While cryptozoology may not be a hard science like chemistry, it might be classified as a sort of social science: a combination of history with a bit of detective mystery thrown in.
When this writer took a philosophy class, he learned that one of the limitations of the scientific method was that it could not even prove that Napoleon existed. Science, in the strictest sense of the term, dealt with observable, repeatable phenomenon. Napoleon, no longer exists. The proof for his existence lies in written records, such as diaries. While social sciences, such as history are not on the same level as hard sciences as chemistry, that does not mean that history is an invalid field of study.
Cryptozoology is dependent on records, oral or written, not direct observation. Since the creatures described may no longer exist, it is a bit frustrating to figure out what the authors of these various accounts meant. That does not, by any means, invalidate the accounts. Part of the problem with our society is our ethno-centric chronological snobbery. We tend to think only Modern Westerners are capable of recording historical events or accurately observing things.
When the natives of what is now Indonesia first reported the existence of giant lizards to the Europeans, the Europeans did not believe the natives. It wasn't until the Europeans encountered these creatures that they finally acknowledged the Komodo dragon's existence. Given the existence of these creatures, shouldn't one wonder if there is a grain of truth to the story of the demigod Maui battling the giant lizard in Hawaii or the painting of the Japanese swordsman Miyamoto Musashi killing a giant lizard?
Just because one did not personally witness an event does not mean it did not occur. Why not give some credence to people who were there? Yes, there is a possibility of garbled transmission through the ages. But then there is a question of half empty or half full? Another problem of Western Moderns is the view that they alone can faithfully transmit information. Just because something was passed down orally does not mean it was NOT faithfully preserved. John Steinbeck marveled in his correspondence about the accuracy of transmission by oral tradition. The scholars, who studied the Kakure Kirishitan (Hidden Christians) of Japan, were amazed at how these people were able to pass on parts of their liturgy for over 200 years.
This writer would add that not only can one glean information on zoology from the ancient records. Velikovsky made several predictions about astronomy based on his study of the ancient records. He correctly predicted that Venus would be a hot planet, while the conventional scientists of the day thought Venus would be a cool planet. While Velikovsky is ridiculed today, the point is he was right on certain issues.
The moderns of today should be less arrogant regarding our ancestors of the past. Heck, our modern earth building equipment can't move those giant boulders in Peru. And we haven't duplicated the pyramids of Egypt. A little humility is in order.