WWD: Edmontosaurus annectens (Patreon)

The species depicted in the show as Anatotitan, but the name has since been sunk into the genus Edmontosaurus, joining a long line of dubious hadrosaurs, such as Trachodon, Anatosaurus, and (later) Ugrunaaluk. Which is too bad because Anatotitan was a pretty good name. This was the most common hadrosaur species in Laramidia at the end of the Mesozoic, making up 1/5th of dinosaur fossils known from Hell Creek (only behind Triceratops and Tyrannosaurus in commonness) and is known from many extremely well-preserved specimens, including hatchlings and several "mummies", so that nearly all of the skin texture and growth stages are known, although further south, to the prairie-like environment dominated by Alamosaurus, it is replaced by the hadrosaur Kritosaurus.

Far from being easy prey for Tyrannosaurus, an adult Edmontosaurus would be a formidable foe, reaching some 12 metres in length and 7 metric tonnes, and could probably run twice as fast. Fossils of exceptionally large animals suggest, in very rare cases, it could reach close to 15 metres in length and over 13 metric tonnes, putting it as one of the largest non-sauropod animals to ever walk the Earth, and the largest denizen of Hell Creek. Getting struck by an eight-metre long tail of that kind of animal would an extremely painful blow, club or no. The individual I've drawn here is about 12.5 metres in length, because +14 metre individuals would've been very uncommon.

The Edmontosaurus in the episode is recycled from the Iguanodon in the earlier episode, and as a result it has some jarring anatomical quirks due to having the same body. Its forelimbs are far too broad and have thumb spikes, while actual hadrosaurs had exceptionally thin forelimbs with no spike claw (an extremely well-preserved Edmontosaurus forelimb shows they stood on one horse hoof-like nail, and a had second smaller dewclaw). The thinness of their forelimbs is a bit of a mystery considering how massive they were, but it's been suggested it made it easier for adults to navigate crowded nest colonies.

"Duck-billed" dinosaur is also a big misnomer here. Their skull does indeed have a rather wide, duckbill-like snout shape, but this is misleading. One specimen preserves a keratinous beak, showing that the wide "duckbill" was in fact an anchorage point for a squared-off, downturned beak when there was flesh on bone, so no duck-likeness would have been visible in life. Together, with its dental "tooth batteries", these formed the basis for one of the sophisticated and efficient chewing mechanisms in nature, and it would have been able to consume and process even the toughest plant material with ease.