PhD student scores scientific publishing coup with whale fossil research
Doctoral student Felix Marx and a squalodontid
fossil from the Department of Geology’s extensive collection. If possible, can you please credit
Associate Professor Ewan Fordyce for the pic.
Just six months into his PhD studies, student Felix Marx has gained a distinction many doctoral candidates only dream about achieving in their lifetimes: being the first author of a research report published in Science, one of the world’s most prestigious scientific journals.
Department of Geology student Felix Marx co-authored an article with Dr Mark Uhen, of George Mason University in the United States, showing that the origin and evolution of modern whales was driven by a combination of food abundance and climate change.
These findings stem from his doctoral research, conducted under the supervision of Professor Ewan Fordyce (University of Otago), Professor Mike Benton and Dr Marcello Ruta (both University of Bristol), into the biodiversity (speciation) and morphological variety of prehistoric cetaceans (whales and dolphins).
Marx says that New Zealand’s rich fossil record of early cetaceans, the remarkable specimens already held in the Geology Museum and the expertise of Professor Fordyce make Otago one of the best places in the world to study early cetaceans.
And even though he had “heard rumours” about the quality and breadth of the collection in the museum, he was overwhelmed on his first visit into the fossil storage underneath the museum shortly after his arrival in August 2009.
Originally from Austria, Marx completed his undergraduate degree at Bristol University in the United Kingdom. His doctoral thesis aims to construct a more complete view of the evolutionary history of whales, one that encompasses not just speciation but morphological diversity as well.
“We know much about how ancient cetaceans first evolved from four-legged ‘landlubbers’ into the sea-going creatures of today, thanks to the last 20 or so years of research,” says Marx. “On the other hand, many questions remain about what drove the evolution of whales after their ancestors had become fully aquatic.”
The aspect of his research published in Science settles uncertainty over whether the fossil record of whale diversity truly reflects the evolutionary history of modern whales, or whether it provides a flawed picture affected by the amount of preserved sedimentary rock available for palaeontologists to search.
“Our analysis of rock, marine plant life and climate-related data sets covering millions of years shows that the fossil record of cetaceans is not the result of a misleading sedimentary rock record. Instead, the diversity of fossil cetaceans seems to be related to the evolution and diversification of diatoms, a prominent group of tiny marine plants which help form the base of the marine food web.”
The fossil record clearly shows that diatoms and whales rose and fell in diversity together during most of the last 30 million years, Marx says.
“When diatoms are dominant in oceans, it creates a shortened food web that would enable more efficient foraging by whales, allowing them to grow larger, more abundant and more diverse.”
By looking at oxygen isotope records – a chemical fingerprint of oceanic temperature and global ice volume over large time scales – Marx and Uhen were able to show that fossil whale diversity was also linked to changes in ancient climate.
“We concluded that the diversity of fossil cetaceans was driven by a combination of food abundance and climate change. Both these factors were probably related, in turn, to continental drift and changes in the Earth’s geography, in particular the isolation of Antarctica from other continents about 30-40 million years ago.”
The isolation of Antarctica led to a new current that released high levels of nutrients into upper layers of the world’s oceans, likely providing ideal conditions for diatoms to flourish, he says.
“Due to their position at the top of the marine food web, whales are strongly affected by global environmental change. Discovering what the past impacts of these changes were will help provide us with new tools to predict how future global changes might affect these animals,” he says.
