The Best Example of Macro-Evolution: ManateesExcellent video can be watched here. Once you watch the video, be sure and check out some of the arguments which I anticipate creationists will make in reguards to this evidence:
1. The Vestigial hip sockets in manatees probably serve a good purpose. How many times have evolutionists been wrong about these "useless" features.
This is one of the most misunderstood issues in evolutionary biology. Vestigial organs are not totally useless (this is not even what the word means). A vestigial organ is a remnant of something which is specified for another function. An example is the ostrich's wing: Wings are specified for flying, but the ostrich simply uses its wings for a lesser function (balance). A vestigial organ is sort of like using an old van as a clubhouse: It works, but the car definitely was not originally built for that purpose, just as the manatees' hipsocket was not originally evolved for the functions (if any) it may have now.
2. Homology is evidence of common design.
I have addressed this argument at a more general level here. But let me just give a simple answer: Is the arrangement of bones and muscles in the manatee's flipper the most optimal for what it does? If it does just as good a job as any other arrangement, then why did God choose that pattern over all the others? Be sure to give a detailed, falsifiable and testable answer.
3. You can't prove those fossil manatees are the ancestors of modern day manatees!
No, I cannot prove that the fossils found even belonged to the species which evolved into modern manatees. But creationists are missing the point: Evolution predicts that fossils showing intermediate characteristics must be found in the fossil record if evolution did in fact take place. Sure enough, we have an embarrassment of riches when it comes to transitional fossils. Creationism, on the other hand, predicts that animals must have been created in distinct and separate 'kinds' and therefore nothing that even appears intermediate should be found. Even if one admits that manatees did evolve from land mammals and wants to call them the same 'kind' they must acknowledge that homological and vestigial structures are very distinct causes of evolution. You must be consistent and accept the homological/vestigial structures that all living things have and acknowledge common descent.