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==== Semicircular canals in primate locomotion ==== |
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==== Semicircular canals in primate locomotion ==== |
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Semicircular Canals are often used by paleontologists and Paleoanthropologists to inform locomotor estimations when there is limited postcranial evidence for a species.[{{Cite journal |last1=Schutz |first1=Heidi |last2=Jamniczky |first2=Heather A. |last3=Hallgrımsson |first3=Benedikt |last4=Garland Jr. |first4=Theodore |date=2014 |title=Shape-shift: Semicircular canal morphology responds to selective breeding for increased locomotor activity |url=https://watermark02.silverchair.com/evolut3184.pdf?token=AQECAHi208BE49Ooan9kkhW_Ercy7Dm3ZL_9Cf3qfKAc485ysgAAA3YwggNyBgkqhkiG9w0BBwagggNjMIIDXwIBADCCA1gGCSqGSIb3DQEHATAeBglghkgBZQMEAS4wEQQMVudx0iaMGiI9piIpAgEQgIIDKZXbxL0CARq-ReOLuhodl7p_CTsFKh7q1xIeWxEVGXT6jib3lPF1bzoneiw5AGJbEPxgUrbilCevlVvru4jZ3xuWUGuxSblXUnDGfEEDkaM06v4sO__sM6kKB5o419eBNfLmbTWEgM3wsHW6TBn-9PM-Osz7lhNDrHeyRCxdxl4BAm1rIoW6jYYEpXqMPTlQMOJl7TsjXX8DXUAI6tFbsSppTFNMF2HNytL68gL3ioqSTvOKzYfugaBHBnHFWUAZIOA0CCuRGRBbry1n87gmUv1U-3QovSLtKCO4GkRJa2f9iAORrrldmG3JtHAe0wP9ZiJTjdL6qKco0-aASEv05a20AMvePjHbYhlKFCdYebg6OGwJY8ZEHeIb4uEEZIvYgIaW3fqxDS-UT0FGAlzkAAUojoLYv08i_S2GECAOX9KqgQ728dMX4vtSfmFJ2qcethhk69CvtiwdxgDd8X4Eqrt6x6UwoDDte1capBDh4Dge9W5oX2NTBtUWUTTMTqidkZYxnd6MCAceN3TVu0uWAyo9Wg1WKq6wst8WOMXEFRjVnPN5rveGu_ZSlUuI4igDupY15UYj8OAtLDAlXmd2OUxvu5w9pJkcL04GuBFE3UXjMCrBRx66UD9ME_2mywECNn5zqE8ztD9Es7SMN0rvlv9kFxic4z0ZYXRhAK-APKQ8PlnZyhIMuUh8NA0mujC1nCKL0R9zS7LS8GtTnCJjCJQyc18SXOjsoAcoUsNYfXgplN6GFw-3zDj1DwrwHeoK47T8LOiC2nVKl64gQZ4EYPKd1x276YcLKyzijrTO1dV7_C4ZlPleLV1j-LBgMRoqIj9GrHh0cn9CIWO2Q5PkKdC8W0ovYn40iopD05XzFfO7J9mo4DAqva24vqV0B0jSIwvclRShK8a02Z0PeOFADyqRQ5_SQvTnVY7CRCUMliPb0Yw3ucCTBKfk8o0TSZoLjTFSH7SMaK3Yn-xAEz3BZyt-2nq_v6xeplk80-0Q-cY8jKl4FTF40pxRcC5tlJyRMJ4yV62qMcUQwk20Qe1sK64c4PAjnsBSYMvXRoyccdBgR5N9EVUXYv-K |journal=The Society for the Study of Evolution |volume=68 |issue=11 |pages=3184–3198 |doi=10.1111/evo.12501 |pmid=25130322 }}][{{Cite journal |last1=Spoor |first1=Fred |last2=Garland Jr. |first2=Theodore |last3=Krovitz |first3=Gail |last4=Ryan |first4=Timothy M. |last5=Silcox |first5=Mary T. |last6=Walker |first6=Alan |title=The Primate semicircular canal system and locomotion |journal=PNAS |date=2007 |volume=104 |issue=26 |pages=10808–10812 |doi=10.1073/pnas.0704250104 |doi-access=free |pmid=17576932 |pmc=1892787 |bibcode=2007PNAS..10410808S }}] Semicircular canals are held within the petrous portion of the temporal bone, a very thick and often well preserved portion of the skull.[{{Cite journal |last1=Gonzales |first1=Lauren A. |last2=Malinzak |first2=Michael D. |last3=Kay |first3=Richard F. |date=2018 |title=Intraspecific variation in semicircular canal morphology—A missing element in adaptive scenarios? |journal=American Journal of Physical Anthropology |volume=168 |issue=1 |pages=10–24 |doi=10.1002/ajpa.23692 |pmid=30408143 }}] In contrast, animals who move more slowly tend to have more variation in general as their canals are not under pressure to maintain a certain morphology.[{{Cite book |last1=Fleagle|first1=J.G.|title=Primate Adaptation and Evolution|last2=Baden|first2=A.L.|last3=Gilbert|first3=C.C.|publisher=Elsevier S & T|year=2024|edition=4th|location=|pages=61–99}}][{{Cite book |last1=Fleagle |first1=John G. |title=Primate Adaptation and Evolution |last2=Baden |first2=Andrea L. |last3=Gilbert |first3=Christopher C. |date=2024 |publisher=Elevier] |year=2026 |isbn=978-0-12-815809-8 |edition=4 |publication-date=2024 |pages=207–229 |language=English}} As a result, there is a noticeable and quantifiable difference in their semicircular canal volumes which can be quantified and used to assign fossil crania or partial crania to a range of speed and by extension infer each locomotion. |
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Semicircular Canals are often used by paleontologists and Paleoanthropologists to inform locomotor estimations when there is limited postcranial evidence for a species.[{{Cite journal |last1=Schutz |first1=Heidi |last2=Jamniczky |first2=Heather A. |last3=Hallgrımsson |first3=Benedikt |last4=Garland Jr. |first4=Theodore |date=2014 |title=Shape-shift: Semicircular canal morphology responds to selective breeding for increased locomotor activity |url=https://watermark02.silverchair.com/evolut3184.pdf?token=AQECAHi208BE49Ooan9kkhW_Ercy7Dm3ZL_9Cf3qfKAc485ysgAAA3YwggNyBgkqhkiG9w0BBwagggNjMIIDXwIBADCCA1gGCSqGSIb3DQEHATAeBglghkgBZQMEAS4wEQQMVudx0iaMGiI9piIpAgEQgIIDKZXbxL0CARq-ReOLuhodl7p_CTsFKh7q1xIeWxEVGXT6jib3lPF1bzoneiw5AGJbEPxgUrbilCevlVvru4jZ3xuWUGuxSblXUnDGfEEDkaM06v4sO__sM6kKB5o419eBNfLmbTWEgM3wsHW6TBn-9PM-Osz7lhNDrHeyRCxdxl4BAm1rIoW6jYYEpXqMPTlQMOJl7TsjXX8DXUAI6tFbsSppTFNMF2HNytL68gL3ioqSTvOKzYfugaBHBnHFWUAZIOA0CCuRGRBbry1n87gmUv1U-3QovSLtKCO4GkRJa2f9iAORrrldmG3JtHAe0wP9ZiJTjdL6qKco0-aASEv05a20AMvePjHbYhlKFCdYebg6OGwJY8ZEHeIb4uEEZIvYgIaW3fqxDS-UT0FGAlzkAAUojoLYv08i_S2GECAOX9KqgQ728dMX4vtSfmFJ2qcethhk69CvtiwdxgDd8X4Eqrt6x6UwoDDte1capBDh4Dge9W5oX2NTBtUWUTTMTqidkZYxnd6MCAceN3TVu0uWAyo9Wg1WKq6wst8WOMXEFRjVnPN5rveGu_ZSlUuI4igDupY15UYj8OAtLDAlXmd2OUxvu5w9pJkcL04GuBFE3UXjMCrBRx66UD9ME_2mywECNn5zqE8ztD9Es7SMN0rvlv9kFxic4z0ZYXRhAK-APKQ8PlnZyhIMuUh8NA0mujC1nCKL0R9zS7LS8GtTnCJjCJQyc18SXOjsoAcoUsNYfXgplN6GFw-3zDj1DwrwHeoK47T8LOiC2nVKl64gQZ4EYPKd1x276YcLKyzijrTO1dV7_C4ZlPleLV1j-LBgMRoqIj9GrHh0cn9CIWO2Q5PkKdC8W0ovYn40iopD05XzFfO7J9mo4DAqva24vqV0B0jSIwvclRShK8a02Z0PeOFADyqRQ5_SQvTnVY7CRCUMliPb0Yw3ucCTBKfk8o0TSZoLjTFSH7SMaK3Yn-xAEz3BZyt-2nq_v6xeplk80-0Q-cY8jKl4FTF40pxRcC5tlJyRMJ4yV62qMcUQwk20Qe1sK64c4PAjnsBSYMvXRoyccdBgR5N9EVUXYv-K |journal=The Society for the Study of Evolution |volume=68 |issue=11 |pages=3184–3198 |doi=10.1111/evo.12501 |pmid=25130322 }}][{{Cite journal |last1=Spoor |first1=Fred |last2=Garland Jr. |first2=Theodore |last3=Krovitz |first3=Gail |last4=Ryan |first4=Timothy M. |last5=Silcox |first5=Mary T. |last6=Walker |first6=Alan |title=The Primate semicircular canal system and locomotion |journal=PNAS |date=2007 |volume=104 |issue=26 |pages=10808–10812 |doi=10.1073/pnas.0704250104 |doi-access=free |pmid=17576932 |pmc=1892787 |bibcode=2007PNAS..10410808S }}] Semicircular canals are held within the petrous portion of the temporal bone, a very thick and often well preserved portion of the skull.[{{Cite journal |last1=Gonzales |first1=Lauren A. |last2=Malinzak |first2=Michael D. |last3=Kay |first3=Richard F. |date=2018 |title=Intraspecific variation in semicircular canal morphology—A missing element in adaptive scenarios? |journal=American Journal of Physical Anthropology |volume=168 |issue=1 |pages=10–24 |doi=10.1002/ajpa.23692 |pmid=30408143 }}] In contrast, animals who move more slowly tend to have more variation in general as their canals are not under pressure to maintain a certain morphology.[{{Cite book |last1=Fleagle|first1=J.G.|title=Primate Adaptation and Evolution|last2=Baden|first2=A.L.|last3=Gilbert|first3=C.C.|publisher=Elsevier S & T|year=2024|edition=4th|location=|pages=61–99}}][{{Cite book |last1=Fleagle |first1=John G. |title=Primate Adaptation and Evolution |last2=Baden |first2=Andrea L. |last3=Gilbert |first3=Christopher C. |date=2024 |publisher=Elevier |isbn=978-0-12-815809-8 |edition=4 |publication-date=2024 |pages=207–229 |language=English}}] As a result, there is a noticeable and quantifiable difference in their semicircular canal volumes which can be quantified and used to assign fossil crania or partial crania to a range of speed and by extension infer each locomotion. |
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=== Malagasy radiation === |
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=== Malagasy radiation === |
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In primates, the [[pelvis]] consists of four parts—the left and the right [[hip bone]]s, which meet at the ventral mid-line, the sacrum, which connects the hip bones dorsally, and the [[coccyx]]. Each hip bone consists of three components, the [[Ilium (bone)|ilium]], the [[ischium]], and the [[Pubis (bone)|pubis]], and at the time of sexual maturity these bones become fused together, though there is never any movement between them. In humans, the ventral joint of the pubic bones is closed. |
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In primates, the [[pelvis]] consists of four parts—the left and the right [[hip bone]]s, which meet at the ventral mid-line, the sacrum, which connects the hip bones dorsally, and the [[coccyx]]. Each hip bone consists of three components, the [[Ilium (bone)|ilium]], the [[ischium]], and the [[Pubis (bone)|pubis]], and at the time of sexual maturity these bones become fused together, though there is never any movement between them. In humans, the ventral joint of the pubic bones is closed. |
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In bipedal primates, the [[Ilium (bone)|ilium]] is shortened, widened, and the blades are located more laterally than in other primates. These morphological changes are due to the stresses involved in bipedal locomotion, where the [[Rectus femoris muscle]] activates on the stationary leg, to counterbalance as the other leg moves forward. [{{Cite journal |last=Senevirathne |first=Gayani |last2=Fernandopulle |first2=Serena C. |last3=Richard |first3=Daniel |last4=Baumgart |first4=Stephanie L. |last5=Christensen |first5=Anika Liv |last6=Fabbri |first6=Matteo |last7=Höppner |first7=Jakob |last8=Jüppner |first8=Harald |last9=Li |first9=Peishu |last10=Bothe |first10=Vivien |last11=Fröbisch |first11=Nadia |last12=Simcock |first12=Ian |last13=Arthurs |first13=Owen J. |last14=Calder |first14=Alistair |last15=Freilich |first15=Naomi |date=21 August], 2025 |title=The evolution of hominin bipedalism in two steps |url=https://www.nature.com/articles/s41586-025-09399-9 |journal=Nature |language=en |volume=645 |issue=8082 |pages=952–963 |doi=10.1038/s41586-025-09399-9 |issn=1476-4687}} |
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In bipedal primates, the [[Ilium (bone)|ilium]] is shortened, widened, and the blades are located more laterally than in other primates. These morphological changes are due to the stresses involved in bipedal locomotion, where the [[Rectus femoris muscle]] activates on the stationary leg, to counterbalance as the other leg moves forward. [{{Cite journal |last=Senevirathne |first=Gayani |last2=Fernandopulle |first2=Serena C. |last3=Richard |first3=Daniel |last4=Baumgart |first4=Stephanie L. |last5=Christensen |first5=Anika Liv |last6=Fabbri |first6=Matteo |last7=Höppner |first7=Jakob |last8=Jüppner |first8=Harald |last9=Li |first9=Peishu |last10=Bothe |first10=Vivien |last11=Fröbisch |first11=Nadia |last12=Simcock |first12=Ian |last13=Arthurs |first13=Owen J. |last14=Calder |first14=Alistair |last15=Freilich |first15=Naomi |date=21 August 2025 |title=The evolution of hominin bipedalism in two steps |url=https://www.nature.com/articles/s41586-025-09399-9 |journal=Nature |language=en |volume=645 |issue=8082 |pages=952–963 |doi=10.1038/s41586-025-09399-9 |issn=1476-4687}}] |
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The shape of the pelvic outlet is remarkably small in bipedal primates compared to that of quadrupedal primates, because a smaller pelvis provides better balance for bipedal locomotion. As such, modern humans must have fully rotational births. Though it is hypothesized that [[Australopithecus afarensis]] had semi-rotational births, no other primates require assisted birth. [{{Cite journal |last=Gruss |first=Laura Tobias |last2=Schmitt |first2=Daniel |date=2015-03-05 |title=The evolution of the human pelvis: changing adaptations to bipedalism, obstetrics and thermoregulation |url=https://pmc.ncbi.nlm.nih.gov/articles/PMC4305164/ |journal=Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences |volume=370 |issue=1663 |pages=20140063 |doi=10.1098/rstb.2014.0063 |issn=1471-2970 |pmc=4305164 |pmid=25602067}}] |
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The shape of the pelvic outlet is remarkably small in bipedal primates compared to that of quadrupedal primates, because a smaller pelvis provides better balance for bipedal locomotion. As such, modern humans must have fully rotational births. Though it is hypothesized that [[Australopithecus afarensis]] had semi-rotational births, no other primates require assisted birth. [{{Cite journal |last=Gruss |first=Laura Tobias |last2=Schmitt |first2=Daniel |date=2015-03-05 |title=The evolution of the human pelvis: changing adaptations to bipedalism, obstetrics and thermoregulation |url=https://pmc.ncbi.nlm.nih.gov/articles/PMC4305164/ |journal=Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences |volume=370 |issue=1663 |pages=20140063 |doi=10.1098/rstb.2014.0063 |issn=1471-2970 |pmc=4305164 |pmid=25602067}}] |
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