DINOSAURS munched on "magic mushrooms" with the same mind-bending highs as LSD, scientists believe.
A sample of hallucinogenic fungus - preserved in amber - reveals it was around when plant-eating giants roamed Earth 100m years ago.
The fungal spores lived on the grasses which were the mainstay of the diets of huge herbivores like the Diplodocus and Stegosaurus.
An analysis of the specimen reveals the fungus is very similar to ergot, the parasitic fungus which is needed to make LSD.
The startling discovery was made by researchers from Oregon State University and the USDA Agricultural Research Service.
The fossil was discovered in an amber mine in Myanmar and dates from about 100m years ago when Earth was dominated by dinosaurs.
Although conifers covered most of the landscape, it's now believed the earliest flowering plants and grasses were just beginning to evolve.
George Poinar Jr, of the university's College of Science, and the research team published their findings in the journal Palaeodiversity.
He said: "This parasitic fungus may have been around almost as long as the grasses themselves, as both a toxin and natural hallucinogen.
"There’s no doubt in my mind that it would have been eaten by sauropod dinosaurs, although we can’t know what exact effect it had on them."
Some grasses have natural defence mechanisms, and ergot is thought to be one of them, helping to repel most herbivores.
It’s bitter and not a preferred food to livestock, and it’s still a problem in cereal and grass seed production, as well as pastures and grazing land.
In both animal and human history, the fungus has been known to cause delirium, bizarre behaviour, convulsions, severe pain and even death.
In the Middle Ages it killed thousands of people during epidemics when ergot-infected rye bread was more common.
More than 1,000 compounds have been extracted or derived from it, some of them valuable medicinal drugs.
They also include, from the mid-1900s, the powerful psychedelic compound lysergic acid diethylamide or LSD.