Shown Their Work: It is arguably the most accurate creature in the series, the only problem being the lack of a tail fluke, which is more of a case of Science Marches On than anything.
Spinosaurus
Accidental Truth: There is a brief moment where they actually get the shape of the sail right during the scene when they’re reconstructing the skeleton.
Adaptational Badass: In Real Life it was a short legged fish eater, here it’s shown devouring Rugops in one bite, killing Carcharodontosaurus with one claw swipe, and skinning Sarcosuchus alive effortlessly.
Artistic License – Paleontology: Where do we start? Spinosaurus is probably the most inaccurate creature in the series. First it’s way too big, it was only 50 feet feet long at most (though at the time the show was made, it was thought to have reached 60 feet long based on controversial measurements), only twice the size of the rugops, not the 240-foot kaiju seen here. Second, though this can be excused due to it being made in 2009, the spino is shaped completely wrong, in reality it had a paddle-like tail, short legs, a dip in its sail, and a long body. Here it looks like a T. rex with a crocodile-like head, long arms and a fin on its back.
Curb-Stomp Battle: The Carcharodontosaurus and Sarchosuchus didn’t stand a chance.
Weaksauce Weakness: Its signature sail is connected to its spine, meaning that if it tried to roll over, its back would break and it would die.
Your Size May Vary: It is shown to be way bigger than 50 feet long during the prehistoric segments, but in the scenes where is shown in the 21st century, it has a much more realistic size.
Acrocanthosaurus
Foil: To T. rex, the narrator draws several comparisons between the two, both are large North American theropods, but Acrocanthosaurus hunted unarmored sauropods and large herbivores whereas tyrannosaurus hunted armored prey like triceratops and Ankylosaurus. Their hunting styles also differ, both mainly used their jaws, but acro would bite the prey several times then follow it until it bled out, while tyrannosaurus would grab them by the neck and crush their spine on the spot.
Adaptational Wimp: In real life it was more than capable of fighting off a titanis, but here it is shown helplessly trying to escape and getting killed instantly, as well as getting killed effortlessly by smilodon.
The Worf Effect: Is just there to serve as a food source for the terror bird.
Smilodon
Shown Their Work: It is shown living solitarily rather than in a pride. And it wrestles the giant sloth to the ground before biting it, which is what the real animal would have done to avoid breaking its signature teeth. It's also shown being terrorized by the terror bird as opposed to the other way around as shown in Walking with Beasts, as in real life, the sabertooths became the dominant predators because the terror birds went extinct.
The Worf Effect: Appears solely so the Terror Bird can steal its kill.
Dire Wolves
Curb-Stomp Battle: Deliver one to the terror bird of all things, thanks to their superior numbers.
Rugops
Artistic License – Paleontology: It’s arms are too long, they should be so ridiculously short that they don’t have elbows. In addition, they should not be pronated.
Butt-Monkey: Are constantly shown getting hunted down and killed by spinosaurus.
The Dog Bites Back: After getting eaten and bullied around by spinosaurs for most of the episode, a pack of them bring one down at the end.
Carcharodontosaurus
Curb-Stomp Battle: Is on the receiving end of one, as the Spinosaurus kills it in a single blow.
The Rival: It’s built up as one to Spinosaurus, but is anticlimactically killed in one blow.
Shown Their Work: It’s actually one of the most accurate animals in the documentary.
Paralatitan
Mighty Glacier: They’re slow, but they’re the only animals in the episode able to have an even fight with spinosaurus 1 on 1.
Science Marches On than anything.
