Opposing Studies and Alternate Hypotheses
Although the pattern of increasing body size over time does have much evidence supporting it, there have been several papers which debated the validity of this rule or the mechanisms which have been proposed.

  • Size Related Bias in planktonic Foramanifera (Arnold et al., 1995)
  • Cope's Rule as the upper limb of an expanding size range (Jablonski, 1997)
Globigerinoides cyclostomus (image by Natalia Vazquez Riveros)