# Tyrannosaurus rex juvenile development research

> Live situation record from CLSTR: https://clstr.news/situations/tyrannosaurus-rex-juvenile-development-research
> Updated: 2026-08-15T16:30:28.000Z. Sources: 2. Developments: 2.

Research published in the journal Biology indicates that newborn Tyrannosaurus rex specimens were significantly smaller than previously understood, with sizes comparable to domestic cats.

Initial findings from a study involving a juvenile skeleton found in Wyoming’s Lance Formation utilized synchrotron computed tomography to reveal rapid bone growth and predatory adaptations in hatchlings. 

Subsequent analysis of a metatarsal bone from the Frenchman Formation in Saskatchewan, Canada, provided further detail. Researchers estimated that a T. rex specimen weighed approximately 2.5 kilograms at death, with a hatching weight of roughly 1.6 kilograms. These fossils, which include relatives such as Gorgosaurus libratus, suggest that even at this early stage, the young dinosaurs possessed functional teeth and long legs, potentially allowing them to hunt shortly after hatching.

## Timeline

### 2026-08-15: T. rex fossils reveal newborn dinosaurs were cat-sized

Paleontologists have discovered the first fossils of a newborn T. rex, revealing the dinosaur weighed only about 1.6 to 2.5 kilograms at a young age and possessed functional teeth and long legs.

2 sources. https://clstr.news/cluster/t-rex-fossils-reveal-newborn-dinosaurs-were-cat-sized

### 2026-07-30: Tyrannosaurus Rex Hatchlings Revealed as Size of House Cats in New Study

New research shows Tyrannosaurus rex hatchlings were cat‑sized yet already predatory, based on a Wyoming fossil analyzed with synchrotron tomography.

2 sources. https://clstr.news/cluster/tyrannosaurus-rex-hatchlings-revealed-as-size-of-house-cats-in-new-study

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Cite as: Tyrannosaurus rex juvenile development research. CLSTR, https://clstr.news/situations/tyrannosaurus-rex-juvenile-development-research