by people who do not know the truth.
Figure 11 Ginger Stone (Picture Source: SpringerLink)
In addition, there are some strange things that are mistaken for fossils, which can always make people laugh.
Conclusion
Fossils are the key to paleontologists traveling through time and space, exploring the secrets of ancient creatures, and are also the "gems" that allow us to witness the legend of life. Between the truth and falsehood, I hope you can keep your eyes open and see the true imprints of life that have been brought out in billions of years.
Produced by: Popular Science China
Author: Wang Xinsong
Production: Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences
Producer: China Popular Science Expo
