Blood flow to long bones indicates activity metabolism in mammals, reptiles and dinosaurs

Roger S Seymour, Sarah L. Smith, C.R. White, Donald M. Henderson, Daniela Schwarz-Wings

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The cross-sectional area of a nutrient foramen of a long bone is related to blood flow requirements of the internal bone cells that are essential for dynamic bone remodelling. Foramen area increases with body size in parallel among living mammals and non-varanid reptiles, but is significantly larger in mammals. An index of blood flow rate through the foramina is about 10 times higher in mammals than in reptiles, and even higher if differences in blood pressure are considered. The scaling of foramen size correlates well with maximum whole-body metabolic rate during exercise in mammals and reptiles, but less well with resting metabolic rate. This relates to the role of blood flow associated with bone remodelling during and following activity. Mammals and varanid lizards have much higher aerobic metabolic rates and exercise- induced bone remodelling than non-varanid reptiles. Foramen areas of 10 species of dinosaur from five taxonomic groups are generally larger than from mammals, indicating a routinely highly active and aerobic lifestyle. The simple measurement holds possibilities offers the possibility of assessing other groups of extinct and living vertebrates in relation to body size, behaviour and habitat.
Original languageEnglish
Pages (from-to)451-456
Number of pages6
JournalProceedings of the Royal Society B: Biological Sciences
Issue number1728
Publication statusPublished - 2012
Externally publishedYes


  • Allometry
  • Blood flow
  • Bone remodelling
  • Metabolic rate
  • Nutrient foramen

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