660 lines
77 KiB
XML
660 lines
77 KiB
XML
<document ID-DOI="10.1098/rspb.2004.2829" ID-GBIF-Dataset="eab7f5e2-fead-415f-98c1-0e26d8fcade9" ID-PMC="PMC1691809" ID-PubMed="15347508" ID-Zenodo-Dep="3726770" approvalRequired="2" approvalRequired_for_document="1" approvalRequired_for_taxonomicNames="1" checkinTime="1585135356930" checkinUser="jeremy" docAuthor="Horner, John R. & Padian, Kevin" docDate="2004" docId="03D3878CFF96FFB2CF4BFAEA3CB057AE" docLanguage="en" docName="HornerPadian2004.pdf.imf" docOrigin="Proceedings of the Royal Society, Series B 271" docStyle="DocumentStyle{}" docTitle="Tyrannosaurus rex" docType="treatment" docVersion="5" lastPageNumber="1879" masterDocId="FFEAFFF4FF96FFB6CC2EFFE33F295278" masterDocTitle="Age and growth dynamics of Tyrannosaurus rex" masterLastPageNumber="1880" masterPageNumber="1875" pageNumber="1875" updateTime="1668129860104" updateUser="ExternalLinkService">
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<mods:titleInfo>
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<mods:title>Age and growth dynamics of Tyrannosaurus rex</mods:title>
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</mods:titleInfo>
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<mods:name type="personal">
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<mods:role>
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<mods:roleTerm>Author</mods:roleTerm>
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</mods:role>
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<mods:namePart>Horner, John R.</mods:namePart>
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</mods:name>
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<mods:name type="personal">
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<mods:role>
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<mods:roleTerm>Author</mods:roleTerm>
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<mods:namePart>Padian, Kevin</mods:namePart>
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</mods:name>
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<mods:typeOfResource>text</mods:typeOfResource>
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<mods:titleInfo>
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<mods:title>Proceedings of the Royal Society, Series B</mods:title>
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</mods:titleInfo>
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<mods:part>
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<mods:date>2004</mods:date>
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<mods:detail type="volume">
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<mods:number>271</mods:number>
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</mods:detail>
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<mods:extent unit="page">
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<mods:start>1875</mods:start>
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<mods:end>1880</mods:end>
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</mods:extent>
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</mods:part>
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<mods:classification>journal article</mods:classification>
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<mods:identifier type="DOI">10.1098/rspb.2004.2829</mods:identifier>
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<mods:identifier type="GBIF-Dataset">eab7f5e2-fead-415f-98c1-0e26d8fcade9</mods:identifier>
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<mods:identifier type="PMC">PMC1691809</mods:identifier>
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<mods:identifier type="PubMed">15347508</mods:identifier>
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<mods:identifier type="Zenodo-Dep">3726770</mods:identifier>
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<treatment ID-DOI="http://doi.org/10.5281/zenodo.3728604" ID-GBIF-Taxon="187974824" ID-Zenodo-Dep="3728604" LSID="urn:lsid:plazi:treatment:03D3878CFF96FFB2CF4BFAEA3CB057AE" httpUri="http://treatment.plazi.org/id/03D3878CFF96FFB2CF4BFAEA3CB057AE" lastPageId="4" lastPageNumber="1879" pageId="0" pageNumber="1875">
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<subSubSection pageId="0" pageNumber="1875" type="nomenclature">
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<paragraph blockId="0.[844,1482,891,1922]" pageId="0" pageNumber="1875">
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Nearly all
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<taxonomicName box="[978,1039,1289,1310]" class="Reptilia" family="Tyrannosauridae" genus="Tyrannosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="0" pageNumber="1875" phylum="Chordata" rank="species" species="rex">
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<emphasis box="[978,1039,1289,1310]" italics="true" pageId="0" pageNumber="1875">T. rex</emphasis>
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</taxonomicName>
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specimens known are presumed on gross morphology to be adult or sub-adult. The smallest of this sample,
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<materialsCitation ID-GBIF-Occurrence="3352123303" box="[935,1048,1350,1371]" collectionCode="MOR" pageId="0" pageNumber="1875" specimenCode="MOR 009">MOR 009</materialsCitation>
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and
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<materialsCitation ID-GBIF-Occurrence="3352123320" box="[1103,1234,1350,1372]" collectionCode="MOR" pageId="0" pageNumber="1875" specimenCode="MOR 1125">MOR 1125</materialsCitation>
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, have a tibial length of 107 cm and a cross-sectional diameter of 15.25 cm by 12.75 cm (major and minor axes). The larger
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<materialsCitation ID-GBIF-Occurrence="3352123304" box="[1365,1481,1411,1433]" collectionCode="MOR" pageId="0" pageNumber="1875" specimenCode="MOR 555">MOR 555</materialsCitation>
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has a tibia 120 cm long. In estimating the thickness between lines of arrested growth (LAGs), known to be annual in living tetrapods and inferred to be so in extinct dinosaurs (
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<bibRefCitation author="Horner, J. R. & de Ricqles, A. & Padian, K." box="[965,1178,1533,1555]" journalOrPublisher="Paleobiology" pageId="0" pageNumber="1875" pagination="295 - 304" part="25" refId="ref5768" refString="Horner, J. R., de Ricqles, A. & Padian, K. 1999 Variation in dinosaur skeletochronology indicators: implications for age assessment and physiology. Paleobiology 25, 295 - 304." title="Variation in dinosaur skeletochronology indicators: implications for age assessment and physiology" type="journal article" year="1999">
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Horner
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<emphasis box="[1056,1110,1533,1555]" italics="true" pageId="0" pageNumber="1875">et al.</emphasis>
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1999
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</bibRefCitation>
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), and hence the number of missing LAGs to complete the age assessment, three alternative assumptions could be made. The missing intervals could be on average thicker (if early growth was more rapid), the same thickness, or thinner (if early growth was the same) than intervals of the preserved inner cortex. We used all three assumptions (see § 2), but the first assumption generally appears most likely: appositional growth rates are inferred to be higher in young dinosaurs than in older ones (as in all other amniotes), because they deposited more highly vascularized tissue beginning in embryonic stages (
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<bibRefCitation author="Horner, J. R. & de Ricqles, A. & Padian, K." box="[1049,1260,1869,1891]" journalOrPublisher="J. Vert. Paleontol." pageId="0" pageNumber="1875" pagination="115 - 129" part="20" refId="ref5806" refString="Horner, J. R., de Ricqles, A. & Padian, K. 2000 Long bone histology of the hadrosaurid dinosaur Maiasaura peeblesorum: growth dynamics and physiology based on an ontogenetic series of skeletal elements. J. Vert. Paleontol. 20, 115 - 129." title="Long bone histology of the hadrosaurid dinosaur Maiasaura peeblesorum: growth dynamics and physiology based on an ontogenetic series of skeletal elements" type="journal article" year="2000">
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Horner
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<emphasis box="[1140,1193,1869,1891]" italics="true" pageId="0" pageNumber="1875">et al.</emphasis>
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2000
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</bibRefCitation>
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,
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<bibRefCitation author="Horner, J. R. & Padian, K. & de Ricqles, A." box="[1273,1332,1869,1890]" journalOrPublisher="Paleobiology" pageId="0" pageNumber="1875" pagination="39 - 58" part="27" refId="ref5859" refString="Horner, J. R., Padian, K. & de Ricqles, A. 2001 Comparative osteohistology of some embryonic and perninatal archo- saurs: developmental and behavioral implications for dinosaurs. Paleobiology 27, 39 - 58." title="Comparative osteohistology of some embryonic and perninatal archo- saurs: developmental and behavioral implications for dinosaurs" type="journal article" year="2001">2001</bibRefCitation>
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;
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<bibRefCitation author="Padian, K. & de Ricqles, A. & Horner, J. R." journalOrPublisher="Nature" pageId="0" pageNumber="1875" pagination="405 - 408" part="412" refId="ref5971" refString="Padian, K., de Ricqles, A. & Horner, J. R. 2001 Dinosaurian growth rates and bird origins. Nature 412, 405 - 408." title="Dinosaurian growth rates and bird origins" type="journal article" year="2001">
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Padian
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<emphasis box="[1429,1482,1869,1891]" italics="true" pageId="0" pageNumber="1875">et al.</emphasis>
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2001
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</bibRefCitation>
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).
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</paragraph>
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</subSubSection>
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<subSubSection lastPageId="4" lastPageNumber="1879" pageId="0" pageNumber="1875" type="description">
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<paragraph blockId="0.[844,1481,1990,2074]" box="[844,1003,1990,2014]" pageId="0" pageNumber="1875">
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<heading allCaps="true" bold="true" box="[844,1003,1990,2014]" fontSize="9" level="1" pageId="0" pageNumber="1875" reason="6">
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<emphasis bold="true" box="[844,1003,1990,2014]" pageId="0" pageNumber="1875">2. METHODS</emphasis>
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</heading>
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</paragraph>
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<paragraph blockId="0.[844,1481,1990,2074]" pageId="0" pageNumber="1875">
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To assess age and growth dynamics in
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<taxonomicName box="[1228,1285,2025,2043]" class="Reptilia" family="Tyrannosauridae" genus="Tyrannosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="0" pageNumber="1875" phylum="Chordata" rank="species" species="rex">
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<emphasis box="[1228,1285,2025,2043]" italics="true" pageId="0" pageNumber="1875">T. rex</emphasis>
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</taxonomicName>
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, we took transverse thin sections at mid-shaft of the tibia, femur and fibula (and in
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</paragraph>
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<caption ID-DOI="http://doi.org/10.5281/zenodo.3726772" ID-Table-UUID="DF056612FF97FFB7CC52FF7D3FCD5A6E" ID-Zenodo-Dep="3726772" httpUri="http://table.plazi.org/id/DF056612FF97FFB7CC52FF7D3FCD5A6E" pageId="1" pageNumber="1876" targetBox="[256,719,171,2070]" targetIsTable="true" targetPageId="1">
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<paragraph pageId="1" pageNumber="1876">
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, been Tcor calcu-;) has of mm bone (Methods bone which of. from Tnon circumference cavity for, marrow retrocalculated
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<emphasis box="[124,145,537,554]" italics="true" pageId="1" pageNumber="1876">C</emphasis>
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;) mm ((radius LAGs bone of medullary of length, number,
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<emphasis box="[124,145,792,807]" italics="true" pageId="1" pageNumber="1876">L</emphasis>
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MR,; fibula; LAGs, fib; preserved retroc femur; LAGs Tlag). 2, § fem in without see; counted tibia explanation, tib thickness be; could sections for cortical that; thin, LAGs incremental labelled Tnon of); v (of preserved number and.; study numbers,parabolic this LAGs LAGs in actual) catalogue with iv (; analysed; with thickness thickness penultimate
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<emphasis box="[96,117,1650,1679]" italics="true" pageId="1" pageNumber="1876">rex</emphasis>
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, MOR cortical) cortical iii the (
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<emphasis box="[96,117,1684,1830]" italics="true" pageId="1" pageNumber="1876">Tyrannosaurus</emphasis>
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; from, Tlag minus maximum are; of thickness radius)ii numbers (Specimens; total mean cortical =). i 1) (Specimen eroded: Table (total lation
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</paragraph>
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</caption>
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<paragraph blockId="1.[784,1422,158,1140]" pageId="1" pageNumber="1876">
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other long bones such as humerus, ulna and metatarsals for comparison as available) in seven specimens (see
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<tableCitation box="[1215,1279,189,208]" captionStart="Table 2" captionStartId="2.[158,219,158,179]" captionTargetBox="[158,1448,290,730]" captionTargetPageId="2" captionText="Table 2. Widths of LAG intervals for each specimen and section of Tyrannosaurus rex examined. (Element identifications are keyed to table 1. Intervals are listed from the outermost cortex inward, in millimetres; numbers in parentheses indicate cortical intervals in which LAGs were obscured from view and could not be counted (see text for extrapolations). inc, incomplete LAG intervals.)" httpUri="http://table.plazi.org/id/DF056612FF94FFB4CCB0FF7D3ECA537E" pageId="1" pageNumber="1876" tableUuid="DF056612FF94FFB4CCB0FF7D3ECA537E">table 1</tableCitation>
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). Although no single bone infallibly records growth dynamics, the tibial midshaft has a rounder cross-section (and therefore is less subject to cortical drift than other bones); its large size and rapid growth delays secondary erosion–reconstruction cycles of the cortex that obliterate primary bone records; and its record of LAGs agrees better with those of other less altered bones (
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<bibRefCitation author="Horner, J. R. & de Ricqles, A. & Padian, K." box="[1170,1362,372,392]" journalOrPublisher="Paleobiology" pageId="1" pageNumber="1876" pagination="295 - 304" part="25" refId="ref5768" refString="Horner, J. R., de Ricqles, A. & Padian, K. 1999 Variation in dinosaur skeletochronology indicators: implications for age assessment and physiology. Paleobiology 25, 295 - 304." title="Variation in dinosaur skeletochronology indicators: implications for age assessment and physiology" type="journal article" year="1999">
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Horner
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<emphasis box="[1252,1301,372,391]" italics="true" pageId="1" pageNumber="1876">et al.</emphasis>
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1999
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</bibRefCitation>
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). The fibula, by contrast, is equally subject to secondary reconstruction in the inner cortex, but it has a very small marrow cavity. Moreover, whereas in other long bones, preserved LAG intervals of the outer cortex comprised only 20–40% of the entire radius, the fibula of MOR 152 preserved 56%, a 40–180% increase over the other long bones.
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</paragraph>
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<paragraph blockId="1.[784,1422,158,1140]" pageId="1" pageNumber="1876">
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We measured or estimated the length, circumference and cortical thickness of each specimen where possible, and assessed the patterns of LAGs in the preserved cortex. We counted LAGs and measured successive distances between them (
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<tableCitation box="[1234,1305,678,697]" captionStart="Table 2" captionStartId="2.[158,219,158,179]" captionTargetBox="[158,1448,290,730]" captionTargetPageId="2" captionText="Table 2. Widths of LAG intervals for each specimen and section of Tyrannosaurus rex examined. (Element identifications are keyed to table 1. Intervals are listed from the outermost cortex inward, in millimetres; numbers in parentheses indicate cortical intervals in which LAGs were obscured from view and could not be counted (see text for extrapolations). inc, incomplete LAG intervals.)" httpUri="http://table.plazi.org/id/DF056612FF94FFB4CCB0FF7D3ECA537E" pageId="1" pageNumber="1876" tableUuid="DF056612FF94FFB4CCB0FF7D3ECA537E">table 2</tableCitation>
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). Histological observations were made through a Nikon petrographic Microscope; LAG intervals were measured and digitized with a Nikon DS-L1 camera to a resolution of 10 цm. By extrapolating these patterns into the marrow cavity, which formerly contained cortical bone now destroyed by erosion and remodelling, we could estimate the number of lines that had been erased. We assumed that the LAGs are annual (
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<bibRefCitation author="Chinsamy, A." box="[1003,1165,892,911]" journalOrPublisher="Mod. Geol." pageId="1" pageNumber="1876" pagination="319 - 329" part="18" refId="ref5560" refString="Chinsamy, A. 1993 Bone histology and growth trajectory of the prosauropod dinosaur Massospondylus carinatus Owen. Mod. Geol. 18, 319 - 329." title="Bone histology and growth trajectory of the prosauropod dinosaur Massospondylus carinatus Owen" type="journal article" year="1993">Chinsamy 1993</bibRefCitation>
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), and that the diameter of the hatchling
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<taxonomicName box="[916,971,923,941]" class="Reptilia" family="Tyrannosauridae" genus="Tyrannosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="1" pageNumber="1876" phylum="Chordata" rank="species" species="rex">
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<emphasis box="[916,971,923,941]" italics="true" pageId="1" pageNumber="1876">T. rex</emphasis>
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</taxonomicName>
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tibia was
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<emphasis box="[1067,1087,923,941]" italics="true" pageId="1" pageNumber="1876">ca</emphasis>
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. 4 mm, based on inferred egg size. Most tibial cross-sections were complete, and centroids could be identified easily. For incomplete sections, we approximated centroids by comparison with more complete specimens.
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</paragraph>
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<paragraph pageId="1" pageNumber="1876">
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<table box="[256,719,171,2070]" gridcols="2" gridrows="11" pageId="1" pageNumber="1876">
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<tr box="[256,719,171,807]" gridrow="0" pageId="1" pageNumber="1876">
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<th box="[256,277,171,807]" gridcol="0" gridrow="0" pageId="1" pageNumber="1876">calibrated age methods of calculation and overall age estimates</th>
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<th box="[305,719,171,807]" gridcol="1" gridrow="0" pageId="1" pageNumber="1876">
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14– 15
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<subScript attach="right" box="[307,324,625,644]" fontSize="7" pageId="1" pageNumber="1876">±</subScript>
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1 (i), 8 – 10 (ii), 10 – 12 (iii) + 11 – 12 13 – 14
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<subScript attach="none" box="[335,352,627,646]" fontSize="7" pageId="1" pageNumber="1876">±</subScript>
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1 (i), 9 – 11 (ii), 13 – 15 (iii) + 11 – 12 11 – 12 (ii), 14 (iii), 16– 18 (iv) + 14
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<superScript attach="left" fontSize="7" pageId="1" pageNumber="1876">± 2 11 – 12 (ii), 14 (iii), 16– 18 (iv) + 14 ±</superScript>
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2 15 – 17 (i) 17 – 18 (v), 20 –22 (ii) + 18
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<subScript attach="none" box="[446,463,351,370]" fontSize="7" pageId="1" pageNumber="1876">
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<superScript attach="none" box="[446,463,351,370]" fontSize="7" pageId="1" pageNumber="1876">±</superScript>
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</subScript>
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2 — — — — 11 – 12 (v), 14 – 16 (ii), 18 – 20 (iii), 20 – 21 (i) + 16 ± 5 11 – 12 (v), 14 – 16 (ii), 18 – 20 (iii), 20 – 21 (i) + 16 ± 5 — — 24– 25(ii), 27 (iii), 22 (v) + 25
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<superScript attach="none" box="[697,714,329,348]" fontSize="7" pageId="1" pageNumber="1876">±</superScript>
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2
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</th>
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</tr>
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<tr box="[256,719,832,960]" gridrow="1" pageId="1" pageNumber="1876">
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<td box="[256,277,832,960]" gridcol="0" gridrow="1" pageId="1" pageNumber="1876">
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<heading box="[256,277,899,960]" centered="true" fontSize="9" level="2" pageId="1" pageNumber="1876" reason="4">retroc</heading>
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<heading box="[256,277,832,895]" centered="true" fontSize="9" level="2" pageId="1" pageNumber="1876" reason="4">LAGs</heading>
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</td>
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<td box="[305,719,832,960]" gridcol="1" gridrow="1" pageId="1" pageNumber="1876">10 –11 10 –11 4 – 14 4 – 14 9 – 11 10 – 15 — — 3 – 4 — 4 – 13 4 – 13 3 – 4 2 – 3 5– 10</td>
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</tr>
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<tr box="[256,719,1001,1131]" gridrow="2" pageId="1" pageNumber="1876">
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<td box="[256,277,1001,1131]" gridcol="0" gridrow="2" pageId="1" pageNumber="1876">
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<heading box="[256,277,1069,1131]" centered="true" fontSize="9" level="2" pageId="1" pageNumber="1876" reason="4">actual</heading>
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<heading box="[256,277,1001,1064]" centered="true" fontSize="9" level="2" pageId="1" pageNumber="1876" reason="4">LAGs</heading>
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</td>
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<td box="[305,719,1001,1131]" gridcol="1" gridrow="2" pageId="1" pageNumber="1876">
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4 3 7 7 4 7 7 7 10 8 6 – 7 6 – 7 10 10
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<emphasis bold="true" box="[696,718,1073,1092]" italics="true" pageId="1" pageNumber="1876">‡</emphasis>
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17
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</td>
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</tr>
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<tr box="[256,719,1196,1237]" gridrow="3" pageId="1" pageNumber="1876">
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<td box="[256,277,1196,1237]" gridcol="0" gridrow="3" pageId="1" pageNumber="1876">MR</td>
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<td box="[305,719,1196,1237]" gridcol="1" gridrow="3" pageId="1" pageNumber="1876">35 45 43 43 46 38 — — — — 44 44 — — 1</td>
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</tr>
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<tr box="[256,719,1307,1365]" gridrow="4" pageId="1" pageNumber="1876">
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<td box="[256,277,1307,1365]" gridcol="0" gridrow="4" pageId="1" pageNumber="1876">
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<heading box="[256,277,1307,1365]" centered="true" fontSize="9" level="2" pageId="1" pageNumber="1876" reason="4">Tnon</heading>
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||
</td>
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||
<td box="[305,719,1307,1365]" gridcol="1" gridrow="4" pageId="1" pageNumber="1876">0 0 0 0 16 10 20 32 22 0 0 0 22 15 11</td>
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</tr>
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<tr box="[256,719,1421,1469]" gridrow="5" pageId="1" pageNumber="1876">
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<td box="[256,277,1421,1469]" gridcol="0" gridrow="5" pageId="1" pageNumber="1876">
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<heading box="[256,277,1421,1469]" centered="true" fontSize="9" level="2" pageId="1" pageNumber="1876" reason="4">Tlag</heading>
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</td>
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<td box="[305,719,1421,1469]" gridcol="1" gridrow="5" pageId="1" pageNumber="1876">16 20 26 27 14 12 18 11 22 29 26 26 22 26 11</td>
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</tr>
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<tr box="[256,719,1515,1566]" gridrow="6" pageId="1" pageNumber="1876">
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<td box="[256,277,1515,1566]" gridcol="0" gridrow="6" pageId="1" pageNumber="1876">
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<heading box="[256,277,1515,1566]" centered="true" fontSize="9" level="2" pageId="1" pageNumber="1876" reason="4">Tcor</heading>
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</td>
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<td box="[305,719,1515,1566]" gridcol="1" gridrow="6" pageId="1" pageNumber="1876">16 20 26 27 30 22 38 43 44 29 26 26 44 41 22</td>
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</tr>
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<tr box="[256,719,1604,1677]" gridrow="7" pageId="1" pageNumber="1876">
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<td box="[256,277,1604,1677]" gridcol="0" gridrow="7" pageId="1" pageNumber="1876">
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<emphasis box="[256,277,1632,1649]" italics="true" pageId="1" pageNumber="1876">C</emphasis>
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</td>
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<td box="[305,719,1604,1677]" gridcol="1" gridrow="7" pageId="1" pageNumber="1876">
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404 404
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<emphasis box="[362,411,1604,1677]" italics="true" pageId="1" pageNumber="1876">ca. 500 ca</emphasis>
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. 500 433 433 — — — — 464 464 — — —
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</td>
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</tr>
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<tr box="[256,719,1707,1760]" gridrow="8" pageId="1" pageNumber="1876">
|
||
<td box="[256,277,1707,1760]" gridcol="0" gridrow="8" pageId="1" pageNumber="1876">
|
||
<emphasis box="[256,277,1726,1741]" italics="true" pageId="1" pageNumber="1876">L</emphasis>
|
||
</td>
|
||
<td box="[305,719,1707,1760]" gridcol="1" gridrow="8" pageId="1" pageNumber="1876">1070 1070 1200 1200 1070 1070 — — — — 1120 1120 — — —</td>
|
||
</tr>
|
||
<tr box="[256,719,1796,1927]" gridrow="9" pageId="1" pageNumber="1876">
|
||
<td box="[256,277,1796,1927]" gridcol="0" gridrow="9" pageId="1" pageNumber="1876">
|
||
<heading box="[256,277,1825,1898]" centered="true" fontSize="9" level="2" pageId="1" pageNumber="1876" reason="4">section</heading>
|
||
</td>
|
||
<td box="[305,719,1796,1927]" gridcol="1" gridrow="9" pageId="1" pageNumber="1876">TI- 1 - C TI- 1 - D TI- 1 a TI- 1 b Fe 1- L 2- B2 a Fe 1- L 2- B2 b T 2 -1 T3 - 1 Fe- 1 -B- 1 Fe- 1 - A- 1 TI- 1 TI- 2 LBF2 -1 F 2 - 1 Fi- 2</td>
|
||
</tr>
|
||
<tr box="[256,719,1972,2070]" gridrow="10" pageId="1" pageNumber="1876">
|
||
<td box="[256,277,1972,2070]" gridcol="0" gridrow="10" pageId="1" pageNumber="1876">specimen</td>
|
||
<td box="[305,719,1972,2070]" gridcol="1" gridrow="10" pageId="1" pageNumber="1876">009 tib 009 tib 555 tib 555 tib 1125 fem 1125 fem 1156 tib 1156 tib 1198 tib 1198 tib 1128 tib 1128 tib 1152 fem 1152 fem 1152 fib</td>
|
||
</tr>
|
||
</table>
|
||
</paragraph>
|
||
<paragraph blockId="1.[784,1422,158,1140]" pageId="1" pageNumber="1876">
|
||
Missing data for major and minor axes and circumferences of bones were calculated using
|
||
<bibRefCitation author="Ramanujan, S." box="[1057,1256,1075,1094]" journalOrPublisher="Q. J. Math." pageId="1" pageNumber="1876" pagination="350 - 372" part="45" refId="ref6047" refString="Ramanujan, S. 1914 Modular equations and approximations to p. Q. J. Math. 45, 350 - 372." title="Modular equations and approximations to p" type="journal article" year="1914">Ramanujan’s (1914)</bibRefCitation>
|
||
formula
|
||
</paragraph>
|
||
<paragraph blockId="1.[784,1422,158,1140]" box="[784,1155,1120,1140]" pageId="1" pageNumber="1876">
|
||
<emphasis box="[784,800,1121,1140]" italics="true" pageId="1" pageNumber="1876">C</emphasis>
|
||
= Π [3(
|
||
<emphasis box="[884,896,1121,1139]" italics="true" pageId="1" pageNumber="1876">a</emphasis>
|
||
+
|
||
<emphasis box="[923,934,1120,1139]" italics="true" pageId="1" pageNumber="1876">b</emphasis>
|
||
)― (
|
||
<emphasis box="[991,1003,1121,1139]" italics="true" pageId="1" pageNumber="1876">a</emphasis>
|
||
+ 3
|
||
<emphasis box="[1043,1054,1120,1139]" italics="true" pageId="1" pageNumber="1876">b</emphasis>
|
||
)(3
|
||
<emphasis box="[1083,1095,1121,1139]" italics="true" pageId="1" pageNumber="1876">a</emphasis>
|
||
+
|
||
<emphasis box="[1122,1133,1120,1139]" italics="true" pageId="1" pageNumber="1876">b</emphasis>
|
||
)],
|
||
</paragraph>
|
||
<paragraph blockId="1.[784,1422,1164,1734]" pageId="1" pageNumber="1876">
|
||
where
|
||
<emphasis box="[848,864,1165,1184]" italics="true" pageId="1" pageNumber="1876">C</emphasis>
|
||
is the circumference and 2
|
||
<emphasis box="[1128,1140,1165,1183]" italics="true" pageId="1" pageNumber="1876">a</emphasis>
|
||
and 2
|
||
<emphasis box="[1201,1212,1164,1183]" italics="true" pageId="1" pageNumber="1876">b</emphasis>
|
||
are the lengths of the major and minor diametral axes, respectively (so the major and minor radii equal
|
||
<emphasis box="[965,977,1226,1244]" italics="true" pageId="1" pageNumber="1876">a</emphasis>
|
||
and
|
||
<emphasis box="[1030,1041,1225,1244]" italics="true" pageId="1" pageNumber="1876">b</emphasis>
|
||
). Bone deposition tends to be thicker along the major axis.
|
||
</paragraph>
|
||
<paragraph blockId="1.[784,1422,1164,1734]" pageId="1" pageNumber="1876">
|
||
Retrocalculations were performed for the medullary cavity and the parts of the inner cortex where the LAGs were obscured by secondary osteons. The number of missing annual intervals was assessed in the following ways: (i) maximum; (ii) penultimate; (iii) mean intervals: the distance in question was divided by the width of the largest (usually innermost) LAG interval, the penultimate LAG interval or the mean of all preserved LAG intervals, respectively; (iv) incremental factor: a mean percentage increase in size of LAG intervals, moving centripetally, was calculated and extrapolated to account for the obscured and missing sections; and (v) parabolic: hypothesizing that LAG intervals were maximal at the innermost preserved LAG, the intervals of the series progressing centrifugally were applied to the missing centripetal series, producing a probable underestimate of growth rate (
|
||
<bibRefCitation author="Erickson, G. M. & Curry Rogers, K. & Yerby, S. A." journalOrPublisher="Nature" pageId="1" pageNumber="1876" pagination="429 - 433" part="412" refId="ref5683" refString="Erickson, G. M., Curry Rogers, K. & Yerby, S. A. 2001 Dinosaurian growth patterns and rapid avian growth rates. Nature 412, 429 - 433." title="Dinosaurian growth patterns and rapid avian growth rates" type="journal article" year="2001">
|
||
Erickson
|
||
<emphasis box="[1373,1422,1684,1703]" italics="true" pageId="1" pageNumber="1876">et al.</emphasis>
|
||
2001
|
||
</bibRefCitation>
|
||
;
|
||
<bibRefCitation author="Horner, J. R. & Padian, K. & de Ricqles, A." box="[845,1023,1714,1734]" journalOrPublisher="Paleobiology" pageId="1" pageNumber="1876" pagination="39 - 58" part="27" refId="ref5859" refString="Horner, J. R., Padian, K. & de Ricqles, A. 2001 Comparative osteohistology of some embryonic and perninatal archo- saurs: developmental and behavioral implications for dinosaurs. Paleobiology 27, 39 - 58." title="Comparative osteohistology of some embryonic and perninatal archo- saurs: developmental and behavioral implications for dinosaurs" type="journal article" year="2001">
|
||
Horner
|
||
<emphasis box="[921,966,1714,1733]" italics="true" pageId="1" pageNumber="1876">et al.</emphasis>
|
||
2001
|
||
</bibRefCitation>
|
||
;
|
||
<bibRefCitation author="Padian, K. & de Ricqles, A. & Horner, J. R." box="[1031,1205,1714,1733]" journalOrPublisher="Nature" pageId="1" pageNumber="1876" pagination="405 - 408" part="412" refId="ref5971" refString="Padian, K., de Ricqles, A. & Horner, J. R. 2001 Dinosaurian growth rates and bird origins. Nature 412, 405 - 408." title="Dinosaurian growth rates and bird origins" type="journal article" year="2001">
|
||
Padian
|
||
<emphasis box="[1103,1148,1714,1733]" italics="true" pageId="1" pageNumber="1876">et al.</emphasis>
|
||
2001
|
||
</bibRefCitation>
|
||
,
|
||
<bibRefCitation author="Padian, K. & Horner, J. R. & de Ricqles, A." box="[1213,1268,1714,1733]" journalOrPublisher="J. Vert. Paleontol." pageId="1" pageNumber="1876" refId="ref6003" refString="Padian, K., Horner, J. R. & de Ricqles, A. 2004 Growth in small dinosaurs and pterosaurs: the evolution of archosaurian growth strategies. J. Vert. Paleontol. (In the press.)" title="Growth in small dinosaurs and pterosaurs: the evolution of archosaurian growth strategies" type="book" year="2004">2004</bibRefCitation>
|
||
).
|
||
</paragraph>
|
||
<paragraph blockId="1.[784,1422,1776,2075]" box="[784,935,1776,1800]" pageId="1" pageNumber="1876">
|
||
<heading allCaps="true" bold="true" box="[784,935,1776,1800]" fontSize="9" level="1" pageId="1" pageNumber="1876" reason="6">
|
||
<emphasis bold="true" box="[784,935,1776,1800]" pageId="1" pageNumber="1876">3. RESULTS</emphasis>
|
||
</heading>
|
||
</paragraph>
|
||
<paragraph blockId="1.[784,1422,1776,2075]" lastBlockId="2.[158,796,837,2075]" lastPageId="2" lastPageNumber="1877" pageId="1" pageNumber="1876">
|
||
All bones sampled have LAGs throughout the outer cortex and inner cortex (when not obscured by secondary osteons) (
|
||
<figureCitation box="[895,987,1870,1892]" captionStart="Figure 1" captionStartId="3.[98,166,847,868]" captionTargetBox="[189,1336,160,827]" captionTargetId="figure@3.[184,1336,160,828]" captionTargetPageId="3" captionText="Figure 1. Bone histology of Tyrannosaurus rex. Transverse thin sections of long bone mid-shafts. (a) MOR 009, composite quadrants of tibia. COR, cortex; MA, major axis; MED, medullary cavity; MI, minor axis; R, radius. (b) MOR 1128, external cortex of tibia, showing typical fibro-lamellar bone and LAG (arrow). In this region the bone is growing at an average rate of 11.2– 17.4 цm d―1, comparable to very rapid growth in the developing mallard (Castanet et al. 1996). (c) MOR 1152, external cortex of fibula showing tight spacing of eight LAGs (arrows) throughout the cortex. The round structures with small centres interrupting the matrix are mature secondary osteons that progressively invade the cortex centrifugally. (d) Detail of (c) showing the outermost cortex with tighter spacing of nine more LAGs. External to these LAGs is a compact area of low vascularity that may reflect the final stages of very slow growth. (e) MOR 1152, outer cortex of femur showing the final closely spaced three LAGs that may correspond to the outermost layer of the fibula. Scale bars: (a) 2 cm; (b–e) 1 mm." figureDoi="http://doi.org/10.5281/zenodo.3726774" httpUri="https://zenodo.org/record/3726774/files/figure.png" pageId="1" pageNumber="1876">figure 1</figureCitation>
|
||
). The LAGs are invariably very thin lines, no thicker than a vascular canal (
|
||
<emphasis box="[1199,1222,1901,1922]" italics="true" pageId="1" pageNumber="1876">ca</emphasis>
|
||
. 20 цm). They are never associated with erosion of pre-existing bone or with rings of avascular bone, and therefore provide no evidence of temporary cessation in growth. The bone tissue in all sections is invariably of the fibro-lamellar complex, as seen in larger extant birds and mammals. Vascularization of the femora and tibiae is mostly circumferential, with frequent radial anastomoses and some longitudinal canals. The fibula contains mostly longitudinal canals, with some radial and circumferential canals. The thickness of the laminae in all bones is almost uniformly 0.17 mm, but in some local regions this is reduced to 0.15 mm or 0.13 mm, with no change in tissue; in no bone does the laminar thickness vary by more than ±7%. Similar thicknesses are recorded in thin sections of the long bones of the small theropod dinosaur
|
||
<taxonomicName authorityName="Leidy" authorityYear="1856" box="[215,300,1118,1139]" class="Reptilia" family="Troodontidae" genus="Troodon" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="2" pageNumber="1877" phylum="Chordata" rank="genus">
|
||
<emphasis box="[215,300,1118,1139]" italics="true" pageId="2" pageNumber="1877">Troodon</emphasis>
|
||
</taxonomicName>
|
||
(0.13 mm), the deer
|
||
<taxonomicName authorityName="Rafinesque" authorityYear="1832" box="[552,661,1118,1139]" class="Mammalia" family="Cervidae" genus="Odocoileus" kingdom="Animalia" order="Artiodactyla" pageId="2" pageNumber="1877" phylum="Chordata" rank="genus">
|
||
<emphasis box="[552,661,1118,1139]" italics="true" pageId="2" pageNumber="1877">Odocoileus</emphasis>
|
||
</taxonomicName>
|
||
(0.13 mm), the elk
|
||
<emphasis box="[238,309,1150,1171]" italics="true" pageId="2" pageNumber="1877">Cerυus</emphasis>
|
||
(0.16 mm) and the moa
|
||
<taxonomicName authorityName="Owen" authorityYear="1843" box="[584,672,1150,1171]" class="Reptilia" family="Dinornithidae" genus="Dinornis" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="2" pageNumber="1877" phylum="Chordata" rank="genus">
|
||
<emphasis box="[584,672,1150,1171]" italics="true" pageId="2" pageNumber="1877">Dinornis</emphasis>
|
||
</taxonomicName>
|
||
(0.17 mm) in the collections of the MOR.
|
||
</paragraph>
|
||
<caption ID-Table-UUID="DF056612FF94FFB4CCB0FF7D3ECA537E" httpUri="http://table.plazi.org/id/DF056612FF94FFB4CCB0FF7D3ECA537E" pageId="2" pageNumber="1877" startId="2.[158,219,158,179]" targetBox="[158,1448,290,730]" targetIsTable="true" targetPageId="2">
|
||
<paragraph blockId="2.[158,1482,158,262]" box="[158,1139,158,179]" pageId="2" pageNumber="1877">
|
||
Table 2. Widths of LAG intervals for each specimen and section of
|
||
<taxonomicName box="[846,1026,158,179]" class="Reptilia" family="Tyrannosauridae" genus="Tyrannosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="2" pageNumber="1877" phylum="Chordata" rank="species" species="rex">
|
||
<emphasis box="[846,1026,158,179]" italics="true" pageId="2" pageNumber="1877">Tyrannosaurus rex</emphasis>
|
||
</taxonomicName>
|
||
examined.
|
||
</paragraph>
|
||
<paragraph blockId="2.[158,1482,158,262]" pageId="2" pageNumber="1877">(Element identifications are keyed to table 1. Intervals are listed from the outermost cortex inward, in millimetres; numbers in parentheses indicate cortical intervals in which LAGs were obscured from view and could not be counted (see text for extrapolations). inc, incomplete LAG intervals.)</paragraph>
|
||
</caption>
|
||
<paragraph pageId="2" pageNumber="1877">
|
||
<table box="[158,1448,290,730]" gridcols="1" gridrows="15" pageId="2" pageNumber="1877">
|
||
<tr box="[158,1448,290,311]" gridrow="0" pageId="2" pageNumber="1877">
|
||
<th box="[158,1448,290,311]" gridcol="0" gridrow="0" pageId="2" pageNumber="1877">MOR 009/TI-1-C: 0.55, 1.60, 3.33,.3.85, 6.44</th>
|
||
</tr>
|
||
<tr box="[158,1448,318,339]" gridrow="1" pageId="2" pageNumber="1877">
|
||
<td box="[158,1448,318,339]" gridcol="0" gridrow="1" pageId="2" pageNumber="1877">MOR 009/TI-1-D: 1.88, 4.3, 3.46, (10.46)</td>
|
||
</tr>
|
||
<tr box="[158,1448,346,367]" gridrow="2" pageId="2" pageNumber="1877">
|
||
<td box="[158,1448,346,367]" gridcol="0" gridrow="2" pageId="2" pageNumber="1877">MOR 555/TI-1a: 0.54,1.70, 2.60, 2.30, 3.20, 6.68, 9.11</td>
|
||
</tr>
|
||
<tr box="[158,1448,374,395]" gridrow="3" pageId="2" pageNumber="1877">
|
||
<td box="[158,1448,374,395]" gridcol="0" gridrow="3" pageId="2" pageNumber="1877">MOR 555/TI-1b: 0.45, 0.83, 0.95, 2.50, 2.32, 3.22, 6.18, 9.30</td>
|
||
</tr>
|
||
<tr box="[158,1448,402,423]" gridrow="4" pageId="2" pageNumber="1877">
|
||
<td box="[158,1448,402,423]" gridcol="0" gridrow="4" pageId="2" pageNumber="1877">MOR 1125/Fe1-L2-B2a: 0.71, 1.09, 3.23, 8.70, 16</td>
|
||
</tr>
|
||
<tr box="[158,1448,430,451]" gridrow="5" pageId="2" pageNumber="1877">
|
||
<td box="[158,1448,430,451]" gridcol="0" gridrow="5" pageId="2" pageNumber="1877">MOR 1125/Fe1-L2-B2b: 0.66, 0.81, 0.94, 1.19, 1.24, 3.33, 3.66, (10)</td>
|
||
</tr>
|
||
<tr box="[158,1448,458,479]" gridrow="6" pageId="2" pageNumber="1877">
|
||
<td box="[158,1448,458,479]" gridcol="0" gridrow="6" pageId="2" pageNumber="1877">MOR 1128/TI-1: 1.63, 2.10, 2.38, 2.98, 3.20, 4.15, 6.45, 3.29 inc</td>
|
||
</tr>
|
||
<tr box="[158,1448,486,507]" gridrow="7" pageId="2" pageNumber="1877">
|
||
<td box="[158,1448,486,507]" gridcol="0" gridrow="7" pageId="2" pageNumber="1877">MOR 1128/TI-2: 1.61, 2.10, 2.45, 2.81, 3.10, 4.16, 6.73, 3.27 inc</td>
|
||
</tr>
|
||
<tr box="[158,1448,513,534]" gridrow="8" pageId="2" pageNumber="1877">
|
||
<td box="[158,1448,513,534]" gridcol="0" gridrow="8" pageId="2" pageNumber="1877">MOR 1152/LBF2-1: 0.17, 0.98, 0.87, 1.71, 1.88, 2.19, 2.81, 3.24, 3.70, 4.22, (22)</td>
|
||
</tr>
|
||
<tr box="[158,1448,541,562]" gridrow="9" pageId="2" pageNumber="1877">
|
||
<td box="[158,1448,541,562]" gridcol="0" gridrow="9" pageId="2" pageNumber="1877">MOR 1152/F2-1: 0.52, 0.84, 0.93, 1.72, 1.94, 2.34, 2.73, 3.18, 3.88, 8.03, (15)</td>
|
||
</tr>
|
||
<tr box="[158,1448,569,618]" gridrow="10" pageId="2" pageNumber="1877">
|
||
<td box="[158,1448,569,618]" gridcol="0" gridrow="10" pageId="2" pageNumber="1877">MOR1152/Fi-2: 0.44 (EFS), 0.21, 0.21, 0.25, 0.23,0.15, 0.55, 0.20, 0.47, 0.41, 0.41, 0.78, 0.91, 1.14, 1.30, 1.10, 1.34, 1.42, (11.03)</td>
|
||
</tr>
|
||
<tr box="[158,1448,625,646]" gridrow="11" pageId="2" pageNumber="1877">
|
||
<td box="[158,1448,625,646]" gridcol="0" gridrow="11" pageId="2" pageNumber="1877">MOR 1156/T2-1: 1.48, 1.69, 1.79, 2.77, 3.03, 3.59, 3.80, (20)</td>
|
||
</tr>
|
||
<tr box="[158,1448,653,674]" gridrow="12" pageId="2" pageNumber="1877">
|
||
<td box="[158,1448,653,674]" gridcol="0" gridrow="12" pageId="2" pageNumber="1877">MOR 1156/T3-1: 0.41, 1.50, 1.13, 1.19, 1.29, 1.88, 4.11, (32)</td>
|
||
</tr>
|
||
<tr box="[158,1448,681,702]" gridrow="13" pageId="2" pageNumber="1877">
|
||
<td box="[158,1448,681,702]" gridcol="0" gridrow="13" pageId="2" pageNumber="1877">MOR 1198/Fe-1-A-1: 1.67, 1.47, 1.63, 2.70, 5.68, 2.08, 4.12, 9.34</td>
|
||
</tr>
|
||
<tr box="[158,1448,709,730]" gridrow="14" pageId="2" pageNumber="1877">
|
||
<td box="[158,1448,709,730]" gridcol="0" gridrow="14" pageId="2" pageNumber="1877">MOR 1198/Fe-1-B-1: 0.50, 1.25, 1.53, 1.68, 3.19, 4.06, 4.78, (25)</td>
|
||
</tr>
|
||
</table>
|
||
</paragraph>
|
||
<paragraph blockId="2.[158,796,837,2075]" pageId="2" pageNumber="1877">As typical theropod long bones grow and the medullary cavities expand, bone deposited early in growth is eroded, so that the remaining bone records only about the last third of the individual’s life history. The internal part of this remaining cortex, furthermore, is frequently remodelled by secondary (Haversian) osteons that obscure LAGs and other records of growth history. To estimate age, this lost information must be retrocalculated, which we carried out for each specimen using several methods (see below), according to the information available for each specimen.</paragraph>
|
||
<paragraph blockId="2.[158,796,837,2075]" pageId="2" pageNumber="1877">
|
||
The tibia of
|
||
<materialsCitation ID-GBIF-Occurrence="3352123310" box="[321,435,1523,1544]" collectionCode="MOR" pageId="2" pageNumber="1877" specimenCode="MOR 009">MOR 009</materialsCitation>
|
||
has a cortical section 16–20 mm thick that represents 4–6 years of fast-growing bone (4–5 LAGs) (see § 2 for all estimates). The radius of the medullary cavity is 35 mm, which could represent as few as 2 years’ additional growth (using an incremental factor based on growth patterns of other specimens at similar size), or up to 10±1 additional years (using a very conservative mean interval retrocalculation). The specimen was still actively growing at death, based on the thickness of the outermost LAG intervals; we estimate its actual age at
|
||
<emphasis box="[766,789,1804,1825]" italics="true" pageId="2" pageNumber="1877">ca</emphasis>
|
||
. 11 years.
|
||
</paragraph>
|
||
<paragraph blockId="2.[158,796,837,2075]" lastBlockId="2.[844,1482,837,2075]" pageId="2" pageNumber="1877">
|
||
The tibia of
|
||
<materialsCitation ID-GBIF-Occurrence="3352123309" box="[314,426,1865,1887]" collectionCode="MOR" pageId="2" pageNumber="1877" specimenCode="MOR 555">MOR 555</materialsCitation>
|
||
has a major axis cortical section of 27.03 mm that represents just over 7 years’ growth. The radius of the medullary cavity is 43 mm, which represents
|
||
<emphasis box="[158,181,1960,1981]" italics="true" pageId="2" pageNumber="1877">ca</emphasis>
|
||
. 4.6 years (maximum interval), 7 years (penultimate interval) or 9–11 years (parabolic). During the broadest LAG intervals preserved, the tibia was growing at rates of 16.7–25 цm d
|
||
<superScript attach="left" box="[351,376,2047,2061]" fontSize="6" pageId="2" pageNumber="1877">―1</superScript>
|
||
, comparable to the most rapid developmental rates of wing bone growth in the mallard (
|
||
<bibRefCitation author="Castanet, J. & Grandin, A. & Abourachid, A. & de Ricqles, A." box="[851,1092,868,890]" journalOrPublisher="C. R. Acad. Sci. (Paris)" pageId="2" pageNumber="1877" pagination="301 - 308" part="319" refId="ref5451" refString="Castanet, J., Grandin, A., Abourachid, A. & de Ricqles, A. 1996 Expression de la dynamique de croissance de l'os periostique chez Anas platyrhynchos. C. R. Acad. Sci. (Paris) 319, 301 - 308." title="Expression de la dynamique de croissance de l'os periostique chez Anas platyrhynchos" type="journal article" year="1996">
|
||
Castanet
|
||
<emphasis box="[963,1019,868,890]" italics="true" pageId="2" pageNumber="1877">et al.</emphasis>
|
||
1996
|
||
</bibRefCitation>
|
||
). The estimated age range of the specimen is 12–18 years, of which 14±2 years appears reasonable. The outermost LAG intervals are less than 1 mm thick, so the animal had effectively stopped actively growing for 2 or 3 years.
|
||
</paragraph>
|
||
<paragraph blockId="2.[844,1482,837,2075]" pageId="2" pageNumber="1877">
|
||
A femoral section of
|
||
<materialsCitation ID-GBIF-Occurrence="3352123321" box="[1101,1229,1024,1046]" collectionCode="MOR" pageId="2" pageNumber="1877" specimenCode="MOR 1125">MOR 1125</materialsCitation>
|
||
taken along the minor axis is 21.83 mm thick, representing 10–11 years. The medullary radius of 38 mm represents 7 years (incremental factor) to 10–11 years (maximum interval), but the preserved maximum interval in this specimen is relatively low. The calculated age range of 17–22 years may be an overestimate; 18±2 years is a more constrained estimate. The outermost two or three LAG intervals are less than 1 mm thick, so the animal had effectively stopped growing at 16±2 years.
|
||
</paragraph>
|
||
<paragraph blockId="2.[844,1482,837,2075]" pageId="2" pageNumber="1877">
|
||
The tibial cross-sections of
|
||
<materialsCitation ID-GBIF-Occurrence="3352123311" box="[1171,1299,1335,1357]" collectionCode="MOR" pageId="2" pageNumber="1877" specimenCode="MOR 1156">MOR 1156</materialsCitation>
|
||
and
|
||
<materialsCitation ID-GBIF-Occurrence="3352123301" box="[1354,1481,1336,1357]" collectionCode="MOR" pageId="2" pageNumber="1877" specimenCode="MOR 1198">MOR 1198</materialsCitation>
|
||
are too incomplete for the retrocalculation of age; however, their preserved thicknesses suggest 11–16 years (average 14±2) and at least 10 years (±1), respectively.
|
||
<materialsCitation ID-GBIF-Occurrence="3352123305" box="[1355,1481,1429,1450]" collectionCode="MOR" pageId="2" pageNumber="1877" specimenCode="MOR 1198">MOR 1198</materialsCitation>
|
||
is approximately the same size as
|
||
<materialsCitation ID-GBIF-Occurrence="3352123315" box="[1204,1319,1460,1482]" collectionCode="MOR" pageId="2" pageNumber="1877" specimenCode="MOR 555">MOR 555</materialsCitation>
|
||
, but like
|
||
<materialsCitation ID-GBIF-Occurrence="3352123322" collectionCode="MOR" pageId="2" pageNumber="1877" specimenCode="MOR 1156">MOR 1156</materialsCitation>
|
||
it appears to have been actively growing, depositing at least 1.5 mm per year of cortical thickness for several years before death.
|
||
</paragraph>
|
||
<paragraph blockId="2.[844,1482,837,2075]" pageId="2" pageNumber="1877">
|
||
The most completely preserved sequence of LAGs from the tibia is of
|
||
<materialsCitation ID-GBIF-Occurrence="3352123313" box="[991,1120,1616,1637]" collectionCode="MOR" pageId="2" pageNumber="1877" specimenCode="MOR 1128">MOR 1128</materialsCitation>
|
||
. Six complete intervals separated by LAGs occur in a section 26.18 mm thick along a radius of
|
||
<emphasis box="[871,894,1679,1700]" italics="true" pageId="2" pageNumber="1877">ca</emphasis>
|
||
. 70 mm. The number of LAGs in the space now occupied by the medullary cavity is estimated to represent from 4 years (incremental factor of 1.25) to 7–8 years (maximum interval), 11–12 years (penultimate interval) or 13 years (mean interval). Each of these figures can be added to 7–8 years of growth represented by the preserved cortex to yield age estimates of (i) 11–12, (ii) 14–16, (iii) 18–20 and (iv) 20–21 years, for a mean estimate of
|
||
<emphasis box="[1238,1261,1898,1919]" italics="true" pageId="2" pageNumber="1877">ca</emphasis>
|
||
. 16 years. Although the outermost LAG intervals are smaller than inner ones, their thicknesses suggest that active growth would have continued for at least 2–3 years.
|
||
</paragraph>
|
||
<paragraph blockId="2.[844,1482,837,2075]" lastBlockId="3.[784,1422,1175,2075]" lastPageId="3" lastPageNumber="1878" pageId="2" pageNumber="1877">
|
||
If
|
||
<taxonomicName box="[891,952,2022,2043]" class="Reptilia" family="Tyrannosauridae" genus="Tyrannosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="2" pageNumber="1877" phylum="Chordata" rank="species" species="rex">
|
||
<emphasis box="[891,952,2022,2043]" italics="true" pageId="2" pageNumber="1877">T. rex</emphasis>
|
||
</taxonomicName>
|
||
’s growth was slowing at a consistent rate, at what age did it virtually stop growing? To extrapolate this, we applied a factor of 0.8, the inverse of the incremental factor of 1.25, to the preserved series of LAG intervals, calibrated from the last three preserved intervals. At this rate of growth decrease, within 5 years
|
||
<materialsCitation ID-GBIF-Occurrence="3352123318" box="[1152,1283,1269,1290]" collectionCode="MOR" pageId="3" pageNumber="1878" specimenCode="MOR 1128">MOR 1128</materialsCitation>
|
||
would have deposited 0.5 mm of bone centrifugally per year, and after 8 years this would have decreased to 0.25 mm yr
|
||
<superScript attach="left" box="[1311,1336,1326,1341]" fontSize="6" pageId="3" pageNumber="1878">―1</superScript>
|
||
. By the sixth year, projected growth is just over 1 цm d
|
||
<superScript attach="left" box="[1279,1304,1358,1372]" fontSize="6" pageId="3" pageNumber="1878">―1</superScript>
|
||
, comparable to very slow growth in living tetrapods (see
|
||
<figureCitation box="[1282,1367,1395,1417]" captionStart="Figure 2" captionStartId="3.[98,166,1913,1934]" captionTargetBox="[127,744,1180,1907]" captionTargetId="graphics@3.[226,674,1226,1836]" captionTargetPageId="3" captionText="Figure 2. Growth trajectories of individual specimens of Tyrannosaurus rex. These are expressed as an annual percentage of attainment of full size (cortical radius of long bones). The variation results from the fact that different bones grow at different rates. The early trajectories of bone growth are estimated (see table 1)." figureDoi="http://doi.org/10.5281/zenodo.3726776" httpUri="https://zenodo.org/record/3726776/files/figure.png" pageId="3" pageNumber="1878">figure 2</figureCitation>
|
||
).
|
||
</paragraph>
|
||
<caption ID-DOI="http://doi.org/10.5281/zenodo.3726774" ID-Zenodo-Dep="3726774" httpUri="https://zenodo.org/record/3726774/files/figure.png" pageId="3" pageNumber="1878" startId="3.[98,166,847,868]" targetBox="[189,1336,160,827]" targetPageId="3">
|
||
<paragraph blockId="3.[98,1415,847,1092]" pageId="3" pageNumber="1878">
|
||
Figure 1. Bone histology of
|
||
<taxonomicName box="[385,565,848,869]" class="Reptilia" family="Tyrannosauridae" genus="Tyrannosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="3" pageNumber="1878" phylum="Chordata" rank="species" species="rex">
|
||
<emphasis box="[385,565,848,869]" italics="true" pageId="3" pageNumber="1878">Tyrannosaurus rex</emphasis>
|
||
</taxonomicName>
|
||
. Transverse thin sections of long bone mid-shafts. (
|
||
<emphasis box="[1090,1102,848,869]" italics="true" pageId="3" pageNumber="1878">a</emphasis>
|
||
)
|
||
<materialsCitation ID-GBIF-Occurrence="3352123317" box="[1117,1225,847,868]" collectionCode="MOR" pageId="3" pageNumber="1878" specimenCode="MOR 009">MOR 009</materialsCitation>
|
||
, composite quadrants of tibia. COR, cortex; MA, major axis; MED, medullary cavity; MI, minor axis; R, radius. (
|
||
<emphasis box="[1132,1143,875,896]" italics="true" pageId="3" pageNumber="1878">b</emphasis>
|
||
)
|
||
<materialsCitation ID-GBIF-Occurrence="3352123316" box="[1157,1279,875,896]" collectionCode="MOR" pageId="3" pageNumber="1878" specimenCode="MOR 1128">MOR 1128</materialsCitation>
|
||
, external cortex of tibia, showing typical fibro-lamellar bone and LAG (arrow). In this region the bone is growing at an average rate of 11.2– 17.4 цm d
|
||
<superScript attach="left" box="[200,224,926,940]" fontSize="6" pageId="3" pageNumber="1878">―1</superScript>
|
||
, comparable to very rapid growth in the developing mallard (
|
||
<bibRefCitation author="Castanet, J. & Grandin, A. & Abourachid, A. & de Ricqles, A." box="[843,1051,931,953]" journalOrPublisher="C. R. Acad. Sci. (Paris)" pageId="3" pageNumber="1878" pagination="301 - 308" part="319" refId="ref5451" refString="Castanet, J., Grandin, A., Abourachid, A. & de Ricqles, A. 1996 Expression de la dynamique de croissance de l'os periostique chez Anas platyrhynchos. C. R. Acad. Sci. (Paris) 319, 301 - 308." title="Expression de la dynamique de croissance de l'os periostique chez Anas platyrhynchos" type="journal article" year="1996">
|
||
Castanet
|
||
<emphasis box="[941,989,931,953]" italics="true" pageId="3" pageNumber="1878">et al.</emphasis>
|
||
1996
|
||
</bibRefCitation>
|
||
). (
|
||
<emphasis box="[1076,1085,932,953]" italics="true" pageId="3" pageNumber="1878">c</emphasis>
|
||
)
|
||
<materialsCitation ID-GBIF-Occurrence="3352123302" box="[1099,1221,931,952]" collectionCode="MOR" pageId="3" pageNumber="1878" specimenCode="MOR 1152">MOR 1152</materialsCitation>
|
||
, external cortex of fibula showing tight spacing of eight LAGs (arrows) throughout the cortex. The round structures with small centres interrupting the matrix are mature secondary osteons that progressively invade the cortex centrifugally. (
|
||
<emphasis box="[1027,1039,987,1008]" italics="true" pageId="3" pageNumber="1878">d</emphasis>
|
||
) Detail of (
|
||
<emphasis box="[1159,1168,988,1009]" italics="true" pageId="3" pageNumber="1878">c</emphasis>
|
||
) showing the outermost cortex with tighter spacing of nine more LAGs. External to these LAGs is a compact area of low vascularity that may reflect the final stages of very slow growth. (
|
||
<emphasis box="[433,442,1043,1064]" italics="true" pageId="3" pageNumber="1878">e</emphasis>
|
||
)
|
||
<materialsCitation ID-GBIF-Occurrence="3352123312" box="[456,578,1043,1064]" collectionCode="MOR" pageId="3" pageNumber="1878" specimenCode="MOR 1152">MOR 1152</materialsCitation>
|
||
, outer cortex of femur showing the final closely spaced three LAGs that may correspond to the outermost layer of the fibula. Scale bars: (
|
||
<emphasis box="[705,717,1071,1092]" italics="true" pageId="3" pageNumber="1878">a</emphasis>
|
||
) 2 cm; (
|
||
<emphasis box="[801,833,1071,1092]" italics="true" pageId="3" pageNumber="1878">b–e</emphasis>
|
||
) 1 mm.
|
||
</paragraph>
|
||
</caption>
|
||
<paragraph blockId="3.[784,1422,1175,2075]" pageId="3" pageNumber="1878">
|
||
According to these estimates, a virtually fully grown
|
||
<taxonomicName class="Reptilia" family="Tyrannosauridae" genus="Tyrannosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="3" pageNumber="1878" phylum="Chordata" rank="species" species="rex">
|
||
<emphasis italics="true" pageId="3" pageNumber="1878">T. rex</emphasis>
|
||
</taxonomicName>
|
||
would have been between 15 and 18 years old. (However, as the femur of
|
||
<materialsCitation ID-GBIF-Occurrence="3352123314" box="[1020,1149,1488,1510]" collectionCode="MOR" pageId="3" pageNumber="1878" specimenCode="MOR 1152">MOR 1152</materialsCitation>
|
||
shows, growth can drop more precipitously than an incremental estimate suggests.) We have not found in any sectioned
|
||
<taxonomicName box="[1195,1259,1552,1573]" class="Reptilia" family="Tyrannosauridae" genus="Tyrannosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="3" pageNumber="1878" phylum="Chordata" rank="species" species="rex">
|
||
<emphasis box="[1195,1259,1552,1573]" italics="true" pageId="3" pageNumber="1878">T. rex</emphasis>
|
||
</taxonomicName>
|
||
tibia or femur evidence of an outer acellular, nearly avascular layer similar to the external fundamental system (EFS) (
|
||
<bibRefCitation author="Cormack, D." journalOrPublisher="New York: Lippincott" pageId="3" pageNumber="1878" refId="ref5588" refString="Cormack, D. 1957 Ham's histology. New York: Lippincott." title="Ham's histology" type="book" year="1957">Cormack 1957</bibRefCitation>
|
||
), that indicates effective cessation of growth. (An EFS has been identified in the ornithischian dinosaur
|
||
<taxonomicName authority="(Horner et al. 2000)" baseAuthorityName="Horner" baseAuthorityYear="2000" box="[784,1126,1708,1730]" class="Reptilia" family="Hadrosauridae" genus="Maiasaura" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="3" pageNumber="1878" phylum="Chordata" rank="genus">
|
||
<emphasis box="[784,898,1709,1730]" italics="true" pageId="3" pageNumber="1878">Maiasaura</emphasis>
|
||
(
|
||
<bibRefCitation author="Horner, J. R. & de Ricqles, A. & Padian, K." box="[911,1118,1708,1730]" journalOrPublisher="J. Vert. Paleontol." pageId="3" pageNumber="1878" pagination="115 - 129" part="20" refId="ref5806" refString="Horner, J. R., de Ricqles, A. & Padian, K. 2000 Long bone histology of the hadrosaurid dinosaur Maiasaura peeblesorum: growth dynamics and physiology based on an ontogenetic series of skeletal elements. J. Vert. Paleontol. 20, 115 - 129." title="Long bone histology of the hadrosaurid dinosaur Maiasaura peeblesorum: growth dynamics and physiology based on an ontogenetic series of skeletal elements" type="journal article" year="2000">
|
||
Horner
|
||
<emphasis box="[1000,1050,1708,1730]" italics="true" pageId="3" pageNumber="1878">et al.</emphasis>
|
||
2000
|
||
</bibRefCitation>
|
||
)
|
||
</taxonomicName>
|
||
.) The absence of an EFS in preserved specimens of
|
||
<taxonomicName box="[1051,1116,1740,1761]" class="Reptilia" family="Tyrannosauridae" genus="Tyrannosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="3" pageNumber="1878" phylum="Chordata" rank="species" species="rex">
|
||
<emphasis box="[1051,1116,1740,1761]" italics="true" pageId="3" pageNumber="1878">T. rex</emphasis>
|
||
</taxonomicName>
|
||
could suggest that none of the animals had stopped growing, although growth was greatly slowing. Without an EFS, the near cessation of growth seems the most practical indicator of full size.
|
||
</paragraph>
|
||
<paragraph blockId="3.[784,1422,1175,2075]" lastBlockId="4.[158,796,159,731]" lastPageId="4" lastPageNumber="1879" pageId="3" pageNumber="1878">
|
||
To test this hypothesis, we examined sections of a femur and fibula of
|
||
<materialsCitation ID-GBIF-Occurrence="3352123307" box="[943,1078,1896,1918]" collectionCode="MOR" pageId="3" pageNumber="1878" specimenCode="MOR 1152">MOR 1152</materialsCitation>
|
||
. The preserved section of the femur allows an estimate of 12–14 years; the record represented by the missing eroded internal cortex cannot be estimated. The fibula from
|
||
<materialsCitation ID-GBIF-Occurrence="3352123308" box="[1049,1176,1990,2012]" collectionCode="MOR" pageId="3" pageNumber="1878" specimenCode="MOR 1152">MOR 1152</materialsCitation>
|
||
is complete, however. Its transverse radius of 22.55 mm was measured from the perimeter to a small erosion room representing the centroid of the bone. It comprises an outer, highly compressed section of 0.44 mm, 17 LAG intervals in a section of 11.08 mm, and an inner cortical area of 11.03 mm, where the record of primary bone structure has been completely erased by secondary osteons. Using the maximum and penultimate interval retrocalculations, the inner cortex could have been deposited in 7.5–10 years. However, the LAG intervals increase centripetally at a rate of
|
||
<emphasis box="[650,673,373,394]" italics="true" pageId="4" pageNumber="1879">ca</emphasis>
|
||
. 1.17 mm, which incremental rate yields no more than 5 years to complete the inner cortex. According to this calculation, the age of the specimen is 22–27 years, plus the time represented by the outer, highly compressed section. Because the last three LAG intervals of the femur drop precipitously in width to less than 1 mm, we infer that the fibular LAG may represent those 3 years. The most likely estimate of the age of this fully grown
|
||
<taxonomicName box="[367,431,618,639]" class="Reptilia" family="Tyrannosauridae" genus="Tyrannosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="4" pageNumber="1879" phylum="Chordata" rank="species" species="rex">
|
||
<emphasis box="[367,431,618,639]" italics="true" pageId="4" pageNumber="1879">T. rex</emphasis>
|
||
</taxonomicName>
|
||
, therefore, was 22–25 years, and full growth was reached at least 3 years before death. This estimate could be too high if the fibula grew at substantially higher rates earlier in life.
|
||
</paragraph>
|
||
</subSubSection>
|
||
<caption ID-DOI="http://doi.org/10.5281/zenodo.3726776" ID-Zenodo-Dep="3726776" httpUri="https://zenodo.org/record/3726776/files/figure.png" pageId="3" pageNumber="1878" startId="3.[98,166,1913,1934]" targetBox="[127,744,1180,1907]" targetPageId="3">
|
||
<paragraph blockId="3.[98,730,1913,2074]" pageId="3" pageNumber="1878">
|
||
Figure 2. Growth trajectories of individual specimens of
|
||
<taxonomicName box="[98,278,1942,1963]" class="Reptilia" family="Tyrannosauridae" genus="Tyrannosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="3" pageNumber="1878" phylum="Chordata" rank="species" species="rex">
|
||
<emphasis box="[98,278,1942,1963]" italics="true" pageId="3" pageNumber="1878">Tyrannosaurus rex</emphasis>
|
||
</taxonomicName>
|
||
. These are expressed as an annual percentage of attainment of full size (cortical radius of long bones). The variation results from the fact that different bones grow at different rates. The early trajectories of bone growth are estimated (see table 1).
|
||
</paragraph>
|
||
</caption>
|
||
<subSubSection pageId="4" pageNumber="1879" type="discussion">
|
||
<paragraph blockId="4.[158,796,798,2075]" box="[158,378,798,822]" pageId="4" pageNumber="1879">
|
||
<heading allCaps="true" bold="true" box="[158,378,798,822]" fontSize="9" level="1" pageId="4" pageNumber="1879" reason="6">
|
||
<emphasis bold="true" box="[158,378,798,822]" pageId="4" pageNumber="1879">4. CONCLUSIONS</emphasis>
|
||
</heading>
|
||
</paragraph>
|
||
<paragraph blockId="4.[158,796,798,2075]" pageId="4" pageNumber="1879">
|
||
These results have several implications for the assessment of age and growth in large dinosaurs. Not all bones provide the same signal of age. Larger or more robust specimens are not necessarily older than smaller more gracile ones. The substantial variation seen in
|
||
<taxonomicName box="[487,554,954,975]" class="Reptilia" family="Tyrannosauridae" genus="Tyrannosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="4" pageNumber="1879" phylum="Chordata" rank="species" species="rex">
|
||
<emphasis box="[487,554,954,975]" italics="true" pageId="4" pageNumber="1879">T. rex</emphasis>
|
||
</taxonomicName>
|
||
skeletons cannot yet reliably be attributed to either age, sexual dimorphism or anagenetic evolution through their known temporal range. Erosion and reconstruction of cortical bone obscure primary tissues useful in skeletochronology. Various methods can retrocalculate destroyed tissue, but none is
|
||
<emphasis box="[672,746,1106,1128]" italics="true" pageId="4" pageNumber="1879">a priori</emphasis>
|
||
better than any other. Independent evidence of growth dynamics is needed from earlier growth stages, which are currently unavailable.
|
||
</paragraph>
|
||
<paragraph blockId="4.[158,796,798,2075]" pageId="4" pageNumber="1879">
|
||
Three out of the seven specimens that we analysed appear to have effectively ceased active growth 2 or 3 years before death, although their cortical radius continued to increase annually by 0.5–0.7% (e.g.
|
||
<materialsCitation ID-GBIF-Occurrence="3352123306" box="[591,716,1319,1341]" collectionCode="MOR" pageId="4" pageNumber="1879" specimenCode="MOR 555">MOR 555</materialsCitation>
|
||
). Four other specimens appear to have still been growing, but LAG interval decreases suggest that each of them would have reached effectively full size in another 1 to 3 years. Evidence from the femora and tibiae suggest, therefore, that
|
||
<taxonomicName box="[208,271,1473,1494]" class="Reptilia" family="Tyrannosauridae" genus="Tyrannosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="4" pageNumber="1879" phylum="Chordata" rank="species" species="rex">
|
||
<emphasis box="[208,271,1473,1494]" italics="true" pageId="4" pageNumber="1879">T. rex</emphasis>
|
||
</taxonomicName>
|
||
reached full size by 16±3 years, but we caution that our sample is small and individual variation may have affected age at maturity. The fibula of
|
||
<materialsCitation ID-GBIF-Occurrence="3352123319" box="[574,700,1533,1555]" collectionCode="MOR" pageId="4" pageNumber="1879" specimenCode="MOR 1152">MOR 1152</materialsCitation>
|
||
suggests a higher range of 22–27 years, although the rate of its inner cortical growth may be underestimated. In any case, within about two decades
|
||
<taxonomicName box="[443,505,1626,1647]" class="Reptilia" family="Tyrannosauridae" genus="Tyrannosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="4" pageNumber="1879" phylum="Chordata" rank="species" species="rex">
|
||
<emphasis box="[443,505,1626,1647]" italics="true" pageId="4" pageNumber="1879">T. rex</emphasis>
|
||
</taxonomicName>
|
||
appears to have effectively stopped growing.
|
||
</paragraph>
|
||
<paragraph blockId="4.[158,796,798,2075]" lastBlockId="4.[844,1482,159,1494]" pageId="4" pageNumber="1879">
|
||
The growth profile of
|
||
<taxonomicName authorityName="Osborn" authorityYear="1905" box="[451,605,1687,1708]" class="Reptilia" family="Tyrannosauridae" genus="Tyrannosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="4" pageNumber="1879" phylum="Chordata" rank="genus">
|
||
<emphasis box="[451,605,1687,1708]" italics="true" pageId="4" pageNumber="1879">Tyrannosaurus</emphasis>
|
||
</taxonomicName>
|
||
is slightly more accelerated than that of the African elephant (
|
||
<taxonomicName baseAuthorityName="Blumenbach" baseAuthorityYear="1797" class="Mammalia" family="Elephantidae" genus="Loxodonta" kingdom="Animalia" order="Proboscidea" pageId="4" pageNumber="1879" phylum="Chordata" rank="species" species="africana">
|
||
<emphasis italics="true" pageId="4" pageNumber="1879">Loxodonta africana</emphasis>
|
||
</taxonomicName>
|
||
), which matures and ceases active growth at 25–35 years (
|
||
<bibRefCitation author="Laws, R. M. & Parker, I. S. C. & Johnstone, R. C. B." box="[227,411,1778,1800]" journalOrPublisher="Oxford: Clarendon" pageId="4" pageNumber="1879" refId="ref5901" refString="Laws, R. M., Parker, I. S. C. & Johnstone, R. C. B. 1975 Elephants and their habitats: the ecology of elephants in North Bunyoro, Uganda. Oxford: Clarendon." title="Elephants and their habitats: the ecology of elephants in North Bunyoro, Uganda" type="book" year="1975">
|
||
Laws
|
||
<emphasis box="[293,344,1778,1800]" italics="true" pageId="4" pageNumber="1879">et al.</emphasis>
|
||
1975
|
||
</bibRefCitation>
|
||
). Estimates for the mass of an adult
|
||
<taxonomicName box="[158,219,1809,1830]" class="Reptilia" family="Tyrannosauridae" genus="Tyrannosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="4" pageNumber="1879" phylum="Chordata" rank="species" species="rex">
|
||
<emphasis box="[158,219,1809,1830]" italics="true" pageId="4" pageNumber="1879">T. rex</emphasis>
|
||
</taxonomicName>
|
||
range from 5000 to 8000 kg (
|
||
<bibRefCitation author="Alexander, R. M." box="[535,716,1808,1831]" editor="P. Currie & K. Padian" journalOrPublisher="San Diego, CA: Academic" pageId="4" pageNumber="1879" pagination="665 - 667" refId="ref5385" refString="Alexander, R. M. 1997 Size and scaling. In The encyclopedia of dinosaurs (ed. P. Currie & K. Padian), pp. 665 - 667. San Diego, CA: Academic." title="Size and scaling" type="book chapter" volumeTitle="The encyclopedia of dinosaurs" year="1997">Alexander 1997</bibRefCitation>
|
||
). Adult male elephants weigh 4500–6000 kg (
|
||
<bibRefCitation author="Laws, R. M. & Parker, I. S. C. & Johnstone, R. C. B." box="[585,783,1839,1861]" journalOrPublisher="Oxford: Clarendon" pageId="4" pageNumber="1879" refId="ref5901" refString="Laws, R. M., Parker, I. S. C. & Johnstone, R. C. B. 1975 Elephants and their habitats: the ecology of elephants in North Bunyoro, Uganda. Oxford: Clarendon." title="Elephants and their habitats: the ecology of elephants in North Bunyoro, Uganda" type="book" year="1975">
|
||
Laws
|
||
<emphasis box="[656,712,1839,1861]" italics="true" pageId="4" pageNumber="1879">et al.</emphasis>
|
||
1975
|
||
</bibRefCitation>
|
||
), with some outliers reported up to 7300 kg (
|
||
<bibRefCitation author="Nowak, R. M." box="[635,783,1870,1892]" journalOrPublisher="Baltimore, MD: Johns Hopkins University Press" pageId="4" pageNumber="1879" refId="ref5945" refString="Nowak, R. M. 1999 Walker's mammals of the aeorld, vol. II. Baltimore, MD: Johns Hopkins University Press." title="Walker's mammals of the aeorld, vol. II" type="book" year="1999">Nowak 1999</bibRefCitation>
|
||
), so the body masses of
|
||
<taxonomicName box="[431,500,1901,1922]" class="Reptilia" family="Tyrannosauridae" genus="Tyrannosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="4" pageNumber="1879" phylum="Chordata" rank="species" species="rex">
|
||
<emphasis box="[431,500,1901,1922]" italics="true" pageId="4" pageNumber="1879">T. rex</emphasis>
|
||
</taxonomicName>
|
||
and African elephants at full size are similar. It follows that the dinosaur and the elephant would have grown at roughly similar rates, consistent with the well vascularized fibro-lamellar tissue that
|
||
<taxonomicName box="[158,222,2023,2044]" class="Reptilia" family="Tyrannosauridae" genus="Tyrannosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="4" pageNumber="1879" phylum="Chordata" rank="species" species="rex">
|
||
<emphasis box="[158,222,2023,2044]" italics="true" pageId="4" pageNumber="1879">T. rex</emphasis>
|
||
</taxonomicName>
|
||
deposited (
|
||
<bibRefCitation author="Castanet, J. & Grandin, A. & Abourachid, A. & de Ricqles, A." box="[351,577,2022,2044]" journalOrPublisher="C. R. Acad. Sci. (Paris)" pageId="4" pageNumber="1879" pagination="301 - 308" part="319" refId="ref5451" refString="Castanet, J., Grandin, A., Abourachid, A. & de Ricqles, A. 1996 Expression de la dynamique de croissance de l'os periostique chez Anas platyrhynchos. C. R. Acad. Sci. (Paris) 319, 301 - 308." title="Expression de la dynamique de croissance de l'os periostique chez Anas platyrhynchos" type="journal article" year="1996">
|
||
Castanet
|
||
<emphasis box="[458,510,2022,2044]" italics="true" pageId="4" pageNumber="1879">et al.</emphasis>
|
||
1996
|
||
</bibRefCitation>
|
||
,
|
||
<bibRefCitation author="Castanet, J. & Rogers, K. C. & Cubo, J. & Boisard, J. J." box="[589,648,2022,2043]" journalOrPublisher="C. R. Acad. Sci." pageId="4" pageNumber="1879" pagination="543 - 550" part="323" refId="ref5502" refString="Castanet, J., Rogers, K. C., Cubo, J. & Boisard, J. J. 2000 Periosteal bone growth rates in extant ratites (ostrich and emu). Implications for assessing growth in dinosaurs. C. R. Acad. Sci. 323, 543 - 550." title="Periosteal bone growth rates in extant ratites (ostrich and emu). Implications for assessing growth in dinosaurs" type="journal article" year="2000">2000</bibRefCitation>
|
||
;
|
||
<bibRefCitation author="Padian, K. & de Ricqles, A. & Horner, J. R." journalOrPublisher="Nature" pageId="4" pageNumber="1879" pagination="405 - 408" part="412" refId="ref5971" refString="Padian, K., de Ricqles, A. & Horner, J. R. 2001 Dinosaurian growth rates and bird origins. Nature 412, 405 - 408." title="Dinosaurian growth rates and bird origins" type="journal article" year="2001">
|
||
Padian
|
||
<emphasis box="[744,796,2022,2044]" italics="true" pageId="4" pageNumber="1879">et al.</emphasis>
|
||
2001
|
||
</bibRefCitation>
|
||
;
|
||
<figureCitation box="[231,318,2053,2075]" captionStart="Figure 1" captionStartId="3.[98,166,847,868]" captionTargetBox="[189,1336,160,827]" captionTargetId="figure@3.[184,1336,160,828]" captionTargetPageId="3" captionText="Figure 1. Bone histology of Tyrannosaurus rex. Transverse thin sections of long bone mid-shafts. (a) MOR 009, composite quadrants of tibia. COR, cortex; MA, major axis; MED, medullary cavity; MI, minor axis; R, radius. (b) MOR 1128, external cortex of tibia, showing typical fibro-lamellar bone and LAG (arrow). In this region the bone is growing at an average rate of 11.2– 17.4 цm d―1, comparable to very rapid growth in the developing mallard (Castanet et al. 1996). (c) MOR 1152, external cortex of fibula showing tight spacing of eight LAGs (arrows) throughout the cortex. The round structures with small centres interrupting the matrix are mature secondary osteons that progressively invade the cortex centrifugally. (d) Detail of (c) showing the outermost cortex with tighter spacing of nine more LAGs. External to these LAGs is a compact area of low vascularity that may reflect the final stages of very slow growth. (e) MOR 1152, outer cortex of femur showing the final closely spaced three LAGs that may correspond to the outermost layer of the fibula. Scale bars: (a) 2 cm; (b–e) 1 mm." figureDoi="http://doi.org/10.5281/zenodo.3726774" httpUri="https://zenodo.org/record/3726774/files/figure.png" pageId="4" pageNumber="1879">figure 1</figureCitation>
|
||
). As
|
||
<bibRefCitation author="Chinsamy, A." box="[384,573,2053,2075]" journalOrPublisher="Mod. Geol." pageId="4" pageNumber="1879" pagination="319 - 329" part="18" refId="ref5560" refString="Chinsamy, A. 1993 Bone histology and growth trajectory of the prosauropod dinosaur Massospondylus carinatus Owen. Mod. Geol. 18, 319 - 329." title="Bone histology and growth trajectory of the prosauropod dinosaur Massospondylus carinatus Owen" type="journal article" year="1993">Chinsamy (1993</bibRefCitation>
|
||
, p. 327) noted, the predominant production of fibro-lamellar tissues in dinosaur bones throughout life ‘would require and thus implies a high metabolic rate’. This metabolic rate was sustained throughout growth, diminishing with age as in all warmblooded animals of today.
|
||
</paragraph>
|
||
<paragraph blockId="4.[844,1482,159,1494]" pageId="4" pageNumber="1879">
|
||
These findings should have implications for studies of palaeoecology and community structure of latest Cretaceous terrestrial environments (
|
||
<bibRefCitation author="Farlow, J. O. & Pianka, E. R." box="[1216,1477,372,394]" journalOrPublisher="Hist. Biol." pageId="4" pageNumber="1879" pagination="21 - 40" part="16" refId="ref5719" refString="Farlow, J. O. & Pianka, E. R. 2002 Body size overlap, habitat partitioning, and living space requirements of terrestrial vertebrate predators: implications for the paleoecology of large theropod dinosaurs. Hist. Biol. 16, 21 - 40." title="Body size overlap, habitat partitioning, and living space requirements of terrestrial vertebrate predators: implications for the paleoecology of large theropod dinosaurs" type="journal article" year="2002">Farlow & Pianka 2002</bibRefCitation>
|
||
;
|
||
<bibRefCitation author="Ruxton, G. D. & Houston, D. C." box="[844,1119,403,424]" journalOrPublisher="Proc. R. Soc. Lond. B" pageId="4" pageNumber="1879" pagination="731 - 733" part="270" refId="ref6122" refString="Ruxton, G. D. & Houston, D. C. 2003 Could Tyrannosaurus rex have been a scavenger rather than a predator? An energetics approach. Proc. R. Soc. Lond. B 270, 731 - 733. (DOI 10.1098 / rspb. 2002.2279.)" title="Could Tyrannosaurus rex have been a scavenger rather than a predator? An energetics approach" type="journal article" year="2003">Ruxton & Houston 2003</bibRefCitation>
|
||
;
|
||
<bibRefCitation author="Sampson, S. & Loewen, S. & Farlow, J. O. & Carrano, M. T." box="[1130,1356,403,425]" journalOrPublisher="J. Vert. Paleontol." pageId="4" pageNumber="1879" pagination="92" part="23 (Suppl. 3)" refId="ref6176" refString="Sampson, S., Loewen, S., Farlow, J. O. & Carrano, M. T. 2003 Ecological and evolutionary implications of gigantism in theropod dinosaurs. J. Vert. Paleontol. 23 (Suppl. 3), 92 A." title="Ecological and evolutionary implications of gigantism in theropod dinosaurs" type="journal article" year="2003">
|
||
Sampson
|
||
<emphasis box="[1238,1289,403,425]" italics="true" pageId="4" pageNumber="1879">et al.</emphasis>
|
||
2003
|
||
</bibRefCitation>
|
||
). Estimates of habitat partitioning and living space requirements have been based on the assumption that tyrannosaurids were ectothermic, because ecological models based on extrapolations from much smaller living guilds do not work if tyrannosaurids were endothermic. Our study indicates that
|
||
<taxonomicName box="[844,907,587,608]" class="Reptilia" family="Tyrannosauridae" genus="Tyrannosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="4" pageNumber="1879" phylum="Chordata" rank="species" species="rex">
|
||
<emphasis box="[844,907,587,608]" italics="true" pageId="4" pageNumber="1879">T. rex</emphasis>
|
||
</taxonomicName>
|
||
grew quickly to adult size, and its growth dynamics suggest high basal metabolic rates to sustain this growth (
|
||
<bibRefCitation author="Chinsamy, A." box="[851,1031,647,670]" journalOrPublisher="Mod. Geol." pageId="4" pageNumber="1879" pagination="319 - 329" part="18" refId="ref5560" refString="Chinsamy, A. 1993 Bone histology and growth trajectory of the prosauropod dinosaur Massospondylus carinatus Owen. Mod. Geol. 18, 319 - 329." title="Bone histology and growth trajectory of the prosauropod dinosaur Massospondylus carinatus Owen" type="journal article" year="1993">Chinsamy 1993</bibRefCitation>
|
||
). The question of its food requirements is a different one from that of endothermy: tyrannosaurids may have grown rapidly but not continuously (as occurs in warm-blooded mammals and birds today). It may be that their food requirements lessened during periods when they were not growing so actively. If so, they may have required less food over the course of a year than living mammalian carnivores do. These questions, unfortunately, are unlikely ever to be answered but we stress that the ecological models in question must be viewed with caution, because they require such substantial extrapolations and assumptions. Tyrannosaurids had masses 30 times larger than those of African lions, the largest land carnivores today, and it is often difficult to interpret the ecological roles, habitat preferences and range requirements of extinct dinosaurs (
|
||
<bibRefCitation author="Farlow, J. O. & Pianka, E. R." box="[851,1100,1106,1128]" journalOrPublisher="Hist. Biol." pageId="4" pageNumber="1879" pagination="21 - 40" part="16" refId="ref5719" refString="Farlow, J. O. & Pianka, E. R. 2002 Body size overlap, habitat partitioning, and living space requirements of terrestrial vertebrate predators: implications for the paleoecology of large theropod dinosaurs. Hist. Biol. 16, 21 - 40." title="Body size overlap, habitat partitioning, and living space requirements of terrestrial vertebrate predators: implications for the paleoecology of large theropod dinosaurs" type="journal article" year="2002">Farlow & Pianka 2002</bibRefCitation>
|
||
).
|
||
</paragraph>
|
||
<paragraph blockId="4.[844,1482,159,1494]" pageId="4" pageNumber="1879">
|
||
Although tyrannosaurs grew at rates comparable to those of some large mammals, other dinosaurs grew even more rapidly, as noted above:
|
||
<taxonomicName box="[1107,1221,1198,1219]" class="Reptilia" family="Hadrosauridae" genus="Maiasaura" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="4" pageNumber="1879" phylum="Chordata" rank="genus">
|
||
<emphasis box="[1107,1221,1198,1219]" italics="true" pageId="4" pageNumber="1879">Maiasaura</emphasis>
|
||
</taxonomicName>
|
||
reached adult size at 7– 8 years (
|
||
<bibRefCitation author="Horner, J. R. & de Ricqles, A. & Padian, K." box="[938,1149,1228,1250]" journalOrPublisher="J. Vert. Paleontol." pageId="4" pageNumber="1879" pagination="115 - 129" part="20" refId="ref5806" refString="Horner, J. R., de Ricqles, A. & Padian, K. 2000 Long bone histology of the hadrosaurid dinosaur Maiasaura peeblesorum: growth dynamics and physiology based on an ontogenetic series of skeletal elements. J. Vert. Paleontol. 20, 115 - 129." title="Long bone histology of the hadrosaurid dinosaur Maiasaura peeblesorum: growth dynamics and physiology based on an ontogenetic series of skeletal elements" type="journal article" year="2000">
|
||
Horner
|
||
<emphasis box="[1029,1083,1228,1250]" italics="true" pageId="4" pageNumber="1879">et al.</emphasis>
|
||
2000
|
||
</bibRefCitation>
|
||
) and large sauropods at 8–11 years (
|
||
<bibRefCitation author="Curry-Rogers, K. A." box="[915,1136,1259,1280]" journalOrPublisher="J. Vert. Paleontol." pageId="4" pageNumber="1879" pagination="654 - 665" part="19" refId="ref5601" refString="Curry-Rogers, K. A. 2000 Ontogenetic histology of Apatosaurus (Dinosauria: Sauropoda): new insights on growth rates and longevity. J. Vert. Paleontol. 19, 654 - 665." title="Ontogenetic histology of Apatosaurus (Dinosauria: Sauropoda): new insights on growth rates and longevity" type="journal article" year="2000">Curry-Rogers 2000</bibRefCitation>
|
||
;
|
||
<bibRefCitation author="Sander, P. M." box="[1149,1296,1259,1281]" journalOrPublisher="Paleobiology" pageId="4" pageNumber="1879" pagination="466 - 488" part="26" refId="ref6226" refString="Sander, P. M. 2000 Long bone histology of the Tendaguru sauropods: implications for growth and biology. Paleobiology 26, 466 - 488." title="Long bone histology of the Tendaguru sauropods: implications for growth and biology" type="journal article" year="2000">Sander 2000</bibRefCitation>
|
||
). This pattern is generally explained by the fact that large taxa grow more rapidly than smaller ones (
|
||
<bibRefCitation author="Case, T. J." box="[1129,1250,1320,1341]" journalOrPublisher="Paleobiology" pageId="4" pageNumber="1879" pagination="320 - 328" part="3" refId="ref5426" refString="Case, T. J. 1978 Speculations on the growth rate and reproduction of some dinosaurs. Paleobiology 3, 320 - 328." title="Speculations on the growth rate and reproduction of some dinosaurs" type="journal article" year="1978">Case 1978</bibRefCitation>
|
||
;
|
||
<bibRefCitation author="Erickson, G. M. & Curry Rogers, K. & Yerby, S. A." box="[1260,1477,1320,1342]" journalOrPublisher="Nature" pageId="4" pageNumber="1879" pagination="429 - 433" part="412" refId="ref5683" refString="Erickson, G. M., Curry Rogers, K. & Yerby, S. A. 2001 Dinosaurian growth patterns and rapid avian growth rates. Nature 412, 429 - 433." title="Dinosaurian growth patterns and rapid avian growth rates" type="journal article" year="2001">
|
||
Erickson
|
||
<emphasis box="[1362,1413,1320,1341]" italics="true" pageId="4" pageNumber="1879">et al.</emphasis>
|
||
2001
|
||
</bibRefCitation>
|
||
;
|
||
<bibRefCitation author="Padian, K. & de Ricqles, A. & Horner, J. R." box="[844,1056,1350,1372]" journalOrPublisher="Nature" pageId="4" pageNumber="1879" pagination="405 - 408" part="412" refId="ref5971" refString="Padian, K., de Ricqles, A. & Horner, J. R. 2001 Dinosaurian growth rates and bird origins. Nature 412, 405 - 408." title="Dinosaurian growth rates and bird origins" type="journal article" year="2001">
|
||
Padian
|
||
<emphasis box="[931,987,1350,1372]" italics="true" pageId="4" pageNumber="1879">et al.</emphasis>
|
||
2001
|
||
</bibRefCitation>
|
||
,
|
||
<bibRefCitation author="Padian, K. & Horner, J. R. & de Ricqles, A." box="[1071,1132,1350,1372]" journalOrPublisher="J. Vert. Paleontol." pageId="4" pageNumber="1879" refId="ref6003" refString="Padian, K., Horner, J. R. & de Ricqles, A. 2004 Growth in small dinosaurs and pterosaurs: the evolution of archosaurian growth strategies. J. Vert. Paleontol. (In the press.)" title="Growth in small dinosaurs and pterosaurs: the evolution of archosaurian growth strategies" type="book" year="2004">2004</bibRefCitation>
|
||
), but another ecological factor may be considered: prey species such as hadrosaurs and sauropods may have found an advantage in growing as rapidly as possible, because large size is a defence against predation.
|
||
</paragraph>
|
||
</subSubSection>
|
||
</treatment>
|
||
</document>
|