Bone histology of Silesaurus opolensisDzik, 2003 from the Late Triassic of Poland

Fostowicz‐Frelik, ?. & Sulej, T. 2009: Bone histology of Silesaurus opolensisDzik, 2003 from the Late Triassic of Poland. Lethaia, Vol. 43, pp. 137–148. The phylogenetic relationships of Silesaurus opolensis have been the subject of intense debate since its discovery. Silesaurus possesses some features characteristic of ornithischian dinosaurs, such as the presence of a beak at the front of the lower jaw, yet it lacks a number of important femoral and dental synapomorphies of Dinosauria. The microstructure of the long bones (femur, tibia and metatarsal) and ribs of this species reveals a relatively intensive rate of growth, comparable with that seen in small dinosaurs and the gracile crocodylomorph Terrestrisuchus. Cortical bone formed mainly by periosteal tissue with fibro‐lamellar matrix (in older specimens parallel fibred) shows very little secondary remodelling and only in one specimen (large tibia ZPAL Ab III/1885) few lines of arrested growth are present in the outermost cortex. The vascularization is relatively dense, mainly longitudinal and ceases towards the periphery, forming almost avascular parallel fibred bone at the bone surface. This indicates maturation and significant decrease in the growth ratio in mature specimens of S. opolensis. The delicate trabeculae exhibit cores formed by the primary cancellous tissue lined with lamellar endosteal bone. The rather intense growth of S. opolensis implies a relatively high metabolic rate. Moreover, evidence from the fibro‐lamellar tissue, predominant in the cortex, suggests that this kind of rapid bone deposition could be more typical of Archosauria than previously assumed, a prerequisite for the evolution of the very fast growth rates observed in large ornithischians, sauropods and large theropods. □Archosauria, Bone histology, Dinosauriformes, Late Triassic, Silesaurus opolensis.     

Osteohistological insight into the early stages of growth in Mussaurus patagonicus (Dinosauria,Sauropodomorpha)

Here, we describe the bone histology of juvenile specimens of the basal sauropodomorph Mussaurus patagonicus and interpret its significance in terms of the early growth dynamics of this taxon. Thin sections from three juvenile specimens (femur length, 111–120 mm) of Mussaurus were analysed. The sampled bones consist of multiple postcranial elements collected from the Late Triassic Laguna Colorada Formation (El Tranquilo Group, Patagonia). The cortical bone is composed of fibrolamellar bone tissue. Vascularisation is commonly laminar or plexiform in the long bones. Growth marks are absent in all the examined samples. The ‘epiphyses’ of long bones are all formed by well-developed hypertrophied calcified cartilage. The predominance of woven-fibred bone matrix in cortical bones indicates a fast growth rate in the individuals examined. Moreover, given the existence of growth marks in adult specimens of Mussaurus, as in other sauropodomorphs, and assuming that the first lines of arrested growth was formed during the first year of life, the absence of growth marks in all the bones suggest that the specimens died before reaching their first year of life. Compared with the African taxon Massospondylus carinatus (another basal sauropodomorph for which the bone histology has been previously studied), it appears that Mussaurus had a higher early growth rate than Massospondylus.     

Non‐traumatic bone infection in stegosaurs from Como Bluff,Wyoming

Palaeopathologies are relatively common in the fossil record; however, bone histological analyses of these are rare as they are more commonly discovered and described using radiological scans. Here, we describe the bone microstructure of infectious abscesses (osteomyelitis) in the long bones of two Stegosaurus individuals from the Como Bluff area of the Late Jurassic Morrison Formation. Multiple lytic, geographical lesions filled with reactive lamellar bone occur in a femur of a juvenile specimen. A single lesion was found in an adult tibia. This lesion is characterized by the presence of spiculated periosteal reactive growth perpendicular to the bone surface and the formation of new trabeculae within the lesion.     

The palaeohistology of the basal ichthyosaur Mixosaurus (Ichthyopterygia,Mixosauridae) from the Middle Triassic: Palaeobiological implications

Here, we provide the first bone histological examination of an ontogenetic series of the basal ichthyosaur Mixosaurus encompassing postnatal to large adult specimens. Growth marks are present in sampled humeri, a femur, a fibula, as well as in other skeletal elements (gastral ribs). Ontogenetic changes are traceable throughout stylo- and zeugopodial development, but interior remodelling and resorption deleted part of the internal growth record in the primary cortex. Mixosaurus humeri started as flat structures consisting of a core of endochondral woven bone and residual calcified cartilage, whereas growth continued by deposition of periosteal fibrolamellar and parallel-fibred bone. Unlike the fast-growing post-Triassic ichthyosaurs that lack growth marks, microstructural and life history data are now becoming available for a basal ichthyosaur. The high growth rate of Mixosaurus may indicate that higher metabolic rates characterised small, non-thunniform ichthyosaurs, as had been suggested already for post-Triassic, cruising forms.     

The relative growth of the limb bones forHomo sapiens —As compared to anthropoid apes

For comparison with previously defined relative long bone lengths of growing anthropoid apes, the relative size increase of the raduus/humerus, tibia/femur and leg/arm lengths forHomo sapiens were determined. Results indicate thatHomo follows other Hominoidea during postnatal growth, maintaining general isometric patterns of relative long bone size increase within the proximal and distal segments of each limb. Variation between genera is primarily proportional, withHomo showing the relatively shortest radii and shorter tibae throughout growth. Between limbsHomo displays specializations toward disproportional increases of the lower limb, suggesting size required allometry for facilitative support. This research was partially supported by NIDR fellowship No. T-32-DE07047.     

Hibernation does not reduce cortical bone density,area or second moments of inertia in woodchucks (Marmota monax)

Long periods of inactivity in most mammals result in bone loss that may not be completely recoverable during an individual's lifetime regardless of future activity. Prolonged inactivity is normal during hibernation, but it remains uncertain whether hibernating mammals suffer decreased bone properties after hibernation that affects survival. We test the hypothesis that relative cortical area (C_A), apparent density, bone area fraction (B.Ar/T.Ar), and moments of inertia do not differ between museum samples of woodchucks (Marmota monax) collected before and after hibernation. We used peripheral quantitative computed tomography to examine bone geometry in the femur, tibia, humerus and mandible. We see little evidence for changes in bone measures with hibernation supporting our hypothesis. In fact, when including subadults to increase sample sizes and controlling age statistically, we observed a trend toward increased bone properties following hibernation. Diaphyses were significantly denser in the humerus, femur, and tibia after hibernation, and relative mandibular cortical area was significantly larger. Similarly, relative mechanical indices were significantly larger in the mandible after hibernation. Although tests of individual measures in many cases were not significantly different prehibernation versus posthibernation, the overall pattern of average increase posthibernation was significant for relative C_A and densities as well as relative diaphyseal mechanical indices when examining outcomes collectively. The exception to this pattern was a reduction in metaphyseal trabecular bone following hibernation. Individually, only humeral B.Ar/T.Ar was significantly reduced, but the average reduction in trabecular measures post‐hibernation was significant when examined collectively. Because the sample included subadults, we suggest that much of the increased bone relates to their continued growth during hibernation. Our results indicate that woodchucks are more similar to large hibernators that maintain skeletal integrity compared to smaller‐bodied hibernators that may lose bone. This result suggests a potential size‐related trend in bone response to hibernation across mammals. J. Morphol., 2012. © 2012Wiley Periodicals, Inc.     

Brief communication: Prenatal and early postnatal stress exposure influences long bone length in adult rat offspring

Stress during the prenatal and early postnatal periods (perinatal stress, PS) is known to impact offspring cognitive, behavioral, and physical development, but effects on skeletal growth are not clear. Our objective was to analyze effects of variable, mild, daily PS exposure on adult offspring long bone length. Twelve pregnant rat dams were randomly assigned to receive variable stress from gestational days 14–21 (Prenatal group), postpartum days 2–9 (Postnatal), both periods (Pre–Post), or no stress (Control). Differences in adult offspring tibia and femur length were analyzed among treatment groups. Mean tibia length differed among groups for males (P = 0.016) and females (P = 0.009), and differences for femur length approached significance for males (P = 0.051). Long bone length was shorter among PS‐exposed offspring, especially those exposed to postnatal stress (Postnatal and Pre–Post groups). Results persisted when controlling for nose–tail length. These differences might reflect early stunting that is maintained in adulthood, or delayed growth among PS‐exposed offspring. This study suggests that PS results in shorter long bones in adulthood, independently of effects on overall body size. Stunting and growth retardation are major global health burdens. Our study adds to a growing body of evidence suggesting that PS is a risk factor for poor linear growth. Am J Phys Anthropol 149:307–311, 2012. © 2012 Wiley Periodicals, Inc.     

Fluctuating asymmetry,body size and sexual selection in the dung fly Sepsis cynipsea — testing the good genes assumptions and predictions

In the dung fly Sepsis cynipsea large and more symmetric males have been shown to enjoy a mating advantage, but we still do not know which mechanism of sexual selection is responsible. Here we test several assumptions and predictions relating to the hypothesis that either trait is indicative of ‘good genes’. We tested for good genes by regressing fitness in good and bad environments (no and high larval competition, respectively) on the family mean for size or asymmetry as expressed in the good environment, separately for both sexes. Body size (hind tibia length or head width) was positively correlated with female fecundity, growth rate of both sexes and larval survivorship for males, but only in the good environment. The corresponding evidence for asymmetry is more equivocal. Mean standardised asymmetry was weakly associated with lower survivorship in the good environment, while growth rates and female fecundity were not. As predicted by sexual selection theory, fore tibia length showed greater asymmetry than other, presumably not sexually selected traits, and asymmetry in fore tibia length was greater for males than females. However, a negative correlation between trait size and asymmetry was only evident for male seta length but not for fore tibia length, fore femur length, or any composite measure of asymmetry. Most crucially, asymmetry was heritable for some female morphological traits (hind tibia length: h² = 0.15; fore femur length: h² = 0.16; mean of all measured traits: h² = 0.27), but not for any male trait. Also, asymmetry of the various traits measured was not correlated within males and only weakly so within females. The crucial assumption that asymmetry of sexually selected traits reflects overall, heritable developmental stability of an individual is thus only partly substantiated by our data. In contrast, large body size is heritable, associated with high fitness and consequently could be indicative of good genes. Fore leg asymmetry may influence male mating success by simply mechanically constraining his ability to hold on to the female.     

New insights from bone microanatomy of the Late Triassic Hyperodapedon (Archosauromorpha,Rhynchosauria): implications for archosauromorph growth strategy

Bone microanatomy of multiple postcranial skeletal elements of several individuals of Hyperodapedon collected from India is reported. This reveals that fibrolamellar bone tissue is predominant in the mid‐ and inner cortices, whereas the peripheral region of the cortex is composed of either parallel‐fibred and/or lamellar bone. The pattern of primary osteons mostly ranges between laminar and subplexiform. Such predominance of fibrolamellar bone tissue in the cortex suggests an overall fast growth, which slowed down considerably later in ontogeny. Four distinct ontogenetic stages are identified based on the bone microstructure. During the juvenile stage, growth was fast and continuous, but it became punctuated during the early and late sub‐adult stages. In adult individuals, growth was slow and showed periodic interruption but did not stop completely, suggesting that Hyperodapedon had an indeterminate growth strategy. Interelemental histovariations affecting cortical thickness, organization of the vascular network, incidence of growth rings and extent of secondary reconstruction are noted. Throughout ontogeny, the femora show higher cortical thickness than humeri and tibiae, suggesting differential appositional growth rate between the skeletal elements. Differences in cortical thickness are noted in the ribs, which suggest differential functional constraints based on anatomical site‐specific occurrences. Although fibrolamellar bone tissue became progressively more dominant towards the archosaurs, there are considerable variations in the growth patterns of the archosauromorphs. This is exemplified by the bone microstructure of Hyperodapedon, which deviates from the generalized slow‐growth pattern proposed for all basal archosauromorphs, suggesting that rapid growth was already present in the archosauromorphs. The cortical thickness of various long bones of Hyperodapedon bears similarity with that of several extant terrestrial quadrupeds, suggesting that Hyperodapedon was essentially a terrestrial quadruped.     

A Systematic Review and Meta-Analysis of Ilizarov Methods in the Treatment of Infected Nonunion of Tibia and Femur

Background

Infected nonunion of tibia and femur are common in clinical practice, however, the treatment of these diseases has still been a challenge for orthopaedic surgeons. Ilizarov methods can eradicate infection, compensate bone defects and promote the bone union through progressive bone histogenesis. The objective of this systematic review was to review current available studies reporting on Ilizarov methods in the treatment of infected nonunion of tibia and femur, and to perform meta-analysis of bone and functional results and complications to evaluate the efficacy of Ilizarov methods.

Methods

A comprehensive literature search was performed from the SCI, PubMed, Cochrane Library; and Embase between January 1995 and August 2015. Some major data were statistically analyzed using weighted means based on the sample size in each study by SPSS 13.0, including number of patients, mean age, mean previous surgical procedures, mean bone defects, mean length of follow-up, bone union, complications per patient, external fixation time, and external fixation index(EFI). Bone results (excellent, good, fair and poor rate), functional results (excellent, good, fair and poor rate) and complications were analyzed by Stata 9.0.

Findings

A total of 590 patients from 24 studies were included in this systematic review. The average of bone union rate was 97.26% in all included studies. The poor rate in bone results and functional results was 8% (95%CI, 0.04–0.12; I² = 44.1%, P = 0.065) and 10% (95%CI, 0.05–0.14; I² = 34.7%, P = 0.121) in patients with infected nonunion of tibia and femur treated by Ilizarov methods. The rate of refracture, malunion, infectious recurrence, knee stiffness, amputation, limb edema and peroneal nerve palsy was respectively 4%, 7%, 5%, 12%, 4%, 13% and 13%.

Conclusions

Our systematic review showed that the patients with infected nonunion of tibia and femur treated by Ilizarov methods had a low rate of poor bone and functional results. Therefore, Ilizarov methods may be a good choice for the treatment of infected nonunion of tibia and femur.     

Bone vascular supply in monitor lizards (Squamata: Varanidae): influence of size, growth, and phylogeny

Bone vascular canals occur irregularly in tetrapods; however, the reason why a species has or lacks bone canals remains poorly understood. Basically, this feature could depend on phylogenetic history, or result from diverse causes, especially cortical accretion rate. The Varanidae, a monophyletic clade that includes species with impressive size differences but similar morphologies, is an excellent model for this question. Cortical vascularization was studied in 20 monitor species, on three bones (femur, fibula, and tibia) that differ in their shaft diameters, and in the absolute growth speed of their diaphyseal cortices. In all species smaller than 398 mm SVL (133-397 mm in sample), bone cortices lack vascular canals, whereas all larger species (460-1,170 mm in sample) display canals. The size 398-460 mm SVL is thus a threshold for the appearance of the canals. The distribution of vascular and avascular bone tissues among species does not precisely reflect phylogenetic relationships. When present, vascular canals always occur in the femur and tibia, but are less frequent, sparser, and thinner in the fibula. Vascular density increases linearly with specific size but decreases exponentially during individual growth. In most species, canal orientation varies between individuals and is diverse in a single section. No clear relationship exists between canal orientation and vascular density. These results suggest that: a) the occurrence and density of bone vascular canals are basically dependant on specific size, not phylogenetic relationships; b) vascular density reflects the absolute growth rates of bone cortices; c) the orientation of vascular canals is a variable feature independent of phylogeny or growth rate.     

Evolution of femur and tibia in higher primates: Adaptive morphological patterns and phylogenetic diversity

Seventy six metrical traits measured on the femur and tibia of three higher primate groups —Ceboidea, Cercopithecoidea, Hominoidea have been processed by various univariate and multivariate statistical methods to survey the process of evolution of the morphology of the femur and tibia in higher primates. Intragroup and intergroup variability, similarity and differences as well as various aspects of scaling and sexual dimorphism have been analyzed to study adaptive trends and phylogenetic diversity in higher primates, in individual superfamilies and to explore the adaptive morphological pattern of early hominids and basic differences between hominids and pongids. Two basic morphotypes of the femur and tibia in higher primates have been determined. They are (1) advanced hominoid morphotype (hominids and pongids) and (2) ancestral higher primate morphotype (platyrrhine and cattarrhine monkeys, early hominoids, and hylobatids). Cebid lower limb bones are adapted to arboreal quadrupedalism with antipronograde features while femur and tibia of cercopithecid monkeys are basically adapted to the semi-arboreal locomotion. Early hominoids (Proconsul) and hylobatids are morphologically different from pongids; some features are close toAteles or other monkey species. Pongids and hominids are taken as one major morphological group with different scaling and some functional and morphological similarities. Numerous analogous features were described on the lower limb skeleton ofPan andPongo showing analogous ecological parameters in their evolution. Major morphological and biomechanical trends are analyzed. It is argued that early advanced hominoid morphology is ancestral both to the pongids and to early hominids. The progressive morphological trend in early hominids has been found fromA. afarensis with ancestral hominid morphology, toH. habilis with an elongated femur and structural features similar to advanced hominids. A detailed phylogenetic analysis of higher primate femur and tibia is also presented.     

Fossil Homo femur from Berg Aukas,northern Namibia

The proximal half of a hominid femur was recovered from deep within a paleokarst feature at the Berg Aukas mine, northern Namibia. The femur is fully mineralized, but it is not possible to place it in geochrono logical context. It has a very large head, an exceptionally thick diaphyseal cortex, and a very low collodiaphyseal angle, which serve to differentiate it from Holocene homologues. The femur is not attributable to Australopithecus, Paranthropus, or early Homo (i.e., H. habilis sensu lato). Homo erectus femora have a relatively longer and AP flatter neck, and a shaft that exhibits less pilaster than the Berg Aukas specimen. Berg Aukas also differs from early modern femora in several features, including diaphyseal cortical thickness and the degree of subtrochanteric AP flattening. The massive diaphyseal cortex of Berg Aukas finds its closest similarity within archaic H. sapiens (e.g., Castel di Guido) and H. erectus (e.g., KNM-ER 736) samples. It has more cortical bone at midshaft than any other specimen, although relative cortical thickness and the asymmetry of its cross-sectional disposition at this level are comparable with those of other Pleistocene fem ora. The closest morphological comparisons with Berg Aukas are in archaic (i.e., Middle Pleistocene) H. sapiens and Neandertal samples. © 1995 Wiley-Liss, Inc.     

A new crocodylomorph specimen from the Araripe Basin (Crato Member,Santana Formation), northeastern Brazil

The fossil fauna of the Santana Formation (Early Cretaceous) comprises many distinct taxa, but crocodylomorphs are poorly understood. Here we describe a new specimen (MPSC-R1137) that consists of a complete hind limb found in the Crato Member, the basal section of the Santana Formation. Based on the characteristics of the fibula (e.g., pronounced variation of the shaft width) and length proportions of the femur and tibia, this specimen can be distinguished from Caririsuchus camposi and Araripesuchus gomesii, which are known from the Romualdo Member (the upper lithostratigraphic unit of the Santana Formation). The only crocodylomorph formally described from the Crato Member is Susisuchus anatoceps, whose holotype lacks elements of the hind limb. On the basis of a comparative anatomical study of the hind limb, which shows no similarities between MPSC-R1137 and other crocodylomorphs from the Araripe Basin, we tentatively classify this new specimen as cf. Susisuchus sp., and provide new anatomical information for this rather derived crocodylomorph.      

Postnatal growth allometry of the extremities in Cebus albifrons and Cebus apella: A longitudinal and comparative study

Cebus albifrons and Cebus apella, partially sympatric capuchin monkeys from South America, are known to differ substantially in adult body mass and bodily proportions. C. apella possesses a robust, stocky build in contrast to the more gracile, relatively longer limbed body design of C. albifrons. Average birth weights and adult body lengths of these two congeners, however, are remarkably similar and do not serve to distinguish them. This study examines longitudinal growth rates and patterns of ontogenetic scaling in the extremities (humerus, radius, hand, femur, tibia, foot) in order to document the nature and magnitude of skeletal changes associated with increasing age and body mass. Our data indicate that the growth rates of the six skeletal components of the limbs differ only slightly and somewhat inconsistently between the two species. Body mass, however, increases at a consistently faster rate in C. apella. Relative to body mass, therefore, the extremities of C. albifrons scale much faster than those of C. apella. This implies that at any given postnatal body mass, C. albifrons is longer limbed than C. apella. Conversely, C. apella is heavier than C. albifrons at any given limb length or age. We suggest that such differences in body mass distribution are causally related to differences in locomotor behavior and foraging strategies. Specifically, the relatively long-limbed C. albifrons is probably more cursorial and tends to travel longer distances each day than C. apella. C. apella is a much more deliberate quadruped and is also characterized by especially vigorous and powerful foraging and feeding behaviors. We also compare our results to other (mostly cross-sectional) studies of skeletal growth allometry in nonhuman primates.     

Spag17 Deficiency Results in Skeletal Malformations and Bone Abnormalities

Height is the result of many growth and development processes. Most of the genes associated with height are known to play a role in skeletal development. Single-nucleotide polymorphisms in the SPAG17 gene have been associated with human height. However, it is not clear how this gene influences linear growth. Here we show that a targeted mutation in Spag17 leads to skeletal malformations. Hind limb length in mutants was significantly shorter than in wild-type mice. Studies revealed differences in maturation of femur and tibia suggesting alterations in limb patterning. Morphometric studies showed increased bone formation evidenced by increased trabecular bone area and the ratio of bone area to total area, leading to reductions in the ratio of marrow area/total area in the femur. Micro-CTs and von Kossa staining demonstrated increased mineral in the femur. Moreover, osteocalcin and osterix were more highly expressed in mutant mice than in wild-type mice femurs. These data suggest that femur bone shortening may be due to premature ossification. On the other hand, tibias appear to be shorter due to a delay in cartilage and bone development. Morphometric studies showed reduction in growth plate and bone formation. These defects did not affect bone mineralization, although the volume of primary bone and levels of osteocalcin and osterix were higher. Other skeletal malformations were observed including fused sternebrae, reduced mineralization in the skull, medial and metacarpal phalanges. Primary cilia from chondrocytes, osteoblasts, and embryonic fibroblasts (MEFs) isolated from knockout mice were shorter and fewer cells had primary cilia in comparison to cells from wild-type mice. In addition, Spag17 knockdown in wild-type MEFs by Spag17 siRNA duplex reproduced the shorter primary cilia phenotype. Our findings disclosed unexpected functions for Spag17 in the regulation of skeletal growth and mineralization, perhaps because of its role in primary cilia of chondrocytes and osteoblasts.     

Natural markers in bone growth

Three features in the long bones, shown by radiograms, have been used as markers for the study of bone growth.

• (I) Transverse lines of arrested growth. Radiograms of six long limb bones from 1,576 individuals were investigated for clearness and persistence of these lines. Both ends of tibia and fibula showed very high frequency of suitable lines for markers, possibly also the distal end of femur and radius.
• (II) Notches in the base of second and fifth metacarpal bones. Measurements of growth from apex of the basal notch to the ends of the shaft were performed on serial hand radiograms. The proportion of growth from distal and basal ends averaged 87:13 in the second and 80:20 in the fifth metacarpal bones.
• (III) Nutrient canals. The initial point of ossification was determined by a prolongation of the nutrient canal intersecting the central axis of the medullary cavity. The proportion of growth from that point to distal and basal ends of the shaft averaged 68:32 and 64:36 for the second and the fifth metacarpal bones, respectively. These values are significantly different from the measurements obtained from the notches.

     

Mathematical modeling of appendicular bone growth in glaucous‐winged gulls

Development of locomotor activity is crucial in tetrapods. In birds, this development leads to different functions for hindlimbs and forelimbs. The emergence of walking and flying as very different complex behavior patterns only weeks after hatching provides an interesting case study in animal development. We measured the diaphyseal lengths and midshaft diameters of three wing bones (humerus, ulna, and carpometacarpus) and three leg bones (femur, tibiotarsus, and tarsometatarsus) of 79 juvenile (ages 0–42 days) and 13 adult glaucous‐winged gulls (Larus glaucescens), a semiprecocial species. From a suite of nine alternative mathematical models, we used information‐theoretic criteria to determine the best model(s) for length and diameter of each bone as a function of age; that is, we determined the model(s) that obtained the best tradeoff between the minimized sum of squared residuals and the number of parameters used to fit the model. The Janoschek and Holling III models best described bone growth, with at least one of these models yielding an R² ≥ 0.94 for every dimension except tarsometatarsus diameter (R² = 0.87). We used the best growth models to construct accurate allometric comparisons of the bones. Early maximal absolute growth rates characterize the humerus, femur, and tarsometatarsus, bones that assume adult‐type support functions relatively early during juvenile development. Leg bone lengths exhibit more rapid but less sustained relative growth than wing bone lengths. Wing bone diameters are initially smaller than leg bone diameters, although this relationship is reversed by fledging. Wing bones and the femur approach adult length by fledging but continue to increase in diameter past fledging; the tibiotarsus and tarsometatarsus approach both adult length and diameter by fledging. In short, the pattern of bone growth in this semiprecocial species reflects the changing behavioral needs of the developing organism. J. Morphol., 2009. © 2008 Wiley‐Liss, Inc.