Data from: Measurement, variation, and scaling of osteocyte lacunae: a case study in birds

Basic issues surrounding osteocyte biology are still poorly understood, including the variability of osteocyte morphology within and among bones, individuals, and species. Several studies have suggested that the volume or shape of osteocytes (or their lacunae) are related to bone and/or organismal growth rate or metabolism, but the nature of this relationship, if any, is unclear. Furthermore, several studies have linked osteocyte lacuna volume with genome size or growth rate and suggested that osteocyte lacuna volume is unrelated to body size. Herein the scaling of osteocyte lacuna volume with body mass, growth and basal metabolic rates, genome size, and red blood cell size is tested using a broad sample of extant birds within a phylogenetic framework. Over 12,000 osteocyte lacuna axes were measured in a variety of bones from 34 avian and four non-avian dinosaur species. Osteocyte lacunae in parallel-fibered bone are scalene ellipsoids; their morphology and volume cannot be reliably estimated from any single thin section, and using a prolate ellipsoid model to estimate osteocyte lacuna volume results in a substantial (ca. 2–7 times) underestimate relative to true lacunar volume. Orthogonal thin sections reveal that in birds, even when only observing parallel-fibered, primary, cortical bone, intra-skeletal variation in osteocyte lacuna volume and shape is very high (volumes vary by a factor of 5.4 among different bones), whereas variation among homologous bones of the same species is low (1.2–44%; mean = 12%). Ordinary and phylogenetically informed bivariate and multiple regressions demonstrate that in birds, osteocyte volume scales significantly but weakly with body mass and mass-specific basal metabolic rate and moderately with genome size, but not with erythrocyte size. Avian whole-body growth rate and osteocyte lacuna volume are weakly and inversely related. Finally, we present the first three-dimensionally calculated osteocyte volumes for several non-avian dinosaurs, which are much larger than previously reported values and smaller than those of large extant avians. Osteocyte volumes estimated from a single transverse section and assuming prolate morphology, as done in previous studies, are relative underestimates in theropod dinosaurs compared to sauropod dinosaurs, raising the possibility that no major change in osteocyte volumes (and genome size) occurred within Theropoda on the lineage leading to birds. Osteocyte volume is intertwined with several organismal attributes whose relative importance varies at a number of hierarchical levels.Input DataInput data includes osteocyte lacuna measurements for extant birds, extinct dinosaurs, and humans (human data from McCreadie et al., 2004). Also included: avian life history attributes, avian phylogeny employed in this study, and R script.Input data.zipOutput dataDinosaur lacuna imagesFile contains images of thin sections of dinosaur bones analyzed in this study. Measured lacunae were labeled using ImageJ. Abbreviations: fem = femur, long = photograph of a longitudinally oriented thin section, tib = tibia, xs = photograph of a thin section representing part of a cross section of a bone.Accipiter cooperi femur 242198Accipiter striatus femur 242034AccipiterCooperi 241009AccipiterStriatus 240638Aegolius 241878 femurAeoglius 241878 humerusBonasa 242039Branta 227638Bubo R1452Cardinalis 241794Colaptes 241887Carduelis 241809Cyanocitta femur 242057Colaptes humerus 241887Cyanocitta 241803Cyanocitta241803.zipDendroica 240871Dendroica 241982Diomedea 210390Grus 116250Dumetella femur 242013Icterus 241804Larus femur 8771Meleagris R1718Otus 240864Otus 241793 femurOtus 241793 humerusParus femur 241934Parus humerus 241963Parus femur 241963Passerella 243058Phalacrocorax idahoensis63156Phalacocrorax idahoensis63156.zipPhalacrocorax idahoensis74435Pheucticus femur 241935Pheucticus femur 241952Piranga 241960Podilymbus 8725Quiscalus 241885Rhea 223136Sitta 241779Spizella 241938Struthio fem R1716Struthio hum R1716Turdus 241899Vermivora femur 242012Vireo 240779Zonotrichia 241280Dromaius R1717 cervical vertZenaita 241897Zenaida 241897.zipDromaius R1717 coracoidDromaius R1717 caudal vertDromaius R1717 dorsal ribDromaius R1717 femurDromaius R1717 fibulaDromaius R1717 frontalDromaius R1717 furculaDromaius R1717 humerusDromaius R1717 ischiumDromaius R1717 metacarpalsDromaius R1717 pedal phalanxDromaius R1717 pedalphalanx.zipDromaius R1717 manual phalanxDromaius R1717 scapulaDromaius R1717 pubisDromaius R1717 radiusDromaius R1717 scleral ossicleDromaius R1717 tarsometatarsusDromaius R1717 sternal ribDromaius R1717 tibiotarsusDromaius R1717 ulnaReadme_DEmicBenso