Charles darwins observation adventures of different species on the galapagos islands have many similar physical characteristics supports the hypothesis hypothesis that these finches

share the same ancestors

Explanation:

Charles Darwin noticed at the Galapagos Islands that the finches, despite obviously having unique traits that classified them as separate species, they actually had many things in common as well, much more than differences. His hypothesis was that all of the different finches on these islands actually have the same ancestors in a small group of finches that migrated to the islands. As the birds started to occupy different niches, they started to specialize, which was mostly manifested in their beaks, as the specialization was mostly in accordance to what they ate, thus gradually giving rise to several different species.

then that particular organisms become extinct.

that is wrong, its not thymus.