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Functional tests of the competitive exclusion hypothesis for multituberculate extinction
Neil F Adams1, Emily J Rayfield1, Philip G Cox2,3
1School of Earth Sciences, University of Bristol, Bristol BS8 1RJ, UK.
Royal Society Open Science
|April 30, 2019
Summary
Rodent skull biomechanics reveal they optimized bite force over skull strength, unlike multituberculates. This functional difference may explain the decline of multituberculate mammals during the Paleogene.
Area of Science:
- Paleontology
- Biomechanics
- Mammalian Evolution
Background:
- Multituberculate mammals were dominant during the Mesozoic but declined in the Paleocene-Eocene.
- Eutherian rodents radiated during this period, with competitive exclusion proposed as a cause for multituberculate extinction.
- The specific traits conferring a rodent advantage remain unclear.
Purpose of the Study:
- To test the hypothesis that superior skull function in rodents led to competitive exclusion of multituberculates.
- To compare the craniomandibular biomechanics of extant rodents and the multituberculate *Kryptobaatar*.
Main Methods:
- Constructed digital skull models of four extant rodents and *Kryptobaatar*.
- Utilized finite-element analysis to assess feeding-induced stresses.
- Calculated bite force production and mechanical resistances to bending and torsion.
Main Results:
- Rodents displayed higher craniomandibular stresses and lower mechanical resistances compared to *Kryptobaatar*.
- Rodents appear to prioritize bite force optimization over skull structural integrity.
- This suggests a functional trade-off in rodent skull mechanics.
Conclusions:
- The competitive exclusion hypothesis, based on superior rodent skull function, is challenged.
- Rodent functional morphology, optimizing bite force at higher stress, may have been key to their success.
- These findings offer functional insights into multituberculate decline in the Paleogene.
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