Why giraffes have short necks … Michael P. Taylor University of Bristol Mathew J. Wedel Western University of Health Sciences
Why giraffes have short necks … … and how sauropods got it right Michael P. Taylor University of Bristol Mathew J. Wedel Western University of Health Sciences
3-meter barrier for all non-aquatic animals
Long-necked sauropod groups Upchurch et al. (2004:fig )
Long-necked sauropod groups Upchurch et al. (2004:fig )
Long-necked sauropod groups I suck... Upchurch et al. (2004:fig )
Long-necked sauropod groups Magic I suck... Upchurch et al. (2004:fig )
Factors contributing to long necks 1. No constraint on vertebral count Paraceratherium (Osborn 1923:fig 1)
Factors contributing to long necks 1. No constraint on vertebral count Mamenchisaurus (modified from Ouyang and Ye 2003:fig. 13) Paraceratherium (Osborn 1923:fig 1)
Factors contributing to long necks 2. Heads that did not process food
Factors contributing to long necks 2. Heads that did not process food Diplodocus
Factors contributing to long necks 2. Heads that did not process food Unholy Diplodocus ☓ Elephas hybrid
Factors contributing to long necks 3. Absolutely large bodies
Factors contributing to long necks 3. Absolutely large bodies
C Factors contributing to long necks 3. Absolutely large bodies Crap.
C Factors contributing to long necks 3A. Large quadrupedal bodies
Crap. C Factors contributing to long necks 3A. Large quadrupedal bodies
C Factors contributing to long necks 3A. Large quadrupedal bodies Crap.
Factors contributing to long necks 3. Absolutely large bodies Parrish (2006) showed that sauropod neck length scales with torso length to the power 1.35
Factors contributing to long necks 3. Absolutely large bodies Carpenter (2006) scaled Amphicoelias fragillimus as 2.2 times Diplodocus. But Parrish suggests neck is 2.2^1.35 = 2.9 times => a neck 22 m long
Factors contributing to long necks 4. Air-sacs overcame dead-space
Factors contributing to long necks 4. Air-sacs overcame dead-space Like ostriches?
Factors contributing to long necks 4. Air-sacs overcame dead-space But what about sperm whales? Paul 1998:fig. 11
Factors contributing to long necks 4. Air-sacs overcame dead-space But what about sperm whales? Paul 1998:fig. 11
Factors contributing to long necks 5. Vertebral architecture Diplodocus carnegii holotype CM 84, cervical 10 (Hatcher 1901:plate III)
Factors contributing to long necks 5. Vertebral architecture Diplodocus carnegii holotype CM 84, cervical 10 (Hatcher 1901:plate III) Neural spine Prezygapophysis Post- zygapophysis Cervical rib Centrum
Cervical vertebral innovations 1. Extreme pneumaticity 2. Bifid neural spines 3. Elongate cervical ribs
Cervical vertebral innovations 1. Extreme pneumaticity Ostrich
Cervical vertebral innovations 1. Extreme pneumaticity Diplodocus
Cervical vertebral innovations 1. Extreme pneumaticity Diplodocus modified from Paul 1998:fig. 1(a)F
Cervical vertebral innovations 1. Extreme pneumaticity Diplodocus cervical cross-sections Paul 1997:fig. 4 Schwarz et al. 2007:fig. 7A2
Cervical vertebral innovations 1. Extreme pneumaticity Diplodocus
Cervical vertebral innovations 1. Extreme pneumaticity Diplodocus
Cervical vertebral innovations 1. Extreme pneumaticity Diplodocus
Cervical vertebral innovations 1. Extreme pneumaticity Red tailed hawk
Cervical vertebral innovations 2. Bifid neural spines Apatosaurus
Long-necked sauropod groups Upchurch et al. (2004:fig )
Long-necked sauropod groups Bifid neural spines evolved at least five times Never secondarily lost? Otherwise found only in the rhea (and only just) Upchurch et al. (2004:fig )
Cervical vertebral innovations 2. Bifid neural spines Alexander (1985) thought the trough was filled with a giant elastin ligament Diplodocus
Cervical vertebral innovations 2. Bifid neural spines Apatosaurus
Cervical vertebral innovations 2. Bifid neural spines Apatosaurus
Cervical vertebral innovations 2. Bifid neural spines Apatosaurus
Cervical vertebral innovations 2. Bifid neural spines Diplodocus (Schwarz et al. 2007:fig. 7A2)
Cervical vertebral innovations 2. Bifid neural spines
Cervical vertebral innovations 2. Bifid neural spines
Cervical vertebral innovations 2. Bifid neural spines
Cervical vertebral innovations 3. Elongate cervical ribs Turkey cervical 7
Cervical vertebral innovations 3. Elongate cervical ribs Turkey cervical 7
Cervical vertebral innovations 3. Elongate cervical ribs 4.1 m Turkey cervical 7 Mamenchisaurus
Cervical vertebral innovations 3. Elongate cervical ribs 4.1 m Mamenchisaurus That lame giraffe Turkey cervical 7
Cervical vertebral innovations 3. Elongate cervical ribs Giraffatitan
Cervical vertebral innovations 3. Elongate cervical ribs Giraffatitan
Cervical vertebral innovations 3. Elongate cervical ribs Giraffatitan
Comparison with birds and crocs Turkey cervical 7
Comparison with birds and crocs Turkey cervical 7
Comparison with birds and crocs Turkey cervical 7 Epipophysis
Comparison with birds and crocs Turkey cervical 7
Comparison with birds and crocs AlligatorMajungasaurusTurkey Majungasaurus from O'Connor 2007:figs. 8, 20
Comparison with birds and crocs AlligatorMajungasaurusTurkey Majungasaurus from O'Connor 2007:figs. 8, 20
Comparison with birds and crocs AlligatorMajungasaurusTurkey Majungasaurus from O'Connor 2007:figs. 8, 20
Comparison with birds and crocs AlligatorMajungasaurusTurkeyGiraffatitan Giraffatitan from Janensch 1950:fig. 46 Majungasaurus from O'Connor 2007:figs. 8, 20
Comparison with birds and crocs AlligatorMajungasaurusTurkeyGiraffatitanCamarasaurus Giraffatitan from Janensch 1950:fig. 46 Camarasaurus from Osborn and Mook 1921:plate LXVII Majungasaurus from O'Connor 2007:figs. 8, 20
Comparison with birds and crocs Analogous but not homologous AlligatorMajungasaurusTurkeyGiraffatitanCamarasaurus Giraffatitan from Janensch 1950:fig. 46 Camarasaurus from Osborn and Mook 1921:plate LXVII Majungasaurus from O'Connor 2007:figs. 8, 20
Why are epipophyses not elongate? Euhelopus (Wiman 1929:plate III)
Why are epipophyses not elongate? Euhelopus (Wiman 1929:plate III)
Why are epipophyses not elongate? Euhelopus (Wiman 1929:plate III)
Why are epipophyses not elongate? Euhelopus (Wiman 1929:plate III)
Why are epipophyses not elongate? Deinonychus (Ostrom 1969:fig. 37)
Why are epipophyses not elongate? Giraffatitan (Janensch 1950:fig. 43)
Why are epipophyses not elongate? Need finer control for precise movements – requires shorter levers Giraffatitan (Janensch 1950:fig. 43)
Why are epipophyses not elongate? Tendon is stronger in tension than bone Giraffatitan (Janensch 1950:fig. 43)
Why are epipophyses not elongate? Muscles expand when they contract lengthways Giraffatitan (Janensch 1950:fig. 43)
Why are epipophyses not elongate? Muscles expand when they contract lengthways Giraffatitan (Janensch 1950:fig. 43)
Why are epipophyses not elongate?
Crap.
Conclusion TaxonMany vertebrae Small head (no dental battery) Large body, four legs Air-sacsPneumatic vertebrae Elongate cervical ribs Giraffe Giant rhinos ✓ Ostrich ✓✓✓✓ Theropods ✓✓✓ Pterosaurs ✓✓ Sauropods ✓✓✓✓✓✓
Conclusion TaxonMany vertebrae Small head (no dental battery) Large body, four legs Air-sacsPneumatic vertebrae Elongate cervical ribs Giraffe X XXXXX Giant rhinos ✓ Ostrich ✓✓✓✓ Theropods ✓✓✓ Pterosaurs ✓✓ Sauropods ✓✓✓✓✓✓
Acknowledgements Everyone who allowed us access to specimens Everyone that we stole images from Western University for sending Matt to the UK Sauroposeidon
Further reading Sauropod Vertebra Picture of the Week: Taylor and Wedel 2013a: Sauroposeidon