Hanyusuchus is an extinct genus of gavialid crocodilian native to South China, containing 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. Hanyusuchus is a recent Holocene taxon, living in southern China from at least the 4th millennium BC (during the Bronze Age) to as late as the 15th century AD, perhaps even later, when increased efforts of government culling and habitat destruction likely led to its extinction.
Discovery and naming Subfossils of Hanyusuchus were initially discovered between February 1963 and February 1980, with a total of six 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 livestock, Han Yu issued a proclamation in which he instructed the crocodiles to leave the area or be killed. 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".
Description
Hanyusuchus is a large, slender-snouted crocodilian, generally resembling the modern false gharial. Each premaxilla contains five teeth, followed by sixteen teeth in each maxilla. The dentary bears eighteen teeth. 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, however, is 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 descriptions telling of crocodiles making "thunder-like sounds in the night". Both the holotype and one of the paratypes indicate that they had reached 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. 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.
Distribution
Subfossil evidence and historic documents all indicate that Hanyusuchus inhabited what is now South China, with subfossils found in Jiangmen and Foshan (Guangdong District). Much of the known material has been subjected to accelerator mass spectrometry radiocarbon dating, revealing their age to roughly correlate with the Bronze Age approximately 3300 to 2900 BP. The osteoderms were not analyzed by Iijima and colleagues; however, older research estimated their age to be 5000 to 4900 BP. Historic reports are notably more recent, dating from the Han dynasty (specifically 210–127) to possibly as recent as the Ming dynasty (ca. 1630). The reports gathered from South China indicate their presence ranging from at least Nanning in the west to the Han River delta in the east. Reports are also known from the northern parts of Hainan Island.
In culture
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