Jerzy Trammer

MAXIMUM BODY SIZE IN A RADIATING CLADE AS A FUNCTION OF TIME

Abstract The behavior of the maximum body size (body length) in an evolving clade is exemplified by the evolutionary histories of Bivalvia, Cetacea, and Camerata (Crinoidea). Changes of the maximum size with time track closely diversification history: when a clade diversifies exponentially, the maximum size also increases exponentially, and when the number of species changes irregularly (at varying rates), the maximum size also changes in that manner. However, within any given clade, the maximum body size changes at lower rates than diversity does. The observed shifts in maximum body size approximate the rate of diversification per unit of time to the power of about 0.5.

Active trends, passive trends, cope's rule and temporal scaling: New categorization of cladogenetic changes in body size

Regimes of cladogenetic change in body size recognized in the fossil record are related to the time scales over which they are observed. A new categorization of regimes of cladogenetic size change is proposed: this scheme includes seventeen types. In a random distribution, the pure, single‐cause regimes are rare (0.01 probability of appearance) while mixed regimes, resulting from the simultaneous operation of two or more causes are frequent (0.115 probability of appearance). Some regimes seem to be nonrandomly distributed.