TL;DR- dragons are what happen when you mash together big cats, big snakes, and big birds of prey

They’re big and scary enough today, and in the past they were even bigger and scarier.

https://en.wikipedia.org/wiki/Haast's_eagle

Relationship with humans

Some believe that these birds are described in many legends of the Māori mythology, under the names pouākai, Hakawai (or Hōkioi in the North Island).[52][53] According to an account given to Sir George Grey—an early governor of New Zealand—Hōkioi were huge black-and-white birds with yellow-green tinged wings and a red crest. In Māori mythology, Pouākai would prey and kill humans along with moa,[54][55][56] which scientists believe could have been possible if the name relates to the eagle, given the massive size and strength of the bird.[52][57] However, it has also been argued that the “hakawai” and “hōkioi” legends refer to the Austral snipe—in particular the extinct South Island species.[58]

For context, Haast’s eagle was about twice the size of today’s Harpy eagle, which itself looks like it came out of a nightmare. See photos at https://www.demilked.com/giant-bird-harpy-eagle/

The linked article mentions that one of the predator types merged into the dragon is raptors (as in birds of prey, not velociraptors)