plazi/treatments-xml
2
0
Fork 0
Code Issues Pull requests Releases Activity
treatments-xml/data/1C/70/87/1C7087B96E3CFFEDFF71FD11AA15F577.xml
maintenance 042285ff4f added 1C
2024-06-21 12:30:48 +02:00

681 lines
87 KiB
XML
Raw Blame History

This file contains invisible Unicode characters

This file contains invisible Unicode characters that are indistinguishable to humans but may be processed differently by a computer. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

<document id="CD59E2A13A59C035D73D729019DCD69C" ID-CLB-Dataset="21507" ID-DOI="10.5281/zenodo.3942851" ID-GBIF-Dataset="ba16ea95-0ab8-4669-b501-cddb7326e00e" ID-Zenodo-Dep="3942851" IM.metadata_requiresApprovalFor="plazi" IM.taxonomicNames_requiresApprovalFor="plazi" checkinTime="1592917892988" checkinUser="jeremy" docAuthor="Kent A. Stevens, Peter Larson, Eric D. Wills &amp; Art Anderson" docDate="2008" docId="1C7087B96E3CFFEDFF71FD11AA15F577" docLanguage="en" docName="Stevensetal2008ABBYY.pdf.imf" docOrigin="Tyrannosaurus rex, the tyrant king, lndiana University Press" docStyle="DocumentStyle{}" docTitle="Tyrannosaurus rex Osborn 1905" docType="treatment" docVersion="9" lastPageNumber="201" masterDocId="E049FFC16E3DFFE4FFDEFFECAE76FFD5" masterDocTitle="Rex, sit: digital modeling of Tyrannosaurus rex at rest" masterLastPageNumber="203" masterPageNumber="192" pageNumber="193" updateTime="1698842841736" updateUser="ExternalLinkService">
<mods:mods id="727650C7B9448FBA2E253D39D18164D7" xmlns:mods="http://www.loc.gov/mods/v3">
<mods:titleInfo id="5C5933F008CC80ACC8196DC923B9A0AB">
<mods:title id="3C4172CE720F2909A39D8271660D8F68">Rex, sit: digital modeling of Tyrannosaurus rex at rest</mods:title>
</mods:titleInfo>
<mods:name id="CC77BE5A1CBDD4126092406B1B631F84" type="personal">
<mods:role id="4F60A5CED8E6AA8D59B0724AB2ED0A89">
<mods:roleTerm id="BB61679BB63A425564790E3485FFC76A">Author</mods:roleTerm>
</mods:role>
<mods:namePart id="8DC525B59FA239372A2E161FFD0953FE">Kent A. Stevens</mods:namePart>
</mods:name>
<mods:name id="2B7E3D36881AAFF1633EB04A1C32E5A7" type="personal">
<mods:role id="05CDBF99B6D7826541CCD83A8D4BDD41">
<mods:roleTerm id="B007D210AA2CEA4E8347F2FB7A1AEEE8">Author</mods:roleTerm>
</mods:role>
<mods:namePart id="B31E05B5D9A7D213F42A83612F2F4A25">Peter Larson</mods:namePart>
</mods:name>
<mods:name id="329C919D595C7D78AC5D359A8CC9B38F" type="personal">
<mods:role id="6630B607016E5654EDDA7B42C072ED07">
<mods:roleTerm id="8208763046269B905A84FBC29F5F7DFF">Author</mods:roleTerm>
</mods:role>
<mods:namePart id="E78E44905E48690629532EC73ECAE982">Eric D. Wills</mods:namePart>
</mods:name>
<mods:name id="5F403371AE650F0C1E4B90F814AEA3F1" type="personal">
<mods:role id="ABCABA3DB161F8CE4BDB055000BEA69F">
<mods:roleTerm id="FD8B25EFBF6E70AF0F921FB71A7553C9">Author</mods:roleTerm>
</mods:role>
<mods:namePart id="AD28596F26226A5D4F6247C806887992">Art Anderson</mods:namePart>
</mods:name>
<mods:typeOfResource id="2AE998E2FD851A53B7BDDCD9E333A6F7">text</mods:typeOfResource>
<mods:relatedItem id="3FF5B92907288AF29E58C6AC9011B1F7" type="host">
<mods:originInfo id="95A7330BADA48F6B3863286F33894250">
<mods:dateIssued id="F69B47E3EC1B6D22066E3DE764FB7093">2008</mods:dateIssued>
<mods:publisher id="E42A9BB47E94544CB369C4ED50310D77">lndiana University Press</mods:publisher>
</mods:originInfo>
<mods:name id="EA6767003D4F48E52751B79C7BC8F19C" type="personal">
<mods:role id="93EDA8D9EE5F6D42399A85CD998CCA40">
<mods:roleTerm id="FDFB8FE82A3EB7E742576ED2ED0B337E">Editor</mods:roleTerm>
</mods:role>
<mods:namePart id="D4B4A7792910FE5BC4AD168261C19520">Peter Larson</mods:namePart>
</mods:name>
<mods:name id="EE8333C56FD5E71D9021F3015FB7232C" type="personal">
<mods:role id="D4F38F005DC8C50401BEBAE2CA70979A">
<mods:roleTerm id="488C46E78B94969D812F8D875B77B6F2">Editor</mods:roleTerm>
</mods:role>
<mods:namePart id="346630DDC730645FF14029E4B6F875B3">Kenneth Carpenter</mods:namePart>
</mods:name>
<mods:titleInfo id="95A0A8C7388500BA8E6C29FD2E24A0C7">
<mods:title id="91E1B53BE431BD63A15FE3CE20583F67">Tyrannosaurus rex, the tyrant king</mods:title>
</mods:titleInfo>
<mods:part id="578AD9B5530101647EA642745149812A">
<mods:extent id="6950F5DE9E07CBC187D8A4C0579CEF2C" unit="page">
<mods:start id="A654AF24805016CF460690937CBEC380">192</mods:start>
<mods:end id="B6F3882058ADC0854042D4A503DFBE68">203</mods:end>
</mods:extent>
</mods:part>
</mods:relatedItem>
<mods:classification id="85F6F79A3719145AE470849AD3558CF1">book chapter</mods:classification>
<mods:identifier id="14C287182A955388B3D11588E8E4D8FC" type="CLB-Dataset">21507</mods:identifier>
<mods:identifier id="48BC3F4B05A5A0BDE7E1C34AD69B66D2" type="DOI">10.5281/zenodo.3942851</mods:identifier>
<mods:identifier id="470D6EDEB8B38497EF88514EC34538C8" type="GBIF-Dataset">ba16ea95-0ab8-4669-b501-cddb7326e00e</mods:identifier>
<mods:identifier id="935D264F32FCD87577B62BAF0EB08D8E" type="Zenodo-Dep">3942851</mods:identifier>
</mods:mods>
<treatment id="1C7087B96E3CFFEDFF71FD11AA15F577" ID-DOI="http://doi.org/10.5281/zenodo.5503883" ID-GBIF-Taxon="165074831" ID-Zenodo-Dep="5503883" LSID="urn:lsid:plazi:treatment:1C7087B96E3CFFEDFF71FD11AA15F577" httpUri="http://treatment.plazi.org/id/1C7087B96E3CFFEDFF71FD11AA15F577" lastPageId="9" lastPageNumber="201" pageId="1" pageNumber="193">
<subSubSection id="DCC365246E3CFFE5FF71FD11AF57F9EB" pageId="1" pageNumber="193" type="nomenclature">
<paragraph id="946636AF6E3CFFE5FF71FD11AF57F9EB" blockId="1.[174,1417,759,2719]" pageId="1" pageNumber="193">
The great theropod
<taxonomicName id="53D94D2C6E3CFFE5FDDAFD11AD47FCF4" authorityName="Osborn" authorityYear="1905" box="[516,817,765,801]" class="Reptilia" family="Tyrannosauridae" genus="Tyrannosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="1" pageNumber="193" phylum="Chordata" rank="species" species="rex">
<emphasis id="A6ADEABD6E3CFFE5FDDAFD11AD47FCF4" box="[516,817,765,801]" italics="true" pageId="1" pageNumber="193">Tyrannosaurus rex</emphasis>
</taxonomicName>
is usually depicted in an active, bipedal pose, perhaps in pursuit of prey or facing off an opponent. Some artists, e.g., Lawrence
<bibRefCitation id="F0484B5E6E3CFFE5FDD8FC8AAC87FC5F" author="Lambe, L. M." box="[518,753,870,906]" journalOrPublisher="Canada Department of Mines, Geologic Survey of Canada, Memoir" pageId="1" pageNumber="193" part="100" refId="ref4718" refString="Lambe, L. M. 1917. The Cretaceous Theropodous Dinosaur Gorgosaurus. Canada Department of Mines, Geologic Survey of Canada, Memoir 100." title="The Cretaceous Theropodous Dinosaur Gorgosaurus" type="book" year="1917">Lambe (1917)</bibRefCitation>
, Gregory S.
<bibRefCitation id="F0484B5E6E3CFFE5FC0CFC8AAAE2FC5F" author="Paul, G. S." box="[978,1172,870,906]" journalOrPublisher="New York Academy of Sciences, New York" pageId="1" pageNumber="193" refId="ref5024" refString="Paul, G. S. 1988. Predatory Dinosaurs of the World. New York Academy of Sciences, New York." title="Predatory Dinosaurs of the World" type="book" year="1988">Paul (1988)</bibRefCitation>
, John Sibbick (
<bibRefCitation id="F0484B5E6E3CFFE5FF63FC71AFDCFC14" author="Norman, D." box="[189,426,925,961]" journalOrPublisher="Prentice Hall General Reference, New York" pageId="1" pageNumber="193" refId="ref4979" refString="Norman, D. 1991. Dinosaur! Prentice Hall General Reference, New York." title="Dinosaur!" type="book" year="1991">Norman 1991</bibRefCitation>
, p. 72), and Michael Skrepnick (
<bibRefCitation id="F0484B5E6E3CFFE5FC3FFC71AB61FC14" author="Currie, P. J. &amp; Koppelhus, E. B. &amp; Shugar, M. A. &amp; Wright, J. L." box="[993,1303,925,961]" journalOrPublisher="Indiana University Press, Bloomington" pageId="1" pageNumber="193" refId="ref4461" refString="Currie, P. J., Koppelhus, E. B., Shugar, M. A., and Wright, J. L. 2004. Feathered Dragons. Indiana University Press, Bloomington." title="Feathered Dragons" type="book" year="2004">Currie et al. 2004</bibRefCitation>
), have provided views of these animals in other, less active postures, including lying prone or squatting. Presumably the animal would rest with a substantial portion of its body mass supported by the prominent pubic boot. Trace fossils of small crouching theropods show both tarsal and pubic-ischiatic impressions (e.g.,
<bibRefCitation id="F0484B5E6E3CFFE5FE0AFB4AAD5CFB1F" author="Gierliriski, G. &amp; Lockley, M. &amp; Milner, A. R. C." box="[468,810,1190,1226]" journalOrPublisher="Dixie State College, St. George, UT" pageId="1" pageNumber="193" pagination="4" refId="ref4533" refString="Gierliriski, G., Lockley, M., and Milner, A. R. C. 2005. Traces of early Jurassic crouching dinosaurs. P. 4 in Tracking Dinosaur Origins: The Triassic / Jurassic Terrestrial Transition Abstract Volume. Dixie State College, St. George, UT." title="Traces of early Jurassic crouching dinosaurs" type="proceedings" volumeTitle="Tracking Dinosaur Origins: The Triassic / Jurassic Terrestrial Transition Abstract Volume" year="2005">Gierliriski et al. 2005</bibRefCitation>
). In the great theropods, descending from a standing pose to a rest position was presumably a straightforward matter of squatting, a process considerably less involved than the complex sequencing of folding movements that some modern large quadrupeds, such as camelids (
<bibRefCitation id="F0484B5E6E3CFFE5FE04FA90AD93FA75" author="Gauthier-Pilters, H. &amp; Daag, A. I." box="[474,997,1404,1440]" journalOrPublisher="University of Chicago Press, Chicago" pageId="1" pageNumber="193" refId="ref4500" refString="Gauthier-Pilters, H., and Daag, A. I. 1981. The Camel: Its Ecology, Behavior and Relationship to Man. University of Chicago Press, Chicago." title="The Camel: Its Ecology, Behavior and Relationship to Man" type="book" year="1981">Gauthier-Pilters and Daag 1981</bibRefCitation>
) and bovids, use to lower their mass to the ground.
<taxonomicName id="53D94D2C6E3CFFE5FD8CFA5CAD0CFA01" authorityName="Osborn" authorityYear="1905" box="[594,890,1456,1492]" class="Reptilia" family="Tyrannosauridae" genus="Tyrannosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="1" pageNumber="193" phylum="Chordata" rank="species" species="rex">
<emphasis id="A6ADEABD6E3CFFE5FD8CFA5CAD0CFA01" box="[594,890,1456,1492]" italics="true" pageId="1" pageNumber="193">Tyrannosaurus rex</emphasis>
</taxonomicName>
might simply have settled vertically in one continuous flexion movement involving the hip, knee, and ankles.
</paragraph>
</subSubSection>
<subSubSection id="DCC365246E3CFFEDFF22F9A3ACD6F8A8" lastPageId="9" lastPageNumber="201" pageId="1" pageNumber="193" type="description">
<paragraph id="946636AF6E3CFFE5FF22F9A3AC00F769" blockId="1.[174,1417,759,2719]" pageId="1" pageNumber="193">
It is in rising from a prone or squatting rest position that some concern for the mechanics of the tvrannosaurid frame might present itself. How could the center of mass (COM) be controlled so that the animal was stable while rising? Was there sufficient mechanical advantage in the major extensor muscles to provide a direct ascent that retraces the trajectory followed in descending to the ground? Were the forelimbs useful in stabilizing the body and in providing thrust during the initial stages of the ascent? To address some of these questions, a fully articulated digital model of
<taxonomicName id="53D94D2C6E3CFFE5FA8AF829AFC5F7CB" authorityName="Osborn" authorityYear="1905" class="Reptilia" family="Tyrannosauridae" genus="Tyrannosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="1" pageNumber="193" phylum="Chordata" rank="species" species="rex">
<emphasis id="A6ADEABD6E3CFFE5FA8AF829AFC5F7CB" italics="true" pageId="1" pageNumber="193">Tyrannosaurus rex</emphasis>
</taxonomicName>
was created where limb movements are delimited
<emphasis id="A6ADEABD6E3CFFE5FAD2F816AB45F7CB" box="[1292,1331,2042,2078]" italics="true" pageId="1" pageNumber="193">by</emphasis>
anatomically based estimates of achievable range of motion, and the position of the instantaneous COM of the animal can be visualized in order to judge balance and stability.
</paragraph>
<paragraph id="946636AF6E3CFFE6FF24F723A8E1FEA4" blockId="1.[174,1417,759,2719]" lastBlockId="2.[654,1897,168,1701]" lastPageId="2" lastPageNumber="194" pageId="1" pageNumber="193">
Extant bipeds that might serve as analogs for studying the sitting and standing movements of
<taxonomicName id="53D94D2C6E3CFFE5FD92F6E8ACDAF6FD" authorityName="Osborn" authorityYear="1905" box="[588,684,2308,2344]" class="Reptilia" family="Tyrannosauridae" genus="Tyrannosaurus" kingdom="Animalia" order="Dinosauria" pageId="1" pageNumber="193" phylum="Chordata" rank="species" species="rex">
<emphasis id="A6ADEABD6E3CFFE5FD92F6E8AC12F6FD" box="[588,612,2308,2344]" italics="true" pageId="1" pageNumber="193">T</emphasis>
.
<emphasis id="A6ADEABD6E3CFFE5FDA5F6E8ACDAF6FD" box="[635,684,2308,2344]" italics="true" pageId="1" pageNumber="193">rex</emphasis>
</taxonomicName>
<emphasis id="A6ADEABD6E3CFFE5FD72F6E8ACC4F6FD" box="[684,690,2308,2344]" italics="true" pageId="1" pageNumber="193">,</emphasis>
include members of the Macropodoidea, notably the large red kangaroo
<emphasis id="A6ADEABD6E3CFFE5FD0BF6D6AC97F68B" box="[725,737,2362,2398]" italics="true" pageId="1" pageNumber="193">(</emphasis>
Macropus
<emphasis id="A6ADEABD6E3CFFE5FC46F6D6AD80F68B" box="[920,1014,2362,2398]" italics="true" pageId="1" pageNumber="193">rufus)</emphasis>
and a variety of birds, particularly the large ratites such as the emu
<emphasis id="A6ADEABD6E3CFFE5FC73F683ABF4F646" box="[941,1410,2415,2451]" italics="true" pageId="1" pageNumber="193">(Dromaius novaehollandiae)</emphasis>
and the ostrich
<emphasis id="A6ADEABD6E3CFFE5FE19F648AFA5F61D" box="[455,467,2468,2504]" italics="true" pageId="1" pageNumber="193">(</emphasis>
Struthio camelus
<emphasis id="A6ADEABD6E3CFFE5FD31F648AD76F61D" box="[751,768,2468,2504]" italics="true" pageId="1" pageNumber="193">).</emphasis>
As animal mass increases, muscular strategies cannot be expected to scale indefinitely (
<bibRefCitation id="F0484B5E6E3CFFE5FBFEF635AB58F628" author="Alexander, R. McN" box="[1056,1326,2521,2557]" journalOrPublisher="Columbia University Press, New York" pageId="1" pageNumber="193" refId="ref4364" refString="Alexander, R. McN. 1989. Dynamics of Dinosaurs and Other Extinct Giants. Columbia University Press, New York." title="Dynamics of Dinosaurs and Other Extinct Giants" type="book" year="1989">Alexander 1989</bibRefCitation>
); the effortless rise of a small passerine from rest to a bipedal stance might require multiple, more deliberate stages of limb extension in a biped of several orders greater weight. The biomechanical principles governing the choice of strategy, particularly as regards scaling with body mass, are not well understood. Motion studies have concentrated on capturing relatively steady-state locomotion (e.g.,
<bibRefCitation id="F0484B5E6E3FFFE6FBA5FEFBABE6FEEE" author="Muybridge, E." box="[1147,1424,279,315]" journalOrPublisher="London: Chapman &amp; Hall" pageId="2" pageNumber="194" refId="ref4929" refString="Muybridge, E. 1899. Animals in Motion. London: Chapman &amp; Hall. Dover reprint, 1957." title="Animals in Motion" type="book" year="1899">Muybridge 1899</bibRefCitation>
: Jenkins etal. 1988), not the transient body movements associated with sitting or standing.
</paragraph>
<paragraph id="946636AF6E3FFFE6FD07FE6DA851FC53" blockId="2.[654,1897,168,1701]" pageId="2" pageNumber="194">To examine the potential movements that take the animal from standing to sitting, and vice versa, it is important to begin with an estimation of the typical stand and sit postures. Movements that smoothly transition between these extremes can then be proposed and analyzed. In their analysis, it is important to understand how the COM translates during the movement. Longitudinal (caudal-cranial) pitching movements in particular would produce instability that would have to be corrected at risk of injury to the great theropod. It is also important to examine range of motion issues throughout the sit-stand movements and the mechanical leverage of large muscle groups for providing the necessary movements.</paragraph>
<paragraph id="946636AF6E3FFFE6FD05FC79AD5FFB2F" blockId="2.[654,1897,168,1701]" pageId="2" pageNumber="194">
Proposals have been offered for how
<taxonomicName id="53D94D2C6E3FFFE6FA9FFC79ABECFC6C" authorityName="Osborn" authorityYear="1905" box="[1345,1434,917,953]" class="Reptilia" family="Tyrannosauridae" genus="Tyrannosaurus" kingdom="Animalia" order="Dinosauria" pageId="2" pageNumber="194" phylum="Chordata" rank="species" species="rex">
T.
<emphasis id="A6ADEABD6E3FFFE6FAB2FC79ABECFC6C" box="[1388,1434,917,953]" italics="true" pageId="2" pageNumber="194">rex</emphasis>
</taxonomicName>
could sit down on its pubic boot, then rise by first using the forearms as props to help anchor the front of the body while the rear legs were straightened. The upper body would then be tilted back to regain an upright standing posture (
<bibRefCitation id="F0484B5E6E3FFFE6F984FBDAA925FB8F" author="Newman, B. H." box="[1626,1875,1078,1114]" journalOrPublisher="Biological Journal of the Linnean Society" pageId="2" pageNumber="194" pagination="119 - 123" part="2" refId="ref4950" refString="Newman, B. H. 1970. Stance and gait in the flesh-eating dinosaur Tyrannosaurus. Biological Journal of the Linnean Society 2: 119 - 123." title="Stance and gait in the flesh-eating dinosaur Tyrannosaurus" type="journal article" year="1970">Newman 1970</bibRefCitation>
). This idea is but one of the potential uses proposed for the forelimbs (
<bibRefCitation id="F0484B5E6E3FFFE6F8F2FB87AD4BFB16" author="Osborn, H. F." journalOrPublisher="Bulletin of the American Museum of Natural History" pageId="2" pageNumber="194" pagination="281 - 296" part="22" refId="ref4995" refString="Osborn, H. F. 1906. Tyrannosaurus, Upper Cretaceous carnivorous dinosaur. Bulletin of the American Museum of Natural History 22: 281 - 296." title="Tyrannosaurus, Upper Cretaceous carnivorous dinosaur" type="journal article" year="1906">Osborn 1906</bibRefCitation>
;
<bibRefCitation id="F0484B5E6E3FFFE6FC8EFB73AA82FB16" author="Horner, J. R. &amp; Lessem, D." box="[848,1268,1183,1219]" journalOrPublisher="Simon &amp; Schuster, New York" pageId="2" pageNumber="194" refId="ref4620" refString="Horner, J. R., and Lessem, D. 1993. The Complete T. rex. Simon &amp; Schuster, New York." title="The Complete T. rex" type="book" year="1993">Horner and Lessem 1993</bibRefCitation>
;
<bibRefCitation id="F0484B5E6E3FFFE6FAD8FB73A8BFFB11" author="Carpenter, K. &amp; Smith, M." box="[1286,1737,1183,1220]" editor="Tanke, D. &amp; Carpenter, K." journalOrPublisher="Indiana University Press, Indiana" pageId="2" pageNumber="194" pagination="90 - 116" refId="ref4410" refString="Carpenter, K., and Smith, M. 2001. Forelimb osteology and biomechanics of Tyrannosaurus rex. P. 90 - 116 in Tanke, D., and Carpenter, K. (eds.). Mesozoic Vertebrate Life. Indiana University Press, Indiana." title="Forelimb osteology and biomechanics of Tyrannosaurus rex" type="book chapter" volumeTitle="Mesozoic Vertebrate Life" year="2001">Carpenter and Smith 2001</bibRefCitation>
;
<bibRefCitation id="F0484B5E6E3FFFE6F905FB4CAD6FFB2F" author="Carpenter, K." journalOrPublisher="Senckenbergiana Lethaea" pageId="2" pageNumber="194" pagination="59 - 76" part="82" refId="ref4387" refString="Carpenter, K. 2002. Forelimb biomechanics of nonavian theropod dinosaurs in predation. Senckenbergiana Lethaea 82: 59 - 76." title="Forelimb biomechanics of nonavian theropod dinosaurs in predation" type="journal article" year="2002">Carpenter 2002</bibRefCitation>
).
</paragraph>
<paragraph id="946636AF6E3FFFE6FD02FAE6A8C7F976" blockId="2.[654,1897,168,1701]" pageId="2" pageNumber="194">In the following, an articulated, 3-dimensional digital reconstruction is used to explore alternative hypotheses regarding the sit-stand movements of this dinosaur. The process of descending and then ascending is amenable to quantitative modeling, taking into consideration the distribution of mass in the animal and the flexibility of those joints involved in the movements, particularly the ankle, knee, and hip within the hind limb, and the potential role of the forelimbs in the process of rising. QuickTime video showing the action is available in the supplemental CD-ROM.</paragraph>
<paragraph id="946636AF6E3FFFE6FF77F8F7AF51F81D" blockId="2.[168,543,1819,1992]" pageId="2" pageNumber="194">
<heading id="CF2E81C36E3FFFE6FF77F8F7AF51F81D" bold="true" fontSize="17" level="1" pageId="2" pageNumber="194" reason="0">Creating an Articulated Digital Model</heading>
</paragraph>
<paragraph id="946636AF6E3FFFE6FD4FF8C8AD90F62B" blockId="2.[656,1898,1824,2718]" pageId="2" pageNumber="194">
DinoMorph software (
<bibRefCitation id="F0484B5E6E3FFFE6FBCEF8C8AA9AF89D" author="Stevens, K. A." box="[1040,1260,1828,1864]" journalOrPublisher="Senckenbergiana Lethaea" pageId="2" pageNumber="194" pagination="23 - 34" part="82" refId="ref5047" refString="Stevens, K. A. 2002. DinoMorph: parametric modeling of skeletal structures. Senckenbergiana Lethaea 82 (1): 23 - 34." title="DinoMorph: parametric modeling of skeletal structures" type="journal article" year="2002">Stevens 2002</bibRefCitation>
) provides a framework with which to create and pose a digital model of
<taxonomicName id="53D94D2C6E3FFFE6FB14F8B4AB8EF8A8" authorityName="Osborn" authorityYear="1905" box="[1226,1528,1880,1917]" class="Reptilia" family="Tyrannosauridae" genus="Tyrannosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="2" pageNumber="194" phylum="Chordata" rank="species" species="rex">
<emphasis id="A6ADEABD6E3FFFE6FB14F8B4ABCAF8A9" box="[1226,1468,1880,1916]" italics="true" pageId="2" pageNumber="194">Tyrannosaurus</emphasis>
rex
</taxonomicName>
. The software can accept 3-dimensional data representing bone morphology (e.g., from computed tomographic [CT] scan or hand digitization), as well as more schematic and simplified representations. In this study, the
<taxonomicName id="53D94D2C6E3FFFE6F9E6F816A910F7CB" authorityName="Osborn" authorityYear="1905" box="[1592,1894,2042,2078]" class="Reptilia" family="Tyrannosauridae" genus="Tyrannosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="2" pageNumber="194" phylum="Chordata" rank="species" species="rex">
<emphasis id="A6ADEABD6E3FFFE6F9E6F816A910F7CB" box="[1592,1894,2042,2078]" italics="true" pageId="2" pageNumber="194">Tyrannosaurus rex</emphasis>
</taxonomicName>
specimen
<materialsCitation id="24B13CF26E3FFFE6FC9EF7C3ADABF786" ID-GBIF-Occurrence="2813096303" box="[832,989,2095,2131]" collectionCode="BHI" pageId="2" pageNumber="194" specimenCode="BHI 3033">BHI 3033</materialsCitation>
(Stan) at the Black Hills Museum of Natural History was used as the source for the digital model. The articulation of the appendicular skeleton and the morphology of the pelvic and pectoral girdles were of particular importance, so they were specifically for this study (
<figureCitation id="0CE22A2A6E3FFFE6F8FBF73CACA2F6F2" captionStart="Figure 11.1" captionStartId="0.[188,282,1895,1923]" captionTargetBox="[6,2068,180,1816]" captionTargetPageId="0" captionText="Figure 11.1. Ray Wilhite using an Immersion Microscribe digitizer on casts of elements of the pelvic girdle of Tyrannosaurus rex specimen BHI 3033 (Stan). Photo courtesy Ray Wilhite and Virtual Surfaces Inc." figureDoi="http://doi.org/10.5281/zenodo.3942853" httpUri="https://zenodo.org/record/3942853/files/figure.png" pageId="2" pageNumber="194" targetBox="[6,2068,180,1816]" targetPageId="0">Fig. 11.1</figureCitation>
). Digitization data of the head was provided from an earlier CT scan made by Virtual Surfaces Inc. and the Black Hills Institute. The remainder of the axial skeleton was modeled schematically, with centra, neural spines, lateral processes, chevrons, and ribs in a dimensionally accurate but simplified form (
<figureCitation id="0CE22A2A6E3FFFE6FC99F636ADA1F62B" box="[839,983,2522,2558]" captionStart="Figure 11.1" captionStartId="0.[188,282,1895,1923]" captionTargetBox="[6,2068,180,1816]" captionTargetPageId="0" captionText="Figure 11.1. Ray Wilhite using an Immersion Microscribe digitizer on casts of elements of the pelvic girdle of Tyrannosaurus rex specimen BHI 3033 (Stan). Photo courtesy Ray Wilhite and Virtual Surfaces Inc." figureDoi="http://doi.org/10.5281/zenodo.3942853" httpUri="https://zenodo.org/record/3942853/files/figure.png" pageId="2" pageNumber="194" targetBox="[180,1909,167,1382]" targetPageId="3">Fig. 11.2</figureCitation>
).
</paragraph>
<paragraph id="946636AF6E3FFFE7FD02F5E2AAABF86D" blockId="2.[656,1898,1824,2718]" lastBlockId="3.[180,1422,1456,2723]" lastPageId="3" lastPageNumber="195" pageId="2" pageNumber="194">
The next step was to estimate the relative placement of each bone within the overall skeletal framework. Along the presacral axial skeleton, the intervertebral separations and overall curvature were determined from measurements and photographs in lateral view. Likewise, the rib cage was formed by painstakingly adjusting each digitally represented dorsal rib to match the curvature, dimensions, and placement of its counterpart in reference photographs that were underlaid within DinoMorph as background images (
<figureCitation id="0CE22A2A6E3EFFE7FE98F965AFAEF978" box="[326,472,1673,1709]" captionStart="Figure 11.1" captionStartId="0.[188,282,1895,1923]" captionTargetBox="[6,2068,180,1816]" captionTargetPageId="0" captionText="Figure 11.1. Ray Wilhite using an Immersion Microscribe digitizer on casts of elements of the pelvic girdle of Tyrannosaurus rex specimen BHI 3033 (Stan). Photo courtesy Ray Wilhite and Virtual Surfaces Inc." figureDoi="http://doi.org/10.5281/zenodo.3942853" httpUri="https://zenodo.org/record/3942853/files/figure.png" pageId="3" pageNumber="195" targetBox="[647,1888,171,1587]" targetPageId="4">Fig. 11.3</figureCitation>
). To refine the 3-dimensional skeletal model, the trunk was successively viewed in anterior, dorsal, and lateral orientations, and for each view, the curvature and placement of the ribs were adjusted so that the digital ribs superimposed precisely over their photographic counterparts. The pelvic girdles, complete with furcula, were then placed on the rib cage as they are mounted on Stan (
<bibRefCitation id="F0484B5E6E3EFFE7FC9FF878AABBF86D" author="Larson, P. L. &amp; Rigby, K., Jr." box="[833,1229,1940,1976]" editor="Carpenter, K." journalOrPublisher="Indiana University Press, Bloomington" pageId="3" pageNumber="195" pagination="247 - 255" refId="ref4882" refString="Larson, P. L., and Rigby, K., Jr. 2005. The furcula of Tyrannosaurus rex. P. 247 - 255 in Carpenter, K. (ed.). Carnivorous Dinosaurs. Indiana University Press, Bloomington." title="The furcula of Tyrannosaurus rex" type="book chapter" volumeTitle="Carnivorous Dinosaurs" year="2005">Larson and Rigby 2005</bibRefCitation>
).
</paragraph>
<caption id="C0A666276E3EFFE7FA07FA54A83EF616" ID-DOI="http://doi.org/10.5281/zenodo.3942855" ID-Zenodo-Dep="3942855" httpUri="https://zenodo.org/record/3942855/files/figure.png" pageId="3" pageNumber="195" startId="3.[1497,1591,1464,1492]" targetBox="[180,1909,167,1382]" targetPageId="3">
<paragraph id="946636AF6E3EFFE7FA07FA54A83EF616" blockId="3.[1494,1901,1457,2499]" pageId="3" pageNumber="195">
Figure 11.2.
<emphasis id="A6ADEABD6E3EFFE7F940FA54A8DEFA01" box="[1694,1704,1464,1492]" italics="true" pageId="3" pageNumber="195">(</emphasis>
A
<emphasis id="A6ADEABD6E3EFFE7F91EFA54A8BCFA01" box="[1728,1738,1464,1492]" italics="true" pageId="3" pageNumber="195">)</emphasis>
Dino­ Morph model of
<taxonomicName id="53D94D2C6E3EFFE7F933FA04A8CFF9E1" authorityName="Osborn" authorityYear="1905" class="Reptilia" family="Tyrannosauridae" genus="Tyrannosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="3" pageNumber="195" phylum="Chordata" rank="species" species="rex">
<emphasis id="A6ADEABD6E3EFFE7F933FA04A800F9E1" italics="true" pageId="3" pageNumber="195">Tyrannosaurus</emphasis>
<emphasis id="A6ADEABD6E3EFFE7F95CF9F4A8CFF9E1" bold="true" box="[1666,1721,1560,1588]" pageId="3" pageNumber="195">rex</emphasis>
</taxonomicName>
specimen
<emphasis id="A6ADEABD6E3EFFE7FA09F9A4A8A2F9B1" box="[1495,1748,1608,1636]" italics="true" pageId="3" pageNumber="195">
<materialsCitation id="24B13CF26E3EFFE7FA09F9A4A81FF9B1" ID-GBIF-Occurrence="2813096304" box="[1495,1641,1608,1636]" collectionCode="BHI" pageId="3" pageNumber="195" specimenCode="BHI 3033">BHI3033</materialsCitation>
(Stan).
</emphasis>
The appendicular skeleton and head
<emphasis id="A6ADEABD6E3EFFE7F9EDF944A8F6F911" box="[1587,1664,1704,1732]" italics="true" pageId="3" pageNumber="195">were</emphasis>
digitized
<emphasis id="A6ADEABD6E3EFFE7FA07F934A82BF921" box="[1497,1629,1752,1780]" italics="true" pageId="3" pageNumber="195">whereas</emphasis>
the axial
<emphasis id="A6ADEABD6E3EFFE7F927F934A869F8F0" italics="true" pageId="3" pageNumber="195">skeleton</emphasis>
was represented schematic
<emphasis id="A6ADEABD6E3EFFE7F95CF8D4A953F881" box="[1666,1829,1848,1876]" italics="true" pageId="3" pageNumber="195">form, with</emphasis>
important dimensions
<emphasis id="A6ADEABD6E3EFFE7FA06F874AB90F861" box="[1496,1510,1944,1972]" italics="true" pageId="3" pageNumber="195">(</emphasis>
e.g., centrum length, neural
<emphasis id="A6ADEABD6E3EFFE7F99BF824A8EFF831" box="[1605,1689,1992,2020]" italics="true" pageId="3" pageNumber="195">spine</emphasis>
height, and intervertebral
<emphasis id="A6ADEABD6E3EFFE7F967F815A85BF791" italics="true" pageId="3" pageNumber="195">separations)</emphasis>
dimensionally
<emphasis id="A6ADEABD6E3EFFE7F8C3F7C4A84CF7A0" italics="true" pageId="3" pageNumber="195">accurate</emphasis>
.
<emphasis id="A6ADEABD6E3EFFE7F98FF7B5A80EF7A0" box="[1617,1656,2137,2165]" italics="true" pageId="3" pageNumber="195">(B)</emphasis>
The axial
<emphasis id="A6ADEABD6E3EFFE7F8C4F7B5A869F770" italics="true" pageId="3" pageNumber="195">skeleton</emphasis>
was
<emphasis id="A6ADEABD6E3EFFE7F9AAF765A8DBF770" box="[1652,1709,2185,2213]" italics="true" pageId="3" pageNumber="195">laid</emphasis>
out with reference to measurements taken
<emphasis id="A6ADEABD6E3EFFE7F974F704A882F6D1" box="[1706,1780,2280,2308]" italics="true" pageId="3" pageNumber="195">from</emphasis>
the mount
<emphasis id="A6ADEABD6E3EFFE7F995F6F5A8FFF6E0" box="[1611,1673,2329,2357]" italics="true" pageId="3" pageNumber="195">and</emphasis>
photographs
<emphasis id="A6ADEABD6E3EFFE7FA06F6A4AB92F6B1" box="[1496,1508,2376,2404]" italics="true" pageId="3" pageNumber="195">(</emphasis>
see text
<emphasis id="A6ADEABD6E3EFFE7F982F6A4A81BF6B1" box="[1628,1645,2376,2404]" italics="true" pageId="3" pageNumber="195">).</emphasis>
Scale bar
<emphasis id="A6ADEABD6E3EFFE7F8C7F6A4A85EF641" italics="true" pageId="3" pageNumber="195">indicates</emphasis>
an overall length of
<emphasis id="A6ADEABD6E3EFFE7FA03F64BA86FF616" box="[1501,1561,2471,2499]" italics="true" pageId="3" pageNumber="195">11.2</emphasis>
m.
</paragraph>
</caption>
<paragraph id="946636AF6E3EFFE7FEDFF825AA6AF618" blockId="3.[180,1422,1456,2723]" pageId="3" pageNumber="195">Next, those DinoMorph parameters governing the position and orientation of all appendicular joints were adjusted to create a neutral standing pose, the starting point for this study. Then, for the major appendicular joints important to this study, a range of motion was determined on the basis of an estimate of the thickness and extent of the intervening cartilage in modern avians and direct manipulation of the casts (Kenneth Carpenter and Yoshio Ito, personal communication June 2005). Direct manipulation assisted in determining, for example, the axis of rotation of the femur head within the acetabulum, and in the forelimb the orientation of the fully extended forelimb with respect to the pectoral girdles.</paragraph>
<paragraph id="946636AF6E3EFFE1FEDFF632AC7EF972" blockId="3.[180,1422,1456,2723]" lastBlockId="5.[176,1410,1556,1705]" lastPageId="5" lastPageNumber="197" pageId="3" pageNumber="195">
In analyzing potential sit-stand strategies of a theropod dinosaur weighing several metric tonnes, it is important to track the trajectory' undertaken bv the COM during hypothesized movement. The COM is computed in DinoMorph bv assigning both a volume and a density to each discrete segment of the skeleton, such as each interval of the axial skeleton associated with an individual vertebra. Fitted conical and elliptical cylinders are used as a first-order approximation to the body cross-sectional area, governed by adjustable parameters (
<figureCitation id="0CE22A2A6E39FFE0FB27F8CDABF9F890" box="[1273,1423,1825,1861]" captionStart="Figure 11.1" captionStartId="0.[188,282,1895,1923]" captionTargetBox="[6,2068,180,1816]" captionTargetPageId="0" captionText="Figure 11.1. Ray Wilhite using an Immersion Microscribe digitizer on casts of elements of the pelvic girdle of Tyrannosaurus rex specimen BHI 3033 (Stan). Photo courtesy Ray Wilhite and Virtual Surfaces Inc." figureDoi="http://doi.org/10.5281/zenodo.3942853" httpUri="https://zenodo.org/record/3942853/files/figure.png" pageId="4" pageNumber="196" targetBox="[173,1905,175,1482]" targetPageId="5">Fig. 11.4</figureCitation>
). The density (i.e., specific gravity) associated with each segment was adjusted to roughly reflect cranial and axial pneumaticity, air sacs, and lungs. The COM was computed by summating the gravitational moments associated with each segment throughout the skeleton. By assigning densities of 0.8-1.0 to presacral regions and 1.0 to segments of the appendicular skeleton and caudal vertebral series, the overall COM was located just anterior to the pubic shaft (see
<figureCitation id="0CE22A2A6E39FFE0FD3CF77AADEFF76F" box="[738,921,2198,2234]" captionStart="Figure 11.1" captionStartId="0.[188,282,1895,1923]" captionTargetBox="[6,2068,180,1816]" captionTargetPageId="0" captionText="Figure 11.1. Ray Wilhite using an Immersion Microscribe digitizer on casts of elements of the pelvic girdle of Tyrannosaurus rex specimen BHI 3033 (Stan). Photo courtesy Ray Wilhite and Virtual Surfaces Inc." figureDoi="http://doi.org/10.5281/zenodo.3942853" httpUri="https://zenodo.org/record/3942853/files/figure.png" pageId="4" pageNumber="196">Fig. 11.4B</figureCitation>
), consistent with estimates by
<bibRefCitation id="F0484B5E6E39FFE0FA0FF77AA97CF76F" author="Henderson, D. M." box="[1489,1802,2198,2234]" journalOrPublisher="Paleobiology" pageId="4" pageNumber="196" pagination="88 - 106" part="25" refId="ref4588" refString="Henderson, D. M. 1999. Estimating the masses and centers of mass of extinct animals by 3 - D mathematical slicing. Paleobiology 25: 88 - 106." title="Estimating the masses and centers of mass of extinct animals by 3 - D mathematical slicing" type="journal article" year="1999">Henderson (1999)</bibRefCitation>
and
<bibRefCitation id="F0484B5E6E39FFE0FD52F720AAE0F725" author="Hutchinson, J. R. &amp; Garcia, M." box="[652,1174,2252,2288]" journalOrPublisher="Nature" pageId="4" pageNumber="196" pagination="1018 - 1021" part="415" refId="ref4647" refString="Hutchinson, J. R., and Garcia, M. 2002. Tyrannosaurus was not a fast runner. Nature 415: 1018 - 1021." title="Tyrannosaurus was not a fast runner" type="journal article" year="2002">Hutchinson and Garcia (2002)</bibRefCitation>
. Small but potentially significant shifts in the instantaneous COM during movements could be detected visually as the movement unfolded. For this study, a lithe reconstruction of the cross sections of soft tissue associated with each segment of the skeleton was chosen to corresponding to recent computations by one of us (P. L.). The resulting overall mass for
<materialsCitation id="24B13CF26E39FFE0FBE1F639AAAAF62C" ID-GBIF-Occurrence="2813096302" box="[1087,1244,2517,2553]" collectionCode="BHI" pageId="4" pageNumber="196" specimenCode="BHI 3033">BHI 3033</materialsCitation>
(Stan) was estimated as ~4400 kg., or about 80% of the mass estimated for the more robust specimen
<materialsCitation id="24B13CF26E39FFE0F93FF5E7AD7FF5B1" ID-GBIF-Occurrence="2813096301" collectionCode="FMNH" pageId="4" pageNumber="196" specimenCode="FMNH PR2081">FMNH PR2081</materialsCitation>
(Sue) by using the same techniques (Stevens et al., in preparation). Although it was possible to estimate as little as 3800 kg for the same skeletal structure
<emphasis id="A6ADEABD6E38FFE1FE89F9F5AF0BF9E8" box="[343,381,1561,1597]" italics="true" pageId="5" pageNumber="197">by</emphasis>
progressively reducing body bulk, particularly in the pelvic region, for this study, the position of the COM was of greater importance than the magnitude.
</paragraph>
<caption id="C0A666276E39FFE0FF7EFF5DAFC1FC4B" ID-DOI="http://doi.org/10.5281/zenodo.3942857" ID-Zenodo-Dep="3942857" httpUri="https://zenodo.org/record/3942857/files/figure.png" pageId="4" pageNumber="196" startId="4.[160,255,177,205]" targetBox="[647,1888,171,1587]" targetPageId="4">
<paragraph id="946636AF6E39FFE0FF7EFF5DAFC1FC4B" blockId="4.[158,565,170,926]" pageId="4" pageNumber="196">
<emphasis id="A6ADEABD6E39FFE0FF7EFF5DAE89FF18" box="[160,255,177,205]" italics="true" pageId="4" pageNumber="196">Figure</emphasis>
11.3.
<emphasis id="A6ADEABD6E39FFE0FEBBFF5DAF06FF18" box="[357,368,177,205]" italics="true" pageId="4" pageNumber="196">(</emphasis>
A
<emphasis id="A6ADEABD6E39FFE0FE56FF5DAFE5FF18" box="[392,403,177,205]" italics="true" pageId="4" pageNumber="196">)</emphasis>
<emphasis id="A6ADEABD6E39FFE0FE43FF5DAC70FF18" bold="true" box="[413,518,177,205]" pageId="4" pageNumber="196">Screen</emphasis>
<emphasis id="A6ADEABD6E39FFE0FF41FF0EAF77FF2B" box="[159,257,226,254]" italics="true" pageId="4" pageNumber="196">image</emphasis>
showing the
<emphasis id="A6ADEABD6E39FFE0FE00FF0EAF13FEF8" italics="true" pageId="4" pageNumber="196">reconstruction</emphasis>
of the trunk
<emphasis id="A6ADEABD6E39FFE0FF40FEADAFF7FE88" box="[158,385,321,349]" italics="true" pageId="4" pageNumber="196">superimposed</emphasis>
on a reference photograph of an
<emphasis id="A6ADEABD6E39FFE0FF41FE4DAF45FE68" box="[159,307,417,445]" italics="true" pageId="4" pageNumber="196">assembly</emphasis>
of
<emphasis id="A6ADEABD6E39FFE0FEB9FE4DAFC3FE68" bold="true" box="[359,437,417,445]" pageId="4" pageNumber="196">casts</emphasis>
of the Stan specimen.
<emphasis id="A6ADEABD6E39FFE0FE43FE3DAFF4FDC8" italics="true" pageId="4" pageNumber="196">Background image</emphasis>
courtesy
<emphasis id="A6ADEABD6E39FFE0FF7EFDDDAF48FD98" box="[160,318,561,589]" italics="true" pageId="4" pageNumber="196">Black Hills</emphasis>
Institute of
<emphasis id="A6ADEABD6E39FFE0FF7CFD8DAF2FFD78" italics="true" pageId="4" pageNumber="196">Geologic Research. (B) DinoMorph</emphasis>
model shown with addition of
<emphasis id="A6ADEABD6E39FFE0FF7EFD1EAF5CFCDB" box="[160,298,754,782]" italics="true" pageId="4" pageNumber="196">digitized</emphasis>
pectoral girdles
<emphasis id="A6ADEABD6E39FFE0FF7FFCCDAEDAFCE8" box="[161,172,801,829]" italics="true" pageId="4" pageNumber="196">(</emphasis>
<emphasis id="A6ADEABD6E39FFE0FF72FCCDAF4BFCE8" bold="true" box="[172,317,801,829]" pageId="4" pageNumber="196">including</emphasis>
furcula
<emphasis id="A6ADEABD6E39FFE0FE69FCCDAE8DFCBB" italics="true" pageId="4" pageNumber="196">
),
<emphasis id="A6ADEABD6E39FFE0FE09FCCDAE83FCBB" bold="true" pageId="4" pageNumber="196">forelimbs</emphasis>
,
</emphasis>
and
<emphasis id="A6ADEABD6E39FFE0FE91FCBEAFDAFCBB" box="[335,428,850,878]" italics="true" pageId="4" pageNumber="196">pelvic</emphasis>
girdle,
<emphasis id="A6ADEABD6E39FFE0FF7EFC6EAEB3FC4B" box="[160,197,898,926]" italics="true" pageId="4" pageNumber="196">all</emphasis>
<emphasis id="A6ADEABD6E39FFE0FF10FC6EAF58FC4B" bold="true" box="[206,302,898,926]" pageId="4" pageNumber="196">based</emphasis>
on Stan.
</paragraph>
</caption>
<caption id="C0A666276E39FFE0FF7AF785AFF0F543" ID-DOI="http://doi.org/10.5281/zenodo.3942859" ID-Zenodo-Dep="3942859" httpUri="https://zenodo.org/record/3942859/files/figure.png" pageId="4" pageNumber="196" targetBox="[173,1905,175,1482]" targetPageId="5">
<paragraph id="946636AF6E39FFE0FF7AF785AFF0F543" blockId="4.[160,572,2146,2711]" pageId="4" pageNumber="196">
<emphasis id="A6ADEABD6E39FFE0FF7AF785AF74F750" box="[164,258,2153,2181]" italics="true" pageId="4" pageNumber="196">Figure</emphasis>
11.4 (opposite).
<emphasis id="A6ADEABD6E39FFE0FDCEF785AC6CF750" box="[528,538,2153,2181]" italics="true" pageId="4" pageNumber="196">(</emphasis>
A
<emphasis id="A6ADEABD6E39FFE0FDECF785AC4AF750" box="[562,572,2153,2181]" italics="true" pageId="4" pageNumber="196">)</emphasis>
Visualization of the
<emphasis id="A6ADEABD6E39FFE0FE01F774AF7CF730" italics="true" pageId="4" pageNumber="196">distribution</emphasis>
of body mass, based on a
<emphasis id="A6ADEABD6E39FFE0FE82F715AC40F6C0" box="[348,566,2297,2325]" italics="true" pageId="4" pageNumber="196">parametric fit</emphasis>
to segments of body cross section of the axial and appendicular
<emphasis id="A6ADEABD6E39FFE0FE1CF666AE9DF602" italics="true" pageId="4" pageNumber="196">skeleton</emphasis>
.
<emphasis id="A6ADEABD6E39FFE0FEDFF657AFA8F602" box="[257,478,2491,2519]" italics="true" pageId="4" pageNumber="196">(B) Computed</emphasis>
COM visualized
<emphasis id="A6ADEABD6E39FFE0FE9EF607AC70F5D2" box="[320,518,2539,2567]" italics="true" pageId="4" pageNumber="196">just anterior</emphasis>
pubis, and above
<emphasis id="A6ADEABD6E39FFE0FE60F5F7AF8AF5E2" box="[446,508,2587,2615]" italics="true" pageId="4" pageNumber="196">pes,</emphasis>
as required
<emphasis id="A6ADEABD6E39FFE0FEEBF5A6AE8AF543" italics="true" pageId="4" pageNumber="196">for static bipedal</emphasis>
balance.
</paragraph>
</caption>
<paragraph id="946636AF6E38FFE1FA0DF8CDA949F85A" blockId="5.[1490,1855,1825,1935]" pageId="5" pageNumber="197">Reconstructing a Sitting Movement</paragraph>
<paragraph id="946636AF6E38FFE2FF6EF8C5AB25FCAE" blockId="5.[174,1414,1828,2618]" lastBlockId="6.[661,1901,797,1426]" lastPageId="6" lastPageNumber="198" pageId="5" pageNumber="197">
It is reasonable to assume that
<emphasis id="A6ADEABD6E38FFE1FD7AF8C5ADAEF898" box="[676,984,1833,1869]" italics="true" pageId="5" pageNumber="197">
<taxonomicName id="53D94D2C6E38FFE1FD7AF8C5ADA4F898" authorityName="Osborn" authorityYear="1905" box="[676,978,1833,1869]" class="Reptilia" family="Tyrannosauridae" genus="Tyrannosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="5" pageNumber="197" phylum="Chordata" rank="species" species="rex">Tyrannosaurus rex</taxonomicName>
,
</emphasis>
and other theropods with distally expanded pubic boots, lowered itself until the majority of its mass bore down on the pubis. Upon ground contact, the orientation of pelvic girdle would have shifted slightly so that the elongate ventral surface of the pubis laid generally parallel to the horizontal ground. The elongate pubic shaft of
<taxonomicName id="53D94D2C6E38FFE1FEE7F7DFAFE3F782" authorityName="Osborn" authorityYear="1905" box="[313,405,2099,2135]" class="Reptilia" family="Tyrannosauridae" genus="Tyrannosaurus" kingdom="Animalia" order="Dinosauria" pageId="5" pageNumber="197" phylum="Chordata" rank="species" species="rex">
T.
<emphasis id="A6ADEABD6E38FFE1FEB8F7DFAFE3F782" box="[358,405,2099,2135]" italics="true" pageId="5" pageNumber="197">rex</emphasis>
</taxonomicName>
places the ventral surface of the pubic boot just below the knee, permitting simultaneous ground contact at the knees and along the pubic boot (
<figureCitation id="0CE22A2A6E38FFE1FEA4F772AC53F717" box="[378,549,2206,2242]" captionStart="Figure 11.1" captionStartId="0.[188,282,1895,1923]" captionTargetBox="[6,2068,180,1816]" captionTargetPageId="0" captionText="Figure 11.1. Ray Wilhite using an Immersion Microscribe digitizer on casts of elements of the pelvic girdle of Tyrannosaurus rex specimen BHI 3033 (Stan). Photo courtesy Ray Wilhite and Virtual Surfaces Inc." figureDoi="http://doi.org/10.5281/zenodo.3942853" httpUri="https://zenodo.org/record/3942853/files/figure.png" pageId="5" pageNumber="197" targetBox="[169,1901,173,724]" targetPageId="6">Figs. 11.5</figureCitation>
-
<figureCitation id="0CE22A2A6E38FFE1FDEFF772AC30F717" box="[561,582,2206,2242]" captionStart="Figure 11.6" captionText="Figure 11.6. With the body mass supported by the pubic boot, the hind limbs appear to have been able to shift from (A) a sitting position (with hip flexed) to (B) kneeling on one knee or (C) both knees, without having to lift the body weight off of the pubic boot. Although the axislike insertion of the femur head within acetabulum suggests little femoral abduction was possible, there was likely sufficient flexibility to provide lateral stability. Moreover, the posterolateral angulation of the acetabular axis caused the knees to splay with femoral protracted, again aiding stability against lateral tipping in addition to clearing the rib cage as necessary in locomotion. " figureDoi="http://doi.org/10.5281/zenodo.3942863" httpUri="https://zenodo.org/record/3942863/files/figure.png" pageId="5" pageNumber="197" targetBox="[153,1883,169,721]" targetPageId="7">6</figureCitation>
). The pubis thus likely provided a stable means to offload the great majority of the animal’s weight, limiting pressure on the respiratory system, and to permit repositioning of the hind limbs without requiring a shifting of weight. The limit of hip flexion (femoral protraction) is difficult to estimate because it was governed by soft tissues, but it likely was sufficient to permit achieving the protraction shown in
<figureCitation id="0CE22A2A6E38FFE1FB71F645ABF3F618" box="[1199,1413,2473,2509]" captionStart="Figure 11.1" captionStartId="0.[188,282,1895,1923]" captionTargetBox="[6,2068,180,1816]" captionTargetPageId="0" captionText="Figure 11.1. Ray Wilhite using an Immersion Microscribe digitizer on casts of elements of the pelvic girdle of Tyrannosaurus rex specimen BHI 3033 (Stan). Photo courtesy Ray Wilhite and Virtual Surfaces Inc." figureDoi="http://doi.org/10.5281/zenodo.3942853" httpUri="https://zenodo.org/record/3942853/files/figure.png" pageId="5" pageNumber="197">Figure 11.5A</figureCitation>
so that the tarsus could lie flat on the ground. The limits of knee and ankle flexion are more obvious in the osteology. It is noteworthy that in a full squat (
<figureCitation id="0CE22A2A6E3BFFE2FCDAFCCFADDDFC92" box="[772,939,803,839]" captionStart="Figure 11.1" captionStartId="0.[188,282,1895,1923]" captionTargetBox="[6,2068,180,1816]" captionTargetPageId="0" captionText="Figure 11.1. Ray Wilhite using an Immersion Microscribe digitizer on casts of elements of the pelvic girdle of Tyrannosaurus rex specimen BHI 3033 (Stan). Photo courtesy Ray Wilhite and Virtual Surfaces Inc." figureDoi="http://doi.org/10.5281/zenodo.3942853" httpUri="https://zenodo.org/record/3942853/files/figure.png" pageId="6" pageNumber="198">
Fig. 11.5
<emphasis id="A6ADEABD6E3BFFE2FC4EFCCFADDDFC92" box="[912,939,803,839]" italics="true" pageId="6" pageNumber="198">A</emphasis>
</figureCitation>
), which brings the pubic boot in contact with the ground, the knee and ankle are nearly fully flexed.
</paragraph>
<caption id="C0A666276E3BFFE2FF70FCC8AC6EF545" ID-DOI="http://doi.org/10.5281/zenodo.3942861" ID-Zenodo-Dep="3942861" httpUri="https://zenodo.org/record/3942861/files/figure.png" pageId="6" pageNumber="198" startId="6.[174,266,804,832]" targetBox="[169,1901,173,724]" targetPageId="6">
<paragraph id="946636AF6E3BFFE2FF70FCC8AC42FA64" blockId="6.[171,584,798,1459]" pageId="6" pageNumber="198">
Figure 11.5.
<emphasis id="A6ADEABD6E3BFFE2FEB7FCC8AC6CFC95" box="[361,538,804,832]" italics="true" pageId="6" pageNumber="198">DinoMorph</emphasis>
model of
<taxonomicName id="53D94D2C6E3BFFE2FE9AFCB8AFE8FCA5" authorityName="Osborn" authorityYear="1905" box="[324,414,852,880]" class="Reptilia" family="Tyrannosauridae" genus="Tyrannosaurus" kingdom="Animalia" order="Dinosauria" pageId="6" pageNumber="198" phylum="Chordata" rank="species" species="rex">
<emphasis id="A6ADEABD6E3BFFE2FE9AFCB8AF2CFCA5" box="[324,346,852,880]" italics="true" pageId="6" pageNumber="198">T.</emphasis>
<emphasis id="A6ADEABD6E3BFFE2FEB6FCB8AFE8FCA5" bold="true" box="[360,414,852,880]" pageId="6" pageNumber="198">rex</emphasis>
</taxonomicName>
Stan
<emphasis id="A6ADEABD6E3BFFE2FE2BFCB8AF3CFC75" italics="true" pageId="6" pageNumber="198">demonstrating</emphasis>
that the
<emphasis id="A6ADEABD6E3BFFE2FE0AFC68AC5DFC75" box="[468,555,900,928]" italics="true" pageId="6" pageNumber="198">pubic</emphasis>
shaft
<emphasis id="A6ADEABD6E3BFFE2FEDDFC58AC63FC05" box="[259,533,948,976]" italics="true" pageId="6" pageNumber="198">is sufficiently long</emphasis>
that,
<emphasis id="A6ADEABD6E3BFFE2FF21FC08AF37FBD5" box="[255,321,996,1024]" italics="true" pageId="6" pageNumber="198">with</emphasis>
the
<emphasis id="A6ADEABD6E3BFFE2FE59FC08AC73FBD5" box="[391,517,996,1024]" italics="true" pageId="6" pageNumber="198">animal's</emphasis>
weight
<emphasis id="A6ADEABD6E3BFFE2FEFCFBF8AFFCFBE5" box="[290,394,1044,1072]" italics="true" pageId="6" pageNumber="198">resting</emphasis>
on the
<emphasis id="A6ADEABD6E3BFFE2FDDFFBF8AEADFBB4" italics="true" pageId="6" pageNumber="198">pubic</emphasis>
boot, the hind
<emphasis id="A6ADEABD6E3BFFE2FE14FBA9AC5DFBB4" box="[458,555,1093,1121]" italics="true" pageId="6" pageNumber="198">limb is</emphasis>
free to assume a
<emphasis id="A6ADEABD6E3BFFE2FE68FB98AC62FB45" box="[438,532,1140,1168]" italics="true" pageId="6" pageNumber="198">broad</emphasis>
range of
<emphasis id="A6ADEABD6E3BFFE2FEE6FB49AECEFB24" italics="true" pageId="6" pageNumber="198">positions from (</emphasis>
A
<emphasis id="A6ADEABD6E3BFFE2FF11FB39AEAFFB24" box="[207,217,1237,1265]" italics="true" pageId="6" pageNumber="198">)</emphasis>
crouch, to
<emphasis id="A6ADEABD6E3BFFE2FE55FB39AFC7FB24" box="[395,433,1237,1265]" italics="true" pageId="6" pageNumber="198">(B)</emphasis>
kneel to
<emphasis id="A6ADEABD6E3BFFE2FF70FAE9AEC1FAF4" box="[174,183,1285,1313]" italics="true" pageId="6" pageNumber="198">(</emphasis>
C
<emphasis id="A6ADEABD6E3BFFE2FF13FAE9AEA0FAF4" box="[205,214,1285,1313]" italics="true" pageId="6" pageNumber="198">)</emphasis>
moderate
<emphasis id="A6ADEABD6E3BFFE2FE5FFAE9AC65FAF4" box="[385,531,1285,1313]" italics="true" pageId="6" pageNumber="198">extension</emphasis>
of the
<emphasis id="A6ADEABD6E3BFFE2FF37FAD9AF6EFA84" box="[233,280,1333,1361]" italics="true" pageId="6" pageNumber="198">hip</emphasis>
and knee, to full leg
<emphasis id="A6ADEABD6E3BFFE2FF38FA89AF0EFA54" box="[230,376,1381,1409]" italics="true" pageId="6" pageNumber="198">extension</emphasis>
when stretched behind the hips
</paragraph>
<paragraph id="946636AF6E3BFFE2FD01FC61A8C5FA45" blockId="6.[661,1901,797,1426]" pageId="6" pageNumber="198">To visualize the descent from a neutral standing pose to a squat, Dino­ Morph was used to interpolate between these 2 extremes of pose. By constraining all joints to movements within their respective ranges of motion, it was determined that a descent movement could be performed that did not induce any significant longitudinal shift in the position of the COM, i.e., it was possible to move the COM in a purely vertical direction, until contact was made between the pubic boot and the ground. The COM, however, then tends to shifts posteriorly during the final settling of weight from the hind feet onto the pubic boot, and it must return anteriorly through some trajectory in the process of rising and regaining bipedal balance.</paragraph>
<paragraph id="946636AF6E3BFFE2FF6EF9E8AFECF93F" blockId="6.[173,476,1540,1770]" pageId="6" pageNumber="198">
<heading id="CF2E81C36E3BFFE2FF6EF9E8AFECF93F" bold="true" fontSize="15" level="2" pageId="6" pageNumber="198" reason="0">Reconstructing Alternative Standing Movements</heading>
</paragraph>
<paragraph id="946636AF6E3BFFE2FD49F9FDA856F79C" blockId="6.[660,1902,1549,2710]" pageId="6" pageNumber="198">
In rising,
<taxonomicName id="53D94D2C6E3BFFE2FCE7F9FDAA10F9E0" authorityName="Osborn" authorityYear="1905" box="[825,1126,1553,1589]" class="Reptilia" family="Tyrannosauridae" genus="Tyrannosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="6" pageNumber="198" phylum="Chordata" rank="species" species="rex">
Tyrannosaurus
<emphasis id="A6ADEABD6E3BFFE2FBE9F9FDAA10F9E0" box="[1079,1126,1553,1589]" italics="true" pageId="6" pageNumber="198">rex</emphasis>
</taxonomicName>
has to cope with lifting the COM by approximately 1.4 m vertically starting with the pubic boot in ground contact and ending in the neutral standing pose, as seen in
<figureCitation id="0CE22A2A6E3BFFE2FA6CF990A806F975" box="[1458,1648,1660,1696]" captionStart="Figure 11.1" captionStartId="0.[188,282,1895,1923]" captionTargetBox="[6,2068,180,1816]" captionTargetPageId="0" captionText="Figure 11.1. Ray Wilhite using an Immersion Microscribe digitizer on casts of elements of the pelvic girdle of Tyrannosaurus rex specimen BHI 3033 (Stan). Photo courtesy Ray Wilhite and Virtual Surfaces Inc." figureDoi="http://doi.org/10.5281/zenodo.3942853" httpUri="https://zenodo.org/record/3942853/files/figure.png" pageId="6" pageNumber="198" targetBox="[173,1905,175,1482]" targetPageId="5">Figure 11.4</figureCitation>
. This could be achieved in principle
<emphasis id="A6ADEABD6E3BFFE2FBC5F95EAA37F903" box="[1051,1089,1714,1750]" italics="true" pageId="6" pageNumber="198">by</emphasis>
pure muscular exertion of the large extensor muscle groups of the hind limb, particularly the M. caudofemoralis longus, the largest contributor to femoral retraction, and secondarily the knee and tarsus extensors. The M. caudofemoralis longus, however,
<emphasis id="A6ADEABD6E3BFFE2F94FF8BDA8DEF8A0" box="[1681,1704,1873,1909]" italics="true" pageId="6" pageNumber="198">is</emphasis>
simultaneously in significant stretch (roughly 115% of that while standing), and the moment (or lever) arm is greatly foreshortened (
<figureCitation id="0CE22A2A6E3BFFE2FA1CF850A820F835" box="[1474,1622,1980,2016]" captionStart="Figure 11.1" captionStartId="0.[188,282,1895,1923]" captionTargetBox="[6,2068,180,1816]" captionTargetPageId="0" captionText="Figure 11.1. Ray Wilhite using an Immersion Microscribe digitizer on casts of elements of the pelvic girdle of Tyrannosaurus rex specimen BHI 3033 (Stan). Photo courtesy Ray Wilhite and Virtual Surfaces Inc." figureDoi="http://doi.org/10.5281/zenodo.3942853" httpUri="https://zenodo.org/record/3942853/files/figure.png" pageId="6" pageNumber="198" targetBox="[147,1388,2065,2722]" targetPageId="7">Fig. 11.7</figureCitation>
). Depending on the particular position of the femur in this deep squat, the moment arm may be less than 40% of that provided when standing.
</paragraph>
<paragraph id="946636AF6E3BFFE2FF71F83FAC6EF545" blockId="6.[171,584,1996,2706]" pageId="6" pageNumber="198">
<emphasis id="A6ADEABD6E3BFFE2FF71F83FAECCF83A" box="[175,186,2003,2031]" italics="true" pageId="6" pageNumber="198">(</emphasis>
not shown
<emphasis id="A6ADEABD6E3BFFE2FE86F83FAF1EF83A" box="[344,360,2003,2031]" italics="true" pageId="6" pageNumber="198">).</emphasis>
Note that
<emphasis id="A6ADEABD6E3BFFE2FDCCF83FAC5AF83A" box="[530,556,2003,2031]" italics="true" pageId="6" pageNumber="198">in</emphasis>
these
<emphasis id="A6ADEABD6E3BFFE2FED7F7EFAF6BF7CA" box="[265,285,2051,2079]" italics="true" pageId="6" pageNumber="198">3</emphasis>
images the tarsus
<emphasis id="A6ADEABD6E3BFFE2FF73F7DFAEB4F79A" box="[173,194,2099,2127]" italics="true" pageId="6" pageNumber="198">is</emphasis>
near the
<emphasis id="A6ADEABD6E3BFFE2FE89F7DFAFECF79A" box="[343,410,2099,2127]" italics="true" pageId="6" pageNumber="198">limit</emphasis>
of flexion;
<emphasis id="A6ADEABD6E3BFFE2FF73F78EAE88F7AB" box="[173,254,2146,2174]" italics="true" pageId="6" pageNumber="198">in (A)</emphasis>
and
<emphasis id="A6ADEABD6E3BFFE2FE91F78EAF0CF7AB" box="[335,378,2146,2174]" italics="true" pageId="6" pageNumber="198">(B),</emphasis>
the knee
<emphasis id="A6ADEABD6E3BFFE2FDC7F78EAC5BF7AB" box="[537,557,2146,2174]" italics="true" pageId="6" pageNumber="198">is</emphasis>
fully flexed. Observe that the knee
<emphasis id="A6ADEABD6E3BFFE2FEE6F72FAF03F70A" box="[312,373,2243,2271]" italics="true" pageId="6" pageNumber="198">just</emphasis>
clears the ground as it
<emphasis id="A6ADEABD6E3BFFE2FEB3F71FAFA1F6DA" box="[365,471,2291,2319]" italics="true" pageId="6" pageNumber="198">swings</emphasis>
through hip
<emphasis id="A6ADEABD6E3BFFE2FEB1F6CFAF6FF675" italics="true" pageId="6" pageNumber="198">flexion-extension, permitting repositioning</emphasis>
of either
<emphasis id="A6ADEABD6E3BFFE2FE71F668AC48F675" box="[431,574,2436,2464]" italics="true" pageId="6" pageNumber="198">hind limb</emphasis>
while continuously
<emphasis id="A6ADEABD6E3BFFE2FE0AF659AC4AF604" box="[468,572,2485,2513]" italics="true" pageId="6" pageNumber="198">resting</emphasis>
on the
<emphasis id="A6ADEABD6E3BFFE2FEC7F609AF06F5D4" box="[281,368,2533,2561]" italics="true" pageId="6" pageNumber="198">pubic</emphasis>
boot. Joint flexibility
<emphasis id="A6ADEABD6E3BFFE2FEE0F5F8AF8FF5E5" box="[318,505,2580,2608]" italics="true" pageId="6" pageNumber="198">estimated in</emphasis>
collaboration with
<emphasis id="A6ADEABD6E3BFFE2FE7BF5A8AC71F5B5" box="[421,519,2628,2656]" italics="true" pageId="6" pageNumber="198">Yoshio</emphasis>
Ito and Kenneth Carpenter.
</paragraph>
</caption>
<paragraph id="946636AF6E3BFFE3FD3EF7B0AA41FBC0" blockId="6.[660,1902,1549,2710]" lastBlockId="7.[151,1395,790,2007]" lastPageId="7" lastPageNumber="199" pageId="6" pageNumber="198">
<emphasis id="A6ADEABD6E3BFFE2FD3EF7B0AA7EF755" box="[736,1032,2140,2176]" italics="true" pageId="6" pageNumber="198">
<taxonomicName id="53D94D2C6E3BFFE2FD3EF7B0AA75F755" authorityName="Osborn" authorityYear="1905" box="[736,1027,2140,2176]" class="Reptilia" family="Tyrannosauridae" genus="Tyrannosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="6" pageNumber="198" phylum="Chordata" rank="species" species="rex">Tyrannosaurus rex</taxonomicName>
,
</emphasis>
while resting on the pubis, could freely retract one or both femora (
<figureCitation id="0CE22A2A6E3BFFE2FCB1F77DAAE2F760" box="[879,1172,2193,2229]" captionStart="Figure 11.1" captionStartId="0.[188,282,1895,1923]" captionTargetBox="[6,2068,180,1816]" captionTargetPageId="0" captionText="Figure 11.1. Ray Wilhite using an Immersion Microscribe digitizer on casts of elements of the pelvic girdle of Tyrannosaurus rex specimen BHI 3033 (Stan). Photo courtesy Ray Wilhite and Virtual Surfaces Inc." figureDoi="http://doi.org/10.5281/zenodo.3942853" httpUri="https://zenodo.org/record/3942853/files/figure.png" pageId="6" pageNumber="198">Figs. 11.5 and 11.6</figureCitation>
) and hence vary the stretch on the M. caudofemoralis. Optimal mechanical advantage occurs when the femur is roughly vertical (i.e., associated with the thrust phase in locomotion). Although the femoral position providing greatest muscle moment would correspond to roughly that in
<figureCitation id="0CE22A2A6E3BFFE2FC4EF689AA16F65C" box="[912,1120,2405,2441]" captionStart="Figure 11.1" captionStartId="0.[188,282,1895,1923]" captionTargetBox="[6,2068,180,1816]" captionTargetPageId="0" captionText="Figure 11.1. Ray Wilhite using an Immersion Microscribe digitizer on casts of elements of the pelvic girdle of Tyrannosaurus rex specimen BHI 3033 (Stan). Photo courtesy Ray Wilhite and Virtual Surfaces Inc." figureDoi="http://doi.org/10.5281/zenodo.3942853" httpUri="https://zenodo.org/record/3942853/files/figure.png" pageId="6" pageNumber="198">Figure 11.5B</figureCitation>
, the placement of the pes in
<figureCitation id="0CE22A2A6E3BFFE2F9EDF689A889F65C" box="[1587,1791,2405,2441]" captionStart="Figure 11.1" captionStartId="0.[188,282,1895,1923]" captionTargetBox="[6,2068,180,1816]" captionTargetPageId="0" captionText="Figure 11.1. Ray Wilhite using an Immersion Microscribe digitizer on casts of elements of the pelvic girdle of Tyrannosaurus rex specimen BHI 3033 (Stan). Photo courtesy Ray Wilhite and Virtual Surfaces Inc." figureDoi="http://doi.org/10.5281/zenodo.3942853" httpUri="https://zenodo.org/record/3942853/files/figure.png" pageId="6" pageNumber="198">
Figure 11.5
<emphasis id="A6ADEABD6E3BFFE2F938F689A889F65C" box="[1766,1791,2405,2441]" italics="true" pageId="6" pageNumber="198">A</emphasis>
</figureCitation>
would appear better suited for elevating bipedally because the hind feet are then un­ der the COM. If
<taxonomicName id="53D94D2C6E3BFFE2FC78F623AD8CF626" authorityName="Osborn" authorityYear="1905" box="[934,1018,2511,2547]" class="Reptilia" family="Tyrannosauridae" genus="Tyrannosaurus" kingdom="Animalia" order="Dinosauria" pageId="6" pageNumber="198" phylum="Chordata" rank="species" species="rex">
T.
<emphasis id="A6ADEABD6E3BFFE2FC13F623AD8CF626" box="[973,1018,2511,2547]" italics="true" pageId="6" pageNumber="198">rex</emphasis>
</taxonomicName>
were not to slowly rise vertically into a stationary standing position, but instead accelerate diagonally from the squat in
<figureCitation id="0CE22A2A6E3BFFE2F949F5E9A913F5FC" box="[1687,1893,2565,2601]" captionStart="Figure 11.1" captionStartId="0.[188,282,1895,1923]" captionTargetBox="[6,2068,180,1816]" captionTargetPageId="0" captionText="Figure 11.1. Ray Wilhite using an Immersion Microscribe digitizer on casts of elements of the pelvic girdle of Tyrannosaurus rex specimen BHI 3033 (Stan). Photo courtesy Ray Wilhite and Virtual Surfaces Inc." figureDoi="http://doi.org/10.5281/zenodo.3942853" httpUri="https://zenodo.org/record/3942853/files/figure.png" pageId="6" pageNumber="198">
Figure 11.5
<emphasis id="A6ADEABD6E3BFFE2F895F5E9A913F5FC" box="[1867,1893,2565,2601]" italics="true" pageId="6" pageNumber="198">A</emphasis>
</figureCitation>
, then, provided the hind limbs direct the ground reaction force diagonally through the COM, no net pitching moment would be created as the animal rose. Much as a sprinter begins a race accelerating and rising gradually out of the blocks, it is not inconceivable that
<taxonomicName id="53D94D2C6E3AFFE3FD2BFCBEAD3FFCA3" authorityName="Osborn" authorityYear="1905" box="[757,841,850,886]" class="Reptilia" family="Tyrannosauridae" genus="Tyrannosaurus" kingdom="Animalia" order="Dinosauria" pageId="7" pageNumber="199" phylum="Chordata" rank="species" species="rex">
T.
<emphasis id="A6ADEABD6E3AFFE3FCC2FCBEAD3FFCA3" box="[796,841,850,886]" italics="true" pageId="7" pageNumber="199">rex</emphasis>
</taxonomicName>
could have accelerated diagonally upward from sitting into forward locomotion. Although it is more likely an option for light young tyrannosaurids, it remains a matter of quantitative modeling to estimate whether that was achievable by an adult.
</paragraph>
<caption id="C0A666276E3AFFE3FA63FCCEA805F7A8" ID-DOI="http://doi.org/10.5281/zenodo.3942863" ID-Zenodo-Dep="3942863" httpUri="https://zenodo.org/record/3942863/files/figure.png" pageId="7" pageNumber="199" startId="7.[1469,1564,802,830]" targetBox="[153,1883,169,721]" targetPageId="7">
<paragraph id="946636AF6E3AFFE3FA63FCCEA805F7A8" blockId="7.[1464,1878,795,2173]" pageId="7" pageNumber="199">
<emphasis id="A6ADEABD6E3AFFE3FA63FCCEA86AFCEB" box="[1469,1564,802,830]" italics="true" pageId="7" pageNumber="199">Figure</emphasis>
11.6.
<emphasis id="A6ADEABD6E3AFFE3F95DFCCEA8BDFCEB" box="[1667,1739,802,830]" italics="true" pageId="7" pageNumber="199">With</emphasis>
the body mass supported
<emphasis id="A6ADEABD6E3AFFE3F8FFFCBDA94BFCB8" box="[1825,1853,849,877]" italics="true" pageId="7" pageNumber="199">by</emphasis>
the
<emphasis id="A6ADEABD6E3AFFE3FA26FC6DA825FC48" box="[1528,1619,897,925]" italics="true" pageId="7" pageNumber="199">pubic</emphasis>
boot, the hind
<emphasis id="A6ADEABD6E3AFFE3FA65FC5DA878FC18" box="[1467,1550,945,973]" italics="true" pageId="7" pageNumber="199">limbs</emphasis>
appear to have been able to shift
<emphasis id="A6ADEABD6E3AFFE3F93CFC0DABB1FBF8" italics="true" pageId="7" pageNumber="199">from (</emphasis>
A
<emphasis id="A6ADEABD6E3AFFE3FA01FBFDAB9CFBF8" box="[1503,1514,1041,1069]" italics="true" pageId="7" pageNumber="199">)</emphasis>
a
<emphasis id="A6ADEABD6E3AFFE3F9CEFBFDABB1FB88" italics="true" pageId="7" pageNumber="199">sitting position (</emphasis>
with hip flexed
<emphasis id="A6ADEABD6E3AFFE3F96AFBADA8C8FB88" box="[1716,1726,1089,1117]" italics="true" pageId="7" pageNumber="199">)</emphasis>
to
<emphasis id="A6ADEABD6E3AFFE3F928FBADA969FB88" box="[1782,1823,1089,1117]" italics="true" pageId="7" pageNumber="199">(B)</emphasis>
kneeling on one knee or
<emphasis id="A6ADEABD6E3AFFE3FA62FB4DABB0FB68" box="[1468,1478,1185,1213]" italics="true" pageId="7" pageNumber="199">(</emphasis>
C
<emphasis id="A6ADEABD6E3AFFE3FA02FB4DAB90FB68" box="[1500,1510,1185,1213]" italics="true" pageId="7" pageNumber="199">)</emphasis>
both
<emphasis id="A6ADEABD6E3AFFE3F999FB4DA941FB68" box="[1607,1847,1185,1213]" italics="true" pageId="7" pageNumber="199">knees, without</emphasis>
having to
<emphasis id="A6ADEABD6E3AFFE3F985FB3CA8F1FB39" box="[1627,1671,1232,1260]" italics="true" pageId="7" pageNumber="199">lift</emphasis>
the body weight off of the
<emphasis id="A6ADEABD6E3AFFE3F90BFAEDA946FAC8" box="[1749,1840,1281,1309]" italics="true" pageId="7" pageNumber="199">pubic</emphasis>
boot. Although the
<emphasis id="A6ADEABD6E3AFFE3F925FADCAB99FAA9" italics="true" pageId="7" pageNumber="199">axislike</emphasis>
insertion of the femur head within
<emphasis id="A6ADEABD6E3AFFE3F910FA7DA87CFA08" bold="true" pageId="7" pageNumber="199">acetabulum</emphasis>
<emphasis id="A6ADEABD6E3AFFE3F9CAFA2DA887FA08" box="[1556,1777,1473,1501]" italics="true" pageId="7" pageNumber="199">suggests little</emphasis>
femoral abduction was possible, there was
<emphasis id="A6ADEABD6E3AFFE3F929F9CDA838F9B8" italics="true" pageId="7" pageNumber="199">likely sufficient</emphasis>
flexibility to provide lateral
<emphasis id="A6ADEABD6E3AFFE3F979F96DA951F948" box="[1703,1831,1665,1693]" italics="true" pageId="7" pageNumber="199">stability.</emphasis>
Moreover, the posterolateral
<emphasis id="A6ADEABD6E3AFFE3FA21F90DA8D1F928" box="[1535,1703,1761,1789]" italics="true" pageId="7" pageNumber="199">angulation</emphasis>
of the acetabular
<emphasis id="A6ADEABD6E3AFFE3F9B4F8FEA968F8FB" box="[1642,1822,1810,1838]" italics="true" pageId="7" pageNumber="199">axis caused</emphasis>
the knees to
<emphasis id="A6ADEABD6E3AFFE3F954F8ADA8ADF888" box="[1674,1755,1857,1885]" italics="true" pageId="7" pageNumber="199">splay</emphasis>
with femoral protracted, again
<emphasis id="A6ADEABD6E3AFFE3FA66F84DA968F868" box="[1464,1822,1953,1981]" italics="true" pageId="7" pageNumber="199">aiding stability against</emphasis>
lateral
<emphasis id="A6ADEABD6E3AFFE3F9F9F83DA8CAF838" box="[1575,1724,2001,2029]" italics="true" pageId="7" pageNumber="199">tipping in</emphasis>
addition to
<emphasis id="A6ADEABD6E3AFFE3FA3BF7EDA814F7C8" box="[1509,1634,2049,2077]" italics="true" pageId="7" pageNumber="199">clearing</emphasis>
the
<emphasis id="A6ADEABD6E3AFFE3F972F7EDA8A2F7C8" box="[1708,1748,2049,2077]" italics="true" pageId="7" pageNumber="199">rib</emphasis>
cage as necessary
<emphasis id="A6ADEABD6E3AFFE3F954F7DEA8D2F79B" box="[1674,1700,2098,2126]" italics="true" pageId="7" pageNumber="199">in</emphasis>
locomotion.
</paragraph>
</caption>
<paragraph id="946636AF6E3AFFE3FF3BFBCBAB55F91D" blockId="7.[151,1395,790,2007]" pageId="7" pageNumber="199">
If the femoral retractor muscles were not in an advantageous state for lifting
<taxonomicName id="53D94D2C6E3AFFE3FED4FBB7AC45FBAA" authorityName="Osborn" authorityYear="1905" box="[266,563,1115,1151]" class="Reptilia" family="Tyrannosauridae" genus="Tyrannosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="7" pageNumber="199" phylum="Chordata" rank="species" species="rex">
<emphasis id="A6ADEABD6E3AFFE3FED4FBB7AC45FBAA" box="[266,563,1115,1151]" italics="true" pageId="7" pageNumber="199">Tyrannosaurus rex</emphasis>
</taxonomicName>
vertically1 out of a squat into a balanced standing position, what were the alternatives? One suggestion (Phillip Manning, personal communication June 2005) borrows from modern analogues. In ratites in particular, the M. gastrocnemius comes into play: the Achilles tendon stores energy when in a state of stretch, which is trapped when the animal’s weight bears down on the tarsus while sitting. By leaning forward onto the its knees, the tendon is released, and the hind limb receives a passive boost. Whether recovery of stored mechanical energy would scale to be of significant value in helping boost
<taxonomicName id="53D94D2C6E3AFFE3FD89F9E8AD0DF9FD" authorityName="Osborn" authorityYear="1905" box="[599,891,1540,1576]" class="Reptilia" family="Tyrannosauridae" genus="Tyrannosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="7" pageNumber="199" phylum="Chordata" rank="species" species="rex">
<emphasis id="A6ADEABD6E3AFFE3FD89F9E8AD0DF9FD" box="[599,891,1540,1576]" italics="true" pageId="7" pageNumber="199">Tyrannosaurus rex</emphasis>
</taxonomicName>
from sitting to standing would require quantitative study. One further concern, beyond the matter of scaling to be effective on a 4000-kg animal, is whether the stored energy would dissipate during the period of rest as the Achilles tendon would stretch.
</paragraph>
<paragraph id="946636AF6E3AFFECFF3FF936A8BFFB1E" blockId="7.[151,1395,790,2007]" lastBlockId="8.[667,1910,1080,2720]" lastPageId="8" lastPageNumber="200" pageId="7" pageNumber="199">
Another approach is to enlist the forelimbs, as suggested by
<bibRefCitation id="F0484B5E6E3AFFE3FB08F936AE8BF8E6" author="Newman, B. H." journalOrPublisher="Biological Journal of the Linnean Society" pageId="7" pageNumber="199" pagination="119 - 123" part="2" refId="ref4950" refString="Newman, B. H. 1970. Stance and gait in the flesh-eating dinosaur Tyrannosaurus. Biological Journal of the Linnean Society 2: 119 - 123." title="Stance and gait in the flesh-eating dinosaur Tyrannosaurus" type="journal article" year="1970">Newman (1970)</bibRefCitation>
, as a potential use for these appendages. When sitting, they are close to the ground and are brought into contact by a slight tipping of the pelvis about the prepubis (
<figureCitation id="0CE22A2A6E3AFFE3FEAEF896AF8FF84B" box="[368,505,1914,1950]" captionStart="Figure 11.1" captionStartId="0.[188,282,1895,1923]" captionTargetBox="[6,2068,180,1816]" captionTargetPageId="0" captionText="Figure 11.1. Ray Wilhite using an Immersion Microscribe digitizer on casts of elements of the pelvic girdle of Tyrannosaurus rex specimen BHI 3033 (Stan). Photo courtesy Ray Wilhite and Virtual Surfaces Inc." figureDoi="http://doi.org/10.5281/zenodo.3942853" httpUri="https://zenodo.org/record/3942853/files/figure.png" pageId="7" pageNumber="199" targetBox="[177,1908,175,1006]" targetPageId="8">Fig. 11.8</figureCitation>
). They could have been instrumental in rising back into a standing position. As shown in
<figureCitation id="0CE22A2A6E3AFFE3FD6FF843AD11F806" box="[689,871,1967,2003]" captionStart="Figure 11.1" captionStartId="0.[188,282,1895,1923]" captionTargetBox="[6,2068,180,1816]" captionTargetPageId="0" captionText="Figure 11.1. Ray Wilhite using an Immersion Microscribe digitizer on casts of elements of the pelvic girdle of Tyrannosaurus rex specimen BHI 3033 (Stan). Photo courtesy Ray Wilhite and Virtual Surfaces Inc." figureDoi="http://doi.org/10.5281/zenodo.3942853" httpUri="https://zenodo.org/record/3942853/files/figure.png" pageId="7" pageNumber="199" targetBox="[140,1870,171,847]" targetPageId="9">Figure 11.9</figureCitation>
, although the forelimb range of motion is curiously limited (
<bibRefCitation id="F0484B5E6E35FFECFBBAFBD1A863FBB4" author="Carpenter, K. &amp; Smith, M." box="[1124,1557,1085,1121]" editor="Tanke, D. &amp; Carpenter, K." journalOrPublisher="Indiana University Press, Indiana" pageId="8" pageNumber="200" pagination="90 - 116" refId="ref4410" refString="Carpenter, K., and Smith, M. 2001. Forelimb osteology and biomechanics of Tyrannosaurus rex. P. 90 - 116 in Tanke, D., and Carpenter, K. (eds.). Mesozoic Vertebrate Life. Indiana University Press, Indiana." title="Forelimb osteology and biomechanics of Tyrannosaurus rex" type="book chapter" volumeTitle="Mesozoic Vertebrate Life" year="2001">Carpenter and Smith 2001</bibRefCitation>
), when each forelimb is extended laterally, with elbow straight and manus extended as well, the arrangement resembles a jack stand (or a pair of bicycle kick stands).
</paragraph>
<caption id="C0A666276E3AFFE3FA64F733A812F57F" ID-DOI="http://doi.org/10.5281/zenodo.3942865" ID-Zenodo-Dep="3942865" httpUri="https://zenodo.org/record/3942865/files/figure.png" pageId="7" pageNumber="199" startId="7.[1466,1561,2271,2299]" targetBox="[147,1388,2065,2722]" targetPageId="7">
<paragraph id="946636AF6E3AFFE3FA64F733A812F57F" blockId="7.[1463,1873,2264,2732]" pageId="7" pageNumber="199">
Figure 11.7.
<emphasis id="A6ADEABD6E3AFFE3F9A7F733A8E2F72E" box="[1657,1684,2271,2299]" italics="true" pageId="7" pageNumber="199">In</emphasis>
ascending
<emphasis id="A6ADEABD6E3AFFE3FA64F6E2A8F7F6FF" box="[1466,1665,2318,2346]" italics="true" pageId="7" pageNumber="199">from repose,</emphasis>
the M.
<emphasis id="A6ADEABD6E3AFFE3F8D9F6E2A946F68F" italics="true" pageId="7" pageNumber="199">caudofemoralis longus is in</emphasis>
stretch
<emphasis id="A6ADEABD6E3AFFE3F9EFF682A88FF65F" box="[1585,1785,2414,2442]" italics="true" pageId="7" pageNumber="199">(-115%) and</emphasis>
the moment arm
<emphasis id="A6ADEABD6E3AFFE3F94DF672A8DCF66F" box="[1683,1706,2462,2490]" italics="true" pageId="7" pageNumber="199">is</emphasis>
greatly foreshortened compared with its neutral state when standing, thus providing poor mechanical advantage.
</paragraph>
</caption>
<caption id="C0A666276E35FFECFF68FBD3AF9DF77C" ID-DOI="http://doi.org/10.5281/zenodo.3942867" ID-Zenodo-Dep="3942867" httpUri="https://zenodo.org/record/3942867/files/figure.png" pageId="8" pageNumber="200" startId="8.[182,277,1087,1115]" targetBox="[177,1908,175,1006]" targetPageId="8">
<paragraph id="946636AF6E35FFECFF68FBD3AF9DF77C" blockId="8.[179,591,1081,2219]" pageId="8" pageNumber="200">
Figure 11.8. When
<emphasis id="A6ADEABD6E35FFECFE3BFBD3AE90FB5E" italics="true" pageId="8" pageNumber="200">resting</emphasis>
on the
<emphasis id="A6ADEABD6E35FFECFEBDFB83AFC9FB5E" box="[355,447,1135,1163]" italics="true" pageId="8" pageNumber="200">pubis,</emphasis>
the
<emphasis id="A6ADEABD6E35FFECFF68FB73AF3EFB6E" box="[182,328,1183,1211]" italics="true" pageId="8" pageNumber="200">forelimbs</emphasis>
are near ground level. They are brought
<emphasis id="A6ADEABD6E35FFECFE9FFB13AFEBFACE" box="[321,413,1279,1307]" italics="true" pageId="8" pageNumber="200">closer</emphasis>
to ground level as a consequence of iniatating a standing movement
<emphasis id="A6ADEABD6E35FFECFEB3FA63AFC0FA7E" box="[365,438,1423,1451]" italics="true" pageId="8" pageNumber="200">from</emphasis>
this resting pose.
<emphasis id="A6ADEABD6E35FFECFE8EFA52AF1EFA0F" box="[336,360,1470,1498]" italics="true" pageId="8" pageNumber="200">A</emphasis>
modest
<emphasis id="A6ADEABD6E35FFECFE27FA52AE8CF9DF" italics="true" pageId="8" pageNumber="200">tipping</emphasis>
of the body, by
<emphasis id="A6ADEABD6E35FFECFDDDFA02AF71F9EF" italics="true" pageId="8" pageNumber="200">pivoting</emphasis>
about the curved anteroventral surface of the prepubis, would have shifted the overall
<emphasis id="A6ADEABD6E35FFECFE3FF941AC44F91C" box="[481,562,1709,1737]" italics="true" pageId="8" pageNumber="200">COM</emphasis>
anteriorly and returned the point of balance to between the hindfeet.
<emphasis id="A6ADEABD6E35FFECFDF9F8D1AC37F88C" box="[551,577,1853,1881]" italics="true" pageId="8" pageNumber="200">In</emphasis>
the process, the
<emphasis id="A6ADEABD6E35FFECFE1FF881AF71F86F" italics="true" pageId="8" pageNumber="200">forelimbs</emphasis>
would have been available to
<emphasis id="A6ADEABD6E35FFECFEADF822AF25F7CC" italics="true" pageId="8" pageNumber="200">assist in stabilizing, if</emphasis>
not
<emphasis id="A6ADEABD6E35FFECFE44F811AC64F7CC" box="[410,530,2045,2073]" italics="true" pageId="8" pageNumber="200">actively</emphasis>
contributing toward
<emphasis id="A6ADEABD6E35FFECFDDFF7C1AE9AF7AC" italics="true" pageId="8" pageNumber="200">raising,</emphasis>
the body, by
<emphasis id="A6ADEABD6E35FFECFE12F7B1AF5EF77C" italics="true" pageId="8" pageNumber="200">pushing against</emphasis>
the ground.
</paragraph>
</caption>
<paragraph id="946636AF6E35FFECFD39FB30A96AF861" blockId="8.[667,1910,1080,2720]" pageId="8" pageNumber="200">
The stout forelimbs, fully extended and acting as struts anchored into the ground by strong manual unguals (which are also well oriented for this anchoring task), are well placed for stabilizing the anterior of this giant theropod in preparation for rising. As the animal shifts its weight, ground reaction forces would have been directed nearly perpendicularly into the cup shape of the glenoid fossa; the compressive load would then distribute along the scapulocoracoid over a span of ribs. If the stout forelimbs were indeed involved in stabilizing the body, it
<emphasis id="A6ADEABD6E35FFECFAABF9BDABFAF9A0" box="[1397,1420,1617,1653]" italics="true" pageId="8" pageNumber="200">is</emphasis>
noteworthy that the ground reaction forces would have communicated directly to the vicinity of the acromion process of the coracoid, and therefore place the furcula, which is directly aligned with this force vector, under significant bending stress. As noted by others (
<bibRefCitation id="F0484B5E6E35FFECFC36F8CAAACCF89F" author="Larson, P. L." box="[1000,1210,1830,1866]" journalOrPublisher="Dino Press" pageId="8" pageNumber="200" pagination="26 - 35" part="5" refId="ref4745" refString="Larson, P. L. 2001. Paleopathologies in Tyrannosaurus rex (in Japanese). Dino Press 5: 26 - 35." title="Paleopathologies in Tyrannosaurus rex" type="journal article" year="2001">Larson 2001</bibRefCitation>
;
<bibRefCitation id="F0484B5E6E35FFECFB13F8CAA822F89F" author="Larson, P. L. &amp; Rigby, K., Jr." box="[1229,1620,1830,1866]" editor="Carpenter, K." journalOrPublisher="Indiana University Press, Bloomington" pageId="8" pageNumber="200" pagination="247 - 255" refId="ref4882" refString="Larson, P. L., and Rigby, K., Jr. 2005. The furcula of Tyrannosaurus rex. P. 247 - 255 in Carpenter, K. (ed.). Carnivorous Dinosaurs. Indiana University Press, Bloomington." title="The furcula of Tyrannosaurus rex" type="book chapter" volumeTitle="Carnivorous Dinosaurs" year="2005">Larson and Rigby 2005</bibRefCitation>
; Lipkin and Carpenter this volume; Rothschild and Molnar this volume), the furcula is frequently found with evidence of healed stress fractures and breaks.
</paragraph>
<paragraph id="946636AF6E35FFECFD39F82AAAE0F75D" blockId="8.[667,1910,1080,2720]" pageId="8" pageNumber="200">
The sprint start discussed earlier would have been assisted bv braced and stabilizing the anterior portion of the body by holding the forelimbs strutlike. Indeed, the resemblance of the initial pose to that of a human sprinter is striking (
<figureCitation id="0CE22A2A6E35FFECFC3AF788AAFEF75D" box="[996,1160,2148,2184]" captionStart="Figure 11.1" captionStartId="0.[188,282,1895,1923]" captionTargetBox="[6,2068,180,1816]" captionTargetPageId="0" captionText="Figure 11.1. Ray Wilhite using an Immersion Microscribe digitizer on casts of elements of the pelvic girdle of Tyrannosaurus rex specimen BHI 3033 (Stan). Photo courtesy Ray Wilhite and Virtual Surfaces Inc." figureDoi="http://doi.org/10.5281/zenodo.3942853" httpUri="https://zenodo.org/record/3942853/files/figure.png" pageId="8" pageNumber="200" targetBox="[192,1924,168,2695]" targetPageId="10">Fig. 11.10</figureCitation>
).
</paragraph>
<paragraph id="946636AF6E35FFEDFD38F776AA44FB40" blockId="8.[667,1910,1080,2720]" lastBlockId="9.[143,1384,920,1919]" lastPageId="9" lastPageNumber="201" pageId="8" pageNumber="200">Alternatively, with the forelimbs serving to anchor the animal, the posterior musculature of the hind limbs could come into play more gradually to elevate the COM even though it was located ahead of the hind feet. With the animal’s weight positioned fractionally between anchored forelimbs and extending hind limbs, the COM could be elevated with the additional mechanical advantage of a second-class lever. The animal would remain in a stable quadrupedal stance during this initial stage of elevation, and progressively; as the femora and knee come out of the deep crouch, the mechanical advantage of the large femoral retractors and knee extensors would have increased. If not intending a sprint start, but merely wishing to regain a stand- ing posture, the great theropod would likely have (1) tipped forward slightly, pivoting about the prepubis, until (2) the forelimbs were in ground contact and helping to anchor the giant, then (3) it would have first raised its rump, much as large herbivores do today, then (4) either step into forward movement or ascended symmetrically into a standing posture.</paragraph>
<caption id="C0A666276E35FFEDFF6BF6C3A822F8CE" ID-DOI="http://doi.org/10.5281/zenodo.3942869" ID-Zenodo-Dep="3942869" httpUri="https://zenodo.org/record/3942869/files/figure.png" lastPageId="9" lastPageNumber="201" pageId="8" pageNumber="200" targetBox="[140,1870,171,847]" targetPageId="9">
<paragraph id="946636AF6E35FFEDFF6BF6C3A822F8CE" blockId="8.[179,588,2344,2717]" lastBlockId="9.[1454,1867,921,1820]" lastPageId="9" lastPageNumber="201" pageId="8" pageNumber="200">
Figure 11.9.
<emphasis id="A6ADEABD6E35FFECFEA7F6C3AFF5F69E" box="[377,387,2351,2379]" italics="true" pageId="8" pageNumber="200">(</emphasis>
A
<emphasis id="A6ADEABD6E35FFECFE45F6C3AF36F6AE" italics="true" pageId="8" pageNumber="200">) Reconstruction</emphasis>
of the pectoral girdles and forelimbs based on CT
<emphasis id="A6ADEABD6E35FFECFE56F62CAE92F5D9" italics="true" pageId="8" pageNumber="200">data (except for</emphasis>
the
<emphasis id="A6ADEABD6E35FFECFEF5F61CAFE3F5D9" box="[299,405,2544,2572]" italics="true" pageId="8" pageNumber="200">radiale</emphasis>
and distal
<emphasis id="A6ADEABD6E35FFECFF6AF5F3AFF1F5EE" box="[180,391,2591,2619]" italics="true" pageId="8" pageNumber="200">carpal, which</emphasis>
were
<emphasis id="A6ADEABD6E35FFECFE31F5F3AF04F5BE" italics="true" pageId="8" pageNumber="200">reconstructed</emphasis>
within
<emphasis id="A6ADEABD6E35FFECFE32F5A3AC34F5BE" box="[492,578,2639,2667]" italics="true" pageId="8" pageNumber="200">Dino-</emphasis>
Morph
<emphasis id="A6ADEABD6E35FFECFEC1F593AF46F54E" box="[287,304,2687,2715]" italics="true" pageId="8" pageNumber="200">).</emphasis>
Three
<emphasis id="A6ADEABD6E35FFEDFE7DF593A802FC69" box="[419,1652,928,2715]" italics="true" lastPageId="9" lastPageNumber="201" pageId="8" pageNumber="200">superim- posed poses</emphasis>
are assume a symmetrically by left ana
<emphasis id="A6ADEABD6E34FFEDFA6EFC13A88DFBCE" box="[1456,1787,1023,1051]" italics="true" pageId="9" pageNumber="201">right forelimbs. With</emphasis>
elbows and manus
<emphasis id="A6ADEABD6E34FFEDF910FBC3A855FBAE" italics="true" pageId="9" pageNumber="201">extended</emphasis>
, the forelimbs can act as a
<emphasis id="A6ADEABD6E34FFEDF9EEFB63A802FB7E" box="[1584,1652,1167,1195]" italics="true" pageId="9" pageNumber="201">jack</emphasis>
stand to
<emphasis id="A6ADEABD6E34FFEDF8D2FB63A874FB0E" italics="true" pageId="9" pageNumber="201">stabilize</emphasis>
the body during ascent, but the
<emphasis id="A6ADEABD6E34FFEDF972FB03A895FADE" box="[1708,1763,1263,1291]" italics="true" pageId="9" pageNumber="201">line</emphasis>
of
<emphasis id="A6ADEABD6E34FFEDFA6EFAF2A864FAEF" box="[1456,1554,1310,1338]" italics="true" pageId="9" pageNumber="201">action</emphasis>
of the ground
<emphasis id="A6ADEABD6E34FFEDF8D7FAF2A864FABF" italics="true" pageId="9" pageNumber="201">reaction</emphasis>
force would have placed the furcula under significant bending
<emphasis id="A6ADEABD6E34FFEDFA6FFA33A864FA2E" box="[1457,1554,1503,1531]" italics="true" pageId="9" pageNumber="201">stress,</emphasis>
consistent with commonly
<emphasis id="A6ADEABD6E34FFEDF9BDF9E3A883F9FE" box="[1635,1781,1551,1579]" italics="true" pageId="9" pageNumber="201">observed</emphasis>
healed fractures.
<emphasis id="A6ADEABD6E34FFEDF915F9D3AB83F95E" italics="true" pageId="9" pageNumber="201">Forelimb</emphasis>
range of motion estimated
<emphasis id="A6ADEABD6E34FFEDF987F973A802F96E" box="[1625,1652,1695,1723]" italics="true" pageId="9" pageNumber="201">in</emphasis>
collaboration with Kenneth Carpenter.
</paragraph>
</caption>
<paragraph id="946636AF6E34FFEDFF02FB4BACD6F8A8" blockId="9.[143,1384,920,1919]" pageId="9" pageNumber="201">
Unlike quadrupeds such as bovids, the disparity between forelimb and hind limb length in
<taxonomicName id="53D94D2C6E34FFEDFE3BFB31AD7AFAD5" authorityName="Osborn" authorityYear="1905" box="[485,780,1244,1281]" class="Reptilia" family="Tyrannosauridae" genus="Tyrannosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="9" pageNumber="201" phylum="Chordata" rank="species" species="rex">
<emphasis id="A6ADEABD6E34FFEDFE3BFB31AD7AFAD5" box="[485,780,1244,1281]" italics="true" pageId="9" pageNumber="201">Tyrannosaurus rex</emphasis>
</taxonomicName>
limited the extent to which it could ascend rump first while maintaining a purchase on the ground with the forelimbs. Before achieving full extension of the hind limb, the animal would have had to break contact between its forelimbs and the ground, and either take a step with one hind limb in order to regain its balance, or remain symmetrically posed on 2 hind limbs, and by means of momentum, body movements, and strength, bring the COM back between the hind feet. Perhaps the furcula injuries reflect mishaps that occurred while attempting to regain its balance, particularly when lame as a result of other injuries, or they may reflect the amount of stress imposed on the shoulder girdle during these maneuvers. In the event of a misstep or other failure to achieve balance between the hindfeet, 4 or more metric tonnes falling on the forelimbs could have precipitated such fractures.
</paragraph>
</subSubSection>
<subSubSection id="DCC365246E34FFEDFA6DF818AA15F577" pageId="9" pageNumber="201" type="discussion">
<paragraph id="946636AF6E34FFEDFA6DF818A8FDF7F3" blockId="9.[1459,1675,2036,2086]" box="[1459,1675,2036,2086]" pageId="9" pageNumber="201">
<heading id="CF2E81C36E34FFEDFA6DF818A8FDF7F3" bold="true" box="[1459,1675,2036,2086]" fontSize="17" level="1" pageId="9" pageNumber="201" reason="0">Conclusion</heading>
</paragraph>
<paragraph id="946636AF6E34FFEDFF51F7EDAA15F577" blockId="9.[143,1385,2042,2725]" pageId="9" pageNumber="201">
The great bulk of an adult
<taxonomicName id="53D94D2C6E34FFEDFDE3F7ECAD14F7F1" authorityName="Osborn" authorityYear="1905" box="[573,866,2048,2084]" class="Reptilia" family="Tyrannosauridae" genus="Tyrannosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="9" pageNumber="201" phylum="Chordata" rank="species" species="rex">
<emphasis id="A6ADEABD6E34FFEDFDE3F7ECAD14F7F1" box="[573,866,2048,2084]" italics="true" pageId="9" pageNumber="201">Tyrannosaurus rex</emphasis>
</taxonomicName>
was capable of being gracefully lowered until it settled its weight on the elongate pubic boot, freeing the animal to adjust its legs much as a sports spectator would use a portable onelegged stool. When it came to rising again to a bipedal stance, the options, particularly for a small tyrannosaurid, would be a sprint start with or without assistance from the forelimbs, or a more gradual elevation using the hind limbs during which the forelimbs played an essential role. The latter was energetically more efficient and might have been preferable for the adult. The forelimbs were literally pivotal in this operation, and mishaps might have resulted in transmission of enormous compressive forces on the pectoral girdles and the delicate furcula that spanned the acromion processes. Although it was perhaps ungainly for the tyrant king to rise rump first, its ascent was likely more elegant than that of modern bovids rising from repose.
</paragraph>
</subSubSection>
</treatment>
</document>
Reference in a new issue View git blame Copy permalink