scholarly journals Rapid Initial Morphospace Expansion and Delayed Morphological Disparity Peak in the First 100 Million Years of the Archosauromorph Evolutionary Radiation

2021 ◽  
Vol 9 ◽  
Author(s):  
Christian Foth ◽  
Roland B. Sookias ◽  
Martín D. Ezcurra
Keyword(s):  
Nearest Neighbor ◽  
Late Triassic ◽  
Geometric Morphometric ◽  
Deep Time ◽  
Morphological Disparity ◽  
Initial Correlation ◽  
Rates Of Evolution ◽  
Burst Pattern ◽  
Comprehensive Picture ◽  
Adaptive Radiations

Adaptive radiations have played a major role in generating modern and deep-time biodiversity. The Triassic radiation of the Archosauromorpha was one of the most spectacular vertebrate radiations, giving rise to many highly ecomorphologically varied lineages—including the dinosaurs, pterosaurs, and stem-crocodylians—that dominated the larger-bodied land fauna for the following 150 Ma, and ultimately gave rise to today’s > 10,000 species of birds and crocodylians. This radiation provides an outstanding testbed for hypotheses relating to adaptive radiations more broadly. Recent studies have started to characterize the tempo and mode of the archosauromorph early adaptive radiation, indicating very high initial rates of evolution, non-competitive niche-filling processes, and previously unrecognized morphological disparity even among non-crown taxa. However, these analyses rested primarily either on discrete characters or on geometric morphometrics of the cranium only, or even failed to fully include phylogenetic information. Here we expand previous 2D geometric morphometric cranial datasets to include new taxa and reconstructions, and create an analogous dataset of the pelvis, thereby allowing comparison of anatomical regions and the transition from “sprawling” to “upright” posture to be examined. We estimated morphological disparity and evolutionary rates through time. All sampled clades showed a delayed disparity peak for sum of variances and average nearest neighbor distances in both the cranium and pelvis, with disparity likely not saturated by the end of the studied time span (Late Jurassic); this contrasts with smaller radiations, but lends weight to similar results for large, ecomorphologically-varied groups. We find lower variations in pelvic than cranial disparity among Triassic-Jurassic archosaurs, which may be related to greater morphofunctional constraints on the pelvis. Contrasting with some previous work, but also confirming some previous findings during adaptive radiations, we find relatively widespread evidence of correlation between sampled diversity and disparity, especially at the largest phylogenetic scales and using average displacement rather than sum of variances as disparity metric; this also demonstrates the importance of comparing disparity metrics, and the importance of phylogenetic scale. Stem and crown archosauromorphs show a morphological diversification of both the cranium and pelvis with higher initial rates (Permian–Middle Triassic and at the base of major clades) followed by lower rates once diversification into niches has occurred (Late Triassic–Jurassic), indicating an “early burst” pattern sensu lato. Our results provide a more detailed and comprehensive picture of the early archosauromorph radiation and have significant bearing on the understanding of deep-time adaptive radiations more broadly, indicating widespread patterns of delayed disparity peaks, initial correlation of diversity and disparity, and evolutionary early bursts.

Bony Patchwork: Mosaic Patterns of Evolution in the Skull of Electric Fishes (Apteronotidae: Gymnotiformes)

2019 ◽  
Vol 59 (2) ◽  
pp. 420-431 ◽  
Author(s):  
Kory M Evans ◽  
Marta Vidal-García ◽  
Victor A Tagliacollo ◽  
Samuel J Taylor ◽  
Dante B Fenolio
Keyword(s):  
Three Dimensional ◽  
Strong Support ◽  
Functional Specialization ◽  
Deep Time ◽  
Selective Pressures ◽  
Rates Of Evolution ◽  
Individual Traits ◽  
The Face ◽  
Electric Fishes ◽  
Mosaic Evolution

Abstract Mosaic evolution refers to the pattern whereby different organismal traits exhibit differential rates of evolution typically due to reduced levels of trait covariation through deep time (i.e., modularity). These differences in rates can be attributed to variation in responses to selective pressures between individual traits. Differential responses to selective pressures also have the potential to facilitate functional specialization, allowing certain traits to track environmental stimuli more closely than others. The teleost skull is a multifunctional structure comprising a complex network of bones and thus an excellent system for which to study mosaic evolution. Here we construct an ultrametric phylogeny for a clade of Neotropical electric fishes (Apteronotidae: Gymnotiformes) and use three-dimensional geometric morphometrics to investigate patterns of mosaic evolution in the skull and jaws. We find strong support for a developmental, three-module hypothesis that consists of the face, braincase, and mandible, and we find that the mandible has evolved four times faster than its neighboring modules. We hypothesize that the functional specialization of the mandible in this group of fishes has allowed it to outpace the face and braincase and evolve in a more decoupled manner. We also hypothesize that this pattern of mosaicism may be widespread across other clades of teleost fishes.

Quantifying morphological change during an evolutionary radiation of Devonian trilobites

Paleobiology ◽  
2012 ◽  
Vol 38 (2) ◽  
pp. 292-307 ◽  
Author(s):  
Francine R. Abe ◽  
Bruce S. Lieberman
Keyword(s):  
Morphological Change ◽  
Fossil Record ◽  
Character State ◽  
Geometric Morphometric ◽  
Biogeographic Patterns ◽  
Ancestral Character State ◽  
Speciation Rates ◽  
Adaptive Radiations ◽  
Geometric Morphometric Analysis ◽  
Heterogeneous Region

The fossil record provides an important source of data on adaptive radiations, and indeed some of the earliest theoretical insights on the nature of these radiations were made by paleontologists. Here we focus on the diverse DevonianMetacryphaeusgroup calmoniid trilobites, known from the Malvinokaffric Realm, which have been considered a classic example of an adaptive radiation preserved in the fossil record. We use a geometric morphometric analysis in conjunction with phylogenetic and biogeographic patterns and data on speciation rates. Using ancestral character state reconstruction during speciation events, we quantify patterns of morphological change in order to assess the role ecological and geographical factors may have played in mediating this radiation. We found no significant differences between the amount of morphological change that occurred during speciation events when ancestors and descendants were in the same area as opposed to when they occupied different areas. Further, the magnitude of morphological divergence did not change through time or with cladogenetic rank. These patterns, in conjunction with the fact that the radiation occurs in a geographically heterogeneous region subjected to repeated episodes of sea-level rise and fall, suggest that at the macroevolutionary scale this radiation may have been motivated more by phenomena that facilitated geographic isolation than by competition.

scholarly journals Deep-time parallel evolution of myrmecoid syndrome in rove beetle symbionts of army ants

2016 ◽  
Author(s):  
Munetoshi Maruyama ◽  
Joseph Parker
Keyword(s):  
Parallel Evolution ◽  
Army Ants ◽  
Deep Time ◽  
Rove Beetles ◽  
Army Ant ◽  
Rove Beetle ◽  
Arthropod Predators ◽  
Adaptive Radiations ◽  
Ecological Dominance ◽  
Temporary Nest

Recent adaptive radiations provide striking examples of convergence, but the predictability of evolution over much deeper timescales is controversial, due to a scarcity of ancient clades exhibiting repetitive patterns of phenotypic evolution. Army ants are ecologically dominant arthropod predators of the world's tropics, with large nomadic colonies housing diverse communities of socially parasitic myrmecophiles. Remarkable among these are many species of rove beetle (Staphylinidae) that exhibit ant-mimicking “myrmecoid” body forms and are behaviorally accepted into their aggressive hosts' societies: emigrating with colonies and inhabiting temporary nest bivouacs, grooming and feeding with workers, but also consuming the brood. Here we demonstrate that myrmecoid rove beetles are strongly polyphyletic, with this novel adaptive morphological and behavioral syndrome having evolved at least twelve times during the evolution of a single staphylinid subfamily, Aleocharinae. Each independent myrmecoid clade is restricted to one zoogeographic region and highly host-specific on a single army ant genus. Dating estimates reveal that myrmecoid clades are separated by substantial phylogenetic distances—as much as 105 million years (My). All such groups arose in parallel during the Cenozoic, as army ants are proposed to have risen to ecological dominance. This work uncovers a rare example of an ancient system of complex morphological and behavioral convergence, with replicate beetle lineages following a predictable phenotypic trajectory during their parasitic coevolution with army ants.

scholarly journals Tooth morphology elucidates shark evolution across the end-Cretaceous mass extinction

PLoS Biology ◽  
2021 ◽  
Vol 19 (8) ◽  
pp. e3001108
Author(s):  
Mohamad Bazzi ◽  
Nicolás E. Campione ◽  
Per E. Ahlberg ◽  
Henning Blom ◽  
Benjamin P. Kear
Keyword(s):  
Mass Extinction ◽  
Mass Extinctions ◽  
Morphological Response ◽  
Geometric Morphometric ◽  
Deep Time ◽  
Predator Species ◽  
Geologic Time ◽  
Marine Predators ◽  
Time Diversity ◽  
Early Paleogene

Sharks (Selachimorpha) are iconic marine predators that have survived multiple mass extinctions over geologic time. Their prolific fossil record is represented mainly by isolated shed teeth, which provide the basis for reconstructing deep time diversity changes affecting different selachimorph clades. By contrast, corresponding shifts in shark ecology, as measured through morphological disparity, have received comparatively limited analytical attention. Here, we use a geometric morphometric approach to comprehensively examine tooth morphologies in multiple shark lineages traversing the catastrophic end-Cretaceous mass extinction—this event terminated the Mesozoic Era 66 million years ago. Our results show that selachimorphs maintained virtually static levels of dental disparity in most of their constituent clades across the Cretaceous–Paleogene interval. Nevertheless, selective extinctions did impact apex predator species characterized by triangular blade-like teeth. This is particularly evident among lamniforms, which included the dominant Cretaceous anacoracids. Conversely, other groups, such as carcharhiniforms and orectolobiforms, experienced disparity modifications, while heterodontiforms, hexanchiforms, squaliforms, squatiniforms, and †synechodontiforms were not overtly affected. Finally, while some lamniform lineages disappeared, others underwent postextinction disparity increases, especially odontaspidids, which are typified by narrow-cusped teeth adapted for feeding on fishes. Notably, this increase coincides with the early Paleogene radiation of teleosts as a possible prey source, and the geographic relocation of disparity sampling “hotspots,” perhaps indicating a regionally disjunct extinction recovery. Ultimately, our study reveals a complex morphological response to the end-Cretaceous mass extinction and highlights an event that influenced the evolution of modern sharks.

scholarly journals Body-shape diversity in Triassic–Early Cretaceous neopterygian fishes: sustained holostean disparity and predominantly gradual increases in teleost phenotypic variety

2018 ◽  
Author(s):  
John Clarke ◽  
Matt Friedman
Keyword(s):  
Early Cretaceous ◽  
Body Shape ◽  
Sister Group ◽  
Late Triassic ◽  
Dominant Group ◽  
Geometric Morphometric ◽  
Extant Species ◽  
Aquatic Vertebrates ◽  
Almost All

Comprising Holostei and Teleostei, the ~32,000 species of neopterygian fishes are anatomically disparate and represent the dominant group of aquatic vertebrates today. However, the pattern by which teleosts rose to represent almost all of this diversity, while their holostean sister-group dwindled to eight extant species and two broad morphologies, is poorly constrained. A geometric morphometric approach was taken to generate a morphospace from more than 400 fossil taxa, representing almost all articulated neopterygian taxa known from the first 150 million years—roughly 60%—of their history (Triassic‒Early Cretaceous). Patterns of morphospace occupancy and disparity are examined to: (1) assess evidence for a phenotypically “dominant” holostean phase; (2) evaluate whether expansions in teleost phenotypic variety are predominantly abrupt or gradual, including assessment of whether early apomorphy-defined teleosts are as morphologically conservative as typically assumed; and (3) compare diversification in crown and stem teleosts. The systematic affinities of dapediiforms and pycnodontiforms, two extinct neopterygian clades of uncertain phylogenetic placement, significantly impact patterns of morphological diversification. For instance, alternative placements dictate whether or not holosteans possessed statistically higher disparity than teleosts in the Late Triassic and Jurassic. Despite this ambiguity, all scenarios agree that holosteans do not exhibit a decline in disparity during the Early Triassic‒Early Cretaceous interval, but instead maintain their Toarcian‒Callovian variety until the end of the Early Cretaceous without substantial further expansions. After a conservative Induan‒Carnian phase, teleosts colonize (and persistently occupy) novel regions of morphospace in a predominantly gradual manner until the Hauterivian, after which expansions are rare. Furthermore, apomorphy-defined teleosts possess greater phenotypic variety than typically assumed. Comparison of crown and stem teleost partial disparity indicates that, despite a statistically significant increase in crown teleost disparity between the Late Jurassic and earliest Cretaceous, stem teleosts remained important long-term contributors to overall teleost disparity during this time.

scholarly journals The macroevolutionary consequences of phenotypic integration: from development to deep time

2014 ◽  
Vol 369 (1649) ◽  
pp. 20130254 ◽  
Author(s):  
A. Goswami ◽  
J. B. Smaers ◽  
C. Soligo ◽  
P. D. Polly
Keyword(s):  
Random Walk ◽  
Convergent Evolution ◽  
Significant Variation ◽  
Reproductive Strategies ◽  
Morphological Evolution ◽  
Evolutionary Change ◽  
Phenotypic Integration ◽  
Response To Selection ◽  
Deep Time ◽  
Rates Of Evolution

Phenotypic integration is a pervasive characteristic of organisms. Numerous analyses have demonstrated that patterns of phenotypic integration are conserved across large clades, but that significant variation also exists. For example, heterochronic shifts related to different mammalian reproductive strategies are reflected in postcranial skeletal integration and in coordination of bone ossification. Phenotypic integration and modularity have been hypothesized to shape morphological evolution, and we extended simulations to confirm that trait integration can influence both the trajectory and magnitude of response to selection. We further demonstrate that phenotypic integration can produce both more and less disparate organisms than would be expected under random walk models by repartitioning variance in preferred directions. This effect can also be expected to favour homoplasy and convergent evolution. New empirical analyses of the carnivoran cranium show that rates of evolution, in contrast, are not strongly influenced by phenotypic integration and show little relationship to morphological disparity, suggesting that phenotypic integration may shape the direction of evolutionary change, but not necessarily the speed of it. Nonetheless, phenotypic integration is problematic for morphological clocks and should be incorporated more widely into models that seek to accurately reconstruct both trait and organismal evolution.

scholarly journals Tip dating supports novel resolutions of controversial relationships among early mammals

2020 ◽  
Vol 287 (1928) ◽  
pp. 20200943
Author(s):  
Benedict King ◽  
Robin M. D. Beck
Keyword(s):  
Early Cretaceous ◽  
Late Jurassic ◽  
Morphological Evolution ◽  
Phylogenetic Analyses ◽  
Late Triassic ◽  
Crown Group ◽  
Jehol Biota ◽  
Rates Of Evolution ◽  
Mammal Evolution ◽  
Minimum Divergence

The estimation of the timing of major divergences in early mammal evolution is challenging owing to conflicting interpretations of key fossil taxa. One contentious group is Haramiyida, the earliest members of which are from the Late Triassic. Many phylogenetic analyses have placed haramiyidans in a clade with multituberculates within crown Mammalia, thus extending the minimum divergence date for the crown group deep into the Triassic. A second taxon of interest is the eutherian Juramaia from the Middle–Late Jurassic Yanliao Biota, which is morphologically very similar to eutherians from the Early Cretaceous Jehol Biota and implies a very early origin for therian mammals. Here, we apply Bayesian tip-dated phylogenetic methods to investigate these issues. Tip dating firmly rejects a monophyletic Allotheria (multituberculates and haramiyidans), which are split into three separate clades, a result not found in any previous analysis. Most notably, the Late Triassic Haramiyavia and Thomasia are separate from the Middle Jurassic euharamiyidans. We also test whether the Middle–Late Jurassic age of Juramaia is ‘expected’ given its known morphology by assigning an age prior without hard bounds. Strikingly, this analysis supports an Early Cretaceous age for Juramaia , but similar analyses on 12 other mammaliaforms from the Yanliao Biota return the correct, Jurassic age. Our results show that analyses incorporating stratigraphic data can produce results very different from other methods. Early mammal evolution may have involved multiple instances of convergent morphological evolution (e.g. in the dentition), and tip dating may be a method uniquely suitable to recognizing this owing to the incorporation of stratigraphic data. Our results also confirm that Juramaia is anomalous in exhibiting a much more derived morphology than expected given its age, which in turn implies very high rates of evolution at the base of therian mammals.

scholarly journals Decoupling of morphological disparity and taxic diversity during the adaptive radiation of anomodont therapsids

2013 ◽  
Vol 280 (1768) ◽  
pp. 20131071 ◽  
Author(s):  
Marcello Ruta ◽  
Kenneth D. Angielczyk ◽  
Jörg Fröbisch ◽  
Michael J. Benton
Keyword(s):  
Mass Extinction ◽  
Phylogenetic Diversity ◽  
Mass Extinctions ◽  
Triassic Boundary ◽  
Morphological Disparity ◽  
Morphological Novelty ◽  
Adaptive Radiations ◽  
Permian Mass Extinction ◽  
Original Potential ◽  
Taxic Diversity

Adaptive radiations are central to macroevolutionary theory. Whether triggered by acquisition of new traits or ecological opportunities arising from mass extinctions, it is debated whether adaptive radiations are marked by initial expansion of taxic diversity or of morphological disparity (the range of anatomical form). If a group rediversifies following a mass extinction, it is said to have passed through a macroevolutionary bottleneck, and the loss of taxic or phylogenetic diversity may limit the amount of morphological novelty that it can subsequently generate. Anomodont therapsids, a diverse clade of Permian and Triassic herbivorous tetrapods, passed through a bottleneck during the end-Permian mass extinction. Their taxic diversity increased during the Permian, declined significantly at the Permo–Triassic boundary and rebounded during the Middle Triassic before the clade's final extinction at the end of the Triassic. By sharp contrast, disparity declined steadily during most of anomodont history. Our results highlight three main aspects of adaptive radiations: (i) diversity and disparity are generally decoupled; (ii) models of radiations following mass extinctions may differ from those triggered by other causes (e.g. trait acquisition); and (iii) the bottleneck caused by a mass extinction means that a clade can emerge lacking its original potential for generating morphological variety.

scholarly journals Morphological and biomechanical disparity of crocodile-line archosaurs following the end-Triassic extinction

2013 ◽  
Vol 280 (1770) ◽  
pp. 20131940 ◽  
Author(s):  
Thomas L. Stubbs ◽  
Stephanie E. Pierce ◽  
Emily J. Rayfield ◽  
Philip S. L. Anderson
Keyword(s):  
Late Cretaceous ◽  
Morphological Variation ◽  
Late Triassic ◽  
Complex Relationship ◽  
Ecological Diversity ◽  
Unique Combination ◽  
Morphological Disparity ◽  
Selective Pressures ◽  
Feeding Modes ◽  
Jaw Biomechanics

Mesozoic crurotarsans exhibited diverse morphologies and feeding modes, representing considerable ecological diversity, yet macroevolutionary patterns remain unexplored. Here, we use a unique combination of morphological and biomechanical disparity metrics to quantify the ecological diversity and trophic radiations of Mesozoic crurotarsans, using the mandible as a morpho-functional proxy. We recover three major trends. First, the diverse assemblage of Late Triassic crurotarsans was morphologically and biomechanically disparate, implying high levels of ecological variation; but, following the end-Triassic extinction, disparity declined. Second, the Jurassic radiation of marine thalattosuchians resulted in very low morphological disparity but moderate variation in jaw biomechanics, highlighting a hydrodynamic constraint on mandibular form. Third, during the Cretaceous terrestrial radiations of neosuchians and notosuchians, mandibular morphological variation increased considerably. By the Late Cretaceous, crocodylomorphs evolved a range of morphologies equalling Late Triassic crurotarsans. By contrast, biomechanical disparity in the Cretaceous did not increase, essentially decoupling from morphology. This enigmatic result could be attributed to biomechanical evolution in other anatomical regions (e.g. cranium, dentition or postcranium), possibly releasing the mandible from selective pressures. Overall, our analyses reveal a complex relationship between morphological and biomechanical disparity in Mesozoic crurotarsans that culminated in specialized feeding ecologies and associated lifestyles.

scholarly journals A new phylogenetic analysis of Phytosauria (Archosauria: Pseudosuchia) with the application of continuous and geometric morphometric character coding

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5901 ◽  
Author(s):  
Andrew S. Jones ◽  
Richard J. Butler
Keyword(s):  
Phylogenetic Analyses ◽  
Late Triassic ◽  
Morphometric Character ◽  
Sister Relationship ◽  
Geometric Morphometric ◽  
Variable Position ◽  
Basal Clade ◽  
Discrete Character ◽  
Tree Topologies ◽  
Character Matrix

Phytosauria is a clade of large, carnivorous, semi-aquatic archosauromorphs which reached its peak diversity and an almost global distribution in the Late Triassic (c. 230–201 Mya). Previous phylogenetic analyses of Phytosauria have either focused primarily on the relationships of specific subclades, or were limited in taxonomic scope, and no taxonomically comprehensive dataset is currently available. We here present the most taxonomically comprehensive cladistic dataset of phytosaurs to date, based on extensive first-hand study, identification of novel characters and synthesis of previous matrices. This results in an almost twofold increase in phylogenetic information scored per taxon over previous analyses. Alongside a traditional discrete character matrix, three variant matrices were analysed in which selected characters were coded using continuous and landmarking methods, to more rigorously explore phytosaur relationships. Based on these four data matrices, four tree topologies were recovered. Relationships among non-leptosuchomorph phytosaurs are largely consistent between these four topologies, whereas those of more derived taxa are more variable. Rutiodon carolinensis consistently forms a sister relationship with Angistorhinus. In three topologies Nicrosaurus nests deeply within a group of traditionally non-Mystriosuchini taxa, leading us to redefine Mystriosuchini by excluding Nicrosaurus as an internal specifier. Two distinct patterns of relationships within Mystriosuchini are present in the four topologies, distinguished largely by the variable position of Mystriosuchus. In two topologies Mystriosuchus forms the most basal clade in Mystriosuchini, whilst in the others it occupies a highly derived position within the Machaeroprosopus clade. ‘Redondasaurus’ is consistently recovered as monophyletic; however, it also nests within the Machaeroprosopus clade. The greatest impact on tree topology was associated with the incorporation of continuous data into our matrices, with landmark characters exerting a relatively modest influence. All topologies correlated significantly with stratigraphic range estimates. Topological variability in our results highlights clades in which further investigation may better elucidate phytosaur relationships.

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