Ears for Breathing?

` Panderichthys was a fish - related to the first land vertebrates - about 370 million years ago. The bits of rock that remain are of utmost interest to scientists, who have discovered that it had ear-like structures.
` In News@Nature, Helen Pearson writes:

...The bony structures in ancient fish, which at some point turned into ears, for example, appear to have had mainly a structural function, bracing the cheek and holding up the jaw....

...Martin Brazeau and Per Ahlberg of Uppsala University in Sweden decided to take a close look at the ear-like features of an ancient, metre-long monster from the Latvian Natural History Museum in Riga....

` They found that Panderichthys had ear-like structures similar to both that of fish and the early landlubbers - a combination of both.

Ancient fish have a narrow channel from the roof of the skull into the mouth, known as a spiracle, which is bounded by a long bone known as the hyomandibula that braces the cheek. In tetrapods, the equivalent bone is stubbier, a step towards the stirrup-like stapes bone that helps to transmit sound waves into our skulls.

The team found that Panderichthys has a wide, straight spiracle rather than a narrow one, and a shortened hyomandibula. They report their findings in Nature¹.

` Sharks and rays have similar structures which help the fish breathe while lying on the sea floor without accidentally gulping down the sea floor.
` Quite useful things, rather like nostrils in a way....
` As it has already been speculated that ear canals evolved from breathing tubes, the enlarged spiracles of Panderichthys seem to confirm this idea.

` Well, I really must go, it is a gorgeous day! Pictures later!