Functional ecological convergence between the thylacine and small prey-focused canids

Area of Science:

• Evolutionary Biology
• Paleontology
• Comparative Anatomy

Background:

• Morphological convergence aids in understanding extinct species' biology and ecology.
• The thylacine (Thylacinus cynocephalus) is often cited as an example of convergent evolution with wolves/dogs.
• Limited ecological data on the thylacine raises questions about its true convergent analogues.

Purpose of the Study:

• To precisely determine convergent analogues of the thylacine using quantitative convergence tests.
• To investigate correlations between cranial shape, diet, phylogeny, and prey size in faunivorous mammals.
• To clarify the functional ecology of the thylacine in comparison to related species.

Main Methods:

• Utilized 3D geometric morphometrics to analyze the thylacine cranium.
• Employed two quantitative convergence tests within a dataset of 56 species.
• Examined patterns of cranial shape correlation with diet, phylogeny, and relative prey size.

Main Results:

• Found a correlation between cranial shape and prey-to-predator body mass ratio.
• The thylacine grouped with predators taking prey smaller than 45% of their body mass.
• Significant convergence was found with African jackals and South American 'foxes', not wolves or dogs.

Conclusions:

• The thylacine exhibited a functional ecology similar to mid-sized canids like jackals and South American foxes.
• It was a predator of small to mid-sized prey, unlike the big-game hunting wolf.
• Superficial similarities can lead to false interpretations of functional ecology; broader comparisons are crucial.