By | September 9, 2016

Among the largest and most terrifying predators of all time were the tyrannosauroids (“tyrant lizards”). The first tyrannosauroids were small, possibly feathered dinosaurs, but over millions of years they evolved into giants, the biggest being Tyrannosaurus (next page). The giant tyrannosauroids had immensely powerful jaws lined with bone-crunching fangs, equipping them to butcher and consume almost any animal they came across.


Key features
■ Large skull and jaws relative to body size
■ Small but powerful arms with only two or three fingers on each hand
■ Long back legs built for running

Tyrannosauroids appeared in the Jurassic Period, 200 million years ago and died out at the end of the Cretaceous Period, 65 million years ago.

Tarbosaurus (TAR-bow-SORE-us)


When: 70–65 million years ago (Late Cretaceous)

Fossil location: Mongolia, China

Habitat: Floodplains

Length: 39 ft (12 m)

Diet: Flesh

While Tyrannosaurus was terrorizing the wildlife of North America, its close relative Tarbosaurus was doing the same in China. Tarbosaurus was almost as big as its cousin but had a more slender skull and even tinier arms. It probably used the same feeding technique, crushing victims in its jaws and then tearing off chunks of flesh while holding the carcass down with its feet.


Tarbosaurus’s skeleton

Tarbosaurus was typical of the gigantic, late tyrannosauroids, with a massive skull, powerful jaws, and huge, banana-shaped teeth. In contrast, its arms were almost ridiculously tiny and its hands had only two fingers each.

Proceratosaurus (PRO-seh-RAT-oh-SORE-us)


When: 175 million years ago (Middle Jurassic)

Fossil location: British Isles

Habitat: Open woodland

Length: 6 ft (2 m)

Diet: Flesh

The only fossil of Proceratosaurus is a remarkably well-preserved skull found in England in 1910. The dinosaur is thought to be a small, early tyrannosauroid and a close relative of Guanlong. Its most distinctive feature is a strange crest perched on the tip of its snout. Because the top of the skull is missing, scientists don’t know if the small nose crest was actually part of a much longer crest like that of Guanlong.

Albertosaurus (al-BERT-oh-SORE-us)


When: 75 million years ago (Late Cretaceous)

Fossil location: Canada

Habitat: Forests

Length: 30 ft (9 m)

Diet: Flesh

Albertosaurus was more lightly built than the largest tyrannosauroids, suggesting it was a swift runner. Its head was huge, with triangular horns in front of the eyes, and its jaws were lined with 60 banana shaped teeth. More than 30 specimens of Albertosaurus have been found, including 22 at a single site that contained a mix of old and young individuals. Some experts think the mass grave is evidence that Albertosaurus lived and hunted in packs. The species was named after Alberta in Canada, where it was first discovered.

Guanlong (GWON-long)


When: 160 million years ago (Late Jurassic)

Fossil location: China

Habitat: Woodlands

Length: 8 ft (2.5 m)

Diet: Flesh

Guanlong was discovered in China in 1996. Its name means “crowned dragon” in Chinese and refers to a hollow crest on the skull, running from the nose to the back of its head. The crest was probably used in display, perhaps helping to attract mates. An early tyrannosauroid, Guanlong was much smaller than the later giants and had three fingers on each hand rather than two. It was a close relative of early feathered dinosaurs and may well have had a coat of fuzzy feathers itself.


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