Aluminium Christmas Trees: While Anomalocaris usually grew about one meter long, there is a two-meter long species from China where this episode is set (A. saron). However, its affiliation to Anomalocaris is disputed, later studies suggest it belonged to an unrelated animal known as Omnidens, and it appeared about ten million years later.
Contested Sequel: While it still has its fans, Monsters likely has the most polarizing reception of any entry in the Walking with... quadrilogy; which largely owes to its less naturalistic and more heavily sensationalized portrayal of its subjects.
Designated Villain: The arthropods. Whereas predators in other instalments are portrayed as Non Malicious Monsters who can only qualify as "villains" because we see things from the perspective of their prey (or aren't villains at all, in some cases), the narrator in the first two episodes of Monsters exaggeratedly paints the predators of human ancestors as though they're vicious, malevolent brutes who are waging some kind of "war on vertebrates" (often presented as underdogs who are "tough on the inside" due to their internal skeletons) and failed to "win" eventual dominance of the earth due to their "inflexibility" (as the narrator often suggests in an oddly-derisive tone). This is even though, like the "villains" of Dinosaurs and Beasts, the arthropods are simply other species of animal doing what they have to do to survive.
Ensemble Dark Horse: Anomalocaris's bizarre design and accolade of being the first ever apex predator has gained it a lot of fans.
For all its hunting prowess and deadliness, the famous crested mammal-ancestor Dimetrodon looks pretty damn goofy when it's running.
Justified in the fact that every land vertebrate at that time period ran more or less like that, and the 10-feet one was likely to outrun everything else. And its following evolutionary stage (the gorgonopsid) loses its "clumsiness" altogether and gallops after prey at high speeds, which it would have done in Real Life.
The sensationalist narration in the first two episodes continuously presenting vertebrates (typically described as "our ancestors") and arthropods as two rival factions warring for "dominance" of the earth for hundreds of millions of years is pretty cheesy, as is the rather "X-treme" introduction and data cards at the start of each segment, giving the series a decidedly pulpier tone than its predecessors. The shot of the Mesothelae spider practically cackling in malicious glee as she creeps up on a nest of hatchling Petrolacosaurus and dramatically raises her fangs over them may well be the cherry on top, made even better by the accompaniment of Branagh's Large Ham narration proclaiming that "THE ARTHROPODS ARE BACK!". As well, many comparisons are made to modern objects like cars and trucks, which were far less common in the two preceding series.
Several of the arthropod characters are assigned more mammalian sound effects to accentuate their monstrousness to the audience; most notably, Brontoscorpio, in its introductory scene, is heard faintly growling and snapping akin to a rabid dog.
The Diictodon cries sound almost like garbled human voices, which can be unsettling or hilarious depending on how you look at it.
The ending scene where the Euparkerialiterally evolves Pokemon-style into an ALLOSAURUS. Most "evolutionary transitions" are shown through cutaways with explanations, but in the final shot it just seems to transform in real time, with the watching Proterosuchus watching in utter confusion and being scared off when the Allosaurus roars.
Nightmare Fuel: The series as a whole can strike this chord for some; it's noticeably Darker and Edgier compared with Beasts and Dinosaurs and makes free use of Anyone Can Die. That combined with the unfamiliar sizes or appearances of most of the animals involved (particularly the invertebrate megafauna of the first two episodes) can give the series a surrealistically disturbing tone befitting of an elongated nightmare.
Sequelitis: This installment is less well-regarded compared to Dinosaurs and Beasts due to its looser accuracy, more sensationalist tone, and being much shorter (having only three episodes instead of six), meaning the narratives of each segment are much more poorly developed.
Special Effect Failure: Walking with Monsters suffers from some particularly bad-looking composition. Animals clip into the scenery, their shadows rarely correspond to the irregularities or the color of the ground, and in some shots they are cropped a little bit too far from the screen's edge, so you can even see parts of the background "through" them.note Though this last one may depend on whether or not you watch it on DVD. At least one version of the Walking with Dinosaurs DVD also has some strange goings on at the edges of the screen as they were intended for CR Ts, which have overscan cropping. These were present in the previous two series, but by 2005 these errors were much less excusable and far more noticeable.
The evolution sequence from Cephalaspis to Hynerpeton (armored jawless fish to early tetrapod/early amphibian) skips a number of steps that would have made interesting sequences in their own right (jawed fish of all sorts, lobe finned fish, etc.).
Ironically, the villain of the third sequence, the giant Hyneria, was actually part of our ancestry (instead of its "enemy" as insisted by the narration). Not all human ancestors were weak.
It would be very difficult to pull off given the completely bizarre nature of some early ecosystems (e.g. Burgess Shale), but imagine if they had just followed the same format used in Walking with Dinosaurs and Walking with Beasts: Six episodes, each set in one particular environment of the past. We'll have with more probabilities seen things like Hallucigenia, Opabinia, Wiwaxia, and others.
Ugly Cute: The Diictodon. They sound adorable as well.
Comment: What? Euparkeria is evolving! Congratulations! Your Euparkeria has evolved into Allosaurus!