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McClelland SC, Attard MRG, Bowen J, Horrocks NPC, Jamie GA, Dixit T, Spottiswoode CN, Portugal SJ. Eggshell composition and surface properties of avian brood-parasitic species compared with non-parasitic species. ROYAL SOCIETY OPEN SCIENCE 2023; 10:221023. [PMID: 37234505 PMCID: PMC10206472 DOI: 10.1098/rsos.221023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Accepted: 05/05/2023] [Indexed: 05/28/2023]
Abstract
The eggs of avian obligate brood-parasitic species have multiple adaptations to deceive hosts and optimize development in host nests. While the structure and composition of the eggshell in all birds is essential for embryo growth and protection from external threats, parasitic eggs may face specific challenges such as high microbial loads, rapid laying and ejection by the host parents. We set out to assess whether eggshells of avian brood-parasitic species have either (i) specialized structural properties, to meet the demands of a brood-parasitic strategy or (ii) similar structural properties to eggs of their hosts, due to the similar nest environment. We measured the surface topography (roughness), wettability (how well surfaces repel water) and calcium content of eggshells of a phylogenetically and geographically diverse range of brood-parasitic species (representing four of the seven independent lineages of avian brood-parasitic species), their hosts and close relatives of the parasites. These components of the eggshell structure have been demonstrated previously to influence such factors as the risk of microbial infection and overall shell strength. Within a phylogenetically controlled framework, we found no overall significant differences in eggshell roughness, wettability and calcium content between (i) parasitic and non-parasitic species, or (ii) parasitic species and their hosts. Both the wettability and calcium content of the eggs from brood-parasitic species were not more similar to those of their hosts' eggs than expected by chance. By contrast, the mean surface roughness of the eggs of brood-parasitic species was more similar to that of their hosts' eggs than expected by chance, suggesting brood-parasitic species may have evolved to lay eggs that match the host nest environment for this trait. The lack of significant overall differences between parasitic and non-parasitic species, including hosts, in the traits we measured, suggests that phylogenetic signal, as well as general adaptations to the nest environment and for embryo development, outweigh any influence of a parasitic lifestyle on these eggshell properties.
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Affiliation(s)
- Stephanie C. McClelland
- Department of Biological Sciences, School of Life and Environmental Sciences, Royal Holloway University of London, Egham, Surrey TW20 0EX, UK
| | - Marie R. G. Attard
- Department of Biological Sciences, School of Life and Environmental Sciences, Royal Holloway University of London, Egham, Surrey TW20 0EX, UK
- School of Engineering and Innovation, Open University, Milton Keynes MK7 6AA, UK
| | - James Bowen
- School of Engineering and Innovation, Open University, Milton Keynes MK7 6AA, UK
| | - Nicholas P. C. Horrocks
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
- Cambridge Institute of Therapeutic Immunology and Infectious Disease (CITIID), Jeffrey Cheah Biomedical Centre, Cambridge Biomedical Campus, Cambridge University, Cambridge CB2 0AW, UK
| | - Gabriel A. Jamie
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
- FitzPatrick Institute of African Ornithology, DST-NRF Centre of Excellence, University of Cape Town, Rondebosch 7701, Cape Town, South Africa
| | - Tanmay Dixit
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
- FitzPatrick Institute of African Ornithology, DST-NRF Centre of Excellence, University of Cape Town, Rondebosch 7701, Cape Town, South Africa
| | - Claire N. Spottiswoode
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
- FitzPatrick Institute of African Ornithology, DST-NRF Centre of Excellence, University of Cape Town, Rondebosch 7701, Cape Town, South Africa
| | - Steven J. Portugal
- Department of Biological Sciences, School of Life and Environmental Sciences, Royal Holloway University of London, Egham, Surrey TW20 0EX, UK
- The Natural History Museum, Tring, Herts HP23 6AP, UK
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Attard MRG, Portugal SJ. Climate variability and parent nesting strategies influence gas exchange across avian eggshells. Proc Biol Sci 2021; 288:20210823. [PMID: 34130502 PMCID: PMC8206688 DOI: 10.1098/rspb.2021.0823] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Embryo survival in birds depends on a controlled transfer of water vapour and respiratory gases through the eggshell, and this exchange is critically sensitive to the surrounding physical environment. As birds breed in most terrestrial habitats worldwide, we proposed that variation in eggshell conductance has evolved to optimize embryonic development under different breeding conditions. This is the first study to take a broad-scale macro-ecological view of avian eggshell conductance, encompassing all key avian taxonomic groups, to assess how life history and climate influence the evolution of this trait. Using whole eggs spanning a wide phylogenetic diversity of birds, we determine that body mass, temperature seasonality and whether both parents attend the nest are the main determinants of eggshell conductance. Birds breeding at high latitudes, where seasonal temperature fluctuations are greatest, will benefit from lower eggshell conductance to combat temporary periods of suspended embryo growth and prevent dehydration during prolonged incubation. The nest microclimate is more consistent in species where parents take turns incubating their clutch, resulting in lower eggshell conductance. This study highlights the remarkable functional qualities of eggshells and their importance for embryo survival in extreme climates.
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Affiliation(s)
- Marie R G Attard
- Department of Biological Sciences, School of Life and Environmental Sciences, Royal Holloway University of London, Egham, Surrey TW20 0EX, UK.,School of Engineering and Innovation, Open University, Milton Keynes MK7 6AA, UK
| | - Steven J Portugal
- Department of Biological Sciences, School of Life and Environmental Sciences, Royal Holloway University of London, Egham, Surrey TW20 0EX, UK.,The Natural History Museum, Tring, Herts HP23 6AP, UK
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McClelland SC, Jamie GA, Waters K, Caldas L, Spottiswoode CN, Portugal SJ. Convergent evolution of reduced eggshell conductance in avian brood parasites. Philos Trans R Soc Lond B Biol Sci 2020; 374:20180194. [PMID: 30967076 DOI: 10.1098/rstb.2018.0194] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Brood parasitism has evolved independently in several bird lineages, giving rise to strikingly similar behavioural adaptations that suggest convergent evolution. By comparison, convergence of physiological traits that optimize this breeding strategy has received much less attention, yet these species share many similar physiological traits that optimize this breeding strategy. Eggshell structure is important for embryonic development as it controls the flux of metabolic gases, such as O2, CO2 and H2O, into and out of the egg; in particular, water vapour conductance ( GH2O) is an essential process for optimal development of the embryo. Previous work has shown that common cuckoos ( Cuculus canorus) have a lower than expected eggshell GH2O compared with their hosts. Here, we sought to test whether this is a trait found in other independently evolved avian brood parasites, and therefore reflects a general adaptation to a parasitic lifestyle. We analysed GH2O for seven species of brood parasites from four unique lineages as well as for their hosts, and combined this with species from the literature. We found lower than expected GH2O among all our observed brood parasites both compared with hosts (except for brown-headed cowbirds ( Molothrus ater)) and compared with the expected rates given their phylogenetic positions. These findings suggest that a lowered GH2O may be a general adaptation for brood parasitism, perhaps helping the parasite nestling to develop greater aerobic fitness. This article is part of the theme issue 'The coevolutionary biology of brood parasitism: from mechanism to pattern'.
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Affiliation(s)
- Stephanie C McClelland
- 1 School of Biological Sciences, Royal Holloway University of London , Egham, Surrey TW20 0EX , UK
| | - Gabriel A Jamie
- 2 Department of Zoology, University of Cambridge , Downing Street, Cambridge CB2 3EJ , UK.,3 FitzPatrick Institute of African Ornithology, DST-NRF Centre of Excellence, University of Cape Town , Rondebosch 7701, Cape Town , South Africa
| | - Katy Waters
- 1 School of Biological Sciences, Royal Holloway University of London , Egham, Surrey TW20 0EX , UK
| | - Lara Caldas
- 1 School of Biological Sciences, Royal Holloway University of London , Egham, Surrey TW20 0EX , UK
| | - Claire N Spottiswoode
- 2 Department of Zoology, University of Cambridge , Downing Street, Cambridge CB2 3EJ , UK.,3 FitzPatrick Institute of African Ornithology, DST-NRF Centre of Excellence, University of Cape Town , Rondebosch 7701, Cape Town , South Africa
| | - Steven J Portugal
- 1 School of Biological Sciences, Royal Holloway University of London , Egham, Surrey TW20 0EX , UK
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Abstract
Why are avian eggs ovoid, while the eggs of most other vertebrates are symmetrical? The interaction between an egg and its environment likely drives selection that will shape eggs across evolutionary time. For example, eggs incubated in hot, arid regions face acute exposure to harsh climatic conditions relative to those in temperate zones, and this exposure will differ across nest types, with eggs in open nests being more exposed to direct solar radiation than those in enclosed nests. We examined the idea that the geographical distribution of both egg shapes and nest types should reflect selective pressures of key environmental parameters, such as ambient temperature and the drying capacity of air. We took a comparative approach, using 310 passerine species from Australia, many of which are found in some of the most extreme climates on earth. We found that, across the continent, egg elongation decreases and the proportion of species with domed nests with roofs increases in hotter and drier areas with sparse plant canopies. Eggs are most spherical in open nests in the hottest environments, and most elongate in domed nests in wetter, shadier environments. Our findings suggest that climatic conditions played a key role in the evolution of passerine egg shape.
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Keeping eggs warm: thermal and developmental advantages for parasitic cuckoos of laying unusually thick-shelled eggs. Naturwissenschaften 2018; 105:10. [PMID: 29294204 DOI: 10.1007/s00114-017-1532-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Revised: 12/10/2017] [Accepted: 12/12/2017] [Indexed: 02/02/2023]
Abstract
Obligate brood parasites have evolved unusually thick-shelled eggs, which are hypothesized to possess a variety of functions such as resistance to puncture ejection by their hosts. In this study, we tested the hypothesis that obligate brood parasites lay unusually thick-shelled eggs to retain more heat for the developing embryo and thus contribute to early hatching of parasite eggs. By doing so, we used an infrared thermal imaging system as a non-invasive method to quantify the temperature of eggshells of common cuckoos (Cuculus canorus) and their Oriental reed warbler (Acrocephalus orientalis) hosts in an experiment that artificially altered the duration of incubation. Our results showed that cuckoo eggshells had higher temperature than host eggs during incubation, but also less fluctuations in temperature during incubation disturbance. Therefore, there was a thermal and hence a developmental advantage for brood parasitic cuckoos of laying thick-shelled eggs, providing another possible explanation for the unusually thick-shelled eggs of obligate brood parasites and earlier hatching of cuckoo eggs compared to those of the host.
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Cao P, Sun BJ, Wang LW, Liang W, Du WG. Proximate mechanisms of earlier hatching in parasitic cuckoos: yolk energy and embryonic metabolism. Biol J Linn Soc Lond 2017. [DOI: 10.1093/biolinnean/blx136] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Igic B, Hauber ME, Moskát C, Grim T, Shawkey MD, Procházka P, Honza M. Brood parasite and host eggshells undergo similar levels of decalcification during embryonic development. J Zool (1987) 2016. [DOI: 10.1111/jzo.12408] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- B. Igic
- Department of Biology and Integrated Bioscience Program; University of Akron; Akron OH USA
- Research School of Biology; The Australian National University; Canberra Australian Capital Territory Australia
| | - M. E. Hauber
- Department of Psychology; Hunter College and the Graduate Center of the City University of New York; New York NY USA
| | - C. Moskát
- MTA-ELTE-MTM Ecology Research Group; a joint research group of the Hungarian Academy of Sciences; the Biological Institute of the Eötvös Loránd University and the Hungarian Natural History Museum; Budapest Hungary
| | - T. Grim
- Department of Zoology and Laboratory of Ornithology; Palacký University; Olomouc Czech Republic
| | - M. D. Shawkey
- Department of Biology and Integrated Bioscience Program; University of Akron; Akron OH USA
- Department of Biology; Terrestrial Ecology Unit; Ghent University; Ghent Belgium
| | - P. Procházka
- Institute of Vertebrate Biology AS CR; Brno Czech Republic
| | - M. Honza
- Institute of Vertebrate Biology AS CR; Brno Czech Republic
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Yu Y, Li Z, Pan J. Changes in pigment, spectral transmission and element content of pink chicken eggshells with different pigment intensity during incubation. PeerJ 2016; 4:e1825. [PMID: 27019785 PMCID: PMC4806607 DOI: 10.7717/peerj.1825] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Accepted: 02/27/2016] [Indexed: 11/22/2022] Open
Abstract
Objective. The objective of this study was to investigate changes in pigment, spectral transmission and element content of chicken eggshells with different intensities of pink pigment during the incubation period. We also investigated the effects of the region (small pole, equator and large pole) and pink pigment intensity of the chicken eggshell on the percent transmission of light passing through the chicken eggshells. Method. Eggs of comparable weight from a meat-type breeder (Meihuang) were used, and divided based on three levels of pink pigment (light, medium and dark) in the eggshells. During the incubation (0–21 d), the values of the eggshell pigment (ΔE, L∗, a∗, b∗) were measured. The percent transmission of light for different regions and intensities of eggshell pigmentation was measured by using the visible wavelength range of 380–780 nm. Result. Three measured indicators of eggshell color, ΔE, L∗ and a∗, did not change significantly during incubation. Compared with other regions and pigment intensities, eggshell at the small pole and with light pigmentation intensity showed the highest percent transmission of light. The transmission value varied significantly (P < 0.001) with incubation time. The element analysis of eggshells with different levels of pink pigment showed that the potassium content of the eggshells for all pigment levels decreased significantly during incubation. Conclusion. In summary, pigment intensity and the region of the eggshell influenced the percent transmission of light of eggshell. Differences in the spectral characteristics of different eggshells may influence the effects of photostimulation during the incubation of eggs. All of these results will be applicable for perfecting the design of light intensity for lighted incubation to improve productivity.
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Affiliation(s)
- Yue Yu
- Department of Biosystems Engineering, Zhejiang University, Hangzhou, China; State Key Laboratory of Soil Plant Machinery System Technology, Beijing, China
| | - Zhanming Li
- Department of Biosystems Engineering, Zhejiang University , Hangzhou , China
| | - Jinming Pan
- Department of Biosystems Engineering, Zhejiang University, Hangzhou, China; State Key Laboratory of Soil Plant Machinery System Technology, Beijing, China
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Bowers EK, White A, Lang A, Podgorski L, Thompson CF, Sakaluk SK, Jaeckle WB, Harper RG. Eggshell porosity covaries with egg size among female House Wrens ( Troglodytes aedon) but is unrelated to incubation onset and egg-laying order within clutches. CAN J ZOOL 2015; 93:421-425. [PMID: 26146408 DOI: 10.1139/cjz-2014-0279] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In birds, the duration of egg incubation (the time from incubation onset to hatching) can affect multiple components of nest success, but what affects incubation duration? Previous studies suggest that incubation duration is affected by both parental behavior and components of the egg, which have yet to be determined. One egg component that may be related to incubation behavior and the time until hatching is eggshell porosity, which affects the exchange of metabolic gasses and water vapor across the shell and, thus, the speed of embryonic development and incubation duration. We tested whether eggshell porosity was associated with the timing of incubation onset by female House Wrens (Troglodytes aedon Vieillot, 1809), and whether porosity varied within clutches in a manner that might be associated with incubation periods and hatching patterns (i.e., synchronous vs. asynchronous hatching). Eggshell porosity was unrelated to the onset of maternal incubation and did not differ between early and later-laid eggs within clutches, but differed significantly among females and covaried with egg size. We conclude that producing all eggshells of similar porosity within clutches, while adjusting incubation onset once most or all eggs are laid, provide facultative maternal control over variation in hatching patterns.
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Affiliation(s)
- E K Bowers
- Behavior, Ecology, Evolution, and Systematics Section, School of Biological Sciences, Illinois State University, Normal, IL, USA
| | - A White
- Department of Biology, Illinois Wesleyan University, Bloomington, IL, USA
| | - A Lang
- Department of Biology, Illinois Wesleyan University, Bloomington, IL, USA
| | - L Podgorski
- Department of Biology, Illinois Wesleyan University, Bloomington, IL, USA
| | - C F Thompson
- Behavior, Ecology, Evolution, and Systematics Section, School of Biological Sciences, Illinois State University, Normal, IL, USA
| | - S K Sakaluk
- Behavior, Ecology, Evolution, and Systematics Section, School of Biological Sciences, Illinois State University, Normal, IL, USA
| | - W B Jaeckle
- Department of Biology, Illinois Wesleyan University, Bloomington, IL, USA
| | - R G Harper
- Department of Biology, Illinois Wesleyan University, Bloomington, IL, USA
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Portugal SJ, Maurer G, Thomas GH, Hauber ME, Grim T, Cassey P. Nesting behaviour influences species-specific gas exchange across avian eggshells. ACTA ACUST UNITED AC 2015; 217:3326-32. [PMID: 25232199 PMCID: PMC4179895 DOI: 10.1242/jeb.103291] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Carefully controlled gas exchange across the eggshell is essential for the development of the avian embryo. Water vapour conductance (GH2O) across the shell, typically measured as mass loss during incubation, has been demonstrated to optimally ensure the healthy development of the embryo while avoiding desiccation. Accordingly, eggs exposed to sub-optimal gas exchange have reduced hatching success. We tested the association between eggshell GH2O and putative life-history correlates of adult birds, ecological nest parameters and physical characteristics of the egg itself to investigate how variation in GH2O has evolved to maintain optimal water loss across a diverse set of nest environments. We measured gas exchange through eggshell fragments in 151 British breeding bird species and fitted phylogenetically controlled, general linear models to test the relationship between GH2O and potential predictor parameters of each species. Of our 17 life-history traits, only two were retained in the final model: wet-incubating parent and nest type. Eggs of species where the parent habitually returned to the nest with wet plumage had significantly higher GH2O than those of parents that returned to the nest with dry plumage. Eggs of species nesting in ground burrows, cliffs and arboreal cups had significantly higher GH2O than those of species nesting on the ground in open nests or cups, in tree cavities and in shallow arboreal nests. Phylogenetic signal (measured as Pagel's λ) was intermediate in magnitude, suggesting that differences observed in the GH2O are dependent upon a combination of shared ancestry and species-specific life history and ecological traits. Although these data are correlational by nature, they are consistent with the hypothesis that parents constrained to return to the nest with wet plumage will increase the humidity of the nest environment, and the eggs of these species have evolved a higher GH2O to overcome this constraint and still achieve optimal water loss during incubation. We also suggest that eggs laid in cup nests and burrows may require a higher GH2O to overcome the increased humidity as a result from the confined nest microclimate lacking air movements through the nest. Taken together, these comparative data imply that species-specific levels of gas exchange across avian eggshells are variable and evolve in response to ecological and physical variation resulting from parental and nesting behaviours.
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Affiliation(s)
- Steven J Portugal
- Structure and Motion Laboratory, The Royal Veterinary College, University of London, North Mymms, Hatfield, Herts AL9 7TA, UK
| | - Golo Maurer
- School of Earth and Environmental Sciences, University of Adelaide, SA 5005 Australia
| | - Gavin H Thomas
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK
| | - Mark E Hauber
- Department of Psychology, Hunter College and the Graduate Center of the City University of New York, 695 Park Avenue, New York, NY 10065, USA
| | - Tomáš Grim
- Department of Zoology and Laboratory of Ornithology, Palacký University, Olomouc, CZ-771 46 Czech Republic
| | - Phillip Cassey
- School of Earth and Environmental Sciences, University of Adelaide, SA 5005 Australia
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Maurer G, Portugal SJ, Hauber ME, Mikšík I, Russell DGD, Cassey P. First light for avian embryos: eggshell thickness and pigmentation mediate variation in development and
UV
exposure in wild bird eggs. Funct Ecol 2014. [DOI: 10.1111/1365-2435.12314] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Golo Maurer
- School of Earth & Environmental Sciences University of Adelaide South Australia5005 Australia
| | - Steven J. Portugal
- Structure and Motion Lab Royal Veterinary College University of London Hawkshead LaneNorth MymmsHertfordshire AL9 7TA UK
| | - Mark E. Hauber
- Department of Psychology Hunter College and the Graduate Center City University of New York 695 Park Avenue New York New York10065 USA
| | - Ivan Mikšík
- Institute of Physiology Academy of Sciences of the Czech Republic Videnska 1083 142 20 Praha Czech Republic
| | - Douglas G. D. Russell
- Bird Group Department of Zoology The Natural History Museum Tring Hertfordshire HP23 6AP UK
| | - Phillip Cassey
- School of Earth & Environmental Sciences University of Adelaide South Australia5005 Australia
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