The function and Evolution of Stegosaur Osteoderms and Hypothesized Sexual Dimorphism inHesperosaurus

bioRxiv (Cold Spring Harbor Laboratory), Journal Year: 2025, Volume and Issue: unknown

Published: April 16, 2025

Abstract Stegosaurus is one of the most iconic organisms in Earth’s history due to its impressive dermal osteoderms. These consisted throat ossicles, two pairs posterior tail spikes, and an estimated 18 large plates arranged staggered rows along neck, back, tail. The function evolution these structures stegosaurs a quintessential question dinosaur paleontology. Although sociosexual display has become popular explanation plate function, sexual dimorphism dinosaurs been contentious topic. Spikes are meanwhile often described as defensive structures, but we consider additional intra-sex combat worthy further study. To investigate questions surrounding stegosaur osteoderms, reevaluate variation North American with attention hypothesized Hesperosaurus , close relative similar We correct errors previous analyses, address challenges hypothesis, use outline analysis effect size statistics provide statistical support that sex possibly had larger, wide/broad (hypothesized male), while other smaller, tall/narrow female). Stegosaur difficult case study for because multiple borne by single individual can result datasets violate assumptions independence. Despite appreciable from head individual, shape seen still consistent presence evidenced both size-independent, two-dimensional well size-versus-shape regression principal component data, high confidence latter. note pathologies on caudal vertebrae, particularly old adults wide-morph spikes. not just predator–prey interactions also intraspecific combat. There currently no unambiguous indication thagomizers alternative hypotheses, such ontogenetic or interspecific variation, yet fully tested. Finally, present hypothetical model osteoderm based fossil extant evidence. Osteoderms adapted defense earlier thyreophorans likely became exapted (i.e., plates) (e.g., spikes stegosaurs, clubs ankylosaurs). Therefore, selection may have initiated differentiation terminal thagomizer induced unique asymmetry . Osteoderm development males could driven physiological upper limits selection, intensity predation pressure dictated females. Increasing might correlate body size, open habitats, spine-like processes, long gular ossicles. Within this evolutionary model, would represent taxon magnitude dimorphism, smaller rounder plates, presumed lack niche occupation within wet, forested, vegetation-rich habitat northern Morrison foreland basin. requires us look more broadly at thyreophoran complex, multifactor models incorporate many previously proposed hypotheses. must sort between primary versus secondary functions ossicles how changed over time.

Language: 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, Journal Year: 2020, Volume and Issue: 131(2), P. 231 - 273

Published: June 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.

Language: Английский

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Reconstructing Vertebrate Paleocolor

Annual Review of Earth and Planetary Sciences, Journal Year: 2020, Volume and Issue: 48(1), P. 345 - 375

Published: May 30, 2020

Melanin and other pigments are now well known to be important in exceptional preservation of soft tissues vertebrates animals. Because confer coloration even structural colors, they have opened a new field paleocolor reconstruction. Since its inception about decade ago, reconstruction color patterns has been performed on several vertebrates, including feathered scale-clad dinosaurs. Iridescence types can also identified through melanosome shape arrangement. How melanosomes fossilize altered become an research subject. Ancient that may range from crypsis brilliant displays revealed insights into the evolution escalation visual systems, nature ancient animal interactions, how unique characteristics birds already arose among ▪ preserve fossils; this opens paths for reconstructing extinct organisms, such as The most abundant pigment is melanin, which chemically preserved microbodies. Melanosome reveals clues original hue ranging reddish brown black gray coloration. Other preserve, porphyrin theropod dinosaur eggshells. Fossil contribute predator-prey key innovations.

Language: Английский

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Estimating the distribution of carotenoid coloration in skin and integumentary structures of birds and extinct dinosaurs

Evolution, Journal Year: 2021, Volume and Issue: 76(1), P. 42 - 57

Published: Nov. 1, 2021

Carotenoids are pigments responsible for most bright yellow, red, and orange hues in birds. Their distribution has been investigated avian plumage, but the evolution of their expression skin other integumentary structures not approached detail. Here, we investigate carotenoid-consistent coloration across tissue types all extant, nonpasserine species (n = 4022) archelosaur outgroups a phylogenetic framework. We collect dietary data subset birds how carotenoid intake may relate to various tissues. find that or nonplumage keratin 50% probability being present recent common ancestor Archosauria. Skin similar at base crown clade, plumage is unambiguously absent shows hundreds independent gains within neognaths, consistent with previous studies. Although our do support strict sequence birds, color integument might evolve correlated manner feathers rarely only region expression. Taxa diets high content also show more body regions types. Our results inform targeted assays carotenoids tissues than feathers, expectations these nonavian dinosaurs. In extinct groups, bare-skin rhamphotheca, especially rich plants, express pigments, which expected feather homologues.

Language: Английский

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Metabolic physiology explains macroevolutionary trends in the melanic colour system across amniotes

Proceedings of the Royal Society B Biological Sciences, Journal Year: 2018, Volume and Issue: 285(1893), P. 20182014 - 20182014

Published: Dec. 12, 2018

Metabolism links organisms to their environment through its effects on thermoregulation, feeding behaviour and energetics. Genes involved in metabolic processes have known pleiotropic some melanic colour traits. Understanding between physiology is critical for understanding the role of, potential constraints on, production. Despite considerable variation rates presumed ancestral coloration vertebrates, few studies looked at a relationship these two systems comparative framework. Here, we test hypothesis that changes melanosome shape integumentary structures track rate across amniotes. Using multivariate analyses incorporating both extant fossil taxa, find significantly faster of evolution taxa with high rates, as well colour- clade-specific differences shape. Phylogenetic tests recover an expansion morphospace maniraptoran dinosaurs, shifts within birds (in songbirds) mammals. These findings indicate another core phenotype influenced by vertebrates. They also provide framework testing gene expression patterns melanocortin system may improve reconstructions extinct taxa.

Language: Английский

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A perspective on the evidence for keratin protein preservation in fossils: An issue of replication versus validation

Palaeontologia Electronica, Journal Year: 2019, Volume and Issue: unknown

Published: Jan. 1, 2019

The preservation potential of biomolecules within vertebrate integument through deep time has recently been subject to much research and controversy.In particular, the proteins, such as collagen keratin, is currently debated.Here, we examine claims from a recent study (Schweitzer et al., 2018, PLoS One), which concludes that feather keratin high potential.We argue this work provides insufficient evidence for protein due issues methodology data interpretation.Additionally, contrast their approach those other published studies in relation question fossils.We worry most perceived Mesozoic polypeptide survival stems repeated replication methods prone false detection, rather than triangulation by validating these with alternative provide independent lines evidence.When explanations exist cited support dinosaur proteins far exceeding predicted limits, it parsimonious reject more extreme taphonomic hypotheses.The instead consistent mode keratinous structures do not fossilize organically polypeptides, but largely pigment and/or calcium phosphate remnants, were originally held matrix now lost.Unsupported models (e.g., preservation) have influence our interpretation fossil data, potentially resulting erroneous paleobiological or evolutionary conclusions, illustrated another paper (Pan 2019, PNAS) also discuss.

Language: Английский

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Study of laser actions by bird’s feathers with photonic crystals

Scientific Reports, Journal Year: 2021, Volume and Issue: 11(1)

Published: Jan. 28, 2021

Abstract Random lasers had been made by some biomaterials as light scattering materials, but natural photonic crystals have rarely reported materials. Here we demonstrate the ability of to drive laser actions sandwiched feathers Turquoise-Fronted Amazon parrot and dye between two plastic films. Parrot comprise abundant crystals, different color compose ratios crystal, which directly affect feather reflectance. In this study, multi-reflection that occurred at interface crystal gain media efficiently reduce threshold; therefore, more constitutes in feathers; lower threshold can be obtained. The random easily integration bird with a simple sustainable manufacturing approach.

Language: Английский

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Escape behaviors in prey and the evolution of pennaceous plumage in dinosaurs

Scientific Reports, Journal Year: 2024, Volume and Issue: 14(1)

Published: Jan. 25, 2024

Numerous non-avian dinosaurs possessed pennaceous feathers on their forelimbs (proto-wings) and tail. Their functions remain unclear. We propose that these were used in displays to flush hiding prey through stimulation of sensory-neural escape pathways prey, allowing the pursue flushed prey. evaluated behavior grasshoppers hypothetical visual flush-displays by a robotic dinosaur, we recorded neurophysiological responses grasshoppers' pathway computer animations dinosaurs. show would have fled more often when proto-wings present, especially distally with contrasting patterns, caudal plumage, large area, was during flush-displays. The reinforcing loop between could contributed evolution larger stiffer for faster running, maneuverability, stronger flush-displays, promoting foraging based flush-pursue strategy. hypothesis can explain presence distribution feathers, plumage color contrasts, as well number other features observed early pennaraptorans. This scenario highlights processes underlying prey's antipredatory reactions may contribute origin major evolutionary innovations predators.

Language: Английский

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Detection of intact polyene pigments in Miocene gastropod shells

Palaeontology, Journal Year: 2024, Volume and Issue: 67(1)

Published: Jan. 1, 2024

Abstract Polyene pigments represent a major class of in present‐day organisms. Their occurrence fossils has been frequently discussed, but to date no spectroscopic evidence found. Here, we use situ Raman spectroscopy examine the chemistry exceptionally well‐preserved gastropod shells with colour preservation from Middle Miocene Vienna Basin (Austria, Hungary). signals indicative presence intact (i.e. non‐hydrogenated) polyene were obtained fossil reddish patterns, thus revealing first record polyenes fossils. The observed values are good agreement those unmethylated (non‐carotenoid) polyenes. Fossil detected representatives superfamily Cerithioidea, not other families found at same localities, demonstrating that is taxon‐specific. Our results show represents valuable tool for non‐destructive screening rare pigments.

Language: Английский

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On the Potential Role of the Neural Crest Cells in Integrating Pigmentation Into Behavioral and Physiological Syndromes

Frontiers in Ecology and Evolution, Journal Year: 2020, Volume and Issue: 8

Published: Sept. 2, 2020

Melanin pigments colour the integument of vertebrates with shades rufous, grey, and black. In numerous wild species, melanin-based colouration associates to different behavioural, physiological, morphological traits, yet proximate basis such associations remains largely unknown. The neural crest/domestication syndrome hypothesis (Wilkins et al. 2014) proposes that correlated changes in pigmentary, traits domestic species result from deficiencies affecting number or development crest cells embryo. Here, we review what extent might also explain observed between distinct vertebrate populations. Genes involved differences some particularly, cichlid fishes. Cells originate embryo's play functions have been previously associated propose potential mechanisms through which association other can be consequence having a common origin at cells. We encourage considering influence as new avenue research, integrating developmental biology evolutionary ecology better understand why how become multiple phenotypic aspects.

Language: Английский

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