The neodiapsid Thadeosaurus colcanapi from the upper Permian of Madagascar

Papers in Palaeontology, Год журнала: 2025, Номер 11(2)

Опубликована: Март 1, 2025

Abstract The enigmatic neodiapsid Thadeosaurus colcanapi (Lower Sakamena Formation, southwestern Madagascar), sole species of the genus , is revised here. attribution 12 21 referred specimens confirmed, spanning all ontogenetic stages, and anatomy redescribed in detail with comments on ontogenetical differences. This new anatomical information included an expanded phylogenetical dataset tailored to examine relationships Permo‐Triassic diapsids. A stem‐saurian position confirmed here for ‘younginiforms’, which are recovered paraphyletic, Youngina representing earlier‐diverging taxon. However, this topology extremely labile, monophyly or paraphyly ‘younginiforms’ could not be unequivocally supported. In contrast, our analyses provide good support a monophyletic Tangasauridae including other ‘younginiforms’. as member sister‐group putative semi‐aquatic Tangasaurinae moderate degree support, despite large amounts missing data lesser‐known tangasaurids partially obscuring understanding tangasaurid interrelationships. Last, considered have inhabited nearshore, probably riparian, environment, although it remains unclear whether was fully terrestrial. Further examinations tangasaurids, well novel morphotype identified Lower Formation Madagascar, evidence deepen evolution palaeoecology Tangasauridae.

Язык: Английский

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Why the Static Allometry of Sexually-Selected Traits Is So Variable: The Importance of Function

Integrative and Comparative Biology, Год журнала: 2019, Номер 59(5), С. 1290 - 1302

Опубликована: Май 6, 2019

Abstract Sexually-selected traits often show positive static allometry, with large individuals bearing disproportionately structures. But many other sexually-selected isometry or even negative trait size varying relatively little body size. We recently proposed that the functions of these (as aggressive signals, weapons, courtship and contact devices) determine their allometries. Positive allometry is generally favored for signals because are selected to emphasize (and thus fighting prowess). In contrast, biomechanics force application in weapons only sometimes select allometry; content less related size; devices be invariant across sizes. Here we summarize arguments favor this “functional allometry” hypothesis expand a comparative test its predictions. Our results indicate sexual have allometric slopes predicted by our hypothesis, regardless which part bears structure.

Язык: Английский

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The longer the better: evidence that narwhal tusks are sexually selected

Biology Letters, Год журнала: 2020, Номер 16(3), С. 20190950 - 20190950

Опубликована: Март 1, 2020

Once thought to be the magical horn of a unicorn, narwhal tusks are one most charismatic structures in biology. Despite years speculation, little is known about tusk's function, because narwhals spend their lives hidden underneath Arctic ice. Some hypotheses propose that tusk has sexual functions as weapon or signal. By contrast, other an environmental sensor. Since assessing function nature difficult, we can use morphological relationships size with body understand this mysterious trait. To do so, collected morphology data on 245 adult male over course 35 years. Based disproportional growth and large variation length found, provide best evidence date indeed sexually selected. combining our results scaling material properties tusk, suggest selected signal used during male–male contests.

Язык: Английский

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Ontogeny of a sexually selected structure in an extant archosaur Gavialis gangeticus (Pseudosuchia: Crocodylia) with implications for sexual dimorphism in dinosaurs

PeerJ, Год журнала: 2020, Номер 8, С. e9134 - e9134

Опубликована: Май 12, 2020

Despite strong evidence for sexual selection in various display traits and other exaggerated structures large extinct reptiles, such as dinosaurs, detecting dimorphism them remains difficult. Their relatively small sample sizes, long growth periods, difficulties distinguishing the sexes of fossil specimens mean that there are little compelling data on these animals. The extant gharial ( Gavialis gangeticus ) is a endangered crocodylian sexually dimorphic size, but males also possesses selected structure, ghara, which has an osteological correlate presence fossa associated with nares. This makes species unique model potentially assessing lineages, dinosaurs pterosaurs, because it large, slow-growing, egg-laying archosaur. Here we assess G. across 106 show narial diagnoses adult male gharials. Males larger than females, level size dimorphism, cranial features, low difficult to detect without priori knowledge sexes, even this dataset. By extension, reptiles very absence sex specific characters, fossa.

Язык: Английский

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The representation of animal behaviour in the fossil record

Animal Behaviour, Год журнала: 2020, Номер 169, С. 65 - 80

Опубликована: Окт. 12, 2020

Язык: Английский

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Fight intensity correlates with stronger and more mechanically efficient weapons in three species of Aegla crabs

Behavioral Ecology and Sociobiology, Год журнала: 2020, Номер 74(5)

Опубликована: Апрель 16, 2020

Язык: Английский

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An effect size statistical framework for investigating sexual dimorphism in non-avian dinosaurs and other extinct taxa

Biological Journal of the Linnean Society, Год журнала: 2020, Номер 131(2), С. 231 - 273

Опубликована: Июнь 12, 2020

Abstract Despite reports of sexual dimorphism in extinct taxa, such claims non-avian dinosaurs have been rare over the last decade and often criticized. Since is widespread sexually reproducing organisms today, under-reporting literature might suggest either methodological shortcomings or that this diverse group exhibited highly unusual reproductive biology. Univariate significance testing, especially for bimodality, ineffective prone to false negatives. Species recognition mutual selection hypotheses, therefore, may not be required explain supposed absence across grade (a type II error). Instead, multiple lines evidence support variation structures consistent with secondary characteristics, strongly suggesting dinosaurs. We propose a framework studying fossils, focusing on likely traits testing against all alternate hypotheses them using evidence. use effect size statistics appropriate low sample sizes, rather than analyse potential divergence growth curves constrain estimates magnitude. In many cases, can reasonably accurate, further developments methods improve sex assignments account intrasexual (e.g. mixture modelling) will accuracy. It better compare magnitude between datasets dichotomously reject fail monomorphism single species, enabling study phylogenies time. defend our approach simulated empirical data, including dinosaur showing even simple approaches yield fairly accurate allowing comparison species high variation.

Язык: Английский

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Exaggerated sexually selected weapons maintained with disproportionately low metabolic costs in a single species with extreme size variation

Functional Ecology, Год журнала: 2021, Номер 35(10), С. 2282 - 2293

Опубликована: Июль 22, 2021

Abstract Larger individuals typically have lower mass‐specific metabolic rates compared to small ones (hypometric scaling). This trend is most evident across species where body size differences can be extreme. Yet, within‐species studies are critical decipher the morphological and physiological mechanisms responsible. However, in species, relatively range appendage of same life stage often precludes such intraspecific comparisons. Sexually selected weapons among exaggerated traits nature; these account for a large portion mass contribute whole‐body energetic maintenance costs. Often larger possess disproportionally relative their size, yet little known about how meet predicted increased demands maintaining disproportionately weapons. New Zealand giraffe weevils, Lasiorhynchus barbicornis (Coleoptera: Brentidae) exhibit an extreme 30‐fold male as well hypermetric scaling sexually rostra used male–male competition. We compare intra‐ interspecific resting by compiling measurements 26 arthropod whose ranges overlap with L. . The rate this pooled sample was not significantly different from we found (slope log–log relationship = 0.67). Male female had similar despite differing substantially rostra, legs antennae. structures that scaled positive allometry males (rostra legs) were increasingly composed cuticle individuals. largest invest ~60% less metabolically active tissue into (weapons) smallest males. Our findings reveal hypometric relationships inter‐ shared diverse group arthropods. study uncovers tremendous difference weapon architecture scale up size; find bear at cost. cost‐saving mechanism may play key role shaping traits. A free Plain Language Summary within Supporting Information article.

Язык: Английский

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Evolution of horn length and lifting strength in the Japanese rhinoceros beetle Trypoxylus dichotomus

Current Biology, Год журнала: 2023, Номер 33(20), С. 4285 - 4297.e5

Опубликована: Сен. 20, 2023

Язык: Английский

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The evolution of honest and dishonest signals of fighting ability

Evolution Letters, Год журнала: 2024, Номер 8(4), С. 514 - 525

Опубликована: Март 8, 2024

Abstract Competition over resources is often decided via aggressive interactions, which may or not escalate to all-out fights. Weapons and body size play important roles in such as they provide reliable cues of an individual’s fighting ability. In contrast, traits like nonfunctional display “weapons” dishonestly exaggerate ability order intimidate opponents into retreating. Signals used the context interactions potentially evolve very different mechanisms than courtship signals, but have received far less theoretical attention. Here, we contrast evolution honest dishonest signals using a game-theoretic model. Contests are assumed consist three discrete stages: from distance, low-intensity physical contact, fighting. At each stage, contestants evaluate their comparison own based on signal. After making this evaluation, decide whether interaction cede opponent. Our model predicts that both can beyond ecological optima, exaggeration more pronounced for signals. Equilibrium levels aggressiveness—as measured by individuals’ propensity next stage—are independent honesty We additionally develop novel approach, causal inference theory, understand how changes underlying parameters shape coevolution multiple traits. use approach study aggression coevolves with signal response cost losing fight.

Язык: Английский

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