Chaoyangopterus: a toothless pterosaur from Cretaceous China

Chaoyangopterus zhangi is a toothless pterosaur from the Early Cretaceous Jiufotang Formation of Liaoning, China. Its holotype preserves the front of the skull and lower jaws, neck, girdles and limbs, but not the rear of the skull or a complete skeleton. Once assigned to Nyctosauridae, it is now generally placed in Chaoyangopteridae within Azhdarchoidea. The pterosaur catalogue places that history beside related forms such as Sinopterus and other Chinese azhdarchoids.

Quick facts

A name from the Jiufotang Formation

Wang Xiaolin and Zhou Zhonghe named Chaoyangopterus zhangi in 2003. Holotype IVPP V 13397 comes from the Jiufotang Formation of Liaoning Province, north-eastern China, and is Aptian in age. The type is an immature individual represented by the front part of the skull and lower jaws, cervical vertebrae, shoulder and pelvic elements, and limb bones. The rear of the skull is missing.

A separate fossil, LPM R0076, has also been referred to Chaoyangopterus. It is a smaller immature individual from a different locality. Because it is not associated with the holotype, the referral is based on anatomical comparison. It should not be combined with IVPP V 13397 as if both fossils formed one skeleton.

Toothless jaws and an incomplete head

The preserved jaws are toothless, and the front of the skull informs the shape of the beak. The missing rear skull limits what can be said about the braincase and complete cranial proportions. Thin bones and incomplete preservation also affect the precision of a reconstruction. The type shows a toothless front end; it does not provide the whole head.

The fossils indicate an animal with a wingspan estimated at about 1.85 metres for the subadult type. This number is reconstructed from preserved limb proportions and restored sections. It is not a measurement of a fully extended fossil wing and does not establish the maximum adult size. A separate estimate for another immature fossil represents another individual, not an adult average.

Why it is not a nyctosaurid

The original description classified Chaoyangopterus among Nyctosauridae. Later analyses recognised similarities with other toothless azhdarchoids, including Shenzhoupterus and Jidapterus, and supported Chaoyangopteridae within Azhdarchoidea. It is therefore not generally considered a true nyctosaurid today.

Classification depends on how anatomical characters are compared across a branching evolutionary tree. Later taxon sampling and character assessments changed the interpretation; the original bones did not change. Azhdarchoid pterosaurs include a range of sizes and body shapes, so family membership alone does not justify copying the anatomy of one relative onto another.

Ecology and what is not preserved

The Jiufotang Formation records a varied Early Cretaceous ecosystem. Its geology places the animal in time and region, while other fossils provide broad context. They do not prove the exact habitat or prey of this individual. No stomach contents or direct feeding traces are reported for the holotype, so its diet remains unknown.

A toothless beak could pick up or handle food, but the fossils do not identify a particular technique. Wing bones support flight, while detailed performance depends on membrane shape and other soft tissues that are not preserved. Colour and behaviour in a full illustration are reconstructions.

A useful but incomplete skeleton

Compared with pterosaurs known only from a jaw tip, Chaoyangopterus preserves multiple body regions and supports meaningful comparisons. It remains incomplete: much of the skull, tail and wing membrane are absent, and the type was still growing. The reliable description keeps observations distinct from estimated span, family assignment and ecological interpretation.