--- title: The Tyrannosaurus T. Rex Dinosaur Could Not Run Top Speed description: According to a new report published in the journal PeerJ, the fastest a Tyrannosaurus rex could have walked was 12 miles per hour. canonical: https://time.com/4864214/t-rex-tyrannosaurus-top-speed-run-running/ author: Sarah Begley article:opinion: false article:content_tier: free article:published_time: 2017-07-19T14:23:59.000Z article:modified_time: 2026-02-23T16:37:02.825Z article:section: Science og:title: The T. Rex Would’ve Broken its Tiny Legs if it Tried to Run og:description: The king of the dinosaurs had a major flaw og:url: https://time.com/4864214/t-rex-tyrannosaurus-top-speed-run-running/ og:site_name: TIME og:image: https://static.time.com/v3/assets/bltea6093859af6183b/bltabdbc19bfe7f3490/6988d641fb4eac55db892f8a/t-rex.jpeg?branch=production&width=3840&quality=75&auto=webp&crop=16:9 og:image:width: 1200 og:image:height: 675 og:image:alt: NETHERLANDS-SCIENCE-PALAEONTOLOGY-MUSEUM og:type: article twitter:card: summary_large_image twitter:title: The T. Rex Would’ve Broken its Tiny Legs if it Tried to Run twitter:description: The king of the dinosaurs had a major flaw twitter:image: https://static.time.com/v3/assets/bltea6093859af6183b/bltabdbc19bfe7f3490/6988d641fb4eac55db892f8a/t-rex.jpeg?branch=production&width=3840&quality=75&auto=webp&crop=16:9 ---  # Turns Out T. Rex Would’ve Broken its Tiny Legs if it Tried to Run by [Sarah Begley](https://time.com/author/sarah-begley/) ## Sarah Begley Jul 19, 2017 2:23 PM UTC  The skeleton of a T rex named Trix is installed in a room of the Naturalis museum of Leiden on September 9, 2016, during the exhibition "T rex in Town". The skeleton of a T rex named Trix is installed in a room of the Naturalis museum of Leiden on September 9, 2016, during the exhibition "T rex in Town".MARTEN VAN DIJL—AFP/Getty Images by [Sarah Begley](https://time.com/author/sarah-begley/) ## Sarah Begley Jul 19, 2017 2:23 PM UTC If the T. rex [chase scene](https://www.youtube.com/watch?v=rxqHVoZ0fzc) in [_Jurassic Park_](http://time.com/3083131/jeff-goldblum-recreates-jurassic-park-scene-in-this-awesome-wedding-photo/) gave you nightmares, rest assured: even if the [dinosaurs](http://time.com/4687329/laser-technology-fossils-dinosaurs-connection-to-birds/) returned to Earth, you’d easily outpace the fearsome beasts in an SUV. According to a new report published in the journal [PeerJ](https://peerj.com/articles/3420/), the fastest a [Tyrannosaurus rex](http://time.com/4406326/new-dinosaur-tiny-arms-tyrannosaurus-rex/) could have walked was 12 miles per hour. That differs with past theories that the T. rex could run. The Washington _Post_ reports that this study varies from past research because it includes weight loads in its calculations. The study’s authors say that testing on a model T. rex revealed the king of the dinosaurs would have snapped its leg bones if it tried to run. However, they acknowledged that they could have differently accounted for factors like tendon elasticity. Still, that’s not to say a speed-walking T. rex heading your way wouldn’t be terrifying. 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