Morphological evolution of the skull roof in temnospondyl amphibians mirrors conservative ontogenetic patterns

2019 ◽  
Vol 188 (1) ◽  
pp. 163-179 ◽  
Author(s):  
Celeste M Pérez-Ben ◽  
Ana M Báez ◽  
Rainer R Schoch
Keyword(s):  
Time Perspective ◽  
Morphological Evolution ◽  
Growth Stages ◽  
Ontogenetic Changes ◽  
Phenotypic Differentiation ◽  
Deep Time ◽  
Skull Roof ◽  
Evolutionary Level ◽  
Ontogenetic Allometry ◽  
Suitable Group

Abstract Addressing the patterns of ontogenetic allometry is relevant to understand morphological diversification because allometry might constrain evolution to specific directions of change in shape but also facilitate phenotypic differentiation along lines of least evolutionary resistance. Temnospondyl amphibians are a suitable group to address these issues from a deep-time perspective because different growth stages are known for numerous Palaeozoic and Mesozoic species. Herein we examine the patterns of ontogenetic allometry in the skull roof of 15 temponspondyl species and their relationship with adult morphological evolution. Using geometric morphometrics, we assessed ontogenetic and evolutionary allometries of this cranial part and the distribution of adult shapes in the morphospace to investigate whether these patterns relate to each other and/or to lifestyle and phylogeny. We found conspicuous stereotyped ontogenetic changes of the skull roof which are mirrored at the evolutionary level and consistency of the adult shape with phylogeny rather than lifestyle. These results suggest that the evolution of adult cranial shape was significantly biased by development towards pathways patterned by ontogenetic change in shape. The retrieved conserved patterns agree with a widespread evolutionary craniofacial trend found in amniotes, suggesting that they might have originated early in tetrapod evolutionary history or even earlier.

scholarly journals Growth allometry and dental topography in Upper Triassic conodonts supports trophic differentiation and molar-like element function

2021 ◽  
Author(s):  
Valentin Samuel Kelz ◽  
Pauline GUENSER ◽  
Michele Mazza ◽  
Manuel Rigo ◽  
Emilia Jarochowska
Keyword(s):  
Growth Stage ◽  
Morphological Evolution ◽  
3D Models ◽  
Late Triassic ◽  
Growth Stages ◽  
Ontogenetic Changes ◽  
Topographic Analysis ◽  
Positive Allometry ◽  
Adult Growth ◽  
Dental Topographic Analysis

Conodont dental elements are distinguished by their high disparity and rapid morphological evolution. P1 elements located in the pharynx are the most rapidly evolving, but their function in the animal has been only investigated in a handful of taxa and proposed to be analogous to mammal molars. This hypothesis predicts that their surface area should show positive allometry with respect to element length, as has been previously identified in 2D projections in two Carboniferous taxa. Here we apply the same method to test this hypothesis in 3D models of platform-bearing P1 elements of two common Late Triassic taxa, Metapolygnathus communisti and Epigondolella rigoi. We further hypothesise that these commonly co-occurring taxa differed in their growth allometry, reflecting their different trophic niches. Platform length grew isometrically with respect to element length, whereas log-transformed platform area showed positive allometry with respect to element length, with slopes equal 3.86 in M. communisti and 4.16 in E. rigoi, supporting a function of the platform analogous to molars and trophic differentiation. We cross-tested the latter interpretation by dental topographic analysis using Dirichlet Normal Energy (DNE). Specimens of the adult growth stage of E. rigoi showed higher DNE values than specimens of the same growth stage in M. communisti, consistent with stronger positive allometry of platform surface and with a higher demand for energy in this species. DNE values of platform surface increased linearly in function of element length and log-transformed platform area, indicating no ontogenetic changes. Based on DNE values available for primates, those of the adult growth stages were similar to those reported for insectivores or folivores in the case of E. rigoi and for folivores or omnivores in the case of M. communisti. Previous studies applying morphological and ultrastructural proxies for the dietary position of conodonts addressed mostly stratigraphically older conodont taxa, but our results indicate that Late Triassic species occupied the predator/scavenger niche in spite of the highly developed diversity of gnathostomes in this niche. We also show that within this broad niche, co-occurring taxa differed in their diets, which supports trophic diversification as an important driver of the remarkable disparity of their elements.

scholarly journals Morphological evolution of the skull roof in extinct temnospondyl amphibians mirrors conservative ontogenetic patterns

2018 ◽  
Author(s):  
Celeste Pérez-Ben ◽  
Ana María Báez ◽  
Rainer Schoch
Keyword(s):  
Morphological Change ◽  
Morphological Evolution ◽  
Life Cycles ◽  
Cranial Morphology ◽  
Growth Stages ◽  
Morphological Disparity ◽  
Cranial Development ◽  
Skull Roof ◽  
Wide Range ◽  
Evolutionary Allometry

Understanding the evolution of development is essential to unravel how morphological evolution proceeds in phenotypic space and how the resulting morphological disparity originates. In particular, the study of ontogenetic allometric patterns and their evolution is relevant because allometry is thought to constrain morphological evolution to specific directions and to promote morphological change by producing pronounced phenotypic differences along phenotypic lines of least evolutionary resistance. The extinct clade of temnospondyl amphibians enables a unique opportunity to investigate the interplay between developmental and morphological evolution in deep time because individuals of different growth stages are known for numerous species. Temnospondyls lived during the Paleozoic and Mesozoic in a wide range of habitats and had different life cycles (e.g., metamorphosing, neotenic). In spite of this, cranial morphology is markedly conserved within the clade. Herein, we investigate whether the ontogenetic allometric patterns of the skull roof in temnospondyls are also conserved or reflect the variety of their ecological adaptations and life-cycles and examine the extent to which the ontogenetic allometry may account for the adult cranial morphology. Using geometric morphometric techniques, we computed the ontogenetic allometries of 13 temnospondyl species and the evolutionary allometry of the clade. A conserved pattern of morphological change during ontogeny not associated to phylogeny or life-style is recovered across the clade. Furthermore, the evolutionary allometry strongly resembles the conserved ontogenetic changes of shape. These results suggest strong ancestral constraints in cranial development, which, in turn, may explain the low morphological disparity in the group.

scholarly journals An integrative method for testing form–function linkages and reconstructed evolutionary pathways of masticatory specialization

2015 ◽  
Vol 12 (107) ◽  
pp. 20150184 ◽  
Author(s):  
Z. Jack Tseng ◽  
John J. Flynn
Keyword(s):  
Mechanical Properties ◽  
Morphological Evolution ◽  
Integrative Approach ◽  
Deep Time ◽  
Integrate Form ◽  
Functional Changes ◽  
Form And Function ◽  
Form Function ◽  
Evolutionary Pathways ◽  
And Function

Morphology serves as a ubiquitous proxy in macroevolutionary studies to identify potential adaptive processes and patterns. Inferences of functional significance of phenotypes or their evolution are overwhelmingly based on data from living taxa. Yet, correspondence between form and function has been tested in only a few model species, and those linkages are highly complex. The lack of explicit methodologies to integrate form and function analyses within a deep-time and phylogenetic context weakens inferences of adaptive morphological evolution, by invoking but not testing form–function linkages. Here, we provide a novel approach to test mechanical properties at reconstructed ancestral nodes/taxa and the strength and direction of evolutionary pathways in feeding biomechanics, in a case study of carnivorous mammals. Using biomechanical profile comparisons that provide functional signals for the separation of feeding morphologies, we demonstrate, using experimental optimization criteria on estimation of strength and direction of functional changes on a phylogeny, that convergence in mechanical properties and degree of evolutionary optimization can be decoupled. This integrative approach is broadly applicable to other clades, by using quantitative data and model-based tests to evaluate interpretations of function from morphology and functional explanations for observed macroevolutionary pathways.

scholarly journals Deep Time and Secular Time: A Critique of the Environmental ‘Long View’

2018 ◽  
Vol 36 (1) ◽  
pp. 63-81 ◽  
Author(s):  
Stefan Skrimshire
Keyword(s):  
Hannah Arendt ◽  
Time Perspective ◽  
Climate Science ◽  
Charles Taylor ◽  
Moral Concern ◽  
Human History ◽  
Giorgio Agamben ◽  
Deep Time ◽  
Future Narratives ◽  
Planetary Processes

The Anthropocene concept allows human history to be imagined within the temporal framework of planetary processes. Accordingly, some environmentalists increasingly favour massively lengthening the temporal horizons of moral concern. Whilst there are defensible reasons for doing so, I wish to take issue with the ‘secular time’ perspective underlying some such approaches. To make my case, I present, in the first section, two recent manifestations of the long view perspective: a) ‘deep future’ narratives in popular climate science and futurism; b) the ideas behind the Long Now Foundation. In the second section, I apply a critical lens to these perspectives via classic analyses of secular time by Charles Taylor, Hannah Arendt and Giorgio Agamben. I conclude by suggesting that these post-secular critiques should be considered alongside recent approaches to the Anthropocene and the ‘geological turn’ from new materialist perspectives.

scholarly journals Finding the weakest link: mechanical sensitivity in a fish cranial linkage system

2018 ◽  
Vol 5 (10) ◽  
pp. 181003 ◽  
Author(s):  
A. Baumgart ◽  
P. Anderson
Keyword(s):  
Morphological Evolution ◽  
Structural Features ◽  
Mechanical Sensitivity ◽  
Weakest Link ◽  
Lower Jaw ◽  
Single Link ◽  
Evolutionary Level ◽  
Variable Influence ◽  
Physical Mechanics ◽  
Insight Into

Understanding the physical mechanics behind morphological systems can offer insights into their evolution. Recent work on linkage systems in fish and crustaceans has suggested that the evolution of such systems may depend on mechanical sensitivity, where geometrical changes to different parts of a biomechanical system have variable influence on mechanical outputs. While examined at the evolutionary level, no study has directly explored this idea at the level of the mechanism. We analyse the mechanical sensitivity of a fish cranial linkage to identify the influence of linkage geometry on the kinematic transmission (KT) of the suspensorium, hyoid and lower jaw. Specifically, we answer two questions about the sensitivity of this linkage system: (i) What changes in linkage geometry affect one KT while keeping the other KTs constant? (ii) Which geometry changes result in the largest and smallest changes to KT? Our results show that there are ways to alter the morphology that change each KT individually, and that there are multiple ways to alter a single link that have variable influence on KT. These results provide insight into the morphological evolution of the fish skull and highlight which structural features in the system may have more freedom to evolve than others.

Cranial morphology and ontogeny of the Permo-Carboniferous temnospondyl Archegosaurus decheni Goldfuss, 1847 from the Saar–Nahe Basin, Germany

2005 ◽  
Vol 96 (2) ◽  
pp. 131-162 ◽  
Author(s):  
Florian Witzmann
Keyword(s):  
Prey Capture ◽  
Three Dimensional ◽  
Nasolacrimal Duct ◽  
Larval Period ◽  
Cranial Morphology ◽  
Growth Stages ◽  
Ontogenetic Changes ◽  
Positive Allometry ◽  
Lateral Process ◽  
Different Growth Stages

ABSTRACTMorphology and ontogenetic changes in the skull and hyobranchium of the Permo-Carboniferous temnospondyl Archegosaurus decheni from the Saar–Nahe Basin (SW Germany) are described in detail, based on 181 skulls ranging from 18 to 279 mm in length. Three-dimensional skull reconstructions including the palate of different growth stages are provided. The extremely elongate choanae and up to four median symphyseal teeth are unique to A. decheni. Among neurocranial elements, the exoccipital is well ossified and forms the paroccipital process as in stereospondyls. The shaft of the stapes which projects into the squamosal embayment grows with positive allometry and possesses a distinct lateral process. The basibranchial is well ossified in adults and exhibits a complex, spoon-like morphology. Small larvae were euryphagous and used non-directed suction and jaw prehension during prey capture. Larger larvae and adults were mainly ichthyophagous, as is indicated by the increasingly elongated snout, differentiation of marginal teeth, and nutrition remains. After a prolonged larval period, juvenile and adult A. decheni remained in the aquatic habitat, as suggested by the presence of lateral line sulci, the ‘aquatic type’ of septomaxilla and choana, and the absence of a nasolacrimal duct.

Elements for the Origin of Life on Land: A Deep-Time Perspective from the Pilbara Craton of Western Australia

Astrobiology ◽  
2021 ◽  
Vol 21 (1) ◽  
pp. 39-59
Author(s):  
Martin J. Van Kranendonk ◽  
Raphael Baumgartner ◽  
Tara Djokic ◽  
Tsutomu Ota ◽  
Luke Steller ◽  
...  
Keyword(s):  
Origin Of Life ◽  
Western Australia ◽  
Time Perspective ◽  
Deep Time ◽  
The Origin Of Life ◽  
Pilbara Craton

scholarly journals Is Rapoport's rule a recent phenomenon? A deep time perspective on potential causal mechanisms

2013 ◽  
Vol 9 (5) ◽  
pp. 20130398 ◽  
Author(s):  
Nikolai M. Veter ◽  
Larisa R. G. DeSantis ◽  
Lindsey T. Yann ◽  
Shelly L. Donohue ◽  
Ryan J. Haupt ◽  
...  
Keyword(s):  
North America ◽  
Seasonal Variability ◽  
Time Perspective ◽  
Latitudinal Gradients ◽  
Deep Time ◽  
Spatial And Temporal Scales ◽  
Occurrence Data ◽  
Rapoport’S Rule ◽  
Ecological Patterns ◽  
Northern Species

Macroecology strives to identify ecological patterns on broad spatial and temporal scales. One such pattern, Rapoport's rule, describes the tendency of species' latitudinal ranges to increase with increasing latitude. Several mechanisms have been proposed to explain this rule. Some invoke climate, either through glaciation driving differential extinction of northern species or through increased seasonal variability at higher latitudes causing higher thermal tolerances and subsequently larger ranges. Alternatively, continental tapering or higher interspecific competition at lower latitudes may be responsible. Assessing the incidence of Rapoport's rule through deep time can help to distinguish between competing explanations. Using fossil occurrence data from the Palaeobiology Database, we test these hypotheses by evaluating mammalian compliance with the rule throughout the Caenozoic of North America. Adherence to Rapoport's rule primarily coincides with periods of intense cooling and increased seasonality, suggesting that extinctions caused by changing climate may have played an important role in erecting the latitudinal gradients in range sizes seen today.

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