What was typical of the late Pleistocene (“end of the Ice Age”) megafaunas?

Throughout Earth’s history, megafaunas have evolved many times – just think of the dinosaurs. During the Ice Age, most of the megafauna species were mammals, but on certain continents and islands some huge reptiles and birds evolved and were also part of the megafauna.

What is a megafauna?

Megafauna is an artificially created zoological concept. To put it very simply, it is a fauna (animal kingdom) with many large species. In a narrower sense, megafauna refers to only a part of the fauna, the large animals living at the same time in the same area. Since it is an artificially created term, it is not used uniformly by researchers. It is generally defined as species that reach or exceed 44 kg body weight at maturity. However, many researchers believe that a different limit (500 kg) should be applied to herbivores.

Does size matter?

Ice Age animals and plants adapted to the changing climate and environment differently. Among plants, many dwarf species evolved and spread over large areas. Their dwarfism allowed them to reduce their evaporation. However, animals have developed in the opposite way. One of the most striking phenomena of the Ice Age fauna was the emergence and proliferation of large mammals. Having a huge body was advantageous in many ways. Large animals have a smaller body surface relative to their mass, thus reducing heat loss. Their shortened ears and tails also reduced heat dissipation. The large bodies allowed them to store more nutrient reserves for times of scarcity. Large animals could migrate greater distances in search of food.

How did the Pleistocene (Ice Age) megafauna evolve?

For many large species to evolve, i.e. to form a megafauna, the most important criterion is that they have abundant food sources. Lush vegetation allows the development of large herbivores, which in turn allows the development of large carnivores. In the Pleistocene, a vegetation belt developed, which researchers have named the mammoth steppe. It was similar to the tundra steppes of today, but was a much more diverse vegetation type providing more plant nutrients. This was one of the factors that allowed the development of the Ice Age megafauna. Another main reason was the cold itself. Larger animals have a smaller body surface area in relation to their body mass than smaller animals, which means that larger animals have a lower specific heat dissipation. This is good for the animal’s thermoregulation, which is very important for species living in cold climates.

The whole world is edible

During the glacial stages of the Ice Age, the amount of forested areas decreased, while the proportion of grassland and wooded steppe increased. Forests generally provided a wide variety of relatively easily digestible food for herbivorous animals. In contrast, the main food sources in grasslands were low-calorie grasses and herbaceous plants which were hard to digest and had to be consumed in big quantities. This required a long intestinal tract and a large stomach, which, of course, could only fit in a large body. The emergence and spread of large herbivorous species then led to the emergence of large predators that preyed on them. This led to the development of the so-called megafauna of the Ice Age. Every continent, and even the larger islands, had their own megafauna. Today, animals of similar size can be found on the savannahs of tropical regions.