For the first time since its discovery 130 years ago, one of the most mysterious vertebrate fossils
Palaeospondylus gunni – it's mysteriousa fish-like fossil vertebrate with a strange set of morphological features, including the absence of teeth and dermal skeleton in the fossil state. A small animal with a body similar to that of an eel lived approximately 390 million years ago. Despite its age, its position on the evolutionary tree was still unclear.
However, recent advances in 3D segmentation and high-resolution imaging have made this previously impossible task possible.
Research conducted by the University of Tokyotogether with ANU and the RIKEN Evolutionary Morphology Laboratory, showed that this specimen was probably one of the earliest ancestors of four-legged animals. The researchers concluded that Palaeospondylus most likely belongs to the Sarcopterygii, a group of lobe-finned fish, due to its cartilaginous skeleton and lack of paired appendages.