The Horns of a Rhino

What large mammal has tough, thick, light-grey skin, and has two large horns coming out of its nose? After reading that description, ideally one’s answer should be a rhinoceros. In most cases, we always picture a rhinoceros to have two horns and light-grey skin, but often forget about the rhinoceros who have darker colored skin and only one horn. There were once hundreds of rhinoceros species however, only five species exist today. The African Black and White rhinos, and the Sumatran rhinos have two horns, but the Indian and Javan rhinos from Asia only have one. Why is it that some rhinoceros have two horns while others only have one? I believe that the second horn certain rhinoceros have first came along as a beneficial mutation, and then eventually due to natural selection and allopatric speciation, certain rhinoceros now have two horns instead of one.
The rhinos that existed about 60 million years ago looked more like today’s horses than the typical rhinoceros we are familiar with. This would explain their unusual diet and rather fast speeds. The weight of a rhino ranges from 750 pounds to 8000 pounds. The expectation should be that for such a massive animal, they would be rather slow; however, that is not the case at all. Similar to a horse, Rhinos can be rather fast as well. When charging at an animal, the Rhino could reach speeds of 56 km/h. With such violent and defensive ways, it is assumed that rhinos are meat eaters; however, that is not the case either. Similar to horses, rhinos are herbivores. They like to eat grass, foliage of trees, and bushes. Eating habits and speed are behavioral characteristics from their ancestors that have remained the same. There are even some physical characteristics that have remained the same like being an odd-toed ungulate. While so many characteristics were carried over from the rhinoceros’ ancestors, there are also many new changes that have evolved; the most significant one is the extra horn.
I believe that the extra