The sculptures -- built of brick and artificial stone on a framework of iron rods -- were built in Crystal Palace park in south London in the 1850s after being moved from the Great Exhibition in Hyde Park. The dinosaurs had been given a Grade II listing in 1973. The upgrade now puts the sculptures in the same preservation category that Buckingham Palace and the Royal Albert Hall enjoy.
"They're believed to be unique and are clearly of exceptional historic interest in a national and probably international context," Culture Minister Margaret Hodge said.
According to English Heritage the sculptures are the "first attempt to accurately reconstruct the three dinosaur species known to the scientific world in the 1850s within their geological environment."
As well as the sculptures, geological strata and a lead mine that are part of Crystal Palace park's "Dinosaur Court" have also received the Grade I listing.
Britain has 9,137 Grade I listed monuments, with the preservation order designed to ensure care is taken over decisions affecting the dinosaurs and that any alterations respect the character and interest of the sculptures.