LIKE much that moves in Twitter-mad Saudi Arabia these days, it started with a single message. A lady in Dammam, the hub of the oil industry on the kingdom’s Gulf coast, tweeted a complaint from a local shopping mall. Agents of the Committee for the Promotion of Virtue and Prevention of Vice (CPVPV), she said, were causing an unpleasant scene. The government-salaried vigilantes, a bearded auxiliary police force familiarly known to Saudis as the Hayaa, had marched officiously into an educational exhibit featuring plaster models of dinosaurs, turned off the lights and ordered everyone out, frightening children and alarming their parents.

It was unclear precisely why the religious police objected to the exhibit, which apparently had been innocently featured at shopping centres across the Gulf for decades. Malls are one of the few public spaces where Saudis mix socially, and so often draw the Hayaa’s attentions. Gone, however, are the days when its agents can go about their business unchallenged.

Within minutes of the incident, a freshly minted Arabic Twitter hashtag, #Dammam-Hayaa-Closes-Dinosaur-Show, was generating scores of theories about their motives. Perhaps, suggested one, there was a danger that citizens might start worshipping dinosaur statues instead of God. Maybe it was just a temporary measure, said another, until the Hayaa can separate male and female dinosaurs and put them in separate rooms. Surely, declared a third, one of the lady dinosaurs had been caught in public without a male guardian. A fourth announced an all-points police alert for Barney the Dinosaur, while another suggested it was too early to judge until it was clear what the dinosaurs were wearing.

Not a few tweets cast the incident in political terms. "Why close the show?" asked one. "It's not as if we don’t see dinosaurs in newspapers and on TV and in the government every day." "They should go after the dinosaurs who sit on chairs," suggested another, seconded by a tweep who advised that dinosaurs in gilt-trimmed cloaks, the garment of choice for senior sheikhs, would make a better target.