Darwin framed a reasonable theory of evolution. When Darwin was busy in giving shape to his findings, he received a manuscript on, "The Tendency of Variations To Depart from the Original type" from Alfred Russel Wallace, in Malaya Archipelago and had taken observations almost identical to Darwin. Wallace had sent his manuscript for critical review. The paper contained complete details of the theory of Origin of Species by means of Natural Selection. Darwin almost yielded to Wallace in developing the theory and agreed to present two papers under joint authorship.
There were many scientists and scholars who influenced Darwin. One of them was Chalres Lyell, who was a geologist who came up with the idea of uniformiraianism. This simply means that the same processes that were at work in the past are at wrk in the present. Lyell was the first geologist able to come up with an estimateof the age of the earth. He was able do so using the processes of erosion to get his answer.
George Cuvier also influenced Darwin greatly. He was the father of comparative anatomy. Cuvier was the first to examine dinsaur fossils and establish that animals in our distant past were different from animals that exist today.
Another influence on Darwin was Alfred Russel Wallace. Many people are unaware of this, but quite independently, they both came up with the same concepts of evolution by natural selection. Hwever, Darwin was able to get his "Origin of Species" off to the publishers first so that is why we never here about Mr. Wallace.