Bats are believed to be the most exotic mammals that ever exist on our planet, but even though they are mammals they can fly like birds. We know that organisms are constantly evolving, so many people wonder what animal it evolved from? Were their ancestors rats?
The ancestor of the mammal
In the scientific classification, the bat is called Chiroptera, belonging to the Mammals subclass. According to statistics of biologists, up to now, there are 1,200 species of bat (Chiroptera), 23% of the total species of mammals class (Mammalia), ranked second after the rodent (mouse) and cashew This also proved successful in the evolution of the bat.
The earliest mammal species appeared in the late Triassic 225 million years ago, due to the ecological control of the dinosaurs, the mammal did not grow much during the Mesozoic era. To avoid direct competition with dinosaurs, early mammals were very small in size, only the size of today’s bats or mice. They choose to be active at night and eat insects. Many species can climb trees.
The ancestors of mammals could not see color clearly during night activities, so their ability to perceive color was greatly impaired. Instead, their hearing and smell are especially sharp. In addition, they evolved and developed a temperature mechanism within the body that helps maintain a stable body temperature. From there they can maintain normal activity even in cold nights. We humans also still inherit many superior traits that these small ancestors inherited.
Pictures of modern mammal ancestors.
Let’s take a look at what “ancestor of all mammals” looked like. Eomaia lived in the early Cretaceous period about 125 million years ago. A complete fossil found in Yixian district, Liaoning, China, is estimated to be about 10-14 cm long and weighs about 20-25 grams. From the teeth and feathers stored in the fossil, it can be seen that this is a species with differentiated teeth, completely different from the reptiles. Eomaia is a small animal and possesses the ability to climb trees very well, so they are also known as the ancestors of tree climbing animals. In essence, Eomaia is our very distant relative.
Through analysis and research, paleontologists found that Eomaia species have absolutely no placenta, which is completely different from all modern mammals. Furthermore, this species has a lower pubic bone, a feature that only exists in marsupial and platypus. According to the phylogenetic analysis in 2013, Eomaia is a relatively primitive mammal and has nothing to do with the Eutheria branch of the mammal class.
The Juramaia sinensis species, unearthed in western Liaoning, China, is 7-10 cm long and weighs about 15 grams. This ancient mammal looked a bit like a large mouse. Judging from the skeletal structure of the forelimbs, it is a climbing plant and is an insectivore. They lived in the Late Jurassic period 160 million years ago and scientists believe it may be the common ancestor of all species of the Eutherian clade. However, Juramaia is in the transition from Metatheria (marsupial) to Eutheria, and it is not yet a part of the Eutheria clade.
According to molecular genetic analysis, the bat has an ancestor of the earliest Eutheria, appearing in the Cretaceous period between 100 to 90 million years ago – sharing a common ancestor with rats and all mammals. branch Eutheria (including humans).
Origin and evolution of the bat
66 million years ago, a giant asteroid hit the Earth. This led to the extinction of the dinosaurs and opened up new growth and development spaces for mammals. Of the three main groups of mammals: platypus, marsupial and Eutheria, the Eutherian clade benefits the most. So far, 6 out of 7 illustrations of the Eutherian branch of animals are still alive and developing on our planet. After the disaster, animals of the Eutheria branch quickly adapted to radiation and filled gaps in the ecosystem. Followed by the development of bats and mice.
At that time, on Earth there were only two continents, north and south, primitive mammals on the two continents developed separately, so they were divided into two groups: the northern mammal population and the western mammal population. Ocean. Both bats and rats belong to the mammal population of the North, but during the subsequent evolutionary stages the ancestors of the bats and mice split into two separate branches.
The rat species belongs to the common order with the group of mammals Archonta. This common order includes primates, flying weasels, rodents, and rabbits. Among them, the order of the human race is the primate. Filipino flying weasels have leather wings, somewhat resembling bats, that can glide long distances, proving that Archonta mammals have also attempted to conquer the sky in history. chemical. However, out of all the animals, only bats of the suborder Laurasiatheria are mammals that successfully conquer the sky.
Laurasiatheria is the largest subgenus of mammals of the Eutheria clade. This subdivision includes Chiroptera (bat), Insectivora (porcupine and shrew), Ungulata (whales and ungulates), and Ferae (Carnivore and pangolin). The evolution of the original Laurasiatheria suborder began when the dinosaurs went extinct. The earliest bat fossils found date back about 55 million years ago.
During the Mesozoic period, bats retain their ancestral form as small insect-eating animals that move around trees and are nocturnal. At this time, Earth is experiencing the Paleocene – Eocene Thermal Maximum. The climate of the Earth is quite hot and humid and this is also the environment for thriving flying insects.
With an increasing number of flying insects, the ancestors of bats evolved to be able to hunt these flying insects. They change their way of moving simply from a tree to constantly jumping between branches, after generations of natural selection, bats gradually form wings and completely change their mode of movement to hover.
In 2003, paleontologists found two original bat fossils in the Eocene strata in Wyoming, USA, the bats Icaronycteris and the Onychonycteris bat. Both species have features of flight: they have membrane wings and muscular shoulders that are developed for flight. In addition, both species of bats have very primitive marks such as short wings, shorter forelimbs than hind legs, which also shows that they cannot fly as fast as modern bats, but they can still Climber on trees like ancestors in the past.
Image of Icaronycteris bats restoration.
However, when analyzing the fossils of the two primitive bats, paleontologists found that they also had significant differences. The bat species Icaronycteris has an enlarged cochlear structure, based on the structure of the ultrasonic bone it can be seen that it can emit ultrasonic waves, which proves that the Icaronycteris bat has the same echolocation ability as bats. great. Whereas Onychonycteris bats do not have such structures, it is known that although this species can fly, it is not yet capable of echolocation.
The discovery of these two ancient bat fossils has great implications for proving the bat’s origin. First, bat flying is derived from moving around trees, not from moving underground. Second, the evolution in flying bats predated the ability to be positioned by echoes. Third, the Icaronycteris bat could be a major clade in the evolutionary tree of modern bats, or at least they are closely related, whereas the Onychonycteris bat is a distant relative, as it is not having the ability to locate by echoes, they were quickly eliminated by natural selection.
Image of the Onychonycteris bats restoration.
We still know very little about the evolution of bats today, mainly because the bats’ skeletons are relatively small and difficult to fossilize. Modern bats are divided into two main branches: insect bats and fruit bats.
Previously there were many rumors that bats evolved from rats or they are related to the flying dinosaurs because the wings have many similarities. But modern science has confirmed that the ancestors of bats were not rats at all, they had a parallel evolutionary relationship and evolved from ancient mammals.