Figure 1: Pterosaur and bird size through time. | Nature Communications

Figure 1: Pterosaur and bird size through time.

From: Competition and constraint drove Cope's rule in the evolution of giant flying reptiles

Figure 1

(a) Pterosaur adult wingspan versus geological age in millions of years (Ma). Bird datapoints represent osteological wingspans, but the likely increment to maximum wingspans from flight feathers is indicated by grey whiskers (50% in Archaeopteryx; 100% in Early Cretaceous birds). The thick grey line indicates maximum bird wingspans during the well-sampled Late Jurassic–Early Cretaceous interval. Thin black lines are major axis regression lines of pterosaur wingspans on geological age. The confidence interval of the Triassic–Jurassic regression line includes zero, indicating an absence of size increases (P=0.396 (regression slope); N=18; slope= −0.0004 (−0.0040 to 0.0031) log10(m)/Ma; intercept=0.079 log10(m) (=1.20 m)); the regression line for the latest Jurassic–Cretaceous indicates increasing body size through time (P<0.001 (regression slope); N=54; slope= −0.0060 (−0.0082 to −0.0039) log10(m)/Ma). (b) One representative time-calibrated cladogram of adult pterosaur specimens with tip diameters proportional to log10(wingspan). In both a,b, silhouettes are indicative of relative size only.

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