Drake: Descriptive Overview
Drakes are large quadruped dragons with fore and hind limbs. They are either carnivorous or omnivorous, usually dwelling in caves in the mountains or a rocky area near or in a body of water.
Often dragons of all varieties are compared to terrifying serpents or gapping crocodiles, and for the drake type in particular, the crocodile is a fitting comparison.
Characteristics of the Body
Drakes have tough, protective scales that help them survive in rugged terrain like mountainous caverns or rocky shores. These scales shed constantly, much like human skin and hair, and are constantly replaced. Lost teeth are similarly replaced over a lifetime.
Since drake is a dragon type, there are many variations on physical appearance. Some are closer to the marine-hunting crocodiles in shape, while others reflect the structure of the larger land-based lizards, like the Komodo Dragon.
Komodo Dragons, the largest living lizard, can grow to be 3 meters (10 ft) long and weigh over 91 kg (200 lbs).  The largest known crocodile, the Saltwater Crocodile, can grow up to 7 meters (23 ft) and reach a weight of up to 1,000 kg (2,205 lbs),  and another crocodile, the Gavial (Gavialis gangeticus) can also grow to a length of 7 meters (23 ft). 
These gigantic sizes, however, are uncommon to rare in their species. The average Saltwater crocodile grows to a respectable length of 4.6 m to 4.9 m (15 ft to 16 ft), which is still quite large. Both the Saltwater Crocodile and the Komodo Dragon are dangerous to humans in their average size, so a drake that is smaller than 3 meters can still be a dangerous monster to humans, especially if it is better equipped to deal with rugged terrain and/or water.
Any living organism can adapt through generations to a particular habitat; these small generational changes can add up, pushing most members of a species to possess very similar traits, such as maximum size. Some species, such as elephants, continue growing, although more slowly after reaching sexual maturity, through most, if not all, of their adult life.  However, a larger size is not always better, since the larger an animal is, the harder it is to hide and to maintain healthy body weight. Even predators need to hide in certain cases, such as injury and even pregnancy, and for any carnivore, hunting can be troublesome if the animal is too large. Larger size requires more calories to maintain health, and more calories requires more hunting, foraging, or scavenging on part of the animal.
So while it is possible that adult drakes could average an enormous size of 10 meters (32.8 ft) with giant specimen reaching sizes equal to that of large prehistoric animals, around 20 meters (65.6 ft), it is unlikely that a species that large would continue its size range through many generations. A scarcity of food would likely kill off larger specimens of the species, and when the rise of the modern human proved to be the next predator for animals, that could easily end the success rate of a larger, and more dangerous, species.
Drake Skeleton based on Komodo Dragon
Assuming drakes would be similar in shape to species like the Komodo Dragon or crocodile, the shape of the drake would be a low-slung belly and shorter legs that turn out. The crocodile can pull its legs under itself, making it the only known member of the reptile family that can walk upright as opposed to with splayed legs, so drakes with splayed legs can walk upright if they have the same configuration as crocodiles.
Illustration 1. Drake Skeleton based on Komodo Dragon. © Kylie 'drago' McCormick.
Both Komodo Dragons and crocodiles can swim, and given the strong connection with dragons and water, it is likely that the drake would be a strong swimmer as well.
It is very likely, given the age and span of the Order Crocodylia, that drakes would be either a species of this order or a closely related Order under the same Division, Archosauria, which also included the dinosaurs. The members of Crocodylia are semi-aquatic reptiles, making them fit for hunting prey in the water and on land, although their adaptations generally favor hunting in the water.
While the Crocodylia Order seems the most likely for a species of drake to be classified, it is also possible that drakes would fall under the Order Squamata, which includes all the scaled reptiles. Drakes being known for their size and teeth, it is also likely that they would belong to the genus Varanus, which contains the monitor lizards, including the Komodo Dragon.
Drake Skeleton based on Feline/Mammal
While a solid comparison can be made between drakes and reptiles of a large size, it is also possible that the drake physiology runs closer to mammals. Illustration 2 is based on feline skeletal structure, with legs under the body as opposed to splayed out to the sides. A feline-style drake would perform better in running and probably in climbing than a reptile-style drake, but would probably not be as successful as a swimmer.
Illustration 2. Drake Skeleton based on feline/mammal anatomy. © Kylie 'drago' McCormick.
A drake with this structure would likely live in a habitat in a mountainous terrain or even a desert-like region that lacks large bodies of water, although a species with this skeletal structure could also live affectively in the rainforest, on the plains, both in and out of water.
Drake Coloration and Pigmentation
The drake would likely be green to brown in color, matching the colors of its closest relatives. The coloration would help the animal hunt with the aid of camouflage.
This does not rule out the possibility of brightly colored drakes. Many species with potent poisons have brightly colored bodies, which highlight them as opposed to camouflaging them. Features like this are more commonly present in small land animals or amphibians rather than larger animals. Members of the genus Dendrobates, commonly called Poison Dart Frogs, such as the Strawberry Poison-dart Frog (Oophaga pumilio), have shockingly bright colors ranging from brilliant red to shining green, assumed to be a warning to predators. Of course, Poison Dart Frogs are poisonous, since their toxins are not used to hunt for prey, so a better example would be the highly colorful coral snakes, members of the Elapidae family, also have bright warning colors to adorn their hide.
It is unlikely a drake would need highly specialized coloration to protect it from predators, and the bright colors would likely make the drake easy to spot by its prey, making hunting a difficult task. That being said, large reptiles like the Komodo Dragon need only to bite their prey; the animal might escape but will die later from the bite. Then the Komodo can simply find the fallen animal with its keen sense of smell. So stealth might not be necessary for drakes.