Is a panda a bear or a cat (a panda is a panda)

Before answering this question, it is necessary to explain the meaning of these two terms. The bear referred to here is what people commonly call "dog bear", such as a black bear; the cat referred to here is not the kind of cat seen in daily life, such as a domestic cat, but a red panda in the raccoon family.

Now that we know the relationship between bears and cats, the next topic is, what is the relationship between pandas and bears, and pandas and red pandas. In fact, this issue has been debated for a century. Whenever a new testing method is mastered or new evidence is discovered, either pandas and bears are regarded as the same family, or they are closer to raccoons. Although we have not devoted more energy to this issue because it is not our main direction of attack, we cannot but take it into consideration. To fully understand the panda, its system location must be involved.

Research data shows that bear scholars believe that pandas belong to the family Ursidae, and Father David, the scientific discoverer of pandas, holds this view; raccoon scholars believe that pandas belong to the family Ursidae, and Milton Edwards is a supporter of this view; molecular biology Through research on panda DNA, scientists have shown that pandas are a subspecies of bears. Since each faction uses its own research results to support its views, "it is reasonable for the public to say it is public, and it is reasonable for women to say it". Without a unified criterion, a consistent conclusion cannot be drawn.

It is normal to have different opinions in scientific research, which is the driving force for scientific development. In the scientific spirit of "the truth becomes clearer with more debate", the author would like to talk about the systematic relationship of pandas based on years of research on panda fossils, from the perspective of paleontology and comparison of ancient and modern times.

Skull: Generally speaking, the panda's skull has a short face and high top and forehead ridges. The current panda (specimen No. V1304) has an inclination angle of about 70 degrees from the highest point to the nasal surface; the Papillon panda (specimen No. 1, Wanxian) is about 60-65 degrees; the black bear (specimen No. V1099) has a long face, a low forehead bulge, and a low forehead. The inclination angle from the frontal surface to the nasal surface exceeds 77 degrees. The panda's zygomatic arch is particularly developed, and the entire bone plate is thick and wide. The zygomatic width of the living panda (specimen No. V1304) is 200-216mm; the width of the cheekbones of the Papilloma panda (specimen No. 1, Wanxian) is 245-256mm; and the width of the black bear is 140-150mm. Observed from the mid-sagittal section of the skull and X-rays, the panda's frontal sinus is very well developed, with irregular transverse partition plates in the cavity. Each transverse plate divides the frontal sinus into chambers of different sizes, which prevents excessive chewing. It has the effect of damaging the brain and reducing the weight of the skull; the skull base is short, the occiput is flat, and it is an isosceles triangle; the nuchal ridge is well developed, and the lower end of the ridge is fused with the posterior articular process. This wide, rough occipital surface and well-developed breasts The protrusion increases the contact surface between the head and the postcranial bones. These anatomical features are not shared by bears, despite some similarities to them.

Mandible: During the evolution of pandas, with the changes in food habits, the development trend from omnivorous to partial and picky eaters is particularly significant in the change in the length of the mandibular symphysis. For example, in the small species of panda 2 million years ago, the symphysis of the mandible was short, and its trailing edge was directly opposite the fourth premolar; in the Panda panda 1 to 10,000 years ago, the symphysis of the mandible was long, and its trailing edge was located behind the first molar. end; the extant species are more elongated, and their posterior edge is located at the front end of the first molar. X-ray observation results show that the trabeculae from the fourth premolar to the first molar in the front part of the panda's mandibular body are relatively dense; the mandibular condyle is strong and is a transverse spiral. These morphological features of the panda mandible also differ from those of bears.

Teeth: Panda’s teeth are quite special among carnivorous animals. As shown in the premolars, the 2nd to 4th premolars all have double roots and three tips. Their labial side is convex outward and the lingual side is flat. On the contrary, the lower premolars have convex lingual surfaces and flat labial surfaces, and there are also varying degrees of enamel ridges on the lingual surfaces; the upper 4th premolars have no "lobes"; the upper molars are wider than they are long and have many tumors on the chewing surface. Shape or ridge.

As for the shape of the skull, mandible and teeth of the red panda, they are far different from those of the panda in terms of size. From a microscopic perspective, such as teeth, the red panda's molars are wider than long, which is consistent with the panda, but the length of the labial side is much longer than the lingual side; in the panda, the length of the labial and lingual surfaces are almost equal. In addition, the chewing surface of the red panda's teeth does not have as many enamel wrinkles or ridges as the panda's, but only four strong tooth tips.

Comparison of skull, mandible and tooth morphology shows that pandas are clearly different from bears, and pandas and raccoons, although they have some similarities with each other. So what factors drove the evolutionary trends in panda skulls, mandibles, and teeth to diverge from those of bears and red pandas? If we go back to western China more than 8 million years ago, we may see low mountains, valleys and forests everywhere. However, in the following millions of years, as the Qinghai-Tibet Plateau continued to rise, the natural environment there underwent tremendous changes. The original mountainous areas gradually turned into a humid environment of swamps and hills.

Due to the biological effects of environmental forces, the bear populations that lived there were deprived of the forest conditions they had relied on for millions of years or more. Under the dual factors of chance and natural selection, the species forced by natural selection broke away from the ancestral bear group and luckily acquired a new adaptation. They haunted jungles or bamboo forests that alternated between swamps and hills, so they were able to survive and thrive. This naturally chosen creature is the intermediate link between the ancestral bear and the panda - the panda. We call the emergence of this new thing China’s “Western Story.”

This story tells us that the birth of the panda is related to the bear, but it is not a bear, so it cannot be placed in the Ursidae family; it is related to the red panda, but it is not a cat, so it cannot be placed in the Procyonidae family. It is an independent species differentiated from the order Carnivora. The system is called Ailuropodidae.

To put it simply, a panda is a panda.

animal tags：