The Middle Jurassic Tiaojishan Formation of northeastern China was home to the tiny long-tailed pterosaur Jianchangopterus zhaoianus. It was first described by Lü Junchang and Bo Xue in 2011, based on a single, mostly complete skeleton of an almost fully grown individual. It’s named for Jianchang County and Zhao Limin, who offered the specimen for scientific study.
The skull is about 4 cm (1.5 inches) long and largely complete, but crushed, disarticulated, and has a crack running through it. Despite this, details of its anatomy can be seen showing that the skull is roughly triangular in profile, and there are seven tooth positions in the upper jaws and six on the lower jaws. The teeth are widely spaced, but restricted to the front half of the jaws. They are robust, slightly recurved cones.
The rest of the skeleton is present on the limestone main slab and counterslab, only missing parts of the right wing. Like many early pterosaurs, Jianchangopterus had short hand bones and a long bony tail. The tail was relatively stiff and may have had a vertical fin at its tip like many of its close relatives. Based on skeletal maturity, Lü and Bo determined that this specimen was almost fully grown. It was a tiny animal, with a wingspan of only 32 cm (12.5 inches), about the same size as a robin.
When it was originally described, Lü and Bo considered Jianchangopterus to be a scaphognathine rhamphorhynchid especially close to Sordes pilosus, known from Upper Jurassic rocks in Kazakhstan. Rhamphorhynchids are fish-eating pterosaurs abundant in Jurassic rocks around the world. They are closely related to monofenestratan pterosaurs, the mostly short-tailed pterosaurs that would come to dominate the Cretaceous.
When Jianchangopterus lived, some 160 million years ago, this part of China was a forest with numerous lakes and rivers. While most rhamphorhynchids ate fish, tiny Jianchangopterus may have eaten insects.
Tiaojishan Formation