唐朝年间,潮州韩江流域存在着一种生性凶猛,能伤人畜的鳄鱼,当时的韩江也因此被称为"鳄溪"或"恶溪"。韩愈祭鳄,并未真正把鳄鱼赶出韩江流域,之后潮州还有鳄鱼的记录。在气候的变化、海岸线的变迁和人类活动的多重作用下,加速了鳄鱼灭亡的进程。如上作用在宋以后就更为明显,在优胜劣汰的规律下,鳄鱼或死或向南方的海域迁徙,最终绝迹于韩江流域。

During the Tang Dynasty in Han River valley of Chaozhou, there was a kind of truculent crocodiles harmful to mankind and other animals. Therefore, Han River was named "Crocodile River" or "Evil River" at that time. But Han Yu didn't drive away the crocodile from Han River valley. There were still records about the crocodile yet. This article presents a new viewpoint on species of crocodiles, according to the materials of historical literature,combining related geographical and zoological knowledge, and analyses the cause of crocodile's extinction by synthesizing the links among climate,environment and human beings.