Size: abundance of large prey has always led to large predators. It happened in the quaternary where giant mammalian predators adapted to large prey. The Mesozoic had an alien amount of large megafauna. For reference, the largest terrestrial animal today is a bush elephant of Africa, the second largest land animal is the Asian elephant, 2 different continents.

The trex small range had 2-3 species of ceratopcians larger than bush elephants, an ankylosaurid species as large as bush elephants, another ankylosaurid species as large as Asian elephants, an ornithopod larger than bush elephants (and lively lived in massive herds), and theid occasionally see the land whale alamosaurus. All of these giant herbivores also had a very short gestation period thanks to egg laying, they could multiply rapidly! All of this fueled the possibility for 10 ton theropod predators. If mammals were to have been the carnivores in this habitat, how big would they get? 10 tons like the trex?

Looks: small and medium sized theropoda tended to have variety in anatomy like a sickle claw. As theropoda got larger their legs became more column like, some kept giant forekimb claws. The largest theropoda all seem to adapt large skulls and tiny arms. How do you think giant mammalian predators would look? How would they hunt?