Ok i do think the Megalodon getting the bleed effect is very oppresive in the water. They are one of the most common water dinos seen so dealing with something that common is a bit problematic. I also have mixed feelings on the thyla change im not a fan of the added bleed but ive never been dismounted off my reaper going through redwoods and i can deal with them easy enough with any of my existing reapers.
as for Wyverns yeah im sad about the nerfs incomming. I still got Lightning my first ever wyvern still from when i started. Ive had many fond memories of using her including how she kep