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Yang Z, Jiang B, Xu J, McNamara ME. Cellular structure of dinosaur scales reveals retention of reptile-type skin during the evolutionary transition to feathers. Nat Commun 2024; 15:4063. [PMID: 38773066 PMCID: PMC11109146 DOI: 10.1038/s41467-024-48400-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Accepted: 04/30/2024] [Indexed: 05/23/2024] Open
Abstract
Fossil feathers have transformed our understanding of integumentary evolution in vertebrates. The evolution of feathers is associated with novel skin ultrastructures, but the fossil record of these changes is poor and thus the critical transition from scaled to feathered skin is poorly understood. Here we shed light on this issue using preserved skin in the non-avian feathered dinosaur Psittacosaurus. Skin in the non-feathered, scaled torso is three-dimensionally replicated in silica and preserves epidermal layers, corneocytes and melanosomes. The morphology of the preserved stratum corneum is consistent with an original composition rich in corneous beta proteins, rather than (alpha-) keratins as in the feathered skin of birds. The stratum corneum is relatively thin in the ventral torso compared to extant quadrupedal reptiles, reflecting a reduced demand for mechanical protection in an elevated bipedal stance. The distribution of the melanosomes in the fossil skin is consistent with melanin-based colouration in extant crocodilians. Collectively, the fossil evidence supports partitioning of skin development in Psittacosaurus: a reptile-type condition in non-feathered regions and an avian-like condition in feathered regions. Retention of reptile-type skin in non-feathered regions would have ensured essential skin functions during the early, experimental stages of feather evolution.
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Affiliation(s)
- Zixiao Yang
- School of Biological, Earth and Environmental Sciences, University College Cork, Cork, Ireland.
- Environmental Research Institute, University College Cork, Cork, Ireland.
| | - Baoyu Jiang
- State Key Laboratory for Mineral Deposits Research, School of Earth Sciences and Engineering and Frontiers Science Center for Critical Earth Material Cycling, Nanjing University, Nanjing, China
| | - Jiaxin Xu
- State Key Laboratory for Mineral Deposits Research, School of Earth Sciences and Engineering and Frontiers Science Center for Critical Earth Material Cycling, Nanjing University, Nanjing, China
| | - Maria E McNamara
- School of Biological, Earth and Environmental Sciences, University College Cork, Cork, Ireland
- Environmental Research Institute, University College Cork, Cork, Ireland
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2
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Fuller LH, Marcet EC, Agarkov LL, Singh P, Donahue SW. The morphology of the interfacial tissue between bighorn sheep horn and bony horncore increases contact surface to enhance strength and facilitate load transfer from the horn to the horncore. Acta Biomater 2024; 174:258-268. [PMID: 38072223 DOI: 10.1016/j.actbio.2023.12.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Revised: 11/22/2023] [Accepted: 12/05/2023] [Indexed: 12/22/2023]
Abstract
The horns of bighorn sheep rams are permanent cranial appendages used for high energy head-to-head impacts during interspecific combat. The horns attach to the underlying bony horncore by a layer of interfacial tissue that facilitates load transfer between the impacted horn and underlying horncore, which has been shown to absorb substantial energy during head impact. However, the morphology and mechanical properties of the interfacial tissue were previously unknown. Histomorphometry was used to quantify the interfacial tissue composition and morphology and lap-shear testing was used to quantify its mechanical properties. Histological analyses revealed the interfacial tissue is a complex network of collagen and keratin fibers, with collagen being the most abundant protein. Sharpey's fibers provide strong attachment between the interfacial tissue and horncore bone. The inner horn surface displayed microscopic porosity and branching digitations which increased the contact surface with the interfacial tissue by approximately 3-fold. Horn-horncore samples tested by lap-shear loading failed primarily at the horn surface, and the interfacial tissue displayed non-linear strain hardening behavior similar to other soft tissues. The elastic properties of the interfacial tissue (i.e., low- and high-strain shear moduli) were comparable to previously measured values for the equine laminar junction. The interfacial tissue contact surface was positively correlated with the interfacial tissue shear strength (1.23 ± 0.21 MPa), high-strain shear modulus (4.5 ± 0.7 MPa), and strain energy density (0.38 ± 0.07 MJ/m3). STATEMENT OF SIGNIFICANCE: The bony horncore in bighorn sheep rams absorbs energy to reduce brain cavity accelerations and mitigate brain injury during head butting. The interfacial zone between the horn and horncore transfers energy from the impacted horn to the energy absorbing horncore but has been largely neglected in previous models of bighorn sheep ramming since interfacial tissue properties were previously unknown. This study quantified the morphology and mechanical properties of the horn-horncore interfacial tissue to better understand structure-property relationships that contribute to energy transfer during ramming. Results from this study will improve models of bighorn sheep ramming used to study mechanisms of brain injury mitigation and may inspire novel materials and structures for brain injury prevention in humans.
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Affiliation(s)
- Luca H Fuller
- Department of Biomedical Engineering, University of Massachusetts, Amherst, MA 01003, USA.
| | - Evan C Marcet
- Department of Biomedical Engineering, University of Massachusetts, Amherst, MA 01003, USA
| | - Laura L Agarkov
- Department of Biomedical Engineering, University of Massachusetts, Amherst, MA 01003, USA
| | - Prisha Singh
- Department of Biomedical Engineering, University of Massachusetts, Amherst, MA 01003, USA
| | - Seth W Donahue
- Department of Biomedical Engineering, University of Massachusetts, Amherst, MA 01003, USA
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3
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Chaves JN, Tattersall GJ, Andrade DV. Energetic costs of bill heat exchange demonstrate contributions to thermoregulation at high temperatures in toco toucans (Ramphastos toco). J Exp Biol 2023; 226:286952. [PMID: 36752123 DOI: 10.1242/jeb.245268] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Accepted: 01/31/2023] [Indexed: 02/09/2023]
Abstract
Body temperature regulation under changes in ambient temperature involves adjustments in heat production and heat exchange rates between the animal and the environment. One mechanism involves the modulation of the surface temperature of specific areas of the body through vasomotor adjustment. In homeotherms, this thermoregulatory adjustment is essential for the maintenance of body temperature over a moderate temperature range, known as the thermal neutral zone (TNZ). The bill of the toco toucan (Ramphastos toco) has been described as a highly efficient thermal window and hypothesized to assist in the thermal homeostasis of this bird. Herein, we directly evaluated the contribution of heat exchange through the bill of the toco toucan and role of the bill in the delimitation of the TNZ. To do this, we measured metabolic rate (MR), via oxygen consumption, over a range of ambient temperatures from 0 to 35°C. MR measurements were made in birds with the bill intact and with the bill insulated. The limits of the TNZ did not differ between treatments, ranging from 10.8 to 25.0°C. The MR differed among treatments only at elevated temperatures (30 and 35°C), reaching 0.92±0.11 ml O2 g-1 h-1 (mean±s.d.) for the intact group and 1.13±0.13 ml O2 g-1 h-1 for the insulated group. These results indicate that although heat dissipation through the bill does not contribute significantly to widening of the TNZ, it may well be critically important in assisting body temperature regulation at higher temperatures extending above the upper limit of the TNZ.
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Affiliation(s)
- Jussara N Chaves
- Departamento de Biodiversidade, Instituto de Biociências, Universidade Estadual Paulista, 13506-900 Rio Claro, São Paulo, Brazil
| | - Glenn J Tattersall
- Department of Biological Sciences, Brock University, St. Catharines, ON L2S 3A1, Canada
| | - Denis V Andrade
- Departamento de Biodiversidade, Instituto de Biociências, Universidade Estadual Paulista, 13506-900 Rio Claro, São Paulo, Brazil
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4
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Lessner EJ, Dollman KN, Clark JM, Xu X, Holliday CM. Ecomorphological patterns in trigeminal canal branching among sauropsids reveal sensory shift in suchians. J Anat 2023; 242:927-952. [PMID: 36680380 PMCID: PMC10093182 DOI: 10.1111/joa.13826] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Revised: 01/03/2023] [Accepted: 01/03/2023] [Indexed: 01/22/2023] Open
Abstract
The vertebrate trigeminal nerve is the primary mediator of somatosensory information from nerve endings across the face, extending nerve branches through bony canals in the face and mandibles, terminating in sensory receptors. Reptiles evolved several extreme forms of cranial somatosensation in which enhanced trigeminal tissues are present in species engaging in unique mechanosensory behaviors. However, morphology varies by clade and ecology among reptiles. Few lineages approach the extreme degree of tactile somatosensation possessed by crocodylians, the only remaining members of a clade that underwent an ecological transition from the terrestrial to semiaquatic habitat, also evolving a specialized trigeminal system. It remains to be understood how trigeminal osteological correlates inform how adaptations for enhanced cranial sensation evolved in crocodylians. Here we identify an increase in sensory abilities in Early Jurassic crocodylomorphs, preceding the transitions to a semiaquatic habitat. Through quantification of trigeminal neurovascular canal branching patterns in an extant phylogenetic bracket we quantify and identify morphologies associated with sensory behaviors in representative fossil taxa, we find stepwise progression of increasing neurovascular canal density, complexity, and distribution from the primitive archosaurian to the derived crocodilian condition. Model-based inferences of sensory ecologies tested on quantified morphologies of extant taxa with known sensory behaviors indicate a parallel increase in sensory abilities among pseudosuchians. These findings establish patterns of reptile trigeminal ecomorphology, revealing evolutionary patterns of somatosensory ecology.
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Affiliation(s)
- Emily J Lessner
- Department of Pathology and Anatomical Sciences, University of Missouri, Columbia, Missouri, USA
| | | | - James M Clark
- Department of Biological Sciences, George Washington University, Washington, District of Columbia, USA
| | - Xing Xu
- Centre for Vertebrate Evolutionary Biology, Yunnan University, Kunming, China.,Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China
| | - Casey M Holliday
- Department of Pathology and Anatomical Sciences, University of Missouri, Columbia, Missouri, USA
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5
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du Toit CJ, Chinsamy A, Cunningham SJ. Comparative morphology and soft tissue histology of the remote-touch bill-tip organ in three ibis species of differing foraging ecology. J Anat 2022; 241:966-980. [PMID: 35938671 PMCID: PMC9482703 DOI: 10.1111/joa.13734] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Revised: 07/13/2022] [Accepted: 07/20/2022] [Indexed: 11/29/2022] Open
Abstract
Ibises (order: Pelecaniformes, family: Threskiornithidae) are probe-foraging birds that use 'remote-touch' to locate prey items hidden in opaque substrates. This sensory capability allows them to locate their prey using high-frequency vibrations in the substrate in the absence of other sensory cues. Remote-touch is facilitated by a specialised bill-tip organ, comprising high densities of mechanoreceptors (Herbst corpuscles) embedded in numerous foramina in the beak bones. Each foramen and its associated Herbst corpuscles make up a sensory unit, called a 'sensory pit'. These sensory pits are densely clustered in the distal portion of the beak. Previous research has indicated that interspecific differences in the extent of sensory pitting in the beak bones correlate with aquatic habitat use of ibises, and have been suggested to reflect different levels of remote-touch sensitivity. Our study investigates the interspecific differences in the bone and soft tissue histology of the bill-tip organs of three species of southern African ibises from different habitats (mainly terrestrial to mainly aquatic). We analysed the external pitting pattern on the bones, as well as internal structure of the beak using micro-CT scans and soft tissue histological sections of each species' bill-tip organs. The beaks of all three species contain remote-touch bill-tip organs and are described here in detail. Clear interspecific differences are evident between the species' bill-tip organs, both in terms of bone morphology and soft tissue histology. Glossy Ibises, which forage exclusively in wetter substrates, have a greater extent of pitting but lower numbers of Herbst corpuscles in each pit, while species foraging in drier substrates (Hadeda and Sacred Ibises) have more robust beaks, fewer pits and higher densities of Herbst corpuscles. Our data, together with previously published histological descriptions of the bill-tip organs of other remote-touch foraging bird species, indicate that species foraging in drier habitats have more sensitive bill-tip organs (based on their anatomy). The vibrations produced by prey (e.g., burrowing invertebrates) travel poorly in dry substrates compared with wetter ones (i.e., dry soil vs. mud or water), and thus we hypothesise that a more sensitive bill-tip organ may be required to successfully locate prey in dry substrates. Furthermore, our results indicate that the differences in bill-tip organ anatomy between the species reflect complex trade-offs between morphological constraints of beak shape and remote-touch sensitivity requirements, both of which are likely related to each species' foraging behaviour and substrate usage. Our study suggests that structures in the bone of the bill-tip organ could provide valuable osteological correlates for the associated soft tissues, and consequently may provide information on the sensory ecology and habitat usage of the birds in the absence of soft tissues.
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Affiliation(s)
- Carla J du Toit
- FitzPatrick Institute of African Ornithology, DSI-NRF Centre of Excellence, Private Bag X3, University of Cape Town, Rondebosch, South Africa.,DSI-NRF Centre of Excellence in Palaeosciences, University of the Witwatersrand, Johannesburg, South Africa.,Department of Biological Sciences, University of Cape Town, Rondebosch, South Africa
| | - Anusuya Chinsamy
- DSI-NRF Centre of Excellence in Palaeosciences, University of the Witwatersrand, Johannesburg, South Africa.,Department of Biological Sciences, University of Cape Town, Rondebosch, South Africa
| | - Susan J Cunningham
- FitzPatrick Institute of African Ornithology, DSI-NRF Centre of Excellence, Private Bag X3, University of Cape Town, Rondebosch, South Africa
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6
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de Medeiros Costa G, Lázaro WL, Sanpera C, Sánchez-Fortún M, Dos Santos Filho M, Díez S. Rhamphotheca as a useful indicator of mercury in seabirds. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 754:141730. [PMID: 32920380 DOI: 10.1016/j.scitotenv.2020.141730] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 08/14/2020] [Accepted: 08/14/2020] [Indexed: 06/11/2023]
Abstract
The evaluation of mercury (Hg) toxicity in wildlife species has prompted a search for sensitive indicators to accurately measure the body burden of Hg. Despite the extensive use of feathers as an indicator of Hg in birds, they do not appear to be an entirely suitable indicator of the extent of contamination in certain conditions and bird species since Hg levels are influenced by the growth period, timing of the last moult and migration. This research aimed to evaluate rhamphotheca as a potential indicator of environmental Hg concentrations in seabirds. We used culled yellow-legged gulls (Larus michahellis) (n = 20) and determined THg in rhamphotheca and feathers. We distinguished between upper and lower rhamphotheca, and divided each one into 16 equal portions along the culmen to analyse their THg content spatially. In each bird, THg was also determined in primary (P1) and secondary (S8) feathers and compared with rhamphotheca. The median (25th, 75th percentile) rhamphotheca Hg concentration was 13.44 (9.63, 17.46) μg/g, which was twofold higher than in the feathers 7.56 (4.88, 12.89) μg/g. Median THg in rhamphotheca was significantly higher (p < 0.05) in females 15.05 (10.35, 23.04) μg/g than in males 12.34 (8.57, 15.19) μg/g, whereas no differences (p > 0.05) were found in the feathers. No significant differences in Hg levels were found between upper and lower beak mandibles or along either. In contrast, significant differences in Hg concentrations were found between the P1 and S8 feathers (mean, 12.04 vs. 6.04 μg/g). No correlation was found between Hg content in rhamphotheca and feathers. Mercury levels in rhamphotheca exhibited stronger significant relationships with weight (R2 = 0.568), length (R2 = 0.524) and culmen (R2 = 0.347) than the levels in the feathers, which showed no correlation. Overall, our results suggest that rhamphotheca is a suitable tissue indicator for Hg monitoring in gulls; however, further studies are needed to extend our research to other bird species.
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Affiliation(s)
- Gerlane de Medeiros Costa
- Programa de Pós-graduação em Ciências Ambientais, Centro de Pesquisa de Limnologia, Biodiversidade, Etnobiologia do Pantanal - CELBE, Universidade do Estado do Mato Grosso - UNEMAT, Campus Cáceres - Avenida Santos Dumont, s/n - Cidade Universitária, Cáceres, MT 78200-000, Brazil
| | - Wilkinson L Lázaro
- Programa de Pós-graduação em Ciências Ambientais, Centro de Pesquisa de Limnologia, Biodiversidade, Etnobiologia do Pantanal - CELBE, Universidade do Estado do Mato Grosso - UNEMAT, Campus Cáceres - Avenida Santos Dumont, s/n - Cidade Universitária, Cáceres, MT 78200-000, Brazil
| | - Carola Sanpera
- Departament de Biologia Evolutiva i Ciències Ambientals, Facultat de Biologia, Universitat de Barcelona, Av. Diagonal 643, 08028 Barcelona, Spain; Institut de Recerca de la Biodiversitat (IRBio), Universitat de Barcelona, Spain
| | - Moisès Sánchez-Fortún
- Departament de Biologia Evolutiva i Ciències Ambientals, Facultat de Biologia, Universitat de Barcelona, Av. Diagonal 643, 08028 Barcelona, Spain; Institut de Recerca de la Biodiversitat (IRBio), Universitat de Barcelona, Spain
| | - Manoel Dos Santos Filho
- Programa de Pós-graduação em Ciências Ambientais, Centro de Pesquisa de Limnologia, Biodiversidade, Etnobiologia do Pantanal - CELBE, Universidade do Estado do Mato Grosso - UNEMAT, Campus Cáceres - Avenida Santos Dumont, s/n - Cidade Universitária, Cáceres, MT 78200-000, Brazil
| | - Sergi Díez
- Environmental Chemistry Department, Institute of Environmental Assessment and Water Research, IDÆA-CSIC, E-08034 Barcelona, Spain.
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7
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Rogalla S, Shawkey MD, Vanthournout B, D'Alba L. Thermoregulation and heat exchange in ospreys (Pandion haliaetus). J Therm Biol 2021; 96:102857. [PMID: 33627285 DOI: 10.1016/j.jtherbio.2021.102857] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 01/08/2021] [Accepted: 01/12/2021] [Indexed: 10/22/2022]
Abstract
The osprey (Pandion haliaetus) is a cosmopolitan and long-distant migrant, found at all thermal extremes ranging from polar to tropical climates. Since ospreys may have an unusually flexible thermal physiology due to their migration over, and use of, a wide range of habitats, they represent an interesting study system to explore thermoregulatory adaptations in a raptor. In this study, we investigated the efficiency of heat exchange between body and environment in ospreys using micro-computed tomography (μ-CT), infrared thermography and behavioral observations. μ-CT revealed that the osprey bill has its largest potential for heat exchange at the proximal bill region, where arteries are situated most closely under the surface. However, thermal images of 10 juvenile ospreys showed that the bill contributes to only 0.3% of the bird's total heat exchange. The long legs and protruding claws played a more prominent role as heat dissipation areas with a contribution of 6% and 7%, respectively. Operative thresholds, i.e. the ambient temperature below which heat is lost, were high (>38.5 °C) in these body parts. However, we found no indication of active regulation of heat exchange. Instead we observed multiple behavioral adaptations starting at relatively low ambient temperatures. At 26.3 °C ospreys had a 50% probability of showing panting behavior and above 27.9 °C they additionally spread their wings to enable heat dissipation from the less insulated ventral side. The thermal images revealed that at an ambient temperature of 32.1 °C ospreys had a 50% probability of developing a ≥2 °C and up to 7.5 °C colder stripe on the head, which was likely caused by cutaneous evaporation. Our observations suggest that ospreys more strongly rely on behavioral mechanisms than on active thermal windows to cope with heat stress. This study not only improves our understanding of the role of different body parts in ospreys' total heat exchange with the environment but further provides an insight about additional adaptations of this raptor to cope with heat stress.
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Affiliation(s)
- Svana Rogalla
- Evolution and Optics of Nanostructures Group, Department of Biology, University of Ghent, K. L. Ledeganckstraat 35, 9000, Ghent, Belgium.
| | - Matthew D Shawkey
- Evolution and Optics of Nanostructures Group, Department of Biology, University of Ghent, K. L. Ledeganckstraat 35, 9000, Ghent, Belgium
| | - Bram Vanthournout
- Evolution and Optics of Nanostructures Group, Department of Biology, University of Ghent, K. L. Ledeganckstraat 35, 9000, Ghent, Belgium
| | - Liliana D'Alba
- Evolution and Optics of Nanostructures Group, Department of Biology, University of Ghent, K. L. Ledeganckstraat 35, 9000, Ghent, Belgium
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8
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du Toit CJ, Chinsamy A, Cunningham SJ. Cretaceous origins of the vibrotactile bill-tip organ in birds. Proc Biol Sci 2020; 287:20202322. [PMID: 33259758 DOI: 10.1098/rspb.2020.2322] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Some probe-foraging birds locate their buried prey by detecting mechanical vibrations in the substrate using a specialized tactile bill-tip organ comprising mechanoreceptors embedded in densely clustered pits in the bone at the tip of their beak. This remarkable sensory modality is known as 'remote touch', and the associated bill-tip organ is found in probe-foraging taxa belonging to both the palaeognathous (in kiwi) and neognathous (in ibises and shorebirds) clades of modern birds. Intriguingly, a structurally similar bill-tip organ is also present in the beaks of extant, non-probing palaeognathous birds (e.g. emu and ostriches) that do not use remote touch. By comparison with our comprehensive sample representing all orders of extant modern birds (Neornithes), we provide evidence that the lithornithids (the most basal known palaeognathous birds which evolved in the Cretaceous period) had the ability to use remote touch. This finding suggests that the occurrence of the vestigial bony bill-tip organ in all modern non-probing palaeognathous birds represents a plesiomorphic condition. Furthermore, our results show that remote-touch probe foraging evolved very early among the Neornithes and it may even have predated the palaeognathous-neognathous divergence. We postulate that the tactile bony bill-tip organ in Neornithes may have originated from other snout tactile specializations of their non-avian theropod ancestors.
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Affiliation(s)
- C J du Toit
- FitzPatrick Institute of African Ornithology, DSI-NRF Centre of Excellence, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa.,DSI-NRF Centre of Excellence in Palaeosciences, University of the Witwatersrand, Johannesburg, Private Bag 3, Wits 2050, South Africa.,Department of Biological Sciences, University of Cape Town, Private Bag X3, Rhodes Gift 7700, South Africa
| | - A Chinsamy
- Department of Biological Sciences, University of Cape Town, Private Bag X3, Rhodes Gift 7700, South Africa
| | - S J Cunningham
- FitzPatrick Institute of African Ornithology, DSI-NRF Centre of Excellence, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa
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9
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Funston GF, Wilkinson RD, Simon DJ, Leblanc AH, Wosik M, Currie PJ. Histology of Caenagnathid (Theropoda, Oviraptorosauria) Dentaries and Implications for Development, Ontogenetic Edentulism, and Taxonomy. Anat Rec (Hoboken) 2019; 303:918-934. [PMID: 31270950 DOI: 10.1002/ar.24205] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Revised: 02/15/2019] [Accepted: 03/06/2019] [Indexed: 11/12/2022]
Abstract
The fossil record of caenagnathid oviraptorosaurs consists mainly of their fused, complexly sculptured dentaries, but little is known about the growth and development of this diagnostic structure. Previous work has suggested that the ridges and grooves on the occlusal surface are either the vestiges of teeth and their alveoli or were adaptations to increase shearing action during mastication. In addition, the distinctiveness of the dentaries has led to their use for species-level taxonomy, without a complete understanding of their variation through ontogeny. Here, we describe additional caenagnathid mandibles from the Dinosaur Park Formation of Alberta, Canada, and perform histological analyses to assess relative ontogenetic stage and the nature of the occlusal elaborations. The results show that the mandibular symphysis is synostosed early in ontogeny and does not accurately reflect ontogenetic stage in caenagnathids. In contrast, the presence of cyclical growth marks in a large specimen shows that mandibles can be used for relative histological maturity estimation. Histological features of the ridges of bone surrounding the lingual groove indicate that they are not the vestiges of tooth-bearing tissues and that caenagnathids did not lose their teeth through ontogeny as suggested in previous work. Instead, increased secondary remodeling in these structures is consistent with their use for food processing. Unexpectedly advanced maturity in a small specimen suggests that at least three caenagnathid species of varying body sizes coexisted in the Dinosaur Park Formation. These results stress the necessity of histological analysis when assessing maturity or ontogenetic trends in fossil material. Anat Rec, 303:918-934, 2020. © 2019 Wiley Periodicals, Inc.
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Affiliation(s)
- Gregory F Funston
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Ryan D Wilkinson
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.,Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada
| | - D Jade Simon
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada
| | - Aaron H Leblanc
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Mateusz Wosik
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada.,New Mexico Museum of Natural History and Science, Albuquerque, New Mexico
| | - Philip J Currie
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
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10
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Urano Y, Sugimoto Y, Tanoue K, Matsumoto R, Kawabe S, Ohashi T, Fujiwara SI. The sandwich structure of keratinous layers controls the form and growth orientation of chicken rhinotheca. J Anat 2019; 235:299-312. [PMID: 30993724 DOI: 10.1111/joa.12998] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/15/2019] [Indexed: 11/26/2022] Open
Abstract
The upper beak bone of birds is known to be overlain by the rhinotheca, which is composed of the horny sheath of keratinous layers. However, the details of the structure and growth pattern of the rhinotheca are yet to be understood. In this study, the microstructure of the rhinotheca from chicken specimens of different growth stages (ranging from 1 to ~ 80 days old) was analyzed using a combination of thin section and scanning electron microscopy observations, and small-angle X-ray scattering analysis. We found that the rhinotheca comprises three different layers - outer, intermediate, and inner layers - throughout its growth. The outer layer arises from the proximal portion of the beak bone and covers the dorsal surface of the rhinotheca, whereas the intermediate and inner layers originate in the distal portion of the beak bone and underlie the outer layer. This tri-layered structure of the rhinotheca was also observed in wild bird specimens (grey wagtail, king quail, and brown dipper). On the median plane, micro-layers making up the outer and inner layers are bedded nearly parallel to the rostral bone at the base. However, more distally positioned micro-layers of the outer layer are more anteverted distally. The micro-layers of the intermediate layer are bedded nearly perpendicular to those of the outer and inner layers on the median plane. The growth of micro-layers in the intermediate layer adds thickness to the rhinotheca, which causes the difference in profile between the beak bone and the rhinotheca in the distal portion of the beak. Moreover, the entire intermediate layer grows distally as new proximal micro-layers form. The outer layer is dragged distally by the intermediate layer as a result of its distal growth, for the three layers are closely packed to each other at their boundaries. Furthermore, the occurrence of the intermediate and inner layers in the distal portion of the rostral bone may be because the distal end of the beak is frequently used and worn, and the rhinotheca therefore needs to be replaced more frequently at the distal end. The rhinotheca structure described here will be an important and useful factor in the reconstruction of the beaks of birds in extinct taxa.
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Affiliation(s)
- Yukine Urano
- Department of Earth and Planetary Sciences, Graduate School of Environmental Studies, Nagoya University, Nagoya, Japan
| | - Yasunobu Sugimoto
- Nagoya University Synchrotron Radiation Research Center, Nagoya, Japan
| | - Kyo Tanoue
- Department of Earth System Science, Fukuoka University, Fukuoka, Japan
| | - Ryoko Matsumoto
- Kanagawa Prefectural Museum of Natural History, Odawara, Japan
| | | | - Tomoyuki Ohashi
- Kitakyushu Museum of Natural History and Human History, Kitakyushu, Japan
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11
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Rico-Guevara A, Sustaita D, Gussekloo S, Olsen A, Bright J, Corbin C, Dudley R. Feeding in Birds: Thriving in Terrestrial, Aquatic, and Aerial Niches. FEEDING IN VERTEBRATES 2019. [DOI: 10.1007/978-3-030-13739-7_17] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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12
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Affiliation(s)
| | - Jaime A. Chaves
- Colegio de Ciencias Biológicas y AmbientalesUniversidad San Francisco de Quito Quito Cumbayá Ecuador
- Galápagos Science CenterPuerto Baquerizo Moreno Galápagos Ecuador
| | - Raymond M. Danner
- Department of Biology and Marine BiologyUniversity of North Carolina Wilmington Wilmington NC USA
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13
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Tattersall GJ, Arnaout B, Symonds MRE. The evolution of the avian bill as a thermoregulatory organ. Biol Rev Camb Philos Soc 2016; 92:1630-1656. [PMID: 27714923 DOI: 10.1111/brv.12299] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Revised: 08/28/2016] [Accepted: 09/01/2016] [Indexed: 11/28/2022]
Abstract
The avian bill is a textbook example of how evolution shapes morphology in response to changing environments. Bills of seed-specialist finches in particular have been the focus of intense study demonstrating how climatic fluctuations acting on food availability drive bill size and shape. The avian bill also plays an important but under-appreciated role in body temperature regulation, and therefore in energetics. Birds are endothermic and rely on numerous mechanisms for balancing internal heat production with biophysical constraints of the environment. The bill is highly vascularised and heat exchange with the environment can vary substantially, ranging from around 2% to as high as 400% of basal heat production in certain species. This heat exchange may impact how birds respond to heat stress, substitute for evaporative water loss at elevated temperatures or environments of altered water availability, or be an energetic liability at low environmental temperatures. As a result, in numerous taxa, there is evidence for a positive association between bill size and environmental temperatures, both within and among species. Therefore, bill size is both developmentally flexible and evolutionarily adaptive in response to temperature. Understanding the evolution of variation in bill size however, requires explanations of all potential mechanisms. The purpose of this review, therefore, is to promote a greater understanding of the role of temperature on shaping bill size over spatial gradients as well as developmental, seasonal, and evolutionary timescales.
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Affiliation(s)
- Glenn J Tattersall
- Department of Biological Sciences, Brock University, 500 Glenridge Avenue, St. Catharines, Ontario, L2S 3A1, Canada
| | - Bassel Arnaout
- Department of Biological Sciences, Brock University, 500 Glenridge Avenue, St. Catharines, Ontario, L2S 3A1, Canada.,Department of Earth Sciences, Brock University, 500 Glenridge Avenue, St. Catharines, Ontario, L2S 3A1, Canada
| | - Matthew R E Symonds
- School of Life and Environmental Sciences, Centre for Integrative Ecology, Deakin University, 221 Burwood Highway, Burwood, 3125, Australia
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14
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Vittori M, Srot V, Žagar K, Bussmann B, van Aken PA, Čeh M, Štrus J. Axially aligned organic fibers and amorphous calcium phosphate form the claws of a terrestrial isopod (Crustacea). J Struct Biol 2016; 195:227-237. [DOI: 10.1016/j.jsb.2016.06.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Revised: 06/03/2016] [Accepted: 06/14/2016] [Indexed: 10/21/2022]
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15
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Alibardi L. Microscopic and immunohistochemical study on the cornification of the developing beak in the turtleEmydura macquarii. J Morphol 2016; 277:1309-19. [DOI: 10.1002/jmor.20576] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Revised: 05/18/2016] [Accepted: 06/23/2016] [Indexed: 01/23/2023]
Affiliation(s)
- Lorenzo Alibardi
- Comparative Histolab and Department of Bigea; Università Di Bologna; via Selmi 3 Bologna 40126 Italy
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16
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Van Hemert C, Armién AG, Blake JE, Handel CM, O'Hara TM. Macroscopic, histologic, and ultrastructural lesions associated with avian keratin disorder in black-capped chickadees (Poecile atricapillus). Vet Pathol 2013; 50:500-13. [PMID: 23399850 DOI: 10.1177/0300985812469637] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
An epizootic of beak abnormalities (avian keratin disorder) was recently detected among wild birds in Alaska. Here we describe the gross, histologic, and ultrastructural features of the disease in 30 affected adult black-capped chickadees (Poecile atricapillus). Grossly, there was elongation of the rhamphotheca, with varying degrees of lateral deviation, crossing, and gapping between the upper and lower beak. Not uncommonly, the claws were overgrown, and there was alopecia, scaling, and crusting of the skin. The most prominent histopathologic features in the beak included epidermal hyperplasia, hyperkeratosis, and core-like intrusions of necrotic debris. In affected birds, particularly those with moderate to severe beak overgrowth, there was remodeling of premaxillary and mandibular bones and various dermal lesions. Lesions analogous to those found in beaks were present in affected claws, indicating that this disorder may target both of these similar tissues. Mild to moderate hyperkeratosis occurred in other keratinized tissues, including skin, feather follicles, and, occasionally, sinus epithelium, but typically only in the presence of microbes. We did not find consistent evidence of a bacterial, fungal, or viral etiology for the beak lesions. The changes observed in affected birds did not correspond with any known avian diseases, suggesting a potentially novel hyperkeratotic disorder in wild birds.
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Affiliation(s)
- C Van Hemert
- United States Geological Survey, Alaska Science Center, 4210 University Dr, Anchorage, AK 99508, USA.
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17
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Greenberg R, Etterson M, Danner RM. Seasonal dimorphism in the horny bills of sparrows. Ecol Evol 2013; 3:389-98. [PMID: 23467758 PMCID: PMC3586648 DOI: 10.1002/ece3.474] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2012] [Revised: 12/11/2012] [Accepted: 12/12/2012] [Indexed: 11/22/2022] Open
Abstract
Bill size is often viewed as a species-specific adaptation for feeding, but it sometimes varies between sexes, suggesting that sexual selection or intersexual competition may also be important. Hypotheses to explain sexual dimorphism in avian bill size include divergence in feeding niche or thermoregulatory demands, intrasexual selection based on increased competition among males, or female preference. Birds also show seasonal changes in bill size due to shifts in the balance between growth rate and wear, which may be due to diet or endogenous rhythms in growth. Insight into the function of dimorphism can be gained using the novel approach of digital x-ray imaging of museum skins to examine the degree to which the skeletal core or the rhamphotheca contribute to overall dimorphism. The rhamphotheca is ever-growing and ever-wearing, varying in size throughout life; whereas the skeletal core shows determinant growth. Because tidal marsh sparrows are more dimorphic in bill size than related taxa, we selected two marsh taxa to investigate dimorphism and seasonality in the size of the overall bill, the skeletal core, and the rhamphotheca. Bill size varied by sex and season, with males having larger bills than females, and bill size increasing from nonbreeding to breeding season more in males. Skeletal bill size varied with season, but not sex. The rhamphotheca varied primarily with sex; males had a larger rhamphotheca (corrected for skeletal bill size), which showed a greater seasonal increase than females. The rhamphotheca, rather than the skeletal bill, was responsible for sexual dimorphism in overall bill size, which was particularly well developed in the breeding season. The size of the rhamphotheca may be a condition-based character that is shaped by sexual selection. These results are consistent with the evidence that bill size is influenced by sexual selection as well as trophic ecology.
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Affiliation(s)
- Russell Greenberg
- Smithsonian Migratory Bird Center, Smithsonian Conservation Biology Institute National Zoological Park, Washington, District of Columbia, 20008
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18
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Genbrugge A, Adriaens D, De Kegel B, Brabant L, Van Hoorebeke L, Podos J, Dirckx J, Aerts P, Herrel A. Structural tissue organization in the beak of Java and Darwin's finches. J Anat 2012; 221:383-93. [PMID: 22938039 DOI: 10.1111/j.1469-7580.2012.01561.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/07/2012] [Indexed: 11/29/2022] Open
Abstract
Birds are well known for occupying diverse feeding niches, and for having evolved diverse beak morphologies associated with dietary specialization. Birds that feed on hard seeds typically possess beaks that are both deep and wide, presumably because of selection for fracture avoidance, as suggested by prior studies. It follows then that birds that eat seeds of different size and hardness should vary in one or more aspects of beak morphology, including the histological organization of the rhamphotheca, the cellular interface that binds the rhamphotheca to the bone, and the organization of trabeculae in the beak. To explore this expectation we here investigate tissue organization in the rhamphotheca of the Java finch, a large granivorous bird, and describe interspecific differences in the trabecular organization of the beak across 11 species of Darwin's finches. We identify specializations in multiple layers of the horny beak, with the dermis anchored to the bone by Sharpey's fibers in those regions that are subjected to high stresses during biting. Moreover, the rhamphotheca is characterized by a tight dermo-epidermal junction through interdigitations of these two tissues. Herbst corpuscles are observed in high density in the dermis of the lateral aspect of the beak as observed in other birds. Finally, the trabecular organization of the beak in Darwin's finches appears most variable in regions involved most in food manipulation, with the density of trabeculae in the beak generally mirroring loading regimes imposed by different feeding habits and beak use in this clade.
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Affiliation(s)
- Annelies Genbrugge
- Laboratory of Biomedical Physics, University of Antwerp, Antwerpen, Belgium
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19
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Soons J, Herrel A, Genbrugge A, Adriaens D, Aerts P, Dirckx J. Multi-layered bird beaks: a finite-element approach towards the role of keratin in stress dissipation. J R Soc Interface 2012; 9:1787-96. [PMID: 22337628 PMCID: PMC3385763 DOI: 10.1098/rsif.2011.0910] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2011] [Accepted: 01/27/2012] [Indexed: 11/12/2022] Open
Abstract
Bird beaks are layered structures, which contain a bony core and an outer keratin layer. The elastic moduli of this bone and keratin were obtained in a previous study. However, the mechanical role and interaction of both materials in stress dissipation during seed crushing remain unknown. In this paper, a multi-layered finite-element (FE) model of the Java finch's upper beak (Padda oryzivora) is established. Validation measurements are conducted using in vivo bite forces and by comparing the displacements with those obtained by digital speckle pattern interferometry. Next, the Young modulus of bone and keratin in this FE model was optimized in order to obtain the smallest peak von Mises stress in the upper beak. To do so, we created a surrogate model, which also allows us to study the impact of changing material properties of both tissues on the peak stresses. The theoretically best values for both moduli in the Java finch are retrieved and correspond well with previous experimentally obtained values, suggesting that material properties are tuned to the mechanical demands imposed during seed crushing.
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Affiliation(s)
- Joris Soons
- Laboratory of Biomedical Physics, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerpen, Belgium.
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20
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Heat loss may explain bill size differences between birds occupying different habitats. PLoS One 2012; 7:e40933. [PMID: 22848413 PMCID: PMC3405045 DOI: 10.1371/journal.pone.0040933] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2012] [Accepted: 06/15/2012] [Indexed: 11/19/2022] Open
Abstract
Background Research on variation in bill morphology has focused on the role of diet. Bills have other functions, however, including a role in heat and water balance. The role of the bill in heat loss may be particularly important in birds where water is limiting. Song sparrows localized in coastal dunes and salt marsh edge (Melospiza melodia atlantica) are similar in size to, but have bills with a 17% greater surface area than, those that live in mesic habitats (M. m. melodia), a pattern shared with other coastal sparrows. We tested the hypotheses that sparrows can use their bills to dissipate “dry” heat, and that heat loss from the bill is higher in M. m. atlantica than M. m. melodia, which would indicate a role of heat loss and water conservation in selection for bill size. Methodology/Principal Findings Bill, tarsus, and body surface temperatures were measured using thermal imaging of sparrows exposed to temperatures from 15–37°C and combined with surface area and physical modeling to estimate the contribution of each body part to total heat loss. Song sparrow bills averaged 5–10°C hotter than ambient. The bill of M. m atlantica dissipated up to 33% more heat and 38% greater proportion of total heat than that of M. m. melodia. This could potentially reduce water loss requirements by approximately 7.7%. Conclusions/Significance This >30% higher heat loss in the bill of M. m. atlantica is independent of evaporative water loss and thus could play an important role in the water balance of sparrows occupying the hot and exposed dune/salt marsh environments during the summer. Heat loss capacity and water conservation could play an important role in the selection for bill size differences between bird populations and should be considered along with trophic adaptations when studying variation in bill size.
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