SVP Taylor & Francis Award Interview: Ornella Bertrand

Following the annual meeting, we're highlighting the student and early career award winners from the society. Today we talk with Dr. Ornella Bertrand (research website here), first place recipient of the Taylor & Francis Best Student Paper Award for her senior authored publication, “First virtual endocasts of a fossil rodent: Ischyromys typus (Ischyromyidae, Oligocene) and brain evolution in rodents.”

What about rodent brains make them an interesting topic of study?
Rodents show a lot of variation in term of lifestyle and number of species. This diversity makes them a great model for better understanding how the brain may change in function of locomotion. For instance, it seems that arboreal squirrels have both a larger visual cortex and a larger overall relative brain size compared to fossorial species. In the case of the visual cortex, this adaptation makes perfect sense because vision is so crucial when living in a 3D complex environment full of trees compared to living inside an underground burrow where hearing might be more critical.  

What is Ischyromys, and what does it tell us about the evolution of the brain in rodents?
Ischyromys is part of the family Ischyromyidae, which is a primitive group of rodents that was mainly present in North America from ~61 to 33 Million years ago. This particular genus was probably fossorial in lifestyle. When compared with an arboreal squirrel from the same epoch, Ischyromys had a smaller relative brain size compared to the arboreal species. It also seemed that its visual cortex might have been less developed. Ischyromys tells us that in the past, similar changes in the brain occurred with specific lifestyles as seen in modern rodents.

Above: Digital endocasts with skulls for Ischyromys typus (A and B) and a modern grey squirrel, Sciurus carolinensis (C). Figure 4 from Bertrand and Silcox 2016.

Can you share an anecdote about the research that might not have made it into the final publication?
While looking for specimens of Ischyromys, I came across a publication that showed an illustration of the Ischyromys brain. I really wanted to see this specimen because it had a feature called the inferior colliculi (Fig. 8B of the publication) but I could not find it and unfortunately, I think this specimen has been lost... While writing the paper, I went to the AMNH in NYC and by chance came across a beautifully preserved specimen that had the inferior colliculi completely visible (Fig. 8A). This specimen nearly didn’t make it into the publication so I’m glad I was at the AMNH at that time!  

If there is any outstanding question that remains following your work, what would that be?
I think there are so many questions that remain to be answered! I have been working more specifically on Ischyromyidae and squirrels to try to understand the relationship between brain and locomotion but I think these questions can be extended to other rodents such as South American rodents that are extremely diverse. More generally this line of research can be extended to all mammals, as the broad question we are trying to answer is whether brain size and shape vary as a function of lifestyle and how do those changes appear on the brain in different mammalian orders?

Citation: Bertrand, O.C., and Silcox, M.T. 2016. First virtual endocasts of a fossil rodent: Ischyromys typus (Ischyromyidae) and brain evolution in rodents. Journal of Vertebrate Paleontology e1095762: 1–20.

Thank you, Ornella, and congratulations!
Posted: 9/11/2017 11:54:49 AM by andyfarkeadmin | with 0 comments
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