Look who got their “Flintstones” vitamins.

A new study has added evidence that some dinosaurs, particularly the Massospondylus carinatus, experienced growth spurts and pauses seasonally, in relation to health and habitat — so that in prosperous years, the animals could almost double in size.

Most animals, including humans, grow steadily over time, ceasing once biological adulthood is achieved, researchers explained. However, the growth of Massospondylus depends on environmental factors such as diet and climate — a trait more commonly seen in plants.

Massospondylus’ sporadic growth pattern is illustrated best by its unique bone structure, which demonstrates “growth rings,” much like many tree species, according to the research, published in Biology Letters on Wednesday. The team of scientists from the American Museum of Natural History say their findings “[show] us there is still so much to learn about these unique creatures,” they said in a statement.

“One year they might gain [220 pounds] of body weight and the next year they’d only grow by [22 pounds],” said paleontologist Kimberley Chapelle.

The largest fossil specimens have indicated that the bipedal dinosaur reached heights of more than 16 feet, and weighed as much as 1,200 pounds on a plant-based diet.

“The final body size may not vary much, but the pattern and trajectory to get there does,” Chappelle later told The Post. “In other words,” she added, “the destination doesn’t change, but the journey does.”

In bountiful years, the Triassic Age dinosaur could grow at an unencumbered pace. In less fortunate seasons, however, Massospondylus would cut back on growth to conserve energy.

Plateosaurus, a relative of Massospondylus, was thought to have grown with similar variability, a quality biologists call developmental plasticity.

Researchers point out that Massospondylus was among the first dinosaurs to be named and cataloged, after paleontologists discovered its fossils in the mid-19th century — “affectionately” dubbed Big Momma, according to Chappelle.

“Massospondylus was one of the first southern African dinosaurs named back in 1854, and we are still learning so much from it,” Chappelle said. “It teaches us so much about our past environments and what southern Africa was like 200 million years ago.”