Mistralazhdarcho maggii was named in 2018 by paleontologists Romain Vullo and colleagues and is based on a partial skeleton found in the Upper Cretaceous ‘Begudian’ Sandstone at the Velaux–La Bastide Neuve locality in Bouches-du-Rhône Department, Southeastern France. The genus is named for the ‘Mistral,’ a cold wind in southern France coming from the northwest. The species name honors Jean-Pierre Maggi, mayor of Velaux and supporter of the paleontological research.
Mistralazhdarcho is known from a single partial and disarticulated specimen discovered in a sandy conglomerate lens. The skeleton is known from a partial mandible, some cervical vertebrae, both humeri, the left radius, right pteroid, partial wing metacarpals and phalanges, and several other indeterminate pieces.
The incomplete mandible is from the front of the jaw and is about 26 cm (10 inches) long, but would have been at least twice as long when complete. It is very long and sharply pointed when seen from the side and was extremely narrow left to right, superficially resembling scissors. The upper portion of the jaw was flat with raised rims probably supporting beak tissue. At the rear part of the preserved specimen is a narrow semicircular bony process called the “median eminence” that rises into mouth.
Vullo and colleagues estimated that this individual had a wingspan of about 4.5 meters (15 feet), but the incompletely ossified limb bones indicate that it was not fully grown. An adult Mistralazhdarcho may have had a wingspan as great as 5-6 m (16.5-20 feet).
Mistralazhdarcho was regarded as an azhdarchid, a family of medium-sized to gigantic pterosaurs common in Upper Cretaceous rocks all over the world. Azhdarchids all have long, toothless jaws resembling living herons and storks. They are thought to have been hunters of terrestrial prey while also possibly hunting near-shore prey. The median eminence seen in the mandible of Mistralazhdarcho is quite similar to a feature found in Alanqa, another azhdarchid known from the Upper Cretaceous Kem Kem Beds of Morocco. In Alanqa, the median eminence articulated with a complementary groove on the lower surface of the upper jaw. Vullo and colleagues suspect that Mistralazhdarcho may have been similar.
When Mistralazhdarcho lived, about 75 million years ago, most of Europe was flooded by shallow seas. The fossils were discovered in rocks formed by an ancient meandering river that once flowed over an Ireland-sized island that now makes up much of southern France.