scholarly journals Crocodylomorph cranial shape evolution and its relationship with body size and ecology

2019 ◽  
Vol 33 (1) ◽  
pp. 4-21 ◽  
Author(s):  
Pedro L. Godoy
Keyword(s):  
Body Size ◽  
Shape Evolution ◽  
Cranial Shape

scholarly journals Crocodylomorph cranial shape evolution and its relationship with body size and ecology

2019 ◽  
Author(s):  
Pedro L. Godoy
Keyword(s):  
Body Size ◽  
Cranial Morphology ◽  
Shape Evolution ◽  
Shape Variation ◽  
Crown Group ◽  
Early Peak ◽  
Group Members ◽  
Phylogenetic Hypotheses ◽  
And Shifts ◽  
Cranial Shape

AbstractCrocodylomorpha, which includes living crocodylians and their extinct relatives, has a rich fossil record, extending back for more than 200 million years. Unlike modern semi-aquatic crocodylians, extinct crocodylomorphs exhibited more varied lifestyles, ranging from marine to fully terrestrial forms. This ecological diversity was mirrored by a remarkable morphological disparity, particularly in terms of cranial morphology, which seems to be closely associated with ecological roles in the group. Here, I use geometric morphometrics to comprehensively investigate cranial shape variation and disparity in Crocodylomorpha. I quantitatively assess the relationship between cranial shape and ecology (i.e. terrestrial, aquatic, and semi-aquatic lifestyles), as well as possible allometric shape changes. I also characterise patterns of cranial shape evolution and identify regime shifts. I found a strong link between shape and size, and a significant influence of ecology on the observed shape variation. Terrestrial taxa, particularly notosuchians, have significantly higher disparity, and shifts to more longirostrine regimes are associated with large-bodied aquatic or semi-aquatic species. This demonstrates an intricate relationship between cranial shape, body size and lifestyle in crocodylomorph evolutionary history. Additionally, disparity-through-time analyses were highly sensitive to different phylogenetic hypotheses, suggesting the description of overall patterns among distinct trees. For crocodylomorphs, most results agree in an early peak during the Early Jurassic and another in the middle of the Cretaceous, followed by nearly continuous decline until today. Since only crown-group members survived through the Cenozoic, this decrease in disparity was likely the result of habitat loss, which narrowed down the range of crocodylomorph lifestyles.

scholarly journals Cranial shape evolution of extant and fossil crocodile newts and its relation to reproduction and ecology

2020 ◽  
Vol 237 (2) ◽  
pp. 285-300 ◽  
Author(s):  
Peter Pogoda ◽  
Marcus Zuber ◽  
Tilo Baumbach ◽  
Rainer R. Schoch ◽  
Alexander Kupfer
Keyword(s):  
Shape Evolution ◽  
Cranial Shape

Warning signals promote morphological diversification in fossorial uropeltid snakes (Squamata: Uropeltidae)

2020 ◽  
Author(s):  
Vivek Philip Cyriac ◽  
Ullasa Kodandaramaiah
Keyword(s):  
Body Size ◽  
Free Space ◽  
Morphological Evolution ◽  
Environmental Constraints ◽  
Shape Evolution ◽  
Head Shape ◽  
Warning Signals ◽  
Morphological Diversification ◽  
Niche Expansion ◽  
Antipredator Defences

Abstract Many species possess warning colourations that signal unprofitability to predators. Warning colourations are also thought to provide prey with a ‘predator-free space’ and promote niche expansion. However, how such strategies release a species from environmental constraints and facilitate niche expansion is not clearly understood. Fossoriality in reptiles imposes several morphological limits on head and body size to facilitate burrowing underground, but many fossorial snakes live close to the surface and occasionally move above ground, exposing them to predators. In such cases, evolving antipredator defences that reduce predation on the surface could potentially relax the morphological constraints associated with fossoriality and promote morphological diversification. Fossorial uropeltid snakes possess varying degrees of conspicuous warning colourations that reduce avian predation when active above ground. We predicted that species with more conspicuous colourations will exhibit more robust body forms and show faster rates of morphological evolution because constraints imposed by fossoriality are relaxed. Using a comparative phylogenetic approach on the genus Uropeltis, we show that more conspicuous species tend to have more robust morphologies and have faster rates of head-shape evolution. Overall, we find that the evolution of warning colourations in Uropeltis can facilitate niche expansion by influencing rates of morphological diversification.

Do convergent ecomorphs evolve through convergent morphological pathways? Cranial shape evolution in fossil hyaenids and borophagine canids (Carnivora, Mammalia)

Paleobiology ◽  
2011 ◽  
Vol 37 (3) ◽  
pp. 470-489 ◽  
Author(s):  
Zhijie Jack Tseng ◽  
Xiaoming Wang
Keyword(s):  
Convergent Evolution ◽  
Shape Change ◽  
Morphological Evolution ◽  
Shape Evolution ◽  
Deep Time ◽  
Phylogenetic Constraint ◽  
Mechanisms Of Adaptation ◽  
Evolutionary Pathways ◽  
Length Reduction ◽  
Cranial Shape

Cases of convergent evolution, particularly within ecomorphological contexts, are instructive in identifying universally adaptive morphological features across clades. Tracing of evolutionary pathways by which ecomorphological convergence takes place can further reveal mechanisms of adaptation, which may be strongly influenced by phylogeny. Ecomorphologies of carnivorous mammals represent some of the most outstanding cases of convergent evolution in the Cenozoic radiation of mammals. This study examined patterns of cranial shape change in the dog (Canidae) and hyena (Hyaenidae) families, in order to compare the evolutionary pathways that led to the independent specialization of bone-cracking hypercarnivores within each clade. Geometric morphometrics analyses of cranial shape in fossil hyaenids and borophagine canids provided evidence for deep-time convergence in morphological pathways toward the independent evolution of derived bone-crackers. Both clades contained stem members with plesiomorphic generalist/omnivore cranial shapes, which evolved into doglike species along parallel pathways of shape change. The evolution of specialized bone-crackers from these doglike forms, however, continued under the constraint of a full cheek dentition and restriction on rostrum length reduction in canids, but not hyaenids. Functionally, phylogenetic constraint may have limited borophagine canids to crack bones principally with their carnassial instead of the third premolar as in hyaenids, but other cranial shape changes associated with durophagy nevertheless evolved in parallel in the two lineages. Size allometry was not a major factor in cranial shape evolution in either lineage, supporting the interpretation of functional demands as drivers for the observed convergence. The comparison between borophagines and hyaenids showed that differential effects of alternative functional “solutions” that arise during morphological evolution may be multiplied with processes of the “macroevolutionary ratchet” already in place to further limit the evolutionary pathways available to specialized lineages.

scholarly journals Evolutionary shifts in extant mustelid (Mustelidae: Carnivora) cranial shape, body size and body shape coincide with the Mid-Miocene Climate Transition

2019 ◽  
Vol 15 (5) ◽  
pp. 20190155 ◽  
Author(s):  
Chris J. Law
Keyword(s):  
Body Size ◽  
Body Shape ◽  
Environmental Changes ◽  
Phenotypic Traits ◽  
Adaptive Landscapes ◽  
Global Cooling ◽  
Body Sizes ◽  
Climate Transition ◽  
Lineage Diversification ◽  
Cranial Shape

Environmental changes can lead to evolutionary shifts in phenotypic traits, which in turn facilitate the exploitation of novel adaptive landscapes and lineage diversification. The global cooling, increased aridity and expansion of open grasslands during the past 50 Myr are prime examples of new adaptive landscapes that spurred lineage and ecomorphological diversity of several mammalian lineages such as rodents and large herbivorous megafauna. However, whether these environmental changes facilitated evolutionary shifts in small- to mid-sized predator morphology is unknown. Here, I used a complete cranial and body morphological dataset to examine the timing of evolutionary shifts in cranial shape, body size and body shape within extant mustelids (martens, otters, polecats and weasels) during the climatic and environmental changes of the Cenozoic. I found that evolutionary shifts in all three traits occurred within extant mustelid subclades just after the onset of the Mid-Miocene Climate Transition. These mustelid subclades first shifted towards more elongate body plans followed by concurrent shifts towards smaller body sizes and more robust crania. I hypothesize that these cranial and body morphological shifts enabled mustelids to exploit novel adaptive zones associated with the climatic and environmental changes of the Mid to Late Miocene, which facilitated significant increases in clade carrying capacity.

EARLY BURSTS OF BODY SIZE AND SHAPE EVOLUTION ARE RARE IN COMPARATIVE DATA

Evolution ◽  
2010 ◽  
pp. no-no ◽  
Author(s):  
Luke J Harmon ◽  
Jonathan B Losos ◽  
T Jonathan Davies ◽  
Rosemary G Gillespie ◽  
John L Gittleman ◽  
...  
Keyword(s):  
Body Size ◽  
Comparative Data ◽  
Shape Evolution ◽  
Size And Shape

scholarly journals Body size and shape evolution in host races of the tickIxodes uriae

2012 ◽  
Vol 108 (2) ◽  
pp. 323-334 ◽  
Author(s):  
Muriel Dietrich ◽  
Lorenza Beati ◽  
Eric Elguero ◽  
Thierry Boulinier ◽  
Karen D. McCoy
Keyword(s):  
Body Size ◽  
Shape Evolution ◽  
Host Races ◽  
Size And Shape

Adolescent Gender Differences in Weight, Activity, and Body-Size Perception

2012 ◽  
Author(s):  
Judith R. Mccalla ◽  
Katie E. Chipungu ◽  
Patrice G. Saab ◽  
Amanda J. Countryman ◽  
Erin N. Etzel ◽  
...  
Keyword(s):  
Gender Differences ◽  
Body Size ◽  
Size Perception ◽  
Body Size Perception
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