Secrets of the Dinosaur Mummy concerns Leonardo, a remarkably well-preserved juvenile Brachylophosaurus that lived (and died) 77 million years ago, during the late Cretaceous period. Discovered in Montana in 2000, Leonardo is pretty much intact (except for his lower back and tail), although the process of petrification has amplified his presumed weight of 2,000 pounds into a full six tons.
Secrets has the usual CGI interludes of roaming herds of Brachylophosauruses (which are convincing and tastefully done), but its main focus is on the techniques used to explore Leonardo's viscera. Since there was no question of cracking the fossil open to reveal its insides (which would have resulted in considerable damage), the research team--led by rogue paleontologist Robert Bakker--had to rely on increasingly powerful imaging techniques.
It's amusing to see the heavy armament that's wheeled in: first, high-intensity X-rays, then even more powerful gamma rays, then a blast of cobalt radiation at NASA's Johnson Space Center (which required the evacuation of the entire complex). So what do these scans accomplish? Well, it's not giving anything away to reveal that, yes, scientists have been able to observe anatomical details in Leonardo's mummy that have not yet been seen in any other dinosaur fossils. It seems that Leonardo had a bird-like crop in its neck (which helped it to digest food), a more extensive beak than previously realized, and an intricate array of different-sized scales on its head, back, underbelly and legs (which had the biggest scales of all, presumably to protect them against the thick underbrush).
The research team was also able to determine how Leonardo died (I won't reveal the details here, but suffice it to say that he had a very bad, awful, not-good dinosaur day), and what he ate in the last few days before he met his demise. In fact, this last nugget of information may be the most important of all, since the pollen and leaves found in Leonardo's gut provide valuable information about the ecosystem of the western United States in the late Cretaceous.