Osteolepis macrolepidotus, a fossil fish from Scotland

Osteolepis macrolepidotus

Roz Wade, Interpretation and Learning Officer for the Museum of Zoology, writes:

I was lucky enough to study Natural Sciences here at Cambridge, specializing in Zoology. Having the museum’s collections to learn from is the most amazing resource for a student. Being able to see the animals, explore how they are put together, getting the light-bulb moment of understanding of “ahhh that’s what that structure is”… I don’t think you can get that from a text book. Nothing beats looking in detail at the animals themselves.

When I was in the third year of my degree I did a research project with Professor Jenny Clack, the Curator of Vertebrate Palaeontology here in the Museum. She showed me this fossil fish over 380 million years old, from the Middle Old Red Sandstone of Scotland, and I was hooked on palaeontology. But fossils of that age are not rare. In fact, fish fossils from the Middle Old Red Sandstone of Scotland are not particularly rare. What is special about this fossil is what is preserved.

At first glance, this fossil looks like a jumble of scales, with no clear bones in the head and not even any fins preserved. But take a close look at the head and you can see that, although there are few recognisable bones there, what is preserved is something much more astonishing. What we can see here is the natural cast of the back part of the brain cavity and inner ear. Look closely at the lump of sediment in the middle of the head and you can see nerve canals branching off it. On either side are the beautifully preserved infills of the semicircular canals of the inner ear. These are the balance organs, and are surprisingly similar to the semicircular canals inside your inner ear that are telling you which way up you are. This is a very ancient sensory system – ears evolved first for balance, not hearing, and semicircular canals are seen in all vertebrates. The physics of the inner ear means that you can tell something about the sensitivity of these organs by looking at their proportions. So not only is it amazing these structures are preserved at all, you can also say something (albeit with many assumptions to cover aspects of the system not preserved) about what these creatures, which went extinct hundreds of millions of years ago, may have sensed.

2 thoughts on “Osteolepis macrolepidotus, a fossil fish from Scotland

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s