Gronkle

A Gronkle (Megadracus Indominii) is an extinct species of dragon that lived Norway, Sweden, Finland, and England. Despite their heavy appearance and tiny wings, they could still fly as their wings were packed with strong muscles, their bodies were very light-weight, and their flight bladders were well-developed due to having small wings. They were carnivorous, so they most likely naturally fed on fish, mollusks, and crustaceans. They had the ability to sleep even when flying after having specialized resting in-flight, so they probably did not need to sleep on the ground.

Extinction
Like all dragons, they became extinct due to habitat loss from humans wanting to convert some lands to agricultural areas for livestock, and due to gronkles hunting livestock, knights and vikings killed them off.

However, like many dragons, their sightings as live animals continues today, even though they're still considered cryptids as no evidence of them being alive today eixst apart from blurry footages and images.