"Tetrapodomorpha encompasses a group of tetrapods that have limbs, as well as their closest relatives in the fish world. The first discovery of this group occurred during the Pragian period in China," said Dr. Choo and his colleagues. "This group underwent significant development in marine and freshwater environments during the Middle to Late Devonian period, resulting in various lineages, including primitive legged tetrapods." The discovery of a new ancient fish species in Australia is taken from the sci.news report on (22/03)."

The respiratory organ of Harajicadectes zhumini exhibits a spiral structure that is believed to facilitate air circulation on the surface. This is consistent with the current African bichir fish, which has a similar shape for extracting oxygen above water," explained Dr. Choo. "This characteristic appeared in several tetrapomodorph lineages during the Middle-Late Devonian period." "Not only Harajicadectes zhumini from central Australia, but large spirals are also observed in Gogonasus from western Australia and in elpistostegalian species like Tiktaalik - the closest relatives of tetrapod quadrupeds."

"Furthermore, this characteristic is also found in Pickeringius, a type of ray-finned fish unrelated to Western Australia, which was first identified in 2018. The presence of this synchronized air-breathing adaptation may have emerged alongside periods of decreased oxygen levels in the atmosphere during the mid-Devonian," revealed Professor John Long from Flinders University. "The ability to synchronize gill respiration with oxygen intake from the air likely provides an adaptive advantage."

"A new type of lobed fin fish variant was found in a remote fossil location in Australia, namely the Harajica Sandstone Member in the Northern Territory, approximately 200 kilometers west of Alice Springs. This species originated from the Middle-Late Devonian period, around 380 million years ago." It is difficult to determine the position of Harajicadectes zhumini in this group because the species acquired specific characteristics through convergence and characteristics from a highly evolutionarily distinct tetrapodomorph branching."