Gregory Erickson and colleagues have studied the growth and life history of tyrannosaurids using bone histology, which can determine the age of a specimen when it died.
A growth curve can be developed when the ages of various individuals are plotted against their sizes on a graph.
Tyrannosaurids grew throughout their lives, but underwent tremendous growth spurts for about four years, after an extended juvenile phase.
Sexual maturity may have ended this rapid growth phase, after which growth slowed down considerably in adult animals.
Examining five Gorgosaurus specimens of various sizes, Erickson calculated a maximum growth rate of about 50 kg (110 lb) per year during the rapid growth phase, slower than in tyrannosaurines like Daspletosaurus and Tyrannosaurus, but comparable to Albertosaurus.

Gorgosaurus spent as much as half its life in the juvenile phase before ballooning up to near-maximum size in only a few years.
This, along with the complete lack of predators intermediate in size between huge adult tyrannosaurids and other small theropods, suggests that these niches may have been filled by juvenile tyrannosaurids.
This pattern is seen in modern Komodo dragons, whose hatchlings start off as tree-dwelling insectivores and slowly mature into massive apex predators capable of taking down large vertebrates.
Other tyrannosaurids, including Albertosaurus, have been found in aggregations that some have suggested to represent mixed-age packs, but there is no evidence of gregarious behavior in Gorgosaurus.
Gregory Erickson and colleagues have studied the growth and life history of tyrannosaurids using bone histology, which can determine the age of a specimen when it died. A growth curve can be developed when the ages of various individuals are plotted against their sizes on a graph. Tyrannosaurids grew throughout their lives, but underwent tremendous growth spurts for about four years, after an extended juvenile phase. Sexual maturity may have ended this rapid growth phase, after which growth slowed down considerably in adult animals. Examining five Gorgosaurus specimens of various sizes, Erickson calculated a maximum growth rate of about 50 kg (110 lb) per year during the rapid growth phase, slower than in tyrannosaurines like Daspletosaurus and Tyrannosaurus, but comparable to Albertosaurus.
Gorgosaurus spent as much as half its life in the juvenile phase before ballooning up to near-maximum size in only a few years. This, along with the complete lack of predators intermediate in size between huge adult tyrannosaurids and other small theropods, suggests that these niches may have been filled by juvenile tyrannosaurids. This pattern is seen in modern Komodo dragons, whose hatchlings start off as tree-dwelling insectivores and slowly mature into massive apex predators capable of taking down large vertebrates. Other tyrannosaurids, including Albertosaurus, have been found in aggregations that some have suggested to represent mixed-age packs, but there is no evidence of gregarious behavior in Gorgosaurus.
Gorgosaurus