uses fossils as clues and uses science and technology to uncover various mysteries and mysteries of paleontology. This is commonly known as "paleontology". Paleontology can be said to be the science of "high-quality reasoning", which reveals the evolution and destruction of ancient creatures, or their journey from ancient existence to modern times. To study paleontology is to witness the history of life, which is a particularly grand theme.
Regarding the history of paleontology, many new insights have been gained, especially in the past ten years. Today we will introduce topics about the birth of life and primitive life forms.
Traces of life recorded on rocks
The Earth is a planet covered by oceans. The consensus now is that the earliest Earth did not have land, or it was at best an "island".
On such an ocean planet, the first life was born. However, there is still no scientific explanation for what the first life looked like and what kind it was.
The oldest known rocks on Earth today are about 4 billion 30 million years old. Rocks older than it are no longer found on the surface of the earth today (to be precise, they are "undiscovered"). This is because the rocks on the earth's surface are constantly damaged by wind and rain, while the rocks on the oceanic plates will gradually sink into the earth's interior over time.
The oldest rock was discovered in 1983 in Acasta, northwest Canada.
This rock has no record of any life activity. However, this does not mean that "there was no life on the earth about 4.03 billion years ago", but because the rock is not "a rock suitable for recording life activities at that time."
4 billion year old rock discovered in Acasta
What was the first life on earth?
In 2017, Takashi Tashiro of the Graduate School of the University of Tokyo and others reported that carbonaceous particles were found in rocks collected about 3.95 billion years ago from the Labrador region in northeastern Canada. According to the analysis of Tashiro and others, this kind of particle is the earliest form of life on earth, and can be said to be the origin of all life on earth.
In other words, there was life in the ocean about 3.95 billion years ago.
However, what remains on the rocks in the Labrador region are always "microparticles of biological origin." It can only prove "evidence of the existence of life", but it is not a "fossil" of the remains of living things. Therefore, the "specific form" of the creatures that lived in the ocean about 3.95 billion years ago is still a mystery.
What was life like in the beginning and what kind of creature was it?
Around this mystery, many scientists are working hard to find the answer.
In 2017, when Takashi Tashiro and others published their paper, Matthew S. Dodd of the London Center for Nanotechnology and colleagues reported their discovery of approximately 3.77 billion-year-old rocks in the northeastern Canadian province of Quebec. tubular microstructure. According to analysis by Dodd and his colleagues, these structures are similar to the microorganisms found around hydrothermal vents today.
Hydrothermal vents are considered to be one of the sites that could have produced primitive life. Hydrogen and Carbon dioxide ejected from minerals in and around the Earth can be used to synthesize organic matter, the building blocks of life. Dodd and his colleagues concluded that these tube-shaped microorganisms belong to early life because their structure is similar to that of microorganisms found around hydrothermal vents.
Hydrothermal vents
"Fossils" made by organisms
Even if they are not biological entities, as long as they are created by organisms, they will be regarded as "fossils".
However, scientists also have different opinions on the treatment of the microstructures discovered by Dodd. They question whether it is really a fossil, and even if it is a fossil, it may be more recent than 3.77 billion years ago.
Let’s look at what other scientists have discovered.In 2016, Alan P. Nutman and others from the University of Wollongong, Australia, reported that they discovered "stromatolites" about 3.7 billion years ago in the Isia region of Greenland. The stone itself is rock.
Stromatolites are rocks formed by cyanobacteria . Therefore, the existence of stromatolites is indirectly evidence of the existence of cyanobacteria 3.7 billion years ago. Cyanobacteria are organisms that carry out photosynthesis , and their existence implies that the production of oxygen occurred 3.7 billion years ago.
However, in the face of this breakthrough discovery, some people also pointed out whether this rock is really a stromatolite.
ISIA stromatolite
Is it a fossil? Or a mineral?
The most famous early life record in the world at present is the Primaevifilum reported in 1993 by J. William Shope of the University of California, Western Australia, in the Pilbara rocks. Its age is about 3.465 billion years old. It is often called the "3.5 billion-year-old fossil."
Many specimens of Primaevifilum have been identified, and although there are some differences between individuals, they are generally arranged in filaments. More specifically, it (Primaevifilum) looks like a string of beads with a thread running through them. They looked just like today's cyanobacteria.
However, regarding the information about Primaevifilum, some people believe that it is "not a fossil, but a mineral without biological involvement." In response to this accusation, Shoop listed the following seven items in his 1998 book "The Lost Fossil Record."
- Primaevifilum is a dark brown to nearly opaque carbonaceous organic matter.
- is a much more complex structure than that of non-biological origin.
- A large number of specimens were discovered.
- It is as consistent as the current living thing.
- can avoid the harmful ultraviolet environment under water.
- and the current cyanobacteria undergo cell division and growth.
- There is isotope that is speculated to have carried out photosynthesis.
Shoop contends that Primaevifilum that meets these seven requirements is "unquestionably a fossil."
The structure of Primaevifilum fossils
Going one step further, Gabon found multi-celled biological fossils 2.1 billion years ago
If Primaevifilum is confirmed to be a cyanobacteria from 3.5 billion years ago, it is a single-cell organism. Unicellular organisms are living organisms that use only one cell to form an individual. Because only one cell survives, the cell itself, although complex in structure, is limited in size and has low morphological diversity. Animals like us humans are " multicellular organisms " that gather a huge number of cells.
In 2010, Abdrazak El Albani and others from the University of Poitiers in France reported that they discovered 250 "multicellular organism" fossils about 2.1 billion years ago in Gabon, west-central Africa.
This multicellular fossil from Gabon looks a bit like a poached egg, with a loose yolk-like center surrounded by wrinkled structures. The wrinkled structures appear to be soft, and each individual fossil has a different shape.
The most eye-catching thing is the "size" of the fossils. The longest one can reach 12 centimeters, which is larger than a child's hand.
In paleontology, fossils whose size cannot be confirmed with the naked eye are called " microfossils ", and fossils whose size can be confirmed with the naked eye are called "macrofossils." Primaevifilum is a microfossil, and the fossil discovered by Albani and others is an excellent macrofossil in terms of size.
Fossils of multicellular organisms from Gabon
Fossils from Gabon face doubts
Many of the organisms that gave rise to large fossils were multicellular because there is a limit to the size of a single cell.Albani and his colleagues also inferred the creature's growth pattern from its shape, which is also characteristic of multicellular organisms.
Chemical analysis also showed that the fossil was formed from pyrite. Pyrite is a mineral composed of sulfur and iron. Generally speaking, the harder the fossil, the more likely it is to remain, while the softer it is, the less likely it is to remain.
However, there are always exceptions to reality, and pyritization is a known mechanism by which soft tissue is preserved as fossils. This multicellular organism was determined to have been preserved by the mineralization of pyrite, although it did not have any hard tissue such as bones or shells.
This multicellular organism has not yet been given a scientific name. Because scientists have so far found no similarities to existing organisms, they are difficult to classify. Some people believe that it may be an "experimental multicellular organism" that only appeared and disappeared during this period.
Others also questioned that the Gabonese fossil was not actually a fossil. Not all researchers accept the "Gabonese multicellular fossils," as is the case with the Québec tubular structures, the Isia stromatolites, and the Primaevifilum.
Pyrite
Conclusion
In summary, early biological fossils are very simple, so they can easily cause controversy.
The form of living things, as the form of living things clearly left fossils, was discovered by us humans, it had to wait until the Sinian period that started about 635 million years ago.
The creatures that existed in the era before the Sinian Period are still a mystery, waiting for people to explore and discover.
Sinian
