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Table 2 Summary table comparing life history distribution across amniotes

From: Different solutions lead to similar life history traits across the great divides of the amniote tree of life

  Characteristics of distribution
Body mass All unimodal and right skewed
Squamata < Aves <  < Mammals
Offspring/female size Offspring/female size ratio approximately the same across placental mammals, birds and squamates (7–8%)
marsupials <  <  < turtles <  < birds ≈ placentals ≈ squamates
Brood size Mode is 1 in mammals, 2 in birds and squamates
Reproductive frequency The overall mode and distribution of reproductive frequency is extremely similar across amniote groups
Relative brood mass All unimodal and right skewed. But no placental mammal has a relative brood mass higher than 70%. Small in turtles, very small in marsupials
Yearly fecundity Distribution of reptiles and birds very similar (right skewed distribution with a mode of 4–6 young). Mammalian mode is 1–2 offspring per year
Reproductive output Similar overall in squamates, birds and mammals (low intercepts associated with steep slopes), low intercept in turtles, very low intercept, and shallow slope in marsupials