Titanoboa
- When: Paleocene
(60–58 mya) - Where: South America
- What: Snake
- Weight: 1.1 metric tons
- Length: 13 meters
- Diet: Carnivorous
- Discovered: 2009
Torosaurus
- When: Late Cretaceous
(70–66 mya) - Where: North America
- What: Ceratopsian
- Weight: 6–9 metric tons
- Length: 7–8 meters
- Diet: Herbivorous
- Discovered: 1891
Triceratops
- When: Late Cretaceous
(68–66 mya) - Where: North America
- What: Ceratopsian
- Weight: 6–12 tons
- Length: 8–9 meters
- Diet: Herbivorous
- Discovered: 1889
Troodon
- When: Late Cretaceous
(75–65 mya) - Where: North America
- What: Theropod
- Weight: 50 kg
- Length: 2 meters
- Diet: Omnivorous
- Discovered: 1856
Tsintaosaurus
- When: Late Cretaceous
(84–72 mya) - Where: Asia
- What: Hadrosaur
- Weight: 3 metric tons
- Length: 8–10 meters
- Diet: Herbivorous
- Discovered: 1958
Tuojiangosaurus
- When: Late Jurassic
(161–155 mya) - Where: Asia
- What: Stegosaur
- Weight: 2–3 tons
- Length: 6–7 meters
- Diet: Herbivorous
- Discovered: 1977
Tyrannosaurus
- When: Late Cretaceous
(68–66 mya) - Where: North America
- What: Theropod
- Weight: 9–14 tons
- Length: 12–13 meters
- Diet: Carnivorous
- Discovered: 1905
Uintatherium
- When: Paleocene to Eocene
(56–37 mya) - Where: North America
- What: Mammal
- Weight: 2 metric tons
- Length: 4 meters
- Diet: Herbivorous
- Discovered: 1872
Utahraptor
- When: Early Cretaceous
(126 mya) - Where: North America
- What: Theropod
- Weight: 500 kg
- Length: 6–7 meters
- Diet: Carnivorous
- Discovered: 1993