Consider a small sauropod of length x , as shown on the left above. Its mass is proportional to x cubed, it stands on leg bones whose cross-sectional area is x squared, and it ingests food through a gullet whose cross-sectional area is x squared. Now consider a larger sauropod of length 2 x , as shown on the right above.

Many aspects of scholarly publishing are presently in flux. But for most journals the process of getting a paper published remains essentially the same as decades ago, the main change being that documents are sent electronically rather than by post. It begins with the corresponding author of the paper submitting a manuscript — sometimes, though not often, in response to an invitation from a journal editor.

Our lungs are made up of millions of tiny bags. Breath in, fill the bags with fresh air, breathe out, empty the bags of spent air. But bird lungs are very different.