Hypercarnivore is defined as an animal whose diet consists of 70% meat. I specifically mentioned endothermic, because ectothermic predators have far lower caloric requirements, 2,000lbs crocodiles today can go MONTHS without needing to eat.

Giants in the cenozoic include:

Andrewsarchus, who is now classified under cetancodotamorpha & as a highly omnivorous mammal, not a hypercarnivore.

S. America short faced bear, who is now also know to be highly omnivorous, NOT a hypercarnivore.

Quinkana, Barinasuchus & Dentaneousuchus were all giant hypercarnivores of the cenozoic but they were all likely endothermic, having very low caloric requirements.

Enteledonts were highly omnivorous, not hypercarnivores.

This leaves the smaller hyaenodonts, polar bears and extinct polar bear ursus maritimus tyrannus as the giant hypercarnivores of the cenozoic. NOT VERY IMPRESSIVE.

This is SIGNIFICANTLY smaller than the hypercarnivores of the mesozoic. You had upright bipedal animals who had to be endothermic in order to effectively move with their posture. These bipedal giants got giant, and many were sustaining themselves on a diet of meat.

What allowed food for these hypercarnivores to be so abundant that they could sustain healthy populations of individuals that could get to 10 tons!!