Fossils give us information about how animals and plants lived in the past. Some animals and plant are only known to us as fossils. By studying the fossil record we can tell how long life has existed on Earth, and how different plants and animals are related to each other.Fossils are important evidence for evolution because they show that life on earth was once different from life found on earth today. Paleontologists can determine the age of fossils using methods like radiometric dating and categorize them to determine the evolutionary relationships between organisms.
Obligate parthenogenesis is the process in which organisms exclusively reproduce through asexual means. Many species have been shown to transition to obligate parthenogenesis over evolutionary time.
Take the species that has the greater number, and the subtract it with the number of the other species. Then you would be able to see how many new species evolved between them.
