"diandongosuchus" was found in a ladinian-age marine limestone formation that has preserved many marine reptiles including thallatosaurs, nothosaurs, pistosaurs, and some protorosaurs. the closely related pseudosuchian "qianosuchus" was found in a marine deposit about northwest of the "diandongosuchus" locality that is slightly older (anisian in age) and possesses many features consistent with a marine lifestyle. however, "diandongosuchus" shows no features that are clear adaptations to a marine lifestyle. possible adaptations include nostrils that are positioned slightly farther back on the skull than most terrestrial pseudosuchians and a greater number of premaxillary teeth (a feature seen in possible semiaquatic archosaurs such as "chanaresuchus" and spinosaurids). fish bones within its stomach contents are additional evidence that it was a marine archosaur. "diandongosuchus" may have had a similar lifestyle to modern marine crocodylians like the saltwater crocodile that live along coastlines yet are not fully marine.