Hindlimb Length Research Articles

Body proportions, skeletal allometry and locomotion in the hadar hominids: a reply to Wolpoff

Wolpoff, 1983a , Wolpoff, 1983b ) has challenged the interpretation of relative limb proportions and locomotion offered by Jungers (1982) for Australopithecus afarensis in comparison to modern humans of similar body size. In this reply, we demonstrate that Wolpoff's conclusions are based on several misconceptions about the biomechanics and energetics of bipedalism and a misapplication of the allometric approach. Compared with modern humans (pygmies) of comparably small size (measured as cstimated body weight and as a linear variable correlated to body weight in modern humans), “Lucy” (AL 288-1) possesses very short hindlimbs outside of the known human range and which are proportioned most similarly to small-bodied African apes. By contrast, relative humerus length of Lucy can be matched precisely in a skeletal sample of human pygmics. A similar combination of relative limb lengths appears to exist in the larger individuals of A. afarensis and probably characterizes all gracile australopithecines (including STS 14). The functional implications of interlimb proportions, relative fore-and hindlimb lengths and relative foot length for locomotor biomechanics in A afarensis are also examined. The original interpretations put forth by Jungers (1982) are reaffirmed and strengthened by new data and appropriate analyses.

Postnatal ontogeny of the musculo‐skeletal system in the Black‐tailed jack rabbit (Lepus californicus)

The ontogeny of 23 postcranial skeletal dimensions, mechanical properties of the third metatarsal and the femur, and the isometric contractile properties of the gastrocnemius muscle were measured in a complete postnatal growth series of the highly cursorial hare Lepus californicus. Newborn hares are handicapped by short limbs, relatively weak muscles and bone tissue, and shorter muscular contractile distances. However, during growth these deficiencies are rapidly overcome. Hind limb length and gastrocnemius contractile distance undergo positive allometry, scaling as (body mass)0·39 and (body mass)0·41, respectively. The mechanical advantage of the gastrocnemius lever system experiences negative allometry (a(body mass)‐0·12), giving young hares larger advantage around their joints. This, combined with initial positive allometry of gastrocnemius contractile force (α(body mass) 1·23) and subsequent negative allometry of contractile force (α(body mass)0·61), results in the production of relatively greater propulsive forces transmitted from the foot to the ground in juveniles than in adults. In addition, the second moment of area of the metatarsal is relatively large in younger animals, and scales in such a way that during the first half of postnatal growth mechanical similarity is maintained between the breaking moment of the bone (α(body mass)1·50) and the moment imposed on the bone by the gastrocnemius (a(body mass)l·54). These ontogenetic changes contribute to the development of a locomotor system which is effective at escape by the time the young hare is only 20% of adult body size, and must forage independently. Differences between the ontogenetic allometry of Lepus, the interspecific allometry of mammals and the ontogenetic allometry of reptiles are noted and considered in a phylogenetic context.

Changes in specific prolactin binding in Rana catesbeiana tadpole tissues during metamorphosis and following prolactin and thyroid-hormone treatment

The prolactin-binding affinity ( K D ) and number of binding sites N in Rana catesbeiana tadpole, tail fin and kidney tissues were studied during metamorphosis and following administration of oPRL and L-T 3 to premetamorphic tadpoles. With increasing developmental stage there was an increase in N; a maximum was found at stage XVIII followed by a gradual decrease in N through metamorphic climax for all 3 tissues. No change in K d was noted. lL-T 3 treatment of premetamorphic tadpoles for 7 days caused a significant decrease in tail length and height and body length and an increase in hindlimb length with a concurrent increase in N of approximately 3-fold while treatment for 1 or 3 days was without effect on tadpole morphology or oPRL binding. oPRL treatment for 7 days caused a significant increase in tail length and height and body length with no significant changes in hindlimb length and a 3–5-fold increase in N. Treatment with both L-T 3 and oPRL for 7 days resulted in an inhibition of the T 3- induced decrease in tail length and height and body length and no inhibition of the hindlimb length increase. N increased in all tissues similar to that found with either treatment alone. No change in K D was noted in any of these studies. Therefore, oPRL and L-T 3 are able to regulate the numbers of specific oPRL-binding sites in amphibian tissues. The change in N with development parallels the reported change in tadpole pituitary capacity to stimulate growth but occurs prior to the reported surge of endogenous T 3 during metamorphosis. Thus, the variation in the number of oPRL-binding sites may be due to the changes in endogenous PRL levels during development.

Body Proportions and Gliding Adaptations of Flying Squirrels (Petauristinae)

Flying squirrels range in length of head and body from less than 90 mm to more than 400 mm. Large flying squirrels are more slender than tree squirrels or small flying squirrels. They have proportionately longer tails than small flying squirrels, but large tree squirrels have the longest tails of all, both absolutely and proportionately. Relative limb lengths decrease with size among flying and tree squirrels, but the ratio of forelimb to hindlimb length is generally higher for flying squirrels than for tree squirrels. The styliform cartilage adds to the area of the patagium, but it is isometric with respect to size. Weight varies by a factor of almost 64 and the area of the patagium by a factor of almost 16, with little divergence from the expected isometric relationship. Therefore “wing loading” varies almost by a factor of four and is estimated to be as low as 30 Newtons/square meter (N/m2) in small petauristines and as great as 110 N/m2 in large ones. Hang gliding seems to provide a good analogue for the gliding of flying squirrels, although the squirrels have lower aspect ratios (l.0 to 2.2) and lower glide ratios (less than 3) than do most hang gliders. From this analogy it seems probable that the heavier “wing loading” of large flying squirrels does not affect the glide ratio (horizontal distance/vertical drop) but that the larger flying squirrels must “fly” faster to maximize their glide ratio. It is also probable that small flying squirrels with lower “wing loadings” are more maneuverable, but large flying squirrels with heavier loadings are less affected by air turbulence.

Body proportions, microhabitat selection, and adaptive radiation of Liolaemus lizards in central Chile.

A biometric analysis of body proportions with presumably functional meaning for microhabitat selection was made on 12 species of Liolaemus lizards in central Chile. Characters studied were forelimb length, hindlimb length, tail length (all standardized by the corresponding snout-vent length), and the ratio forelimb/hindlimb length. It is shown that irrespective of terrestrial, saxicolous, or arboreal habits, Liolaemus species are remarkably similar in body proportions. The only exceptions are: L. lemniscatus, an open ground-dweller which exhibits significantly shorter limbs; and L. chiliensis and L. schroederi, both shrub-climbers which exhibit significantly longer tail. It is concluded that the adaptive radiation of Liolaemus lizards in central Chile has been accomplished mainly by diversification of activity time, food size, and microhabitat type. Morphological divergence in body proportions seems to have played an unimportant role.

Osteology and Anuran Systematics: Intrapopulational Variation in Hyla Lanciformis

Trueb, L. (Museum of Natural History and Department of Systematics and Ecology, The University of Kansas, Lawrence, Kansas 66045) 1977. Osteology and anuran systematics: Intrapopulational variation in Hyla lanciformis. Syst. Zool. 26:165-184.-Although osteological features are utilized frequently in comprehensive systematic reviews of anuran taxa, no serious attempt has been made to quantify the data and assess its variation other than in a descriptive context. Such assessments first must be made at the population level; thus, 119 osteological were madeon a of adult males and females of the Neotropical frog Hyla lanciformis (Anura: Hylidae). The results of this study show that nearly 50% of these characters demonstrate relatively low levels of variation in both sexes within the population. This suggests that osteological features can be quantified, and selected characters can be utilized to generate an osteological profile of a taxon to be used in concert with other numerical data for subsequent analyses. [Osteology; intrapopulational variation; Anura; Hyla lanciformis.] To a great extent the history of anuran classification -represents a chronology of investigations of anuran osteology. In the earliest classification of anurans (Wagler, 1830; Dumeril and Bibron, 1841), frogs were divided into two groups depending upon the presence (Phaneroglossa) or absence (Aglossa) of a tongue. The utility of the latter classification and others which followed (e.g. Thomas, 1854; Bruch, 1863; L'Isle, 1877) based on pupil shape and amplectic type were not accepted widely once Cope (1864, 1865) defined arcifery and firmisterny and designated two primary anuran groups on the basis of apparent dichotomous pectoral girdle structure. Boulenger (1882) perpetuated Cope's designations by describing series (Arcifera and Firmisternia) within the order Anura. This classification prevailed until Noble (1922) established five suborders of anurans predicated on differences in thigh musculature and, principally, the structure of vertebral centra. Noble's conclusions largely stood unchallenged until recent reassessments by Griffiths (1963), Inger (1967), Kluge and Farris (1969), Starrett (1973), Sokol (1975), and Duellman (1975). A glance at more recent work at familial and generic levels (e.g. see Zweifel, 1956, on pelobatids; Lynch, 1971, on leptodactylids; Tihen, 1962, on bufonids; Duelhman, 1970, on hylids; Trueb, 1970, on hylids; Laurent, 1940, 1941 a and b, 1943, and 1944, on ranids and rhacophorids; Parker, 1934, on microhylids) demonstrates the pervasiveness of osteological criteria in studies of anuran relationships. Scarcely a species description exists which does not specify snout-vent length. Moreover, morphometric assessments of head width, and hind limb length are presented, usually, as a matter of procedure and frequently are expressed as proportions of the snout-vent length. Among other characters commonly encountered are the shape of the snout, various cranial features (e.g. condition of dermal bone and presence or absence of cranial elements and dentition), fusion of limb bones, development of prehallux and prepollex, and number of presacral vertebrae. It is patently obvious that these characters are osteological as are the standard measurements of head, body and limb dimensions. Another issue of paramount importance in understanding the relationships among modem anurans is the fossil record, the interpretation of which is contingent almost exclusively on osteological criteria. All too

The growth and development of rats given a low-protein diet.

1. Weanling (24-d-old) rats of a black and white hooded strain were allowed free access for 28 d to a diet containing 5% casein supplemented with methionine, and sucrose as the carbohydrate. Controls were fed on a 25% casein diet with a corresponding reduction in sucrose. Animals given the deficient diet were killed either at 52 d of age or after subsequent rehabilitation on the 25% casein diet when aged 140 d. These animals were compared with controls killed at these two ages and at the start of the experiment.2. The skeletons were X-rayed, skeletal maturity was determined according to a scoring system, and various bones were measured. The forebrain and cerebellum were analysed for cholesterol and DNA and the brain stem for cholesterol only. The DNA content of the paired quadriceps muscles and the livers was also determined.3. On the low-protein diet the body-weight rose by 7 g compared with the control value of 115 g. On rehabilitation, the body-weight of the previously malnourished group showed the expected growth spurt, but failed to attain that of the controls at 140 d.4. With the exception of the pelvis width, all the bones grew a little during the period on the low-protein diet. After rehabilitation, the hind limb, pelvis, iliac and spine lengths and the bi-iliac width remained smaller than these measurements in the corresponding controls, whereas there was no difference in the length of the fore limb, width of the pelvis or in the bone maturity score.5. The forebrains and cerebellums of the malnourished rats did not increase in weight, whereas some increase occurred in the brain stem. The concentration of cholesterol in the forebrains of the deficient animals was the same as that in controls of the same age, but on rehabilitation the concentration did not rise to the control value. The concentration of cholesterol in the cerebellum and brain stem of the deficient rats was lower than in controls of the same age but, whereas that in the cerebellum attained an almost normal level on rehabilitation, that in the brain stem remained significantly lower. The low-protein diet prevented the normal increase in cerebellum DNA and the amount remained low in the rehabilitated animals.6. The experimental diet caused a complete cessation of growth of the quadriceps muscles, and even after rehabilitation they weighed less than their controls. The DNA content, however, was not significantly lower.7. The low-protein diet did not permanently affect either the weight or DNA content of the liver.

HANDEDNESS IN THE BROWN‐THROATED PARAKEET ARATINGA PERTINAX EST RELATION WITH SKELETAL ASYMMETRY

SUMMARYObservations on 56 specimens of Aratinga pertinax when bringing food to the beak prove that 28 birds were right‐handed while the other 28 were left‐handed. A biometric analysis reveals a slight departure from bilateral symmetry in hindlimb bones in close relationship with handedness. In the right‐handed birds, there is a significant predominance in the length of the right hindlimb as a whole and all right limb segments. The opposite holds true in left‐handed parrots (except for the femur). Right‐handed birds are in general more highly asymmetrical than left‐handed ones. There is a positive correlation between asymmetry of homologous segments of a pair of limbs and the asymmetry of the other segments of the same pair of limbs. The absence of significant negative correlations between bilateral differences of the different segments of a limb indicates that departures from bilateral symmetry tend to affect the limb as a whole, and thus is not in agreement with the rule of compensating variations.

Effect of water-miscible preparation of vitamin D2 on metamorphosis of thiourea and citrate treated Rana pipiens larvae.

SummaryAn immersion experiment using hind-limb length increase of R. pipiens tadpoles has shown that although Vit. D2 enhances metamorphosis it does not counteract the effect of thiourea. Addition of citrate reduces the Vit. D2 effect.

THE EFFECTS OF HYDROGEN ION CONCENTRATION UPON THE METAMORPHIC PATTERN OF THYROXIN- AND IODINE-TREATED TADPOLES

1. It has been shown quantitatively that the degree of response of the hind limbs of tadpoles to the action of thyroxin is dependent upon the lengths of the limbs at the beginning of treatment. 2. Both the potency of the inducing substance and the rate of penetration of the substance into the animal might be involved in the effects of hydrogen ion concentration on induced development. 3. Changes in hydrogen ion concentration affect the inducing power of thyroxin and iodine differently. With thyroxin, it is the rate of penetration of the molecule which determines the amount of growth, but with iodine it is the chemical form in which the substance has entered the animal which is of prime importance. 4. The hydrogen ion concentration of thyroxin solutions does not affect their potency when they are injected into tadpoles. 5. Change in hydrogen ion concentration of the environment does not affect the potency of thyroxin injected into tadpoles. 6. When thyroxin is administered in the environmental solution its effects, as measured by increase in hind limb length are greater at higher than at lower hydrogen ion concentrations in the range tested. 7. Since the potency of thyroxin is unaffected by change in hydrogen ion concentration when the thyroxin solution is injected, the above fact (point 6) seems explicable only on the basis of differences in the rate of penetration of thyroxin into the animals at the different hydrogen ion concentrations. 8. These differences in penetration of the thyroxin at different hydrogen ion concentrations may be the result of a differential effect of hydrogen ion concentration upon the rate of metabolism of the animal. The metabolic rate is significantly greater when the tadpoles are kept in solutions of higher hydrogen ion concentration than when they are kept in solutions of low hydrogen ion concentration. It is postulated that the rate of metabolism, since it controls the rate of intake of the environmental fluid and therefore of dissolved thyroxin, also controls the amount of thyroxin-induced development. 9. Change in hydrogen ion concentration of iodine solutions affects their potency when injected into tadpoles. A peak of effectiveness is reached at about the neutral point, with a lowered efficiency as the hydrogen ion concentration is either increased or decreased from this point. 10. Change in hydrogen ion concentration of the environment affects the potency of iodine injected into tadpoles. The effect is similar to that noted in point 9. 11. The hydrogen ion concentration of the environment seems to affect the chemical nature of the iodine in solution in the environment. If this is so, it is possible that the differences in the metamorphic effects of iodine at different hydrogen ion concentrations are dependent upon the chemical form of iodine present. 12. The effect of hydrogen ion concentration on normal development is similar to that on thyroxin-induced development; an effect on the rate of metabolism of the animal causes increased growth in more acid solutions.

Role of Hypophysis in the Initiation of Metamorphosis in Bufo.

The importance of the pars anterior of the hypophysis in the control of the thyroid gland has been clearly shown in many ways and by many investigators. The writer has shown that under normal conditions of iodine content in food and water, amphibian larvae fail to metamorphose in the absence of either or both of these glands. The stage at which development ceases is the same in each instance.It is natural to inquire which of the two glands takes the leading role in initiating the process of thyroid secretion. A crucial experiment consists in making transplants of the hypophysis taken from tadpoles of different stages of development into a uniform stage shortly before the beginning of metamorphosis. The recipients of these transplants were selected tadpoles of Bufo halophilus with a total length of 25-28 mm. and a hind limb length of 1-2 mm. At the end of from 10 to 18 days they were killed and preserved for study.The transplants were placed in pockets under the skin median and caudal to the right eye wher...