New research has thrown up some interesting clues about how mammals have coped with global warming in the past. A new paper describes how during the Paleocene–Eocene Thermal Maximum (PETM), a global warm period 56 million years ago, a jackal-sized carnivorous mammal Dissacus praenuntius changed its diet to survive.
It began eating more bones alongside meat. This dietary shift, uncovered through dental microwear texture analysis (a method that reads tiny scratches and pits on fossil teeth), reveals how ancient species responded to extreme environmental stress.
From Cheetah-Like to Hyena-Like Chewing
The PETM was a brief time interval characterized by a 5–8 °C (9–14 °F) global average temperature rise. Before the PETM, Dissacus fed like a modern cheetah, slicing through tough meat. But during and after this global warming event, its teeth showed signs of crunching harder materials such as bone. Researchers concluded this by observing wear patterns similar to modern lions and hyenas. Most likely because its usual prey diminished or became harder to catch.
This change also coincided with a mild shrinkage in body size, which further suggests that prey had become rarer. This indicates that limited food availability, rather than temperature alone, was a major factor driving body shrinkage in Dissacus.
Adaptability is an important quality in evolutionary survival
The study examined 24 well-preserved molar specimens from closely situated fossil sites in Wyoming’s Bighorn and Clarks Fork basins, spanning pre-PETM, PETM, and early post-PETM intervals. This tight stratigraphic control adds confidence that the dietary signatures reflect actual temporal ecological shifts.
Detailed dental microwear texture analysis reveals that Dissacus exhibited hallmarks of increased bone-crushing behavior during and after the PETM. Evidence such as higher tooth surface complexity and lower directional wear provide strong, measurable evidence that Dissacus consumed more hard, brittle materials like bone during warming.
Researchers emphasize that Dissacus was not a bone-crusher by specialization. The microwear data reveal it became durophagous (bone-eating opportunist) under stress, highlighting adaptive flexibility.
The research could provide lessons for today
The PETM is arguably our best past comparison through which we can understand how global warming and the carbon cycle operate in a greenhouse world.
“The effect of climate change and ecological disruption on species diets is critical for understanding the evolution of mammalian adaptations and potential risks from the current climate crisis.” wrote Andrew Schwartz, lead author of the paper. Though Dissacus lived successfully for 15 million years, it eventually went extinct, likely overwhelmed by environmental shifts and rising competition.