Hanyusuchus
Hanyusuchus is an extinct genus of gavialid crocodilian from the Holocene of South China. It contains a single species, Hanyusuchus sinensis. Reaching a total body length of 5.43–6.19 metres (17.8–20.3 ft), it shares characteristics of both tomistomines and derived gharials, such as a possibly sexually dimorphic vocal structure. Cut marks found on multiple fossil specimens, as well as archaeological evidence, suggest the presence of repeated conflicts between Hanyusuchus and humans. Hanyusuchus was a recent species, living in southern China from approximately the 4th millennium BC (during the Bronze Age) to as late as the 15th century AD, perhaps even later, when increased efforts of government officials and habitat destruction likely led to its extinction.
Fossils of Hanyusuchus were initially discovered between February 1963 and February 1980, with a total of 6 specimens ranging from skulls to postcrania and osteoderms being known. These however were dismissed as belonging to a modern genus and forgotten for the following years. Eventually the bones were recognized as belonging to a unique genus and described as such by Masaya Iijima and colleagues in 2022. Hanyusuchus is named after Han Yu (768–824), a Chinese poet and government official active during the Tang Dynasty. After a rash of crocodile attacks on humans and lifestock, Han Yu issued a proclamation in which he instructed the crocodiles to leave the area or be killed.[2] The second part of the name derives from the Greek soûkhos meaning crocodile. The species name "sinensis" is a commonly used epithet in taxonomy meaning "from China".
Hanyusuchus was a large, slender snouted crocodilian generally resembling the modern False Gharial. Each premaxilla contained five teeth, followed by sixteen teeth in each maxilla and eighteen in the dentary. The pterygoid bone of Hanyusuchus is occupied by a series of enlarged sinuses thought to be homologous to the enlarged posterior chamber of the pterygoid bulla seen in extant gharials. The structure is however expanded towards the back of the skull in a novel way, increasing the morphological variety of the bulla. However, as parts of the palate are broken in Hanyusuchus, it cannot be determined whether or not it had the anterior chamber. These chambers are internally connected to the nasopharyngeal duct and, depending on the length of the chambers, are used to change the harmonics of vocalisations. In modern gharials the pterygoid bulla is tied to ontogeny and sexual maturity in males and coupled with the growth of a soft tissue structure (ghara). In combination, the bulla serves to alter sounds, while the ghara exaggerates it, which is used in attracting mates. Although no indication for a ghara is described Hanyusuchus, the enlarged sinuses show a clear adaptation towards an acoustic function. This is supported by contemporary description telling of crocodiles making "thunder-like sounds in the night".[1]
Both the holotype and one of the paratypes indicate that they were of full sexual maturity. The known specimens vary in total body length between 5.43–6.19 m (17.8–20.3 ft). Historical reports likewise indicate the presence of 6 m (20 ft) long crocodilians in South China.[1]
Historical records dating to the years 849 and 1040 describe the crocodiles living in South China as being brownish yellow in colour, sometimes deep green and occasionally white. Young animals were described as yellow to white. However such records may not be entirely reliable.[1]
