Prehistoric kangaroos changed their diets to survive climate change

For many years, scientists believed that prehistoric kangaroos in Australia had specialized diets, relying specifically on certain types of plants or vegetation for their survival. This idea suggested that they were unable to adapt to changes in their environment, such as shifts in climate or vegetation patterns.

When the kangaroos’ preferred food sources became scarce, it was assumed that their dietary inflexibility contributed to their extinction. This theory placed dietary specialization as a key reason for the disappearance of some kangaroo species during the Pleistocene epoch.

However, recent research challenges these assumptions, suggesting that these marsupials were more resilient than we initially realized.

Diverse diets of prehistoric kangaroos

The study was carried out by experts from Flinders University and the Museum and Art Gallery of the Northern Territory (MAGNT).

The researchers used cutting-edge techniques to analyze the microscopic patterns of wear on fossilized kangaroo teeth. These patterns revealed the types of food the kangaroos ate.

The results showed that prehistoric kangaroos were not limited to specific types of food. Instead, they were generalists, capable of eating a wide variety of plants. This flexibility in diet helped them survive environmental changes over time.

Focusing on fossils from the Victoria Fossil Cave at the Naracoorte Caves World Heritage Area in South Australia, the experts analyzed kangaroo diets across 12 extinct species and compared them with 17 modern species.

The Naracoorte region contains the richest and most diverse fossil deposits of kangaroos from the Pleistocene epoch, making it an ideal location for this research.

Flexible diets helped kangaroos survive

“Our study shows that most prehistoric kangaroos at Naracoorte had broad diets. This dietary flexibility likely played a key role in their resilience during past changes in climate,” explained lead researcher Dr. Sam Arman.

Contrary to previous assumptions, the study revealed that most species were mixed feeders, capable of consuming both shrubs and grasses.

“The distinctive short-faced kangaroo anatomy led to a widespread view that sthenurines were unable to adapt their diets when climate change altered vegetation patterns, leading to their extinction,” said study co-author Professor Gavin Prideaux.

However, the findings suggest that their ability to consume a wide range of foods provided a survival advantage during periods of scarcity.

Complex extinction dynamics

While the ability to adapt their diets likely helped prehistoric kangaroos survive for a time, it wasn’t the only factor influencing their fate.

The extinction of these megafaunal kangaroos also involved other challenges, such as their large body size, how they moved (locomotion), and their interactions with early humans, who may have hunted them or altered their habitats.

To better understand these complex extinction dynamics, the researchers plan to study fossils from other Pleistocene sites. They will focus on the critical period between 60,000 and 40,000 years ago – a time when many large animal species disappeared.

This broader investigation could reveal how different factors worked together to drive kangaroo extinctions.

“Identifying what drove the late Pleistocene megafaunal extinctions on the continents remains one of the most contested topics in historical science,” noted the study authors.

“This is especially so in Australia, which lost 90% of its large species by 40,000 years ago, more than half of them kangaroos.”

Insights into ecosystem vulnerabilities

The study highlights the ecological roles of prehistoric marsupials, offering valuable insights into the evolution of Australia’s ecosystems.

“Understanding the resilience of ancient species helps contextualize why Australia has been so vulnerable to introduced large mammals like pigs, camels, and deer,” noted Professor Prideaux.

Dr. Arman uses a relatable analogy to describe dietary flexibility: “Most of the time, I don’t need to engage four-wheel drive, but this capability becomes crucial when I do need it.”

Extinction of Australia’s megafauna

The research, funded by the Australian Research Council, reflects a long-standing partnership between Flinders University and MAGNT.

The research also honors the traditional custodians of the Naracoorte region, the Meintangk, Marditjali, and Potaruwutj peoples, and acknowledges the contributions of volunteers and students in collecting and preparing specimens.

The study marks an essential step in understanding the resilience of prehistoric kangaroos, their adaptable diet and the complex interplay of factors that led to the extinction of Australia’s megafauna.

The study is published in the journal Science.

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