Recently, the Institute of Vertebrate Zoology and Paleo anthropology of the Chinese Academy of Sciences published a new research result in the academic weekly Journal of Vertebrate Zoology. A major discovery was made in pale ontological archaeology led by a related scientific team, which found a multi-filled fish fossil, Oriental fish, in the Middle Devonian of northeastern Chugging Prefecture.
It is also known that the Oriental fish successfully escaped the Ordovician extinction event 400 million years ago and survived until the middle of the Devonian, it is also the largest number of known gill sacs armor fish, more than 7 times than other primitive armor fish in the Silurian period, and it survived about 20 million years later than other animals of the same period. So what kind of fish is the Oriental fish? And how did it escape the biological extinction 400 million years ago? Today I will talk to you about the oriental fish that thing.
What kind of fish is the oriental fish?
When we talk about Oriental fish, we have to mention the armor fish, which is the general name of an armored fish living in the ocean in the Ordovician period, and their fossils have only been excavated in the Silurian-Devonian strata in northern China and Vietnam today. The armored fishes discovered by archaeologists so far can be divided into three major groups, namely, three monopolistic groups of True Armour ed Fishes, Poly dactyls, and South China Fishes, and our main character today, Oriental Fishes, belongs to Poly dactyls.
The most amazing thing about this fish is the number of their gills, as the most important organ of fish, fish generally have four gills, gills play a role in the water to absorb oxygen to breathe, the lack of it fish is very difficult to survive in the water. What is surprising is the number of gill sacs in helmet fish, which varies greatly among different taxa.
According to the analysis of archaeologists, when the armor fish first appeared in the earth's oceans, they only had 6 pairs of gill sacs, however, during the Devonian period, the number of gill sacs of armor fish began to gradually increase upwards, until the era of the emergence of the Oriental fish, the evolution of the number of gill sacs of armor fish reached the peak, the Oriental fish evolved 45 pairs of gill sacs, which is simply unbelievable. Therefore, to this day, why the Oriental fish has so many gill sacs has been a difficult mystery to solve in the academic world, and there are many different possibilities.
So, how did the Oriental fish escape from the biological extinction 400 million years ago?
In the Ordovician extinction event 400 million years ago, almost the entire ocean life was hit hard, after this event, the earth once no fish can survive, but the Oriental fish miraculously survived, and evolved for 2000 years more, how in the end this is done?
In this regard, some paleontologists believe that: is the evolution of the number of gill sacs makes it a unique survival advantage in the ocean. The Ordovician is known as the peak of the fish era, especially the helmet fish survival area, at that time in the vicinity of the equator, here is particularly suitable for fish life, but to the middle of the Mud pan Period, the global marine environment has changed, plants began to grow on land on a large scale, which also let the original desolate land suddenly vibrant, but the ensuing problem is the emergence of the problem of land weathering, plants on land The nutrients created by the plants on land began to "feed" to the ocean, which made the ocean began to over-nourish. Do some people say more nutrients are not a good thing?
However, the ocean is very deadly over-nutrition, just as the excess nutrients in the river water will multiply microorganisms, such as cyanobacteria, these microorganisms a lot of oxygen originally belonged to other marine life, so in the late Ordovician period of the ocean, there was a large-scale asphyxia phenomenon.
The number of gill sacs that evolved in Oriental fish played a huge role in the continuation of their populations. From the fossils, it is found that a small number of gill sacs were sufficient to ensure their daily oxygen intake, so it can be inferred that the lack of oxygen in the ocean was not a fatal blow to them, which allowed them to escape from the Ordovician extinction, but other marine organisms were not so lucky.
So why did the Oriental fish evolve so many gill sacs at the most suitable time for fish survival? Could they have predicted the later extinction?
The possibility of prophecy is certainly false, but paleontologists are surprised by the fact that the fossils of the Oriental fish show that the number of gill sacs reached 45 pairs, which is more than seven times that of the most primitive armored fish. Why would the Oriental fish evolve such a large number of gill sacs if it couldn't predict the future?
Archaeologists believe that although the ancestors of the oriental fish armor fish lived in the era of the most suitable for fish survival, their living environment is not necessarily superior, armor fish live in shallow sea environment, this area even the most suitable for fish survival in the era of its oxygen content is also insufficient, so armor fish to survive and adapt to the environment will have to evolve, this is the survival of the fittest, the survival of the fittest. The number of gill sacs began to increase, and this laid the foundation for the continuation of the population later. So, gentlemen, what do you think is the reason why the Oriental fish escaped the Ordovician biological extinction?