From fetus to adult—an allometric analysis of the giraffe vertebral column

Sittert, S.J. van; Skinner, J. D.; Mitchell, G.

doi:10.1002/jez.b.21353

Cited by 31 publications

(48 citation statements)

References 25 publications

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“…This difference was not significant (P > 0.05) and the finding suggests that lung volume in giraffes can be determined from lung mass. The small size of the lungs probably is related to the small abdomino-thoracic cavity (Murie, 1872) arising from the adjustments to skeletal morphology needed to support the neck (van Sittert et al, 2010). The reduction in space without a parallel reduction in volume of the digestive system must have the effect that digestive organs occupy thoracic space and so limit lung volume.…”

Section: Discussionmentioning

confidence: 99%

Lung volumes in giraffes, Giraffa camelopardalis

Mitchell¹,

Skinner²

2011

Comparative Biochemistry and Physiology Part A: Molecular &

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We have measured lung mass and trachea dimensions in 46 giraffes of both genders ranging in body mass from 147 kg to 1441 kg, calculated static and dynamic lung volumes, and developed allometric equations that relate changes in them to growth. We found that relative lung mass is 0.6 ± 0.2% of body mass which is significantly less than it is in other mammals (1.1 ± 0.1%). Total lung volume is significantly smaller (46.2 ± 5.9 mL kg −1 ) than in similar sized mammals (75.0 ± 2.1 mL kg −1 ). The lung volume:body mass ratio decreases during growth rather than increase as it does in other mammals. Tracheal diameter is significantly narrower than in similar sized mammals but dead space volume (2.9 ± 0.5 mL kg −1 ) is larger than in similar sized mammals (2.4 ± 0.1 mL kg −1 ). Our calculations suggest that tidal volume (10.5 ± 0.2 mL kg −1 ) is increased compared to that in other mammals(10.0 ± 0.2 mL kg −1 ) so that the dead space:tidal volume ratio is the same as in other mammals. Calculated Functional Residual Capacity is smaller than predicted (53.4 ± 3.5 vs 33.7 ± 0.6 mL kg −1 ) as is Expiratory Reserve Volume (47.4 ± 2.6 vs 27.2 ± 1.0 mL kg −1 , but Residual Volume (6.0 ± 0.4 mL kg −1 ) is the same as in other similar sized mammals (6.0 ± 0.9 mL kg −1 . Our calculations suggest that Inspiratory Reserve Volume is significantly reduced in size (11.6 ± 1.6 vs 3.8 ± 2.4 mL kg −1 ), and, if so, the capacity to increase tidal volume is limited. Calculated dynamic lung volumes were the same as in similar sized mammals. We have concluded that giraffe morphology has resulted in lung volumes that are significantly different to that of similar sized mammals, but these changes do not compromise ventilatory capacity.

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Section: Discussionmentioning

confidence: 99%

Lung volumes in giraffes, Giraffa camelopardalis

Mitchell¹,

Skinner²

2011

Comparative Biochemistry and Physiology Part A: Molecular &

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“…17-3] but not in alert rest [95], [96]. The giraffe Giraffa camelopardalis naturally rises in ONP (B, note the deep insertion of condyles within cotyles consistent with dissections [15]), and assumes approximately this pose in locomotion and alert rest [63], [89], [92], [93]. The nearly straight necks of the Giant Anteater Myrmecophaga tridactyla (C), also mounted in ONP, is characteristic of habitual alert resting pose of alert rest, locomotion pose and feeding.…”

Section: Methodsmentioning

confidence: 99%

The Articulation of Sauropod Necks: Methodology and Mythology

Stevens

2013

PLoS ONE

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Sauropods are often imagined to have held their heads high atop necks that ascended in a sweeping curve that was formed either intrinsically because of the shape of their vertebrae, or behaviorally by lifting the head, or both. Their necks are also popularly depicted in life with poses suggesting avian flexibility. The grounds for such interpretations are examined in terms of vertebral osteology, inferences about missing soft tissues, intervertebral flexibility, and behavior. Osteologically, the pronounced opisthocoely and conformal central and zygapophyseal articular surfaces strongly constrain the reconstruction of the cervical vertebral column. The sauropod cervico-dorsal vertebral column is essentially straight, in contrast to the curvature exhibited in those extant vertebrates that naturally hold their heads above rising necks. Regarding flexibility, extant vertebrates with homologous articular geometries preserve a degree of zygapophyseal overlap at the limits of deflection, a constraint that is further restricted by soft tissues. Sauropod necks, if similarly constrained, were capable of sweeping out large feeding surfaces, yet much less capable of retracting the head to explore the enclosed volume in an avian manner. Behaviorally, modern vertebrates generally assume characteristic neck postures which are close to the intrinsic curvature of the undeflected neck. With the exception of some vertebrates that can retract their heads to balance above their shoulders at rest (e.g., felids, lagomorphs, and some ratites), the undeflected neck generally predicts the default head height at rest and during locomotion.

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“…Several studies have addressed the unique specializations of the Giraffa camelopardalis C7 and T1 vertebrae, suggesting atypical cervicothoracic anatomic features, possibly contributing to neck lengthening [8,9]. An osteological study of foetal and adult giraffe vertebrae concluded that substantial cervical lengthening occurs after birth [10]. While the extant giraffe neck has been adequately researched, osteological demonstration of the fossils and evolutionary transformation of the neck is lacking.…”

Section: Introductionmentioning

confidence: 99%

Fossil evidence and stages of elongation of theGiraffa camelopardalisneck

et al. 2015

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Several evolutionary theories have been proposed to explain the adaptation of the long giraffe neck; however, few studies examine the fossil cervical vertebrae. We incorporate extinct giraffids, and the okapi and giraffe cervical vertebral specimens in a comprehensive analysis of the anatomy and elongation of the neck. We establish and evaluate 20 character states that relate to general, cranial and caudal vertebral lengthening, and calculate a length-to-width ratio to measure the relative slenderness of the vertebrae. Our sample includes cervical vertebrae (n=71) of 11 taxa representing all seven subfamilies. We also perform a computational comparison of the C3 of Samotherium and Giraffa camelopardalis, which demonstrates that cervical elongation occurs disproportionately along the cranial–caudal vertebral axis. Using the morphological characters and calculated ratios, we propose stages in cervical lengthening, which are supported by the mathematical transformations using fossil and extant specimens. We find that cervical elongation is anisometric and unexpectedly precedes Giraffidae. Within the family, cranial vertebral elongation is the first lengthening stage observed followed by caudal vertebral elongation, which accounts for the extremely long neck of the giraffe.

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From fetus to adult—an allometric analysis of the giraffe vertebral column

Cited by 31 publications

References 25 publications

Lung volumes in giraffes, Giraffa camelopardalis

Lung volumes in giraffes, Giraffa camelopardalis

The Articulation of Sauropod Necks: Methodology and Mythology

Fossil evidence and stages of elongation of theGiraffa camelopardalisneck

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