Giganotosaurus

The giganotosaurus was the largest carnivorous dinosaur ever, on land. When it as unearthed, it was thought that it was a herbivore, but in construction, they realized that it wasn't. The giganotosaurus had also the largest head of any theropod, but it had the smallest brain in proportion. It was the size and shape of a banana! Its head was 1.8 m long and it was filled with 25 cm long teeth. Its large nostrils and eyes also tell that the giganotosaurus had good senses, so it wasn't such a dumb dinosaur after all. In fact, it was discovered that it hunted in packs. As if one wasn't scary enough! This is known because it probably descended from allosaurus, and it hunted the largest known dinosaur, called argentinosaurus. One 16 m long, 9 ton predator couldn't bring down one 40 m long, 90 ton sauropod, so there must have been about 5 or 6 of them hunting one adult sized argentinosaurus.

Fact file
Description: a bipedal carnivore.
Order: saurischia.
Period: late cretaceous period, about 100 mya.
Name translation: giant southern lizrad.
Length: 16 m.
Height (at the hips): 5 - 6.5 m.
Weight: 8 tonnes.
Bite force: 1500 PSI.

Carnotaurus

The carnotaurus is a large theropod, which means it walked on two legs. It was a typical example of a dinosaur. It had crests, or horns, above it's eyes and used them as a weapon to head-butt they're competitor or prey. Only one specimen was found, and surprisingly, a nearly complete skeleton, most of its skin remains and rotting food in its ribs. A discovery like this is extremely rare in paleontology.

Fact file
Description: a bipedal carnivore
Order: saurischia
Period: late cretaceous period, about 70 mya
Name translation: carnivorous bull
Length: 9 m
Height: 3-4 m at the hips
Weight: 1-4 tonnes
Bite force: 3700 PSI