Simplify the following text for a Grade 12 native English-speaking person.
Original: Biologist Stephen Jay Gould said the ichthyosaur was his favorite example of convergent evolution , where similarities of structure are analogous not homologous , for this group :
Simplified: Biologist Stephen Jay Gould said the ichthyosaur was his favorite example of convergent evolution . Its similarities to fish are not homologous , caused by common descent , but analogous , caused by selection in the same environment :