Growth of Grey Kangaroos and the Reliability of Age Determination from Body Measurements II.* The Western Grey Kangaroos, Macropus fuliginosus fuliginosus, M. f. melanops and M. f. ocydromus

Poole, WE; Carpenter, SM; Wood, JT

doi:10.1071/wr9820203

Cited by 29 publications

(36 citation statements)

References 3 publications

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“…In humans, for example, the ratio decreases from 0.8 at birth to 0.4 by 3 mo of age (Keen 1955;Joyce et al 2004). This postnatal change in ventricular mass ratio is not evident in our data because the youngest joey had been breathing air for approximately 3 mo, as estimated from its body mass of 85 g (Poole et al 1985), and smaller animals ought to develop faster than human neonates. The external work of the heart is related to the product of blood flow rate (cardiac output) and blood pressure.…”

Section: The Right ∶ Left Ventricular Mass Ratiomentioning

confidence: 53%

“…Young pouch joeys are permanently attached to the teat and show limited movement as their hind legs are practically nonexistent (Sharman and Pilton 1964), but as development progresses, the legs become longer and muscular (Poole et al 1985) until the joey begins to venture tentatively from the pouch (Dawson 2012). The gradual increase in overall motility is probably important, because once joeys vacate the pouch, they have to hop as fast as their mothers.…”

Section: Biphasic Cardiac Allometry and The Transition To Independentmentioning

confidence: 97%

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Biphasic Allometry of Cardiac Growth in the Developing KangarooMacropus fuliginosus

Snelling¹,

Taggart²,

Maloney³

et al. 2015

Physiological and Biochemical Zoology

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Interspecific studies of adult mammals show that heart mass (M(h), g) increases in direct proportion to body mass (M(b), kg), such that M(h) ∝ M(b)(1.00). However, intraspecific studies on heart mass in mammals at different stages of development reveal considerable variation between species, M(h) ∝ M(b)(0.70-1.00). Part of this variation may arise as a result of the narrow body size range of growing placental mammals, from birth to adulthood. Marsupial mammals are born relatively small and offer an opportunity to examine the ontogeny of heart mass over a much broader body size range. Data from 29 western grey kangaroos Macropus fuliginosus spanning 800-fold in body mass (0.084-67.5 kg) reveal the exponent for heart mass decreases significantly when the joey leaves the pouch (ca. 5-6 kg body mass). In the pouch, the heart mass of joeys scales with hyperallometry, M(h(in-pouch)) = 6.39 M(b)(1.10 ± 0.05), whereas in free-roaming juveniles and adults, heart mass scales with hypoallometry, M(h(postpouch)) = 14.2 Mb(0.77 ± 0.08). Measurements of heart height, width, and depth support this finding. The relatively steep heart growth allometry during in-pouch development is consistent with the increase in relative cardiac demands as joeys develop endothermy and the capacity for hopping locomotion. Once out of the pouch, the exponent decreases sharply, possibly because the energy required for hopping is independent of speed, and the efficiency of energy storage during hopping increases as the kangaroo grows. The right:left ventricular mass ratios (0.30-0.35) do not change over the body mass range and are similar to those of other mammals, reflecting the principle of Laplace for the heart.

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Section: The Right ∶ Left Ventricular Mass Ratiomentioning

confidence: 53%

Section: Biphasic Cardiac Allometry and The Transition To Independentmentioning

confidence: 97%

Biphasic Allometry of Cardiac Growth in the Developing KangarooMacropus fuliginosus

Snelling¹,

Taggart²,

Maloney³

et al. 2015

Physiological and Biochemical Zoology

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“…The variability in body measurements of the weaning pademelons made curve fitting difficult and in both cases we failed to fit the second hyperbola of a broken-stick model described previously [9] to the second growth phase of pademelons (Eqn. 3: Ln m = b4+b3/Age−b3/j, for age>j days).…”

Section: Resultsmentioning

confidence: 99%

A Two-Phase Model for Smoothly Joining Disparate Growth Phases in the Macropodid Thylogale billardierii

et al. 2011

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Generally, sigmoid curves are used to describe the growth of animals over their lifetime. However, because growth rates often differ over an animal's lifetime a single curve may not accurately capture the growth. Broken-stick models constrained to pass through a common point have been proposed to describe the different growth phases, but these are often unsatisfactory because essentially there are still two functions that describe the lifetime growth. To provide a single, converged model to age animals with disparate growth phases we developed a smoothly joining two-phase nonlinear function (SJ2P), tailored to provide a more accurate description of lifetime growth of the macropod, the Tasmanian pademelon Thylogale billardierii. The model consists of the Verhulst logistic function, which describes pouch-phase growth – joining smoothly to the Brody function, which describes post-pouch growth. Results from the model demonstrate that male pademelons grew faster and bigger than females. Our approach provides a practical means of ageing wild pademelons for life history studies but given the high variability of the data used to parametrise the second growth phase of the model, the accuracy of ageing of post-weaned animals is low: accuracy might be improved with collection of longitudinal growth data. This study provides a unique, first robust method that can be used to characterise growth over the lifespan of pademelons. The development of this method is relevant to collecting age-specific vital rates from commonly used wildlife management practices to provide crucial insights into the demographic behaviour of animal populations.

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“… Approximate ages of pouch young were calculated on the basis of body mass following Poole et al. (). …”

Section: Methodsmentioning

confidence: 99%

The fibular meniscus of the kangaroo as an adaptation against external tibial rotation during saltatorial locomotion

2017

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The kangaroo knee is, as in other species, a complex diarthrodial joint dependent on interacting osseous, cartilaginous and ligamentous components for its stability. While principal load bearing occurs through the femorotibial articulation, additional lateral articulations involving the fibula and lateral fabella also contribute to the functional arrangement. Several fibrocartilage and ligamentous structures in this joint remain unexplained or have been misunderstood in previous studies. In this study, we review the existing literature on the structure of the kangaroo 'knee' before providing a new description of the gross anatomical and histological structures. In particular, we present strong evidence that the previously described 'femorofibular disc' is best described as a fibular meniscus on the basis of its gross and histological anatomy. Further, we found it to be joined by a distinct tendinous tract connecting one belly of the m. gastrocnemius with the lateral meniscus, via a hyaline cartilage cornu of the enlarged lateral fabella. The complex of ligaments connecting the fibular meniscus to the surrounding connective tissues and muscles appears to provide a strong resistance to external rotation of the tibia, via the restriction of independent movement of the proximal fibula. We suggest this may be an adaptation to resist the rotational torque applied across the joint during bipedal saltatory locomotion in kangaroos.

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Growth of Grey Kangaroos and the Reliability of Age Determination from Body Measurements II.* The Western Grey Kangaroos, Macropus fuliginosus fuliginosus, M. f. melanops and M. f. ocydromus

Cited by 29 publications

References 3 publications

Biphasic Allometry of Cardiac Growth in the Developing KangarooMacropus fuliginosus

Biphasic Allometry of Cardiac Growth in the Developing KangarooMacropus fuliginosus

A Two-Phase Model for Smoothly Joining Disparate Growth Phases in the Macropodid Thylogale billardierii

The fibular meniscus of the kangaroo as an adaptation against external tibial rotation during saltatorial locomotion

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