A review of paleontological finite element models and their validity

Abstract

Finite element analysis (FEA) is a powerful quantitative tool that models mechanical performance in virtual reconstructions of complex structures, such as animal skeletons. The unique potential of FEA to elucidate the function, performance, and ecological roles of extinct taxa is an alluring prospect to paleontologists, and the technique has gained significant attention over recent years. However, as with all modeling approaches, FE models are highly sensitive to the information that is used to construct them. Given the imperfect quality of the fossil record, paleontologists are unlikely to ever know precisely which numbers to feed into their models, and it is therefore imperative that we understand how variation in FEA inputs directly affects FEA results. This is achieved through sensitivity and validation studies, which assess how inputs influence outputs, and compare these outputs to experimental data obtained from extant species. Although these studies are restricted largely to primates at present, they highlight both the power and the limitations of FEA. Reassuringly, FE models seem capable of reliably reproducing patterns of stresses and strains even with limited input data, but the magnitudes of these outputs are often in error. Paleontologists are therefore cautioned not to over-interpret their results. Crucially, validations show that without knowledge of skeletal material properties, which are unknowable from fossilized tissues, absolute performance values such as breaking stresses cannot be accurately determined. The true power of paleontological FEA therefore lies in the ability to manipulate virtual representations of morphology, to make relative comparisons between models, and to quantitatively assess how evolutionary changes of shape result in functional adaptations.

Comparative finite element analysis of the cranial performance of four herbivorous marsupials

“…Finite element analysis (FEA) is an engineering technique that reconstructs stress, strain, and deformation in response to applied loads, taking into account the material properties and geometry of the structure (Richmond et al, ; Rayfield, ; Bright, ). The FE method centers on representing complex geometry by a finite number of elements with simple geometries, readily analyzed using mathematics.…”

Jaw morphology and fighting forces in stag beetles

“…These structures are subdivided into a large number of small elements (a mesh), for which stresses (Von Mises stresses), strains and displacements are calculated (Bright, 2014;Dumont et al, 2009;Rayfield, 2007). Using the same method that we used to create the surface meshes of the heads, we also made surface models of the jaw cuticle for all 16 species.…”

“…The FE model of C. metallifer was previously successfully validated with an experimental measurement of the jaw deformation during biting using an optical technique (digital image correlation; Goyens et al, 2014b). This ensures that the model accurately reproduces the biological reality (Bright, 2014;Rayfield, 2007). For a detailed description of the model and its validation, see Goyens et al (2014b).…”

Accuracy of mandibular force profiles for bite force estimation and feeding behavior reconstruction in extant and extinct carnivorans

“…Although this non-destructive approach has gained in popularity, it remains anchored in numerous assumptions, including some about cranial and muscle architecture and the amount of force generated by the jaw musculature (Fastnacht et al, 2002;Bright, 2014). While muscle architecture can be inferred from muscle scars and dissection of extant relatives, the amount of force muscles can generate is often based, in the absence of empirically determined values, on bite force estimates derived from jaw musculature reconstructions (e.g.…”

“…As noted above, bite force estimates derived from such methods tend to dramatically underestimate true bite force in mammalian predators. As such, although FEA can be used to document and compare stress and load distributions in skulls of different morphology, use of this method to infer the bite force generated by a predator or to infer stress distribution during 'typical bite' ought to be done with caution (Bright, 2014). While other approaches have been developed to produce more accurate bite force estimates in carnivorans (e.g.…”