Carnivores biting capacities have fascinated generations evolutionary biologists, palaeontologists and zoologists for decades. Biting faster or harder can dramatically influence the ecology and behaviour of mammalian carnivores. Nonetheless, there’s an intrinsic trade-off between force and velocity as you can’t optimise for both simultaneously, and the impact of such a trade-off on carnivores’ morphology and diversity is still poorly understood.

In a groundbreaking study published in the prestigious journal Nature Communications, a team of international researchers led by Profs. Gabriele Sansalone and Carmelo Fruciano has made a significant discovery about the diversity of skull shapes in carnivores.

The team studied the skulls of 132 different carnivore species showing that some animals have evolved to bite hard, while others have evolved to bite fast. This balance between force and speed is a key factor in how an animal hunts and feeds, and therefore, in its survival and evolution.

The researchers found that the rates of evolution in form (i.e., how fast is the evolution of the physical shape of the skull) are not directly linked to the rates of evolution in function (i.e., how fast is the evolutionary change in how the skull is used for biting). They discovered that skull shapes optimising for speed are more diverse, while a much smaller range of shapes optimise for force.

“This suggests that the relationship between form and function is not one-to-one and that distinct morphologies (for example, bone-cracking hyaenids, bamboo-eating ursids and hypercarnivorous felids for force) can produce very similar functional outputs”, commented Gabriele Sansalone. Carmelo Fruciano added that “Our findings suggest that there may be many more ways to evolve a fast bite, but fewer ways to evolve a powerful one. As a result, species that prioritise bite force may be less common, simply because they are less likely to evolve. This could help understand the general question of why some groups of animals are more variable than others.”

The team also discovered that the same relationship between form and function is common to placental and marsupial carnivores. Stephen Wroe, another author of the study commented “This is really exciting as it further supports the idea that the different developmental strategy of marsupials does not limit their functional or morphological diversity”.

In summary, the team’s findings highlight the complexity of evolution and the subtle interplay of form and function in shaping the natural world. They also underscore the importance of trade-offs, a concept that is widely applicable across the tree of life.

This study was made with contributions from researchers at institutions from Italy (Institute for Marine Biological Resources and Biotechnology of the National Research Council, University of Modena and Reggio Emilia and University of Catania), Australia (the University of New England) and the UK (British Antarctic Survey).

The study can be freely accessed at https://www.nature.com/articles/s41467-024-47620-x

 For more information, please contact the corresponding authors at gabriele.sansalone@unimore.it and carmelo.fruciano@unict.it