Qianosuchus

Qianosuchus is an extinct genus of aquatic poposauroid archosaur from the middle Triassic (Anisian) Guanling Formation of Pan County, China. It is represented by two nearly complete skeletons and a crushed skull preserved in the limestone. Qianosuchus was at least 3 metres long, and had several skeletal adaptations which indicate a semi-marine lifestyle, similar to modern-day saltwater crocodiles. These adaptations have not been seen in any other archosaur from the Triassic.

== Description == left|thumb|318x318px|Skeletal diagram Qianosuchus had a skull around 33 cm (13 inches) long, with an elongated snout. The rostrum formed by the premaxilla is shallow at the front of the skull but deepens posteriorly. Each premaxilla has nine long teeth, and the maxillae bear eighteen teeth each. All the teeth are laterally compressed, curved backwards and serrated, like those of most other carnivorous archosaurs. The nares are expanded and elongated and almost collide with the antorbital fenestrae, meaning that the septum (bony wall) between them is thin and lightweight. Unusually, the jugal forms no part of the border of the antorbital fenestra. Each orbit had a large and well-developed scleral ring in it, which would have reinforced the eyeball under pressure when Qianosuchus was diving. The frontal bones have deep fossae (depressions) on their upper surface, which stretch backwards to the sutures with the parietals. Another such fossa is present between the two parietals themselves. The dentary turns down very slightly at the tip; a precise tooth count is unknown due to the bone being hidden by the maxillary teeth in the fossils. The hyoid bones are long and slender, with slightly expanded ends. left|thumb|Color-coded diagram of the skull Qianosuchus had nine cervical, fifteen dorsal, two sacral and at least 50 caudal vertebrae. The posterior end of the tail is missing in both skeletons. The neural spines grow taller posteriorly (further down the tail), making the caudal vertebrae tall but thin in that area. The first 23 caudal vertebrae have transverse processes, but these processes are lost further back. The vertebral centra grow shorter posteriorly, making the tail more flexible than the neck. Some of the more anterior caudal vertebrae have chevron bones ventral to them which also increase the height of the tail. All presacral vertebrae have small osteoderms at the top of their neural spines. The cervical ribs are elongate, at least four times the length of their corresponding centra, and may have had strong muscles attached enabling it to create suction in its throat while lunging forward at prey by expanding the oesophagus. The dorsal ribs are expanded and pachyostotic at their distal ends.