| Comments |
Ga=billion years ago. The maximum body volume of organisms preserved in the fossil
record has increased by ~16 orders of magnitude over the last
3.5 billion years (Fig. 1). Increase in maximum size occurred
episodically, with pronounced jumps of approximately 6 orders
of magnitude in the mid-Paleoproterozoic (~1.9 Gya) and
during the Ediacaran through Ordovician (600–450 Mya). Thus,
~75% of the overall increase in maximum body size over
geological time took place during 2 geologically brief intervals
that together comprise <20% of the total duration of life on
Earth. The 1st event coincides with appearance of single-celled eukaryotes: the 2nd with the appearance of multi-cellular eukaryotes. See Olivia P. Judson, The energy expansions of evolution, Nature ecology & evolution, 28 April 2017, p.3 right column 6th paragraph: "Around 575 million years ago (Ma), during the Ediacaran Period, a new form of life began to become abundant: animals (ref 84)." |