Argentinadraco

The Upper Cretaceous Portezuelo Formation of Neuquén Province, Argentina was home to Argentinadraco barrealensis. It was named in 2017 by Alexander Kellner and Jorge Calvo, and is based on a single incomplete mandible. The name translates to “Argentina dragon from Lake Barreales.” 

The mandible is mostly complete, but missing both the front and rear tips. The fragment is about 26 cm (10 inches) long, but may have been double that length when complete. When seen from above, the mandible is Y-shaped, with an extremely long and narrow symphysis. The symphyseal region ranges from about 15 mm to 6 mm (about 1/2 to 1/4 inch) wide, and probably would have tapered to a sharp point. 

When seen from the side, the most prominent feature is a rounded crest on the bottom of the jaws at the rear-most part of the symphysis. In front of the crest, the jaw is about 3.5 cm deep, and tapers toward the tip. The oral margin of the jaws is mostly flat throughout the narrow symphysis. Further back, a central groove bound by two ridges and adjacent grooves running parallel to the long-axis are visible in the region above the crest. The entirety of the oral margin and symphyseal region including the crest were probably covered in keratin in life, forming a beak. 

Nothing else of the skeleton is known, but comparison to other pterosaurs allows us to at least estimate the wingspan to be 2.5 to 3 meters (8-10 feet). 

Kellner and Calvo compared Argentinadraco to several toothless pterosaurs including pteranodontids, nyctosaurids, tapejarids, thalassodromids, chaoyangopterids, and azhdarchids. They found that it bore similarities to thalassodromids, chaoyangopterids, and azhdarchids, but could not confidently assign it to any one of those families. Kellner and Calvo tentatively placed Argentinadraco in the Azhdarchidae based on overall shape and late occurrence. 

Azhdarchids are medium- to large-sized pterosaurs found in Cretaceous rocks from all over the world. They have long and narrow skulls, long necks, and comparatively short wings. Most azhdarchids are thought to have been terrestrial predators, but Kellner and Calvo think Argentinadraco may have done something different. They note the grooves and ridges on the lower jaw were probably met by complementary ridges and grooves on the upper jaw. They speculate that it may have used its blade-like mandible to plow through beach sand in search of prey, grasping it tightly with the ridges and grooves. 

Argentinadraco lived in the Late Cretaceous, approximately 90 million years ago. Its environment was a temperate forested plain, crossed by several meandering rivers. It lived alongside the theropods Megaraptor, Unenlagia, and Patagonykus, as well as the titanosaurs Futalognkosaurus and Mendozasaurus.