Pachycephalosaurus

American  

[pak-i-sef-uh-luh-sawr-uhs] / ˌpæk ɪˌsɛf ə ləˈsɔr əs /

noun

1. Paleontology. a genus of two-legged, herbivorous dinosaurs with distinctively thick, domed skulls edged with bony bumps and spikes.

2. (pachycephalosaurus) a dinosaur of the genus Pachycephalosaurus.

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pachycephalosaurus Scientific  

/ păk′ĭ-sĕf′ə-lə-sôr′əs /

1. A large herbivorous dinosaur of the genus Pachycephalosaurus of the late Cretaceous Period. It grew to about 7.6 m (25 ft) long and had a domed skull up to 25.4 cm (10 inches) thick that was lined with small bumps and spikes. The thick skull may have been used for head-butting during mating displays.

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Example Sentences

At the Wednesday auction, which featured more than 100 items, a Ceratosaurus skeleton from the late Jurassic period sold for $26m and the skull of a Pachycephalosaurus sold for $1.4m.

From BBC • Jul. 16, 2025

Dinosaurs like Pachycephalosaurus had sturdy skulls, and knocking heads remains common in bighorn sheep, chameleons and even whales.

From New York Times • Jun. 2, 2022

But it isn’t really known whether Stygimolochs existed: Horner believes the fossils found were just juveniles of another dinosaur called Pachycephalosaurus.

From The Verge • Jun. 19, 2018

And some dinosaur names are real doozies: Tyrannosaurus rex, Pachycephalosaurus, Parasaurolophus, the list goes on and on.

From Scientific American • Sep. 19, 2012

If this were an Indiana Jones movie, he would smash into something wonderful at the bottom -- the skull of a Pachycephalosaurus, say.

From Time Magazine Archive