 The end of the rapid growth phase suggests the onset of sexual maturity in Albertosaurus , although growth continued at a slower rate throughout the animals ' lives . Sexual maturation while still actively growing appears to be a shared trait among small and large dinosaurs as well as in large mammals such as humans and elephants . This pattern of relatively early sexual maturation differs strikingly from the pattern in birds , which delay their sexual maturity until after they have finished growing . 
