Why did carnivora outcompete mesonychia and creodonta?

Answer 1

Mesonychids:

There were two main disadvantages as concerns Mesonychids against both Carnivores and Creodonts. First, Mesonychids were generalized hunters making them less capable in any specific habitat and affording that benefit to Carnivores and Creodonts. Second, Mesonychids were generally larger than Carnivores and Creodonts and required more food to sustain them. As a result, they were out-competed.

Creodonts:

Creodonts share some benefits with Carnivores like binocular vision, claws, and shearing carnassial teeth. Some species even had more bite force than carnivores, but they had two distinct disadvantages. They were neither as fast or as efficiently designed as Carnivores. They also lacked the raw intelligence that Carnivores had, allowing Carnivores to hunt in packs and establish social relationships. Additionally, Carinvore intelligence led to more advanced hunting procedures and "hand-eye" coordination.