Sea Monsters (Walking with) – A Retrospective Review

[Infinity Blade]

Sea Monsters – A Walking with Dinosaurs Trilogy: A Retrospective Review




About 71% of the Earth’s surface is covered in water, and of that water, the oceans hold 96.5% of it (USGS->). Indeed, life on Earth began in the oceans, dating back to at least 3.5 billion years (Schopf et al., 2017). Ever since then, the seas have been filled with countless lifeforms that lived and died throughout the ages. Some stayed in the oceans, some left, and some who left even came back. And some were undoubtedly terrifying…

This series of posts will review an old BBC documentary that holds a special place in the minds of many: Sea Monsters – A Walking with Dinosaurs Trilogy. It follows Nigel Marven as he travels back in time to visit the “seven deadliest seas” of the Phanerozoic (although, as you’ll see through this review, how “deadly” an ancient sea was is kind of arbitrary), treating us to an expansion of the BBC’s Walking with universe. Although it hasn’t quite been 20 years since it aired, I was inspired to review this anyway after seeing a mini-review on Twitter. So put on your diving gear and maybe get a speargun ready! Because we’re going to dive into this (figuratively, but not actually literally).


Directory:

- Dangerous Seas (this post)
- Into the Jaws of Death->
- To Hell...and Back?->

• We start off with a montage of Nigel Marven running from various theropods in the two-part Chased by Dinosaurs series (I still need to review the second episode of that). The narrator, Karen Hayley, has an awesome line: “…no matter how bad things get on land, the one thing you should never, ever do, is get in the water”.
• This is accompanied by Nigel jumping into the sea off of a cliff to escape a pursuing Tarbosaurus. While he’s safe from the Tarbosaurus’ grasp (if this were Speckles the Tarbosaurus, it might’ve been a different story lol), a Xiphactinus swims right past him soon after entering the water.
• From the get-go, we’re shown the order in which Nigel will travel to (although, if you’re not familiar with the history of life on Earth or its named periods, you may still be puzzled), and that each sea will be “deadlier” than the preceding one. From “least” to “most deadly” we have the Ordovician, the Triassic, the Devonian, the Eocene, the Pliocene, the Jurassic, and the Cretaceous. Again, whether or not you really agree with the ranking here is up to you. Personally, I’d say the period with the two largest macropredators that ever lived plus a whole slew of other terrifying oceanic predators is the most intimidating (the Miocene), but that’s just me.
  
  It also may be worth asking “deadly to whom?”. If we’re solely talking about how deadly to humans, that adds another layer of complexity to the ranking, as we have no real way of knowing how aggressive any of these predators would be to humans had they lived with us. For example, we live in an age where elephant-sized macropredatory dolphins chomp and ram everything from small fish to whales to death, yet these same dolphins only very, very rarely attack humans in the wild. Similarly, I might consider megalodon to be the most physically powerful predator seen in this documentary, but would a megalodon really see a skinny primate three orders of magnitude smaller than itself a good meal (so there’s room to disagree with me as well)?
• Nigel has this really cool (but super long) map of the history of life on Earth with him. When I was a little kid, I actually tried making one myself. Good times, good times.
• Forgive me for any mistakes I make here. The early Paleozoic is not my strong suit.
  
  Anyway, we first travel to the Late Ordovician 450 Ma (this would put us at the Katian). The track and the overall barren look of the landscape do a good job of showing us an alien, inhospitable world (this track comes back when Nigel realizes that Earth’s days were shorter back then, further giving us the impression of an alien planet). There are no insects flying around, no worms in the soil, and no plants on land.
  
  But from research I did while reviewing this, it appears there actually were plants on land at this time after all. Evidence for embryophytes (land plants) goes all the way back to the early Middle Ordovician, over 470 million years ago (Strother et al., 1996; Rubinstein et al., 2010). Molecular clock studies also support the appearance of embryophytes between the middle Cambrian and early Ordovician (Morris et al., 2018). Also, evidence of burrows has been described in an Ordovician paleosol (Shear, 2000). The kind of terrestrial environment shown in this segment (no worms, no soil, and no plants on land) certainly existed at one point, but it appears to have been even earlier than shown here.
• The people making Sea Monsters apparently went through great pains to get their animals right. The eurypterids, the first animals we see here, are an example. The team sent a bunch of emails to Simon Braddy, a paleontologist at University of Bristol. He said that “They sent me several e-mails so I could comment on the way they had made the eurypterids...Their first model was not very good at all, but in the end I think they had got it just right” (link->). Now, I’m no invertebrate expert, and of course, paleontological knowledge has expanded a lot since 2003. But from looking at this anatomical diagram of Megalograptus-> (the genus depicted in Sea Monsters), I’d say it looks about right too.
• Nigel gets the base of his legs cut up by the eurypterid’s pincers. I’d probably shit my pants if those pincers made any sort of contact with my skin, Jesus Christ.
• Nigel and the crew spend the night at the Ordovician beach. I wonder, did they have those oxygen masks hooked up to their faces so they’d get enough oxygen while sleeping?
• The next morning, Nigel goes out to the middle of the bay with a large trilobite carcass he found the day before as bait for the real creature he’s after: giant orthocones (apparently supposed to be Cameroceras). He also has a camera hooked up to the carcass to get a view of whatever comes over to scavenge. Although it takes a while, an orthocone finally grabs ahold of the corpse and the camera goes offline. When he dives down, he sees a Cameroceras swimming around and even feeding on the sea scorpions.
  
  But how big is Cameroceras, really? Historically, Cameroceras was a wastebasket taxon where other endocerid genera were placed. This included Endoceras giganteum, the largest verified shell of which was 5,733 mm (5.73 meters) long (Klug et al., 2015). I don’t have a published paper on the largest Cameroceras (only these two pieces of art by Fabio Alejandro->), but it looks like the really giant sizes can’t be assigned to Cameroceras.
• More recent work also suggests that, contrary to many earlier depictions, most species of orthocone would not have been able to swim well if oriented horizontally. Instead, they likely lived their lives oriented vertically (Peterman & Ritterbrush, 2021), as seen in this reconstruction->.
• Nigel leaves the Ordovician with a horde of eurypterids climbing onto his boat, and moves on to the Triassic (PETA would definitely get on his ass for throwing some of the sea scorpions out of his way). Since the segment is set 230 million years ago, we’re looking at the Carnian here.
  
  Nigel sees a Coelophysis run by on the beach and then just moves on. “Dinosaurs, been there, done that”, he’s probably thinking.
• Nigel rides a Nothosaurus (which would definitely get him in hot water with PETA). He’s able to do so by grabbing the back of its jaws to prevent it from biting him, stating that although they have powerful jaw-closing muscles, the jaw-opening muscles are very weak (as in crocodilians).
  
  How much does this align with reality? While the skull of Nothosaurus does have a lot of room for jaw adductors (despite it being very narrow, elongated, and longirostrine), it also shows evidence of a strongly developed depressor mandibulae muscle (as you can see here->, marked ‘dm’), which opens the jaws. This powerful muscle and the strong epaxial muscles suggest Nothosaurus could open its jaws rapidly. So for an animal with strong muscles for rapidly opening the jaws, Nothosaurus would probably require more effort to keep its jaws closed than a crocodilian. The powerful adductors suggest it could snap its jaws rapidly as well. What we’re looking at here is an animal that would swing its head to the sides to rapidly snap up fish and small to large soft-shelled invertebrates (although, small pachypleurosaurs and small cyamodontoid placodonts have been found in the stomach contents of another nothosaur, Lariosaurus) (Rieppel, 2002).
• Nigel comes across a Tanystropheus foraging on the ocean floor. There has been debate over the years as to whether Tanystropheus was a terrestrial or aquatic animal. For what it’s worth, the most recent study, which involves a three-dimensional reconstruction of the skull of T. hydroides (previously thought to be a “large morph” of the genus, but turned out to be a novel species), found that the nares were placed on top of the snout and that the dentition was much like a fish trap. This suggests the skull was specialized for aquatic hunting. However, the overall body plan of Tanystropheus was poorly hydrodynamic and the limbs had limited adaptations for an aquatic lifestyle. If it was aquatic, it certainly wasn’t a fast or efficient swimmer. It’s thought, therefore, that Tanystropheus was limited to coastal environments. It would have been an ambush hunter, laterally swinging its head to snap up fish (similar to Nothosaurus) (Spiekman et al., 2020), just as Nigel claims here.
• But then Nigel grabs the reptile by the tail, only for it to escape by having the tail detach, like in modern lizards. This, of course, is not supported by fossil evidence. Lizards with detachable tails have fracture zones running vertically along each relevant caudal vertebra, which work like the perforated lines in paper towels.
• The detached tail Nigel holds in his hands is then eaten up by a Cymbospondylus, the real sea monster he came to see here.
  
  How big is Cymbospondylus? It depends on the species. Some species weren’t anything special in size, but others, like C. youngorum were huge. How huge depends on who you ask. One recent study tried to estimate the size of this ichthyosaur using the size of the humerus as a proxy, resulting in a whopping 17.6 meters long and 44,698 kg (Sander et al., 2021). But in his recent Princeton field guide on Mesozoic sea reptiles, Greg Paul tones this down five-fold, giving us an animal that’s more 14 meters long and 9 tonnes (Paul, 2022). Personally, the latter somehow sounds more sensible to me.
  
  Here’s a size chart with multiple species of Cymbospondylus together (link->). Despite the uncertainty in size, even the smallest specimen on there is pretty impressive in size.
• And keep in mind that this sea reptile was not something to sneeze at either, despite its snout and dental morphology. Although the prey taken was probably not humongous relative to its size, it’s not like it would have been restricted to tiny fish or cephalopods either. An ichthyosaur with grasping teeth and a long snout, Guizhouichthyosaurus (5 meters long), was found with the remains of a 4 meter thalattosaur in its stomach. The smaller reptile was most likely killed, then dismembered by the larger ichthyosaur. According to the authors, the thalattosaur was roughly one-seventh the body mass of the ichthyosaur (Jiang et al., 2020). Extrapolating this to the size of C. youngorum (assuming it weighed as much as Greg Paul estimates), we’d be looking at prey items weighing as much as ~1.3 tonnes (depending on how rough “roughly” is).
• Ngl, the track that plays as the Cymbospondylus tests Nigel as a prey item is pretty nice. Suspenseful and dramatic. Unlike the orthocone, the ichthyosaur at least considers taking a bite out of the time traveler, so I guess they weren’t lying when they said they aimed to make each sea deadlier than the previous.
• Right after Karen Hayley introduces us to the Devonian, the camera pans to Nigel looking down on his time map and pointing to one part, with a sound effect as if he’s dipping his finger into water (accompanied by ominous “time” sound effects, for lack of a better word). Then suddenly, DEADASS RIGHT AFTERWARDS, Nigel turns his head to the viewer to talk to them. It’s just an abrupt transition that I couldn’t help but chuckle a bit.
• Nigel tells us how mind bogglingly vast deep time is. Which…yeah. The amount of time between his first and second adventures in this episode is 220 million years. That’s literally the amount of time separating creatures like Coelophysis and Postosuchus and you. To the Triassic reptiles of the Carnian, the orthocones and eurypterids were already ancient as balls.
• A Dunkleosteus is filmed on their first dive, and is said by Nigel to be 30 feet long and 4 or 5 tons, weighing as much as “two or three elephants”. The highest recent estimates for Dunkleosteus suggest it may have been up to 8.8 meters long (Ferrón et al., 2017) and I don’t know how heavy. If Dunkleosteus weighed that much (4 tonnes doesn’t sound unreasonable), it would absolutely not weigh as much as two or three elephants, unless you’re referring to African forest elephants (which I doubt he is). 4 t is the weight of one bull Asian elephant.
• The Dunkleosteus model also seems to be out of date. I can at least point out that the tail would have actually been shaped more like a shark’s than what it used to be depicted as (Ferrón et al., 2017). I’m not sure about anything else beyond that.
• Nigel catches a Bothriolepis with a fishing rod as bait for the Dunkleosteus. He gets in a round shark cage (it’s round under the logic that the jaws of large predators would slide off of it, akin to a dog biting a beach ball) to lure it. After an encounter with a Stethacanthus (which is not actually a true shark as claimed here*) Dunkleosteus eventually arrives. It bangs the cage to a worrying extent, and the episode ends with a close-up of the Dunk.

Verdict:

Some inaccuracies are noticeable in this first episode. I’d say most of them are probably just cases of science marching on, although a few were never quite accurate to begin with (either being exaggeration or just flat-out made up). Nevertheless, it’s by no means all outdated material. The eurypterids seem to hold up to this day (at least from what I can tell), as does the orthocone with the exception of its horizontal posture (and I guess size?). The Cymbospondylus is regarded as a serious hazard, which is rightful in my opinion despite its likely piscivorous habits.

Because this are the first and thus “least deadly” seas, things haven’t gone too awry so far, although I’d say you could argue that they start to become a little this way by the time Nigel encounters the Dunkleosteus. I know Nigel never really gets hurt again after this episode, but I forgot if things ever go really wrong eventually. We’ll see.

[Infinity Blade]

Into the Jaws of Death

• The Dunkleosteus rams into the shark cage, denting the bars. I genuinely wonder if placoderms could have done that to other animals. I mean, with that armor protecting the head, maybe it’s not out there to imagine a Dunkleosteus doing that to its prey?
• Eventually the Dunkleosteus bites Nigel’s mail-clad Bothriolepis, cutting through it (so Nigel wins his bet that the Dunkleosteus could bite through mail). Normally, mail is pretty much impervious to cuts, which is why it was so widespread as an armor for ancient, medieval, and early modern militaries (and why it continues to be used for sharks). I don’t really know how modern shark suits are constructed (i.e. whether the mail is butted, riveted, or something else), but given the sheer amount of force behind Dunkleosteus’ jaws (6,000 N at the “fang” tip and 7,400 N at the blades) and the extreme amounts of pressure concentrated on a small area, I honestly wouldn’t bet against Dunkleosteus being capable of this feat in real life.
• A juvenile Dunkleosteus swims by looking for scraps left behind by the adult venturing near Nigel’s cage. Unfortunately for it, it’s cannibalized by the adult and has its armored remains regurgitated out.
• ”…the meanest sea mammal that’s ever lived”
  
  laughs in Livyatan melvillei
• The first animal Nigel comes across in the Eocene is an Arsinoitherium (whose name I’ve heard pronunciated in a number of ways and I’m not sure which one’s correct). It’s depicted with a small proboscis (perhaps due to the logic that elephants are one of its closest living relatives), but looking at its skull, it just doesn’t look like it could support even a small one (many reconstructions do not give it a proboscis either).
• Nigel then tries giving it an apple. Nigel, you’re the GOAT, but it’s a giant herbivore the size of a rhino. With humongous horns like a rhino. What dafuq are you doing?
• Predictably the Arsinoitherium charges at a slow trot(?). Mind you, although arsinoitheres looked like rhinos, they actually had columnar, graviportal legs like elephants instead of rhinos (link->), and so we could expect them to move something like elephants.
• Nigel tells us that Arsinoitherium is more closely related to the elephant than rhinos, which is true. A recent finding of the earliest known embrithopods points towards embrithopods being an early offshoot of the Tethytheria, splitting off before the elephant-sirenian split (Gheerbrant et al., 2018).
  
  As for the semi-aquatic lifestyle, evidence from tooth wear, the graviportal limbs, isotope analysis (Clementz et al., 2008), and occurrence in what would have been relatively dry environments suggest Arsinoitherium was instead a terrestrial animal (though, I don’t see why it couldn’t have sometimes taken a dip at times).
• Nearby where the Arsinoitherium swims, Nigel comes across a pod of Dorudon that are expectedly identical to the ones seen in Walking with Beasts. Although the Dorudon just swim around Nigel harmlessly and the scene is played more for wonder and intrigue than anything else, I feel like Dorudon could easily have been dangerous to humans as well. Although dwarfed by Basilosaurus, adults were still 5 meters long and weighed a full metric ton (Voss et al., 2019; Waugh & Thewissen, 2021). And it’s not called “spear-tooth” for nothing.
• Nigel finally goes after a Basilosaurus. His plan involves dunking a microphone underwater to see if he can hear a Basilosaurus call. This call would be recorded and would then be played back underwater to attract the whale. Nigel is successful, but the call they use is what I assume is a modern whale’s call. I’m no expert on whale vocalizations, but something tells me it couldn’t and wouldn’t work like this in reality (come to think of it, I have no clue what a Basilosaurus would even sound like). Although Basilosaurus was found to have an asymmetrical skull, which is associated with high-frequency sound production and echolocation in modern whales, these creatures also have specialized organs that are needed to produce high-frequency sounds (the melon, nasal sacs, and phonic lips). Archaeocetes like Basilosaurus lack osteological evidence for having any of these. Therefore, the cranial asymmetry exhibited by Basilosaurus and other archaeocetes was likely an adaptation for hearing prey (Fahlke et al., 2011). Or, as Thomas Halliday once put it, they “can listen to the music of the oceans, but they have not yet learned to sing”.
• The Basilosaurus Nigel and his crew were trying to entice then bumps into their boat. When Nigel finally sees it, he notes how non-reptilian it looks (in fact, modern paleoartists would reconstruct it so it looks a touch more mammalian than it does here), but also how it’s unlike any whale alive today. The callback sounds from the boat increasingly distress it and it eventually bites the speaker off.
  
  “Basilosaurus had never heard such bullshit before.” (read it in Kenneth Branagh’s voice)
• 36 million years from now, this Basilosaurus is going to be found with some metal found in its gut.
• Now we’ve moved onto the Pliocene. I love how the sequence opens up with a megalodon’s dorsal fin surfacing and moving through the water.
  
  I also agree with Hayley’s (the narrator’s, in case you’ve forgotten) remark. 4 million years ago, early hominins, our immediate ancestors, were indeed romping around in Africa. At the same time, this sauropod-sized apex predator shark was swimming around in the oceans, and already had been for several millions of years (although, it was nearing the end of its existence at that point). That is kinda shocking.
• Unfortunately, Livyatan melvillei was unable to join megalodon for this episode. The Doyalist explanation, of course, is that Livyatan hadn’t yet been discovered when Sea Monsters was made. The Watsonian explanation is that Livyatan was probably already extinct at this point.
• One neat, if small, tidbit here is that Nigel gets into a disagreement with his crew on what to do first. While Nigel wants to go straight out to see an adult megalodon, his crew members think they should look for juveniles first; Nigel is eventually forced to concede. This small detail humanizes the crew, whereas they’ve mostly just been background characters before.
• In the shallower waters, Nigel quickly runs into an Odobenocetops. Although the bizarre tusks are compared to those of narwhals as jousting weapons, this is only really partially true for narwhals. The narwhal tusk probably has multiple functions, with recent evidence suggesting that the most important one is serving as a sexual signal. In such a scenario, actual physical fighting is NOT the objective. That said, head scarring and broken tusks do occur in males (more often than in females), and it’s thought that this is probably a result of lateral strikes. Narwhal tusks are not built for ramming or direct stabbing (Graham et al., 2020), which could explain why broken tusks are so common (they’re not really durable structures).
• After seeing a juvenile megalodon try to capture the Odobenocetops (it fails btw), Nigel and his crew make a decoy of an Odobenocetops in order to learn how a megalodon would attack its prey (a camera is hooked up to it). The view of the dummy camera quickly trailing through the seemingly empty ocean until a shark shows up out of nowhere to take a bite out of it is perhaps just a liiiiittttllle unnerving. I mean, it’s still not horrifying, but maybe if you have thalassophobia and/or are afraid of sharks, it might bolster the scare factor.
• The program surmises that juvenile megalodon attacked prey in a similar manner to great white sharks today, but that adults might have done so differently. Idk what megalodon experts think of this, but I do know some think it’s possible that juvenile megalodon might have competed with adult great whites.
• The crew lures an adult megalodon by pouring fish blood and guts in the water, and try to keep it near with a chum bag. Nigel’s goal is to attach a camera onto the shark. Unfortunately, he finds it too difficult to do it within the confines of his shark cage, so he eventually resurfaces and attempts to do it from the deck of the boat. The last thing that happens in this episode is the shark bursts out of the water with the chum bag above it. Nigel is seen at first, but then the megalodon’s massive body blocks our view of him. Once the megalodon dives back down, Nigel is nowhere to be seen…

Verdict:

The first thing I want to talk about here is whether or not the threat level is actually increasing here, as you might expect with each sea supposedly being deadlier than the last. I would say that the threat level of these sea monsters – or at least the vibe we get – sort of increases with the Dunkleosteus, goes a bit back down with the Basilosaurus, and then peaks with the megalodon at the very end. Here’s what I mean by that.

The Dunkleosteus’ power as a predator is firmly established when we see it biting through a mail-clad Bothriolepis. This thing clearly had a deadly bite. It’s then seen cannibalizing a younger Dunk, so there is no doubt in the viewer’s mind that this was a ferocious predator. It’s the most frightening display of predatory power we’ve seen since the orthocone killed the sea scorpion in the first segment.

In the Basilosaurus segment, the giant whale shows up, swims around, and bites off a speaker. That’s pretty much it. Of course, Nigel knows to be wary around the giant archaeocete, but its presence is not played for drama or terror as much as that of the Dunkleosteus or the megalodon. If you wanted to see a more terrifying display of this whale’s predatory prowess, see Walking with Beast’s “Whale Killer”.

Now, the megalodon. The megalodon isn’t even doing anything that terrible (it’s not causing mass destruction everywhere), it’s just exploring the boat, the shark cage, and (understandably) occasionally taking lunges at the chum bag. However, it doesn’t need to. Just being near this 50 tonne shark is enough to make Nigel admit that he’s nervous. When the adult megalodon shows up, dramatic orchestral music plays, and you get this sense of dread and urgency for Nigel to do what he needs to do and gtfo of the water. It peaks at the end when the megalodon partially breaches out of the water and Nigel disappears from the deck of the boat, making it look as if the megalodon took Nigel with it. Of course, that’s not the case, but you still know that our favorite time traveler has been knocked into the water…with a 50 tonne shark. That eats whales for breakfast.

So, at least in regards to establishing threat level of each age’s respective sea monster, I feel like we reach a high with the Devonian segment, a low with the Eocene segment, and a peak with the Pliocene segment. However, this isn’t to say that the Eocene segment is bad; after all, we do get to see Arsinoitherium (even if it’s not perfect by today’s knowledge), thus expanding the WW-verse. Of course, the entire Pliocene and Devonian segments are expansions of WW lore, so they certainly get points for it too.

[creature386]

I really liked the ranking as a kid simply because I like rankings and I didn't really question it's internal logic. But, like you said, deadliness is very, very subjective.

Ad hoc, I can think of two ways of measuring it:

1. Deadly to humans. This is the way the habitability of planets is being often being measured and it makes intuitive sense. However, going by this, the Ordovician would probably rank far higher than it did simply because it was a very alien world where you'd need far better life support systems than in any other time period other than the Devonian. For starters, with so little atmospheric oxygen, refilling your breathing mix would be a chore.
2. Deadly in a vs-sense, that is "members of this ecosystem could outcompete or otherwise kick the ass of members of a different ecosystem". This might have been what Nigel was going for and it's probably what the main target audience of small, dino-loving boys that such shows are marketed at (sorry, a bit self-deprecation here) finds most exciting.

Looking at it under this lens, it makes perfect sense:

7. Ordovician: That one's self-explanatory. The apex predators there weren't that big or bad yet.
6. Triassic: Probably a case of Science Marches On because it used to be assumed that Triassic marine ecosystems had been badly crippled by the P-T mass extinction back then. I do wonder how the discovery of Thalattoarchon might have shaken things up had they set things a bit earlier.
5. Devonian: This one makes sense, as it's got the Dunkleosteus which is the first animal introduced in the show which lets Jaws music play in the background just by appearing.
4. Eocene: On paper, it's a reasonable step up from the Devonian, but as you noted, the Basilosaurus isn't established as much as a threat as Dunk was. So, while what's told is a step up, what's shown is a step down.
3. Pliocene: Yeah, this one would have ranked much higher and they set this in the Miocene and had Livyathan already been discovered.

My memory of the Jurassic and Cretaceous segments is a bit rusty (I'll let you cover them next time), but I think their placement makes sense within the show's premises.

[Infinity Blade]

To Hell…and Back?

• Nigel emerges from the water and calls one of his crew mates an idiot. I think this is the only time I’ve ever seen Nigel get visibly angry at another person in these time-traveling paleodocs of his. Of course, I’d be pretty flustered too if I was sharing the water with a 50 tonne shark that can gobble up an entire killer whale in just five bites.
  
  Don’t worry, he apologizes for this soon after.
• The creepy orchestral music continues to play, but the matter is resolved quickly, as Nigel attaches the camera on the megalodon. A few days later, the crew is able to track down the camera, which reveals a megalodon swimming up from the bottom to ambush a large whale.
• Nigel moves onto the penultimate sea, the Kimmeridgian one (155 Ma). Liopleurodon, the target of this segment, is nearing the end of its temporal range.
• As fearsome as Liopleurodon was, there were even larger and more powerful pliosaurs in the Late Jurassic, namely certain species of Pliosaurus itself. This, of course, was made before we started gaining a better understanding of the size of some of these giant pliosaurs, so I presume that’s why Liopleurodon is portrayed as the giant it is (rivaling the Leedsichthys in size) and being a supposed cut above megalodon in deadliness.
• Leedsichthys could get freaking enormous. Sizes of up to 44.9 tonnes remain viable (Ferrón et al., 2018). Definitely no marine reptiles at that time and place getting that big (although, not all specimens were this large).
• Here-> is a good recent life reconstruction of Leedsichthys, by the way.
• The creepy track playing in the background is easily one of my favorites in the entire Sea Monsters trilogy.
  
  As one of the Leedsichthys fails to keep up with its shoal, it attracts smaller predators particularly Metriorhynchus and Hybodus. With the creepy music playing, you get an increasing sense that something’s not right, and someone’s going to die. Well indeed, the marine crocs and hybodonts bite chunks out of the giant fish, which does nothing in response. While we don’t quite see it die yet in this scene, you know that the Leedsichthys is as good as dead.
• Watching all this, you might be wondering: how often was Leedsichthys attacked? There are healed pathological fin rays from Leedsichthys that show evidence of attack by predatory marine reptiles (Liston, 2006; Johanson et al., 2022). The marine reptiles in question included pliosaurs, as well as plesiosauroids or small pliosaurs (based on the size of the bite marks).
  
  There is also a Leedsichthys skull bone, probably a hyomandibula, with an embedded “crocodile” (probably Metriorhynchus sp.) tooth in it, as well as bite marks made by hybodonts (just like in this segment). These are most likely the result of scavenging (Liston, 2006). However, because the Leedsichthys here is so weakened that it can do literally nothing, I can buy metriorhynchids and hybodonts eating such an animal alive by starting at the fins.
  
  Reading this you might be wondering how this giant fish was able to defend itself at all. First, it was huge, which in and of itself is crucial defense. Second, based on the depth of the caudal fin (2.74 meters), the body itself was estimated to have been 1.5-2 meters deep, which would have made it difficult for predators with limited jaw gape to bite it (Liston, 2006) (the fact that the few confirmed healed injuries, probably from predation, are on the fin rays, further convinces me of this). Also, the large size of the tail and the flexibility of the body suggest that Leedsichthys was well built for acceleration, improving its ability to perform fast-starts (bursts of acceleration <1 second long) (Liston, 2006). A high metabolism, possibly even endothermy, in this fish have been supported by the two studies I’ve cited here (on the basis of bone histology in Johanson et al.), which would suggest very fast, active bursts of speed when escaping from predators. Lastly, and this isn’t proposed by any study (only by me), I can’t help but wonder if Leedsichthys could actually fight back against predators. The skull roof supposedly sported bony bosses. So if this gigantic fish, up to ~45 tonnes, which could accelerate quickly thanks to its anatomy and high metabolism, rammed into a predator with its bony head…well, you get the idea. The outcome, I imagine, wouldn’t be pretty.
• Anyway, enough about Leedsichthys, let’s talk Liopleurodon. The Liopleurodon in the WW-verse are not bothered by shark repellent, but avoid squid-laced dummies that release putrescine. I’m by no means an expert on animal repellents, so I can’t say anything much about this, except the fact that it’s an interesting thought.
• The nighttime dive scene is actually pretty great too. Nigel and the cameraman need light to be able to see through the darkness, revealing two adult Liopleurodon ripping into the Leedsichthys carcass. The track playing is a nightmarish, dramatic orchestral piece that’s perfect for a feeding frenzy. Nigel decides he wants to get closer, forcing him to use the smell suit on a Liopleurodon that comes too close. If he just decided to use the shark repellent, he’d have been that night’s appetizer.
• At last, Nigel arrives in…Hell’s Aquarium!!! The Campanian Western Interior Seaway, to be exact.
  
  I actually like the ambient noise we first hear on the Cretaceous beach. A bunch of Hesperornis squawking, some flying creature (probably a pterosaur) making a stock red-tailed hawk sound…yeah. That’s an aesthetic.
• This segment takes place 75 Ma. On the land there are T. rex relatives, but not T. rex itself. We do get to see T. rex later, the same model as in WWD, inexplicably misplaced in time.
• So…why is this the “deadliest” sea in Nigel’s opinion? According to him, it’s due to the entire array of deadly sea monsters. Marine reptiles (especially mosasaurs), sharks (Cretoxyrhina and arguably Squalicorax as well), and even some horrifying fish (Xiphactinus). The Western Interior Seaway was home to plenty of predators, I’ll grant that. But you could argue that say, the Miocene seas were chock full of fearsome predators too, a few of which were much bigger than any of the ones you’d have found in the Cretaceous seas. So yeah, whether or not you agree with this being the “deadliest” sea of all is up to you.
• After looking through a slick of blood (from a captured Hesperornis) and catching a glimpse of the WIS’s predators, we also see a T. rex (again, temporally misplaced) roaring over the edge of a rock across the sea (it makes a stock monster/dinosaur roar instead of its trademark roar in WWD). A sight like that would go so hard if you could see it irl.
• Nigel decides that diving in this sea of mosasaurs is too dangerous for him. Again, you have to wonder what’s so bad about mosasaurs that couldn’t be said of a super-sized pliosaur or shark.
• Pteranodon is seen flying around the boat. It actually lived about ten million years earlier.
• Poor Archelon.
• I love how Nigel spends his time casually feeding a Pteranodon.
  
  But anyway, using an ROV, Nigel and the crew get some nice footage in of a group of Elasmosaurus and a live Archelon. Nigel being Nigel, he decides he can’t resist and goes against his earlier word: he dives in to swim with it.
  
  What a Chad.
• This soon comes to an end, though, with something being caught on the radar. The sight of a Xiphactinus is enough to get Nigel to resurface. The track playing has calm bits where Nigel’s enjoying his time with the Archelon and more creepy, suspenseful parts where the crew is nervously trying to get him out of the water. Luckily Nigel safely gets back on the raft…
  
  …until a mosasaur capsizes it. And turns out to have a family with it (ohhhhh...is THAT what's so bad about mosasaurs?). The three men who were in the raft immediately attempt to gtfo of the water. The mosasaurs show impressive displays, bursting out of the water to attack the boat they mistook as prey, all while Nigel and the others frantically swim back to the boat before the giant lizards decide to turn on them. In the background, the Sea Monsters theme plays.
  
  This scene plays the “deadliest sea” thing perfectly.
• ”And the worst was over…almost…”
  
  Oh god, this ending…
  
  The crew spends the night in the Cretaceous sea, sleeping in their boat. The radar keeps sounding and reveals the silhouettes of a bunch of mosasaurs…all coming towards the boat. The mosasaurs close in, cue frightening music with Impossible Pictures logo…and that’s the end of the series.

Final verdict:

I think for the final two deadliest seas, they do an appropriate job of illustrating the threat levels. Nigel needs the smell suit to defend himself from the Liopleurodon, and has to resurface once he’s used it up.

And then there’s Hell’s Aquarium. While it’s arguable if it would really be the deadliest sea out of the seven depicted in this whole series, they do play it up for what it’s advertised. Nigel doesn’t even want to dive in until a ride with an Archelon proves too irresistible. And guess what? After f*cking around, he finds out. He encounters a Xiphactinus, and then a whole family of mosasaurs that capsize his boat. His first instinct isn’t “I wanna dive with this or watch it from a shark cage or get close to it!”. No, it’s “I gotta gtfo”.

As I was writing this verdict, it actually hit me. Have you noticed how the rest of the “main” sea monsters in the other segments never number more than two at any given time? Nigel deals with one orthocone, one Cymbospondylus, one adult Dunkleosteus, one Basilosaurus, one adult megalodon, and two Liopleurodon in a feeding frenzy. Here, he deals with a whole family of mosasaurs. Some look notably smaller and are obviously juveniles, but it’s still a very formidable family. Could this be the reason for Nigel and his crew’s panicked reaction, more than any other sea? Maybe. Now, mosasaur sociality is arguable, and I don’t think we technically have any more evidence of such social life (to protect young, as the program claims) for some of the other creatures depicted in the whole program. I don’t think it’s impossible per se either, though.

(However, I am disappointed especially by the lack of shark representation in Hell's Aquarium. Nigel's reasoning for it being the worst is the variety of big predator species, but we don't really get much of the WIS's sharks, like Cretoxyrhina. We get some Xiphactinus, but the mosasaurs definitely carried the whole thing.)

The last, but certainly not the least, thing separating Nigel’s experience in the Campanian ocean from the rest is that it’s the only one with an ambiguous ending. I mean, maybe we can presume that Nigel and his crew made it out alive, if we use his real life as a proxy…but I don’t know.

Also, I love their expansion of the WW-verse with all their other creatures. Leedsichthys, Metriorhynchus, pretty much everything in Hell’s Aquarium (except for the oddly misplaced T. rex).

So does Hell’s Aquarium deserve it’s name? TL:DR; the way they portrayed it compared to the others (mosasaurs attacking in groups), maybe. In real life, arguable.

[Infinity Blade]

Dec 1, 2022 22:47:55 GMT 5 creature386 said:

Ad hoc, I can think of two ways of measuring it:

1. Deadly to humans. This is the way the habitability of planets is being often being measured and it makes intuitive sense. However, going by this, the Ordovician would probably rank far higher than it did simply because it was a very alien world where you'd need far better life support systems than in any other time period other than the Devonian. For starters, with so little atmospheric oxygen, refilling your breathing mix would be a chore.

Fair enough.

6. Triassic: Probably a case of Science Marches On because it used to be assumed that Triassic marine ecosystems had been badly crippled by the P-T mass extinction back then. I do wonder how the discovery of Thalattoarchon might have shaken things up had they set things a bit earlier.

You’re probably right about the Science Marches On bit. If we really wanted to talk about the worst of the Triassic, screw Thalattoarchon or Cymbospondylus. We got Himalayasaurus->. In fact, if this size estimate is accurate, it would probably come the closest to Livyatan or megalodon in sheer power.

4. Eocene: On paper, it's a reasonable step up from the Devonian, but as you noted, the Basilosaurus isn't established as much as a threat as Dunk was. So, while what's told is a step up, what's shown is a step down.

Oh yeah, Basilosaurus should have been a much larger, more powerful animal overall than Dunkleosteus. I can easily see it being a step up.

[creature386]

(Why do I always take so long with my replies?)

I've gotta admit, when I was a kid, the top pick seemed very reasonable to me. Thanks to National Geographic's Sea Monsters (which I already knew about even then), it had been my instinct to assume that the Western Interior Sea Way was far more biodiverse than all the environments shown so far, even if there had been no data to back this up. I guess you could cite the Cretaceous Neoselachian radiation as an argument to put the Cretaceous sea before the Jurassic sea, but that makes the lack of shark representation even more criminal. At least compared to the Miocene, you could make the case that, other than Brygmophyseter and Albicetus, none of the iconic macroraptorial sperm whales had been described so far when the show first aired and they weren't really understood as a phenomenon yet either. They probably didn't want to finish with a one-Meg show (though, to be fair, even then, there also were some co-mega sharks known, like Otodus chubutensis) after giving the bronze and silver medal to, as far as they knew, more colorful environments. Not that it matters. The ranking is entertainment and, as you noticed, Nigel sold the first two ranks well.