In 2005 paleontologist Lü Junchang named a new boreopterid pterosaur, Zhenyuanopterus longirostris, based on an incredible specimen discovered in the Lower Cretaceous Yixian Formation in Liaoning, northeastern China. The genus is named for Sun Zhenyuan, who provided the specimen to Lü. The species name translates to “long snout,” and is in reference to the species’ incredibly long, narrow snout.
Zhenyuanopterus is known from a single specimen, which is articulated and almost entirely complete with very little distortion or bone loss from any part of the skeleton. The individual is lying on its belly with legs and wings spread, although its right wing is twisted out of life position. The skull is preserved on its left side with its right side up and available for study.
The skull is 54 cm (21 inches) long. The rostrum is extremely low and narrow at only about 3 cm (just over an inch) tall, with the entire skull being only about 6 cm (2.5 inches) tall at its tallest point. There is a bony crest on the top of the snout that begins abruptly about halfway along its length. The eyes are small and positioned near the rear of the skull. Both the upper and lower jaws are lined with dozens of long, needle-shaped teeth pointing more or less vertically, with the longest teeth concentrated near the ends of the jaws. The teeth are so long in fact, they extend above and below the margins of the rostrum when the mouth was closed.
The rest of the skeleton shows that Zhenyuanopterus had a stout, medium-length neck, a short torso, and relatively long tail for a short-tailed pterosaur. The wings are extremely robust, and its wingspan would have been at least 3.5 m (11.5 feet). Its legs are short and feet especially small.
When Lü first described Zhenyuanopterus, he considered it to be a boreopterid, especially close to the namesake genus, Boreopterus. Subsequent phylogenetic analyses have supported this idea. Zhenyuanopterus and Boreopterus are so similar in fact, Mark Witton and others have suggested that Zhenyuanopterus may be a fully grown individual of Boreopterus.
Lü also thought that the unusual long-snouted genera Feilongus and Moganopterus were boreopterids, but research by others have shown that, although Feilongus and Moganopterus are closely related, they were large ctenochasmatids rather than borepterids. Boreopterids are ornithocheiroids, a large lineage of long-winged pterosaurs including the ornithocheirids, istiodactylids, pteranodontids, and nyctosaurids.
While most ornithocheiroids were aerial fishers, the unusually long snout and long delicate teeth may have been more useful ambushing aquatic prey, or even straining out very small food items from the water. When Zhenyuanopterus was alive, about 125-130 million years ago, Liaoning was a land of temperate forests with many swamps and lakes, a perfect habitat for hunting.