Early Sirenians 

Finally, actually nice comments. Everyone else isn't even commenting on the video, just the editing.

To be fair, Pinnipeds haven't been around as long as Manatees and Dugongs, of the order Sirenia, and they haven't had enough time to fully adapt to the ocean. Also, some Sirenians, like .manatees don't exclusively live in the Ocean. Some live in the Amazon River Basin, and in the Congo River. I understand though.

It has nothing to do with time. It's diet and predation. Sirenians are "grazers", pinnipeds are active predators. Manatees spend their time in brackish and fresh water away from most large Shark species and don't have to worry about bears in the arctic. Pinnipeds dive to great depths in search of squid and fish, sirens are shallow water only. Look at an animal and it will tell you what it does for a living, it's very simple. Dugong and manatee lifestyles don't necessitate great dexterity and agility to operate in their daily lives, ergo not as "dynamic" in their realm. I've seen a dugong get the shit scared out of him in person....they can put a move when need be, I promise you! Not like a sea lion evading a white level, but getting gone none the less!

www.nature.com/articles/d41586-022-04421-w. This is a study I've linked. The oldest DNA is around 2 million years old, and DNA usually completely degrades after 6.8 million years according to Colossal Bioscience. Pezosiren's DNA is long lost to time. Also, we have so few remains, and no members of it's family remaining. So, while it would be cool, Pezosiren will likely never be resurrected. Thanks for asking