Australosuchus is an extinct monospecific genus of crocodylian belonging to the subfamily Mekosuchinae. The type and only known species Australosuchus clarkae lived during the Late Oligocene and the Early Miocene in the Lake Eyre Basin of South Australia. It was described in 1991 by Paul Willis and Ralph Molnar from fossil material discovered at Lake Palankarinna.
Australosuchus is among the mekosuchines with the southernmost distribution, being found exclusively at a latitude below 27°S, which is the basis for its scientific name meaning "southern crocodile". This range is peculiar, as no material of this species is known from any of the more northern localities, which are known from their highly diverse crocodilian fauna. Likewise, although crocodilian remains are common in the southern localities too, they seem to exclusively belong to Australosuchus, not featuring any of the taxa present in areas such as the Riversleigh World Heritage Area. One explanation suggests that Australosuchus was especially cold-resistant compared to contemporary forms like Baru and was thus able to inhabit freshwater systems too cold for its relatives.
History and naming
One of the earliest discovered mekosuchines, Australosuchus was named in 1991 shortly after the publication of Baru. This makes it only the fourth mekosuchine to have been formally described and one of the species that first lead to the recognition of an endemic Australian Cenozoic group of crocodilians. Like many other mekosuchines, remains of this genus had been known long before its formal description, with the fossils of Australosuchus having been mentioned in literature as far back as 1968. The holotype of Australosuchus is specimen QM F16788, a partial skeleton collected in 1975 that includes a nearly complete skull and lower jaw, various vertebrae, parts of the forelimbs and the dorsal armor. The holotype was unearthed from the Etadunna Formation near Lake Palankarinna, South Australia. In addition to a vast quantity of additional fossils from the Late Oligocene to Miocene Etadunna Formation, there is also fossil material from the Namba Formation near Lake Pinpa and Lake Tarkarooloo as well as the Wipijiri Formation near Lake Ngapakaldi. Some fossils were initially described as stemming from the Mampuwordu Sands, which has been interpreted to be Late Pliocene to Early Pleistocene in age, but this is generally deemed unlikely. Instead, it has been proposed that the fossils were reworked from the underlying strata of the Etadunna Formation.
The name of Australosuchus derives from the Latin "australis" and the Greek "suchus", which in combination mean "southern crocodile". The species name on the other hand honors Elaine Clark, a dedicated supporter of the Riversleigh Research Project.
Description
Australosuchus was a medium-sized crocodilian with a moderately broad and flattened skull.