Junior

"Infant’s probably only a few weeks old. Never left the nest. Offspring that young, parents won’t leave it for too long."

- Roland Tembo

The Infant T. rex (a.k.a Junior) is one of the main dinosaurs featured in the film The Lost World: Jurassic Park. Movies=

Birth
The Infant T. rex was born on Isla Sorna to two individuals who were Tyrannosaurus rex clones that had went wild after Hurricane Clarissa stuck the island. He, like all cloned Tyrannosaurus juveniles, spend his early life in a nest with his parents providing him food.

Isla Sorna Incident (1997) and Capture
When he was only a few weeks old, InGen, who brought his and his parents' species back to life, sent a team of hunters to capture Isla Sorna's wild dinosaurs for newly appointed CEO Peter Ludlow's Jurassic Park: San Diego. The Hunter's leader, Roland Tembo, was interested in hunting the juvenile's father. When he found the nest the young Tyrannosaurus was living in, he and fellow InGen Hunter Ajay Sidhu captured the juvenile with the intentions of using him as bait to lure his parents to their camp.

While being used as bait, Peter Ludlow, who wondered away from the hunters' camp in a drunken stupor and accidentally broke its leg. Then during the fiasco at the camp, caused by Gatherers Nick Van Owen and Sarah Harding releasing the captured dinosaurs, Nick found the injured baby and took him back to the Fleetwood RV Mobile Lab, where Sarah applied first aid to his broken leg. Knowing that his cry can be heard and answered, Kelly begged her father, Ian Malcolm, to take her to the High Hide for safety. Eventually, the baby's cry is answered by his mother and father, and Nick, Sarah, and Ian were able to finish fixing his broken leg and he was soon released him back into the wild with its parents. However, despite having their son returned to them, both parents pushed the mobile lab off the cliff it was on.

The infant was then later recaptured by the Hunters at the conclusion of the Isla Sorna Incident of 1997, and was shipped to the new Jurassic Park in San Diego, California via Peter Ludlow's jet. Ian and Sarah later arrived at the facility to find and retrieve him during his father's rampage throughout the city. They used the infant to lure the Tyrannosaur Buck once again to stop the angry father from causing more damage to San Deigo and to take them both back to their home on Isla Sorna. The plan works, and in the Buck's attempt to retrieve his son, Ludlow gets wounded by the adult. The Infant Tyrannosaur's father decided to let him finish off Peter so he could teach him how to hunt on his own. After killing Peter Ludlow, Sarah then tranquilized the adult male in the nick of time before the order to kill it can be done.

The two Tyrannosaurs were later transported back to Isla Sorna after the San Diego Incident and became reunited with the female. The last sighting of the Infant was him and his family on a plain next to the Stegosaurus herd and a flock of Pteranodon.

Trivia

 * It is fan speculation that the sub-adult T. rex that was killed by the Spinosaurus in Jurassic Park III is Junior itself, however it's more likely that it is simply just a rogue animal.
 * Due to some specimens recently found of juvenile T. rex, it is possible that baby T. rex actually had longer skulls, therefore making the infant unrealistic. However, it is possible, though unlikely, that the specimens in question represent a different genus, known as Nanotyrannus.
 * In the film it was mentioned the juvenile was a couple of weeks old; it would have been too long for it to be that old, although it is implied that InGen accelerated the growth of their dinosaurs, which could account for this issue.
 * The dependence of young tyrannosaurs on their parents is very apparent with this baby dinosaur. When it is injured and taken away from its parents, it barely ever stops howling for them, indicating that it is not yet capable of surviving on its own and requires its parents to come to its rescue.
 * -|Games=

Chaos Island: The Lost World
The baby rex appears in Chaos Island: The Lost World. In some missions, the player's objective is to bring it back to its parents or to find it.

The Lost World: Jurassic Park (arcade game)
The baby rex appears in the fourth and fifth stages of The Lost World: Jurassic Park arcade game.
 * -|Toys=

The Lost World Series 1
The baby rex appears in The Lost World Series 1. It is codenamed "Junior". Like in the film, it has a leg wound.
 * -|Comics=

Jurassic Park: Redemption
In the Jurassic Park: Redemption comic series, Peter Ludlow survived the attacks from the juvenile and his father, albeit disfigured and crippled.