Reconstruction of an early Devonian fish has revealed a bill like a platypus, probably used for similar purposes. The discovery surprised palaeontologists because the fish is so different from everything else we've found from the era. It suggests fishes were much more specialized early on in their evolution than previously thought.
In 1980 Dr Gavin Young of the Australian National University discovered a partial skeleton of a new species at Lake Burrinjuck in New South Wales. He named it Brindabellaspis stensioi after the nearby Brindabella mountain range, but the fossil was lacking what proved to be the really interesting parts. Young has since found other specimens from the same species and Dr Benedict King, then at Flinders University, put them together to reconstruct Brindabellaspis.
“This was one strange-looking fish,” King said in a statement. “The eyes were on top of the head, and the nostrils came out of the eye sockets. There was this long snout at the front, and the jaws were positioned very far forward.”
In Royal Society Open Science King revealed that the long bill contained an advanced sensory system. “We imagine it used the bill to search for prey, somewhat like a platypus, while the eyes on top of the head looked out for danger from above,” said Professor John Long, who co-authored the paper and supervised King's PhD.
King's PhD was on electric sensory systems, like the ones platypuses and sharks possess. Long told IFLScience they initially thought the bill might have been yet another example of this. However, King could find no evidence of anything resembling electric sensors. Instead, the authors concluded the bill housed a modified form of the pressure sensor system that other fishes have, with two tubes running down the snout and restrictions on the sensory canal that likely allowed it to sense movements of prey.
On the other side of Australia, the Gogo deposits have amazed palaeontologists with early fish so well preserved they have been described as “swimming in stone”. The preservation at Lake Burrinjuck is not quite as good, but Long told IFLScience these deposits are even more important because at 405 million years old they precede Gogo by more than 20 million years.
This means the site preserves the oldest example we have of a tropical reef hosting diverse jawed fishes suggesting – then as now – these were what Young called “hotspots for evolution”, rich in the placoderms that were the dominant fish of the day. “We have slightly earlier examples but they are isolated bits,” Long said. So far 70 species have been found from this location alone, but none like Brindabellaspis. “It's really unusual to find something that is so specialized so early,” Long said. We still haven't found intact mouthparts, however, so we are largely guessing its diet.