<P> Around the same time, Andreas Vesalius was also making some strides of his own . A young anatomist of Flemish descent made famous by a penchant for amazing charts, he was systematically investigating and correcting the anatomical knowledge of the Greek physician Galen . He noticed that many of Galen's observations were not even based on actual humans . Instead, they were based on animals such as oxen . Up until that point, Galen and his teachings had been the authority on human anatomy . The irony is that Galen himself had emphasized the fact that one should make one's own observations instead of using those of another, but this advice was lost during the numerous translations of his work . As Vesalius began to uncover these mistakes, other physicians of the time began to trust their own observations more than those of Galen . An interesting observation made by some of these physicians was the presence of homologous structures in a wide variety of animals which included humans . These observations were later used by Darwin as he formed his theory of Natural Selection . </P> <P> Edward Tyson is regarded as the founder of modern comparative anatomy . He is credited with determining that marine mammals are, in fact, mammals . Also, he concluded that chimpanzees are more similar to humans than to monkeys because of their arms . Marco Aurelio Severino also compared various animals, including birds, in his Zootomia democritaea, one of the first works of comparative anatomy . In the 18th and 19th century, great anatomists like George Cuvier, Richard Owen and Thomas Henry Huxley revolutionized our understanding of the basic build and systematics of vertebrates, laying the foundation for Charles Darwin's work on evolution . An example of a 20th - century comparative anatomist is Victor Negus, who worked on the structure and evolution of the larynx . Until the advent of genetic techniques like DNA sequencing, comparative anatomy together with embryology were the primary tools for understanding phylogeny, as exemplified by the work of Alfred Romer . </P> <P> Comparative anatomy is still taught, particularly in the field of paleontology . </P>

What conclusion can you make about the skeletal structure of these two organisms