Part 5: Spirits of the Ice Forest ("of the Silent Forest" in the book)

Time: 106 million years BCE

Place: "Antarctica," part of a giant continent made up of present-day Antarctica, South America, and Australia

Actual Locations: New Zealand

The setting and cast of this episode are the most unfamiliar for the veteran dinosaur watcher. Most of the action takes place in a silent forest a few hundred miles from the South Pole, a locale that simply didn’t exist in past popular saurian narratives. It’s a cold, harsh world that is dark for months on end; everything shows up in a washed-out grey-green. But it’s not a wasteland or an ice sheet: it’s a dense forest of ferns, conifers, swampy pools … and the huge flat head of what looks like a bullfrog pops out to snatch at the corpse of a small dinosaur on the shore!

The star of this show is Leaellynasaura (sounds like "Lianna-saura"; was it discovered and named by a Welshman?), an elegant 7-foot biped with—wait for it—huge eyes "and an enlarged optic lobe that enabled it to see in the dark." There’s plenty of animatronic action with these creatures, who warn one another of predators and scatter; build nests of rotting leaves to incubate eggs whose temperature they monitor with sensitive beaks; and chase off an egg-snatching mammal called Steropodon, a secondary cuddly hero who looks like a cross between an opossum and a raccoon.

Koolasuchus is the heavy: 16 feet long but only 1 foot high, it looks like a giant, squashed salamander with an outsized arrow-shaped head. It’s actually a throwback to a time before the dinosaurs: an amphibian that survived only in the polar regions because it was too cold for crocodiles. Koolashuchus hibernates in the swamp during the winter, and makes a laborious 200-meter crawl to its summer quarters in the river. A Dwarf Allosaur, "only" 20 feet long, provides some additional threat to our cuddly heroes as well.

The big dumb-guy role is taken by Muttaburrasaurus, an herbivore whose enlarged snout (the head looks like a camel’s with yellow balloons on its nose) may have been useful for making distinctive calls. We get a closeup of blood-sucking insects on its ears and eyes. A lizard known as the Tuatara, another reptile that predates the dinosaurs but will live on into present-day New Zealand, makes an appearance, as does the Weta, a giant brown cricket-like insect.

As the lighter part of the year winds down, plant photosynthesis stops, Southern Lights dance across the sky, there’s a time lapse sequence of ice crystals and creamy ice forming on various objects, and the scene turns almost pitch black under the trees. "But with image-enhancement, it is possible to get a Leaellynasaura’s-eye view of the clan," says Branagh, and the visuals of frozen ground and pools, of the clan gone into suspended animation, resemble infrared photography.