How much does the largest continental mammal ever weigh

The giant rhinoceros, the largest terrestrial mammal in history, lived in Eurasia about 40 million to 22 million years ago. Their extremely rapid growth in size has left an important evolutionary mystery behind.
  Recently, the research team of the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences (hereinafter referred to as the Institute of Paleoanthropology) reported on the discovery of the Junggar giant rhinoceros in the late Early Oligocene Qingshuiying Formation in Lingwu City, Ningxia Hui Autonomous Region, and calculated the number of rhinoceros including it. The weight of most giant rhinos. The related results were published online in the international journal Historical Biology.
  The fossils in Lingwu area are rich in diversity, among which the giant rhinoceros is a typical representative. In the past, scientists have estimated the weight of the giant rhinoceros in a variety of ways at 15 to 20 tons. In this study, the researchers used the limb bones of a variety of living mammals as training data, and the teeth without suitable limb bones were used as supplements to calculate the weight of 16 species of giant rhinoceros. Among them, the original Salamulun rhinoceros weighed about 1.5 tons, while the advanced Junggar rhinoceros was more than 20 tons.
  According to Deng Tao, the corresponding author of the paper and director of the Institute of Ancient Spine, this study divides the evolution of the giant rhinoceros into three stages according to the rate of body weight growth.
  The ancestral stage is the evolution from the ancestral rhino to the primordial rhinoceros. After the climatically favorable period of the Early Eocene, global temperatures continued to decline. Affected by this, the living environment of the early stage of the giant rhino became relatively open and arid. During this period, the weight gain of the giant rhinoceros did not exceed the maximum growth rate of the rhinoceros. However, at this growth rate, the Salamulun rhinoceros, which lived in the late Middle Eocene to the early late Eocene (42 million to 38 million years ago), has become one of the largest terrestrial mammals at that time.
  The second stage is the evolution of the giant rhinoceros from the Eocene to the late Eocene. This is also the period of the fastest weight gain in the evolutionary history of giant rhinos, far exceeding the growth rate of any branch of the rhinoceros. The middle Erdun rhinoceros weighs about 5 tons and is one of the largest animals living in the same environment. In the Paleogene, central and western China was located in an arid zone at a latitude of 30° to 50°. The climate was similar to that of the savanna today. Giant rhinoceros could migrate long distances in such an environment.
  The third stage is the period when the advanced giant rhinoceros diverged in the Oligocene, and most of the giant rhinos found so far are the products of this stage. After another dramatic turnaround at the turn of the Eocene and Oligocene, the Erden rhinoceros became extinct, and larger rhinoceros such as the rhinoceros and the Junggar rhinos appeared. During this stage, the weight gain rate of the giant rhino is usually between the previous two stages. The giant rhinoceros fossils in Lingwu were found in a set of light gray-green sandy mudstones containing layers of gypsum more than 5 cm thick. Some of the skeletons are also filled with gypsum, reflecting the relatively arid environment of the time. At this time, there were several scenes of coexistence of giant rhinos. Due to their large size, these rhinos may not be able to adapt to forest environments, so they did not reach Western Europe, which is warmer and wetter than East Asia.
  In addition to the giant rhinoceros, the research team also selected a variety of rhinoceros for comparison and background, and found that many branches showed a trend of body size growth, while the growth rate and rate of the giant rhinoceros was much greater than that of other branches. From the late Oligocene to the early Miocene, after the extinction of the giant rhinoceros, the group of rhinoceros and rhinoceros began to evolve in an increasing direction. The plate-toothed rhino feeds on growing herbs. The researchers explained that perhaps due to the lack of a long neck to feed on the leaves of tall trees, the growth rate and upper limit of the body weight of the plate-toothed rhinoceros were much lower than those of the giant rhinoceros.