Sunosuchus shartegensis Efimov, 1988 Chalawan (from Thai: ชาละวัน [t͡ɕʰāːlāwān]) is an extinct genus of pholidosaurid mesoeucrocodylian known from the Late Jurassic or Early Cretaceous Phu Kradung Formation of Nong Bua Lamphu Province, northeastern Thailand.

The first fossil of Chalawan was a nearly complete lower jaw collected in the early 1980s from a road-cut near the town of Nong Bua Lamphu, in the upper part of the Phu Kradung Formation.

[3] In the early 2000s another locality of the Phu Kradung Formation was discovered near the village of Kham Phok, Mukdahan Province, yielding amongst other remains the anterior tip of a crocodylomorph mandible which was assigned to Sunosuchus thailandicus and described the pholidosaurid affinity of the specimen.

[4] This interpretation remained tentative until the discovery of previously unnoticed skull material associated with the Kham Phok mandible (specimen PRC102-143) which led to the reassignment of Chalawan to the Pholidosauridae.

While vertebrate fossil discoveries point at a Late Jurassic origin, palynology data instead suggests that the Formation represents Early Cretaceous sediments.

It was collected from "Layer 2" of the Tithonian (Late Jurassic) Ulan Malgait beds, in the Shar Teeg locality, of the Govi-Altai Province of Outer Mongolia, embedded in grey clay.

[8] As the paper synonymizing the two crocodylomorphs appeared shortly before Martin et al.'s description of the cranial material, the taxonomic status of "S." shartegensis remains unknown.