Tri-Rex

Tri-Rex is a Tyrannosaurus rex from the Animorphs continuity.

This is the best this thing's ever going to get.

The Tri-Rex came into existence when Jake, Cassie, and Marco broke into one of the Yeerks' genetic experimentation labs, and discovered a morph so powerful a single human could not hope to take on its form alone. But through the use of an advance morphing technique, each concentrates on a segment of the titanic beast and they merge together to become this powerful T-Rex! A team of one, the Tri-Rex is an unstoppable force, the prehistoric beast from the future!

Toys

Animorphs

As is this.

• Tri-Rex (Super, 1999)

The Tri-Rex toy is made up of three components—Jake, Cassie, and Marco—who each transform into different parts of Tri-Rex.

• More information on Tri-Rex Cassie at TFU.info
• More information on Tri-Rex Jake at TFU.info
• More information on Tri-Rex Marco at TFU.info

Notes

• It is unclear just how a combiner works in the context of the Animorphs fiction, particularly on a mental level. Then again, the same could be said of combiners in normal Transformers fiction as well.
• That's because they can't combine in the books. This Backstory is completely made up FOR the toy line. There was a book where Cassie, Marco, Jake, and Ax all acquired T-Rex DNA (due to time travel) but they all transformed into individual Tyrannosaurs.