Microanatomy of the radius and lifestyle in amniotes (Vertebrata, Tetrapoda)

Radial cross-sections of 49 species of extant and two species of extinct amniotes of known lifestyle have been studied in order to assess the relationship between lifestyle (aquatic, amphibious or terrestrial) and bone microanatomy. Most compactness profile and body size parameters exhibit a phylogenetic signal; therefore, classical statistical tests should not be used. Permutational multiple linear regressions show an ecological signal in most compactness profile parameters and in the cross-section maximal diameter. A linear discriminant analysis is performed with these parameters to distinguish the various lifestyles. The discriminant function based on taxa of known lifestyle is used to infer the lifestyle of three extinct amniotes: the early nothosaur Pachypleurosaurus (amphibious), the therapsid Lystrosaurus (amphibious) and the synapsid Ophiacodon (aquatic). These predictions are congruent with classical palaeoecological interpretations. This model may be very useful when attempting to infer the ancestral lifestyle of amniotes and other early limbed vertebrates.     

Evolution of bone microanatomy of the tetrapod tibia and its use in palaeobiological inference

Bone microanatomy appears to track changes in various physiological or ecological properties of the individual or the taxon. Analyses of sections of the tibia of 99 taxa show a highly significant (P 相似文献   

Microanatomy of the amniote femur and inference of lifestyle in limbed vertebrates

The femoral microanatomy of 155 species of extant amniotes (57 species of mammals, 15 species of turtles, 56 species of lepidosaurs, and 27 species of birds) of known lifestyle is studied to demonstrate a possible link between some basic parameters of bone structure and specific lifestyles, as well as phylogenetic relationships between taxa. Squared change parsimony with random taxon reshuffling and pairwise comparisons reveal that most compactness and size parameters exhibit both phylogenetic and ecological signals. A discriminant analysis produces several inference models, including a ternary model (aquatic, amphibious, terrestrial) that yield the correct lifestyle in 88% of the cases. These models are used to infer the lifestyle of three extinct Permian temnospondyls: Eryops megacephalus, Acheloma dunni, and Trimerorhachis insignis. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 109 , 644–655.     

Bone microanatomy and lifestyle: A descriptive approach

Starting in 2004, our lab has published several studies on the relationship between bone microanatomy, lifestyle (aquatic to terrestrial), and the phylogeny of tetrapods. These studies emphasized quantitative and statistical analyses. Therefore, the raw data used in these studies were never published. This is unfortunate because no model captures all information in biological data. This paper remedies this situation by providing the detailed anatomical drawings used in our previous studies. These constitute the largest set of standardized cross-section images of appendicular long bones (tibiae, radii, and humeri) ever published, at least as far as the number of represented species (over one hundred) is concerned. All major aquatic to terrestrial extant tetrapod clades are represented (lissamphibians, mammals, turtles, squamates, and crocodilians). The comparative figures show that aquatic tetrapods differ most from the others, whereas amphibious taxa differ much less from their terrestrial relatives.     

Biomechanical evolution of solid bones in large animals: a microanatomical investigation

Graviportal taxa show an allometric increase of the cross‐sectional area of supportive bones and are assumed to display microanatomical changes associated with an increase in bone mass. This evokes osteosclerosis (i.e. an increase in bone compactness observed in some aquatic amniotes). The present study investigates the changes in bones' microanatomical organization associated with graviportality and how comparable they are with aquatically acquired osteosclerosis aiming to better understand the adaptation of bone to the different associated functional requirements. Bones of graviportal taxa show microanatomical changes that are not solely attributable to allometry. They display a thicker cortex and a proportionally smaller medullary cavity, with a wider transition zone between these domains. This inner cancellous structure may enable to better enhance energy absorption and marrow support. Moreover, the cross‐sectional geometric parameters indicate increased resistance to stresses engendered by bending and torsion, as well as compression. Adaptation to a graviportal posture should be taken into consideration when analyzing possibly amphibious taxa with a terrestrial‐like morphology. This is particularly important for palaeoecological inferences about large extinct tetrapods that might have been amphibious and, more generally, for the study of early stages of adaptation to an aquatic life in amniotes.     

Novel data on aetosaur (Archosauria,Pseudosuchia) osteoderm microanatomy and histology: palaeobiological implications

One of the most striking features of aetosaurs is the possession of an extensive bony armour composed of dorsal, ventral and appendicular osteoderms. With the purpose of establishing the main histological changes during ontogeny and the degree of histological variation within the armour, we analysed the bone histology of dorsal (paramedian and lateral), ventral and appendicular osteoderms from different taxa from the Late Triassic of South America, including Aetosauroides scagliai, Aetobarbakinoides brasiliensis and Neoaetosauroides engaeus. Histological data support an intramembranous origin for osteoderms. Nevertheless, evidence for metaplastic ossification (i.e. structural fibres) at advanced ontogenetic stages, in at least some elements, is also present. A variant type of parallel fibred bone, which we have named ‘crossed parallel fibred bone’, is characterized for aetosaurs. In this pseudosuchian group, osteoderms exhibit very important microstructural changes during ontogeny, which can be useful for determining ontogenetic stages from isolated elements. Histological data suggest a relatively early onset of sexual maturity among aetosaurs. Microanatomical analysis from different taxa reveal that having high values of compactness is the plesiomorphic condition for Aetosauria. The notably increased compactness of the osteoderms does not appear to be related to size, ontogeny, sex or reproductive status of the individuals. Although a high degree of compactness of osteoderms and other bones has been considered as evidence for an aquatic lifestyle in vertebrates, such an inference contradicts the current concept of a fully terrestrial lifestyle in aetosaurs.     

Lifestyle-Based Approaches Provide Insights into Body Size Variation Across Environmental Gradients in Anurans

Body size of organisms as a fitness-related phenotype has evolved in response to local conditions, often through the size-dependent thermoregulatory mechanisms. The direction and degree of this response should depend on animals’ lifestyle in terms of the preference for terrestrial or aquatic conditions, especially so for adult anurans that differ in lifestyle among species but all must maintain certain body temperatures for metabolism. It may be expected that anuran species frequently exposed to terrestrial environments characterized by fluctuant thermal conditions are more plastic in body size along thermal gradients than those highly relaying on aquatic environments where thermal conditions are relatively stable. We test this prediction using both interspecific and intraspecific data. With anurans in China as the model organisms, we show that across terrestrial species but not aquatic species, body size decreases with increasing ambient temperature. From the published literature worldwide, we summarized that more terrestrial versus fewer aquatic species follow the predicted ecogeographical size patterns. In addition, both interspecific and intraspecific data reveal that arboreal anurans do not exhibit the size cline, probably because relatively warm climates experienced by these species impose weak selective pressures on heat conservation or adaptation to tree-climbing constrains the variation in body size. Our finding highlights the importance of taking lifestyle into account when assessing macroevolutionary trends in body size for anurans in particular and ectothermic taxa in general.     

Trabecular architecture in the humeral metaphyses of non-avian reptiles (Crocodylia,Squamata and Testudines): Lifestyle,allometry and phylogeny

The lifestyle of extinct tetrapods is often difficult to assess when clear morphological adaptations such as swimming paddles are absent. According to the hypothesis of bone functional adaptation, the architecture of trabecular bone adapts sensitively to physiological loadings. Previous studies have already shown a clear relation between trabecular architecture and locomotor behavior, mainly in mammals and birds. However, a link between trabecular architecture and lifestyle has rarely been examined. Here, we analyzed trabecular architecture of different clades of reptiles characterized by a wide range of lifestyles (aquatic, amphibious, generalist terrestrial, fossorial, and climbing). Humeri of squamates, turtles, and crocodylians have been scanned with microcomputed tomography. We selected spherical volumes of interest centered in the proximal metaphyses and measured trabecular spacing, thickness and number, degree of anisotropy, average branch length, bone volume fraction, bone surface density, and connectivity density. Only bone volume fraction showed a significant phylogenetic signal and its significant difference between squamates and other reptiles could be linked to their physiologies. We found negative allometric relationships for trabecular thickness and spacing, positive allometries for connectivity density and trabecular number and no dependence with size for degree of anisotropy and bone volume fraction. The different lifestyles are well separated in the morphological space using linear discriminant analyses, but a cross-validation procedure indicated a limited predictive ability of the model. The trabecular bone anisotropy has shown a gradient in turtles and in squamates: higher values in amphibious than terrestrial taxa. These allometric scalings, previously emphasized in mammals and birds, seem to be valid for all amniotes. Discriminant analysis has offered, to some extent, a distinction of lifestyles, which however remains difficult to strictly discriminate. Trabecular architecture seems to be a promising tool to infer lifestyle of extinct tetrapods, especially those involved in the terrestrialization.     

Axial allometry in a neutrally buoyant environment: effects of the terrestrial‐aquatic transition on vertebral scaling

Ecological diversification into new environments presents new mechanical challenges for locomotion. An extreme example of this is the transition from a terrestrial to an aquatic lifestyle. Here, we examine the implications of life in a neutrally buoyant environment on adaptations of the axial skeleton to evolutionary increases in body size. On land, mammals must use their thoracolumbar vertebral column for body support against gravity and thus exhibit increasing stabilization of the trunk as body size increases. Conversely, in water, the role of the axial skeleton in body support is reduced, and, in aquatic mammals, the vertebral column functions primarily in locomotion. Therefore, we hypothesize that the allometric stabilization associated with increasing body size in terrestrial mammals will be minimized in secondarily aquatic mammals. We test this by comparing the scaling exponent (slope) of vertebral measures from 57 terrestrial species (23 felids, 34 bovids) to 23 semi‐aquatic species (pinnipeds), using phylogenetically corrected regressions. Terrestrial taxa meet predictions of allometric stabilization, with posterior vertebral column (lumbar region) shortening, increased vertebral height compared to width, and shorter, more disc‐shaped centra. In contrast, pinniped vertebral proportions (e.g. length, width, height) scale with isometry, and in some cases, centra even become more spool‐shaped with increasing size, suggesting increased flexibility. Our results demonstrate that evolution of a secondarily aquatic lifestyle has modified the mechanical constraints associated with evolutionary increases in body size, relative to terrestrial taxa.     

Histological study of karaurids,the oldest known (stem) urodeles

Little is known about the initial phases of lissamphibian history (before the Cretaceous), because their fossil record is quite scanty. Only the morphology of the earliest members has been investigated, although other sets of data, from bone microanatomy and histology, are known to yield valuable paleobiological information. In the present study, we provide the first histological and microanatomical data on the oldest known stem-urodeles, the karaurids, from the Middle Jurassic. Three humeri from the Upper Bathonian, Oxfordshire, referred to juvenile or subadult individuals of Marmorerpeton and to an unnamed caudate of undetermined (but obviously non-larval) ontogenetic stage, were sampled in order to shed new light on the habitat and ontogeny of these basal caudates. The great compactness of the three humeri suggests that these salamanders were aquatic. The presence of extensive amounts of calcified cartilage in the humeri greatly strengthens the case for the presence of neoteny in these taxa, a suggestion that had initially been made on the basis of a few morphological characters. This constitutes the oldest known occurrence of neoteny in lissamphibians. Finally, bone histology reveals that the growth of Marmorerpeton and the related unnamed caudate was fairly slow and cyclic, a characteristic of extant lissamphibians.     

Comparative pollen morphology and ultrastructure of the Callitrichaceae

The Callitrichaceae are an aquatic family of dicots that include the single, geographically cosmopolitan genus Callitriche. Callitriche contains 40-50 terrestrial, amphibious, and obligately submersed species, and it is the only known genus in the plant kingdom with co-occurring aerial and hydrophilous pollination syndromes. Pollen morphology and ultrastructure were described for 13 Callitriche species using scanning electron and transmission electron microscopy. Representative taxa of each growth form were examined; these included three terrestrial species (C. deflexa, C. peploides, and C. nuttallii), nine amphibious species (C. brutia, C. cophocarpa, C. cophocarpa-stagnalis hybrid, C. cribrosa, C. hamulata, C. heterophylla var. heterophylla, C. lusitanica, C. marginata, and C. trochlearis), and one obligately submersed species (C. truncata). Of the amphibious taxa, C. heterophylla var. heterophylla and C. trochlearis had internal geitonogamy, a type of internal self-fertilization. Pollen from all taxa was spheroidal, small, intectate, and lacked well-defined apertures. Taxa primarily differed with respect to exine thickness, surface ornamentation, and the presence or absence of aperture-like regions. The pollen of terrestrial species, as well as that of C. marginata, had well-developed exines with thick sculptured and basal layers. In general, amphibious taxa produced pollen with distinct, but thinner, exines than that of terrestrial taxa. Pollen of the amphibious taxa with internal geitonogamy had a thicker basal layer than species without internal geitonogamy, whereas the overall exine was reduced in C. hamulata and absent in C. brutia and C. lusitanica. Pollen of the obligately submersed C. truncata also lacked an exine. These palynological data were correlated with growth habits and related pollination biologies, as well as with phylogenetic interpretations of Callitrichaceae. Exine reduction or loss has evolved at least twice in the family, and it is associated with aneuploid reduction in chromosome number.     

Inner architecture of vertebral centra in terrestrial and aquatic mammals: A two‐dimensional comparative study

Inner vertebral architecture is poorly known, except in human and laboratory animals. In order to document this topic at a broad comparative level, a 2D‐histomorphometric study of vertebral centra was conducted in a sample of 98 therian mammal species, spanning most of the size range and representing the main locomotor adaptations known in therian taxa. Eleven variables relative to the development and geometry of trabecular networks were extracted from CT scan mid‐sagittal sections. Phylogeny‐informed statistical tests were used to reveal the respective influences of phylogeny, size, and locomotion adaptations on mammalian vertebral structure. The use of random taxon reshuffling and squared change parsimony reveals that 9 of the 11 characteristics (the two exceptions are total sectional area and structural polarization) contain a phylogenetic signal. Linear discriminant analyses suggest that the sampled taxa can be arranged into three categories with respect to locomotion mode: a) terrestrial + flying + digging + amphibious forms, b) coastal oscillatory aquatic taxa, and c) pelagic oscillatory aquatic forms represented by oceanic cetaceans. Pairwise comparison tests and linear regressions show that, when specific size increases, the length of trabecular network (Tt.Tb.Le), as well as trabecular proliferation in total sections (Pr.Tb.Tt), increase with positive allometry. This process occurs in all locomotion categories but is particularly pronounced in pelagic oscillators. Conversely, mean trabecular width has a lesser increase with size in pelagic oscillators. Trabecular orientation is not influenced by size. All tests were corrected for multiple testing. By using six structural variables or indices, locomotion mode can be predicted with a 97.4% success rate for terrestrial forms, 66.7% for coastal oscillatory, and 81.3% for pelagic oscillatory. The possible functional meaning of these results and their potential use for paleobiological inference of locomotion in extinct taxa are discussed. J. Morphol., 2013. © 2013 Wiley Periodicals, Inc.     

Amphibious adaptations in a newly recognized amphibious fish: Terrestrial locomotion and the influences of body size and temperature

Amphibious animals are adapted for both aquatic and terrestrial habitats. The conflicting requirements for dual habitats are perhaps most pronounced in the air‐breathing fishes, which represent an intermediate stage between the totally aquatic habitat and terrestrial colonization. A key requirement for amphibious fishes is terrestrial locomotion. The different densities and compositions of air and water impose constraints for efficient terrestrial locomotion that differ from those required for aquatic locomotion. I investigated terrestrial locomotion in a small South African fish, Galaxias ‘nebula’, by exposing 60 individual fish to air in specially designed raceways and quantifying movement type and occurrence as a function of availability of water, fish size and environmental temperature. Nebula showed a sustained undulating form of terrestrial locomotion characteristic of amphibious fishes and also a transient ballistic locomotion (jumps) typical of fully aquatic species. Terrestrial movement was influenced by fish size, with medium‐sized fish undertaking more jumps towards water, and fewer jumps away from water, than their smaller or larger conspecifics. In contrast, axial undulation was mainly influenced by temperature. However, there was no consistent pattern in temperature effects presumably because temperature is just one of a suit of environmental factors that may affect terrestrial locomotion. Nebula's amphibious adaptations allow it to cope with the unpredictability inherent in its natural environment.     

The structural mechanics and evolution of aquaflying birds

Mass‐specific bone strength was examined in the forelimb and hindlimb of 64 species of birds to determine if aquaflying birds (which utilize the wings for propulsion underwater) differ in their skeletal strength compared with other avian taxa. Long bone strengths were estimated from cross‐sectional measurements. Compared with the expectation from geometric similarity, humeral section modulus in volant birds scales nearly isometrically, while femoral strength scales with significant positive allometry. Penguin mass‐specific humeral strength is greatly elevated, but the average humeral strength in species that are propelled by the wings in both air and water do not differ from the values calculated in non‐diving taxa. However, amphibious flyers have gracile femora. Comparative analyses using independent contrasts were utilized to examine the impact of phylogenetic signal. The residual measured for the penguin–procellariiform humeral strength contrast was larger in magnitude (residual of 2.14) than at any other node in the phylogeny. The data strongly indicate that the transition from an amphibious flight condition to a fully aquatic condition involves greater changes in mechanical factors than the transition from purely aerial locomotion to amphibious wing use. There remains the possibility that a historical effect, such as ancestral body size, has impacted the mechanical scaling of penguins. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99 , 687–698.     

Shell bone histology indicates terrestrial palaeoecology of basal turtles

The palaeoecology of basal turtles from the Late Triassic was classically viewed as being semi-aquatic, similar to the lifestyle of modern snapping turtles. Lately, this view was questioned based on limb bone proportions, and a terrestrial palaeoecology was suggested for the turtle stem. Here, we present independent shell bone microstructural evidence for a terrestrial habitat of the oldest and basal most well-known turtles, i.e. the Upper Triassic Proterochersis robusta and Proganochelys quenstedti. Comparison of their shell bone histology with that of extant turtles preferring either aquatic habitats or terrestrial habitats clearly reveals congruence with terrestrial turtle taxa. Similarities in the shell bones of these turtles are a diploe structure with well-developed external and internal cortices, weak vascularization of the compact bone layers and a dense nature of the interior cancellous bone with overall short trabeculae. On the other hand, 'aquatic' turtles tend to reduce cortical bone layers, while increasing overall vascularization of the bone tissue. In contrast to the study of limb bone proportions, the present study is independent from the uncommon preservation of appendicular skeletal elements in fossil turtles, enabling the palaeoecological study of a much broader range of incompletely known turtle taxa in the fossil record.     

Long bone microstructure gives new insights into the life of pachypleurosaurids from the Middle Triassic of Monte San Giorgio,Switzerland/Italy

The long bone microstructure of four pachypleurosaurid taxa from Monte San Giorgio (Switzerland/Italy) was studied. Pachypleurosaurids are secondarily aquatic reptiles that lived during the Middle Triassic in varying marine environments of the Tethys. All four pachypleurosaurids show high compactness values in their long bones based on a thick cortex and a calcified cartilaginous core, which remains in the medullary region throughout the ontogeny. Parts or even the entire embryonic bone layer composed of a mixture of woven-fibered bone tissue and parallel-fibered bone tissue is preserved in both pachypleurosaurid genera. The rest of the cortex consists of lamellar-zonal bone tissue type. Differences in the microstructure of the bones between the pachypleurosaurids are reflected in the occurrence of remodelling processes, which, if present, affect the innermost growth marks of the cortex or the calcified cartilaginous core. Further variation is present in the spacing pattern of the growth cycles, as well as in the degree of vascularisation of the lamellar-zonal bone tissue type. Our data on the microstructure of the long bones support previous studies on morphology and facies distribution, which indicated different habitats and adaptation to a secondary aquatic lifestyle for each pachypleurosaurid taxon. Life history data furthermore reflect different longevities and ages at sexual maturity. The bone histological data of the stratigraphically youngest and oldest pachypleurosaurid species might indicate possible climate-dependant reproductive seasons similar to Recent lacertilian squamates.     

Functional morphology of cercopithecoid primate metacarpals

The primate fossil record suggests that terrestriality was more common in the past than it is today, particularly among cercopithecoid primates. Whether or not a fossil primate habitually preferred terrestrial substrates has typically been inferred from its forelimb anatomy. Because extant large-bodied terrestrial cercopithecine monkeys utilize digitigrade hand postures during locomotion, being able to identify if a fossil primate habitually adopted digitigrade postures would be particularly revealing of terrestriality in this group. This paper examines the functional morphology of metacarpals in order to identify osteological correlates of digitigrade versus palmigrade hand postures. Linear measurements were obtained from 324 individuals belonging to digitigrade and palmigrade cercopithecoid species and comparisons were made between hand posture groups. Digitigrade taxa have shorter metacarpals, relative to both body mass and humerus length, than palmigrade taxa. Also, digitigrade taxa tend to have metacarpals with smaller dorsoventral diameters, relative to the product of body mass and metacarpal length, compared to palmigrade taxa. The size and shape of the metacarpal heads do not significantly differ between hand posture groups. Multivariate analyses suggest that metacarpal shape can only weakly discriminate between hand posture groups. In general, while there are some morphological differences in the metacarpals between hand posture groups, similarities also exist that are likely related to the fact that even digitigrade cercopithecoids can adopt palmigrade hand postures in different situations (e.g., terrestrial running, arboreal locomotion), and/or that the functional demands of different hand postures are not reflected in all aspects of metacarpal morphology. Therefore, the lack of identifiable adaptations for specific hand postures in extant cercopithecoids makes it difficult to determine a preference for specific habitats from fossil primate hand bones.     

Effects of oceanic salinity on body condition in sea snakes

Since the transition from terrestrial to marine environments poses strong osmoregulatory and energetic challenges, temporal and spatial fluctuations in oceanic salinity might influence salt and water balance (and hence, body condition) in marine tetrapods. We assessed the effects of salinity on three species of sea snakes studied by mark-recapture in coral-reef habitats in the Neo-Caledonian Lagoon. These three species include one fully aquatic hydrophiine (Emydocephalus annulatus), one primarily aquatic laticaudine (Laticauda laticaudata), and one frequently terrestrial laticaudine (Laticauda saintgironsi). We explored how oceanic salinity affected the snakes' body condition across various temporal and spatial scales relevant to each species' ecology, using linear mixed models and multimodel inference. Mean annual salinity exerted a consistent and negative effect on the body condition of all three snake species. The most terrestrial taxon (L. saintgironsi) was sensitive to salinity over a short temporal scale, corresponding to the duration of a typical marine foraging trip for this species. In contrast, links between oceanic salinity and body condition in the fully aquatic E. annulatus and the highly aquatic L. laticaudata were strongest at a long-term (annual) scale. The sophisticated salt-excreting systems of sea snakes allow them to exploit marine environments, but do not completely overcome the osmoregulatory challenges posed by oceanic conditions. Future studies could usefully explore such effects in other secondarily marine taxa such as seabirds, turtles, and marine mammals.     

Comparative limb bone scaling in turtles: Phylogenetic transitions with changes in functional demands?

Several terrestrial vertebrate clades include lineages that have evolved nearly exclusive use of aquatic habitats. In many cases, such transitions are associated with the evolution of flattened limbs that are used to swim via dorsoventral flapping. Such changes in shape may have been facilitated by changes in limb bone loading in novel aquatic environments. Studies on limb bone loading in turtles found that torsion is high relative to bending loads on land, but reduced compared to bending during aquatic rowing. Release from torsion among rowers could have facilitated the evolution of hydrodynamically advantageous flattened limbs among aquatic species. Because rowing is regarded as an intermediate locomotor stage between walking and flapping, rowing species might show limb bone flattening intermediate between the tubular shapes of walkers and the flattened shapes of flappers. We collected measurements of humeri and femora from specimens representing four functionally divergent turtle clades: sea turtles (marine flappers), softshells (specialized freshwater rowers), emydids (generalist semiaquatic rowers), and tortoises (terrestrial walkers). Patterns of limb bone scaling with size were compared across lineages using phylogenetic comparative methods. Although rowing taxa did not show the intermediate scaling patterns we predicted, our data provide other functional insights. For example, flattening of sea turtle humeri was associated with positive allometry (relative to body mass) for the limb bone diameter perpendicular to the flexion-extension plane of the elbow. Moreover, softshell limb bones exhibit positive allometry of femoral diameters relative to body mass, potentially helping them maintain their typical benthic position in water by providing additional weight to compensate for shell reduction. Tortoise limb bones showed positive allometry of diameters, as well as long humeri, relative to body mass, potentially reflecting specializations for resisting loads associated with digging. Overall, scaling patterns of many turtle lineages appear to correlate with distinctive behaviors or locomotor habits.     

Temnospondyli bite club: ecomorphological patterns of the most diverse group of early tetrapods

Temnospondyls were a successful group of early tetrapods that lived during the Palaeozoic and Mesozoic periods. Different ecomorphotypes were present (terrestrial, amphibious and fully aquatic) with a wide range of lifestyles. Herein, we analysed several clades of temnospondyls using geometric morphometrics, Finite Element Analysis, and comparative phylogenetic analysis. Some temnospondyli clades were 'crocodilomorph' feeding analogues. The skull analysis reveals a concordance between form and feeding function, in amphibious and fully aquatic feeders. The form of terrestrial feeders could be consequences of adaptative or phylogenetical constraints. Basal temnospondyls, as edopoids, were able to leave the water and feed on land. Eryopids continued as terrestrial feeders, although some members showed a shift to increased aquatic feeding. The aquatic environment was especially occupied by archegosaurs during the Permian. After the Permo-Triassic extinction, trematosaurs and capitosaurs returned to the aquatic environment and their members were amphibious and fully aquatic feeders until their disappearance.