A study published in the journal "Dietary change across the Paleocene-Eocene Thermal Maximum in the Mesonychid Dissacus Praenuntius" highlights the effects of climate change on species diet. The Paleocene Eocene Thermal Maximum (PETM) was one of the most rapid and intense climate change events in Earth’s history. It happened about 56 million years ago and lasted around 270,000 years. Global surface temperatures rose by about 5.4-5.9°C due to a massive release of carbon dioxide. Rainfall patterns changed sharply, with a drop in average precipitation but an increase in extreme seasonal rainfall events.
Importance of the PETM for Understanding Climate Change Today
The PETM is important for scientists because it offers clues about how animals adapt to sudden climate and habitat changes. This can help predict how today’s mammals might respond to modern global warming.
The PETM is important for scientists because it offers clues about how animals adapt to sudden climate and habitat changes. This can help predict how today’s mammals might respond to modern global warming.
Facts About the Extinct Mammal Dissacus Praenuntius
The focus of this study is on Dissacus Praenuntius, an extinct mammal from the order Mesonychia. This animal lived across the Holarctic region during the late Paleocene and early Eocene, including during the PETM. Fossils are especially common in the Bighorn Basin of Wyoming, a region with one of the most complete fossil records for this time.
Dissacus Praenuntius was a small to medium-sized predator, weighing between 12 and 20 kilograms. It was a mesocarnivore, meaning it ate mainly meat but could consume other foods as well. Its body structure suggests it was a pursuit predator, running down prey with long, narrow limbs adapted for forward movement.
Climate and Habitat Changes in the Bighorn Basin During the PETM
Before the PETM, the Bighorn Basin was covered in humid subtropical forests. These forests were later replaced by open, dry tropical forests and savannas. Many new plant species adapted to dry conditions appeared. Scientists have found evidence of progressive aridification, meaning the land became drier reaching its peak in the latter half of the PETM.
How did mammal's body size changed during the PETM?
Mammals responded to these changes in different ways. Many species, such as Ectocion, Copecion, Sifrhippus, Uintacyon, and Palaeonictis, became smaller in body size. This pattern, known as “dwarfing,” could be caused by higher temperatures (as described by Bergmann’s rule) or by reduced food availability due to lower primary productivity. In many cases, both factors may have played a role.
Teeth and Body Adaptations of Dissacus Praenuntius
Although Dissacus looked similar to modern carnivores like wolves, it was more closely related to hoofed mammals (ungulates). Its teeth were adapted for tearing flesh and breaking bone. Although it lacked the specialized slicing teeth (Carnassials) found in modern carnivores.
Its lower molars had tall, sharp peaks called protoconids, and the tooth shape helped with the grip and to cut meat. Some features also allowed it to handle hard food items like bone. However, it was not a specialist in bone-crushing and could process hard objects but did not rely on them as its main food source.
How do scientists study diet with Dental Microwear Texture Analysis?
Researchers used Dental Microwear Texture Analysis (DMTA) to study the diet of Dissacus Praenuntius. In this method researchers examines the microscopic wear patterns on teeth which are created when an animal chews its food. Softer foods like flesh leave different patterns than harder foods like bone.
Importantly, dental microwear records the animal’s diet in the weeks before death, not its entire lifetime. This means the method can detect short-term dietary changes across different time periods, such as before, during, and after the PETM.
Predictions About the Diet of Dissacus praenuntius Before Research
Before the study, scientists expected that the dental microwear of Dissacus praenuntius would match that of generalist carnivores, predators that eat both flesh and some bone, but not heavily specialized in either direction.
They also predicted that there would be no major change in dental microwear across the PETM, even though body size decreased. If this were the case, it would suggest that body size reduction was an adaptation to lower prey body mass, without a significant change in diet.
Diet Change in Dissacus Praenuntius During the PETM
The results were surprising. Dissacus Praenuntius did change its diet during the PETM. The dental microwear showed that it consumed less flesh and more bone during and after the PETM compared to before it. This indicates a shift toward a more durophagous diet - meaning one that includes harder foods like bone.
“We conclude that Dissacus Praenuntius consumed less flesh and more bone during and after the PETM in comparison to before the event.”
The change in diet happened alongside a body mass reduction of about 20%. The smallest fossil specimen was found from a time just after the peak PETM temperatures, suggesting that it was food shortage and not just the heat which was a major factor in this adaptation.
What the PETM Teaches Us About Animal Adaptation to Climate Change?
You might be wondering why a 56-million-year-old carnivore matters. Here’s the thing: studying the past gives us a window into our own future. The PETM is the finest natural analogue for our current climate crisis. This study demonstrates the ways in which climate change compelled predators to adapt their foraging strategies in the PETM era. Lower prey abundance probably compelled Dissacus Praenuntius to subsist increasingly on bone and maybe other fallbacks.
Through learning about how this prehistoric predator adapted, scientists can gain important insight into how contemporary animals may respond to climate-forced changes in habitat and food supply. It emphasizes the role of flexibility in dieting for survival during periods of ecological stress.