Feeding biomechanics inAcanthostegaand across the fish–tetrapod transition

Abstract

Acanthostega is one of the earliest and most primitive limbed vertebrates. Its numerous fish-like features indicate a primarily aquatic lifestyle, yet cranial suture morphology suggests that its skull is more similar to those of terrestrial taxa. Here, we apply geometric morphometrics and two-dimensional finite-element analysis to the lower jaws of Acanthostega and 22 other tetrapodomorph taxa in order to quantify morphological and functional changes across the fish -tetrapod transition. The jaw of Acanthostega is similar to that of certain tetrapodomorph fish and transitional Devonian taxa both morphologically (as indicated by its proximity to those taxa in morphospace) and functionally (as indicated by the distribution of stress values and relative magnitude of bite force). Our results suggest a slow tempo of morphological and biomechanical changes in the transition from Devonian tetrapod jaws to aquatic/semi-aquatic Carboniferous tetrapod jaws. We conclude that Acanthostega retained a primitively aquatic lifestyle and did not possess cranial adaptations for terrestrial feeding.

Accounting for differences in element size and homogeneity when comparing Finite Element models: Armadillos as a case study

“…Quantifying stress data at specific points has been useful in ecomorphological analyses (Fortuny et al, 2011;Serrano-Fochs et al, 2015), but these analyses are hindered by the lack of information about the whole model. Dumont et al (2005) and McHenry et al (2007) first used Von Mises Stress values as a descriptive statistic to compare the results of different FE analyses, and this method has been used frequently since then (Parr et al, 2012;Aquilina et al, 2013;Figueirido et al, 2014;Fish and Stayton, 2014;Neenan et al, 2014). Recently, Tseng approached the same problem with a solution based in the normalization of the values of each element of the mesh to obtain statistical metrics to compare different models (Tseng, 2008;Tseng and Binder, 2010;Tseng et al, 2011a).…”

“…In the last decade, researchers have used virtual reconstruction of vertebrate structures in order to perform biomechanical comparisons among taxa (Gunz et al, 2009;Doyle et al, 2009;Degrange et al, 2010;Fletcher et al, 2010;Attard et al, 2014;Figueirido et al, 2014;Neenan et al, 2014). According to O'Higgins and Milne (2013, p.1), "With further mathematical, engineering and statistical development the combination of computational methods as FEA, MDA and Morphometric Geometrics Methods (GMM) should open up new avenues of investigation of skeletal form and function in evolutionary biology" (MDA: Multibody Dynamics Analysis).…”

Variation in the shape and mechanical performance of the lower jaws in ceratopsid dinosaurs (Ornithischia, Ceratopsia)

“…The current arguments follow those enacted for a similar study on the lower jaw across the fish/tetrapod transition (Neenan et al. ). In the current work, it is difficult if not impossible to generate a number of 3D models on practical grounds, outlined below.…”

Morphology and preliminary biomechanical interpretation of mandibular sutures in Metoposaurus krasiejowensis (Temnospondyli, Stereospondyli) from the Upper Triassic of Poland

“…Similar to the skull, the mandible of Metoposaurus krasiejowensis is a conglomerate of ten bones (dentary, splenial, postsplenial, angular, surangular, articular, prearticular, coronoid, intercoronoid, precoronoid) that are adapted to resist various loads during feeding (Jupp and Warren 1986). Among non-amniote, extinct tetrapods, sutures and their biomechanical implications for the lower jaw have only been studied in the Devonian Acanthostega gunnari (Neenan et al 2014;Porro et al 2015). The mandibles of extinct taxa have been sectioned/histologically sampled (e.g., Carroll 1964;Heaton 1979;Haridy et al 2017a, in press) but without a similar treatment or level of detailed study to that presented here.…”