For the very first main target animal to be rescued for the newly constructed Prehistoric Park aquarium, Drew heads off to the Devonian period to rescue the dunkleosteus. Unfortunately, despite his high confidence in how well the mission will go, he soon discovers the hard way how the current working relationship between Jack and Leon is actually a much bigger problem then he was initially willing to believe. Meanwhile, back at the park, Kyle and Linda are on the case when the dimetrodon start acting particularly more difficult to work with than usual.
- Amazing Technicolor Wildlife: Many of the animals dwelling within the Devonian period Gogo reef prove quite spectacularly and brightly colored.
- An Arm and a Leg: Very narrowly averted twice. Leon first almost gets one of his arms bitten off when an onychodus lunges out of hiding in a hunting attempt and snaps its teeth dangerously close to his position while trying to snap at some mollusk eating placoderms that were originally in the area very closet to where Leon was positioned. Drew himself also later ends up at risk of getting one of his own arms bitten off at the very least after he accidentally gets it stuck between the bars of the shark cage he's in while a foursome of dunkleosteus are attempting to hunt him.
- Battle in the Rain: Averted. While Leon comes very close to at least punching Jack in the face after one moment of antagonism too many, the sound of the danger alarm going off to alert him and Jack of Drew's plight is enough to prevent them from coming to blows.
- Big Damn Heroes: Upon realizing just how much danger Drew has ended up getting in under their watch thanks to their latest (and final) squabble, Jack and Leon are able to hurriedly get their act back together just in time to pull Drew back up to the surface and onto the Ancient Mariner's deck right as it's looking as if Drew will be doomed to either getting killed or maimed by a foursome of dunkleosteus.
- Birds of a Feather: As explained by Kyle, Rommel and Otrera the dimetrodon prove to be this by virtue of their shared large size, shared high levels of power, and shared aggressive, temperamental, and group dominating personalities. Linda even namedrops this very trope immediately after Kyle has finished explaining to her why Rommel and Otrera are arguably a good match as far as mating compatibility goes.
- Bittersweet Ending: While the dunkleosteus are successfully rescued and added to the park's repertoire of animals (alongside multiple other Devonian aquatic animal species), Leon and Jack find themselves suspended from active rescue mission work due to their ill-timed Teeth-Clenched Teamwork induced clashes and arguments almost getting Drew maimed or killed.
- Both Sides Have a Point: While they both act like total jerks to each other in the process of expressing as much, both Leon and Jack bring up several valid points against each other over the course of their arguments. As Jack points out, Leon has done very little (if anything) to prove himself to have any sort of skill or competence to justify his being hired, has at least twice fallen on the receiving end of an unpleasant incident that could have easily been avoided by someone with more skill, and relies too much on his broadcasting device or similar machines more often than not. He also likewise subtly points out later that Leon's efforts at saving Yolanda back in South of Heaven would have been doomed to fail if Andrias the proterogyrinus hadn't been released into the crassigyrinus pool to keep the smaller carnivorous amphibians at bay. Leon, however, is also quick to point out how Jack's history of reckless behavior and relying on luck and the first semblance of a plan he randomly thinks up in the heat of the moment are not the safest ways to go about their potentially immensely dangerous work, that his tendency to always tell jokes isn't exactly reassuring in times when potentially dangerous situations are about to unfold, and that he really ought to have at least thanked him for helping to assist Yolanda in escaping from the crassigyrinus on account of her being Jack's friend.
- Brutal Bird of Prey: The teratornis duo's continued status as this is something that Adrian is shown at the park attempting to undo while Drew, Jack, and Leon are away. So far, the emphasis is strictly on attempting.
- Canon Foreigner: An undiscovered species of Devonian anomalocariid (something there is so far no evidence of in the fossil record in Real Life) is present and rescued over the course of this mission.
- Continuity Nod: Drew twice makes references to how Jack and Leon were able to put aside their differences and work together just fine during Return of the King despite initial antagonism, with the latter resulting in the both of them pointing out how they'd technically ended up undergoing a particularly big argument that needed to be broken up by Alice during that same mission. Another nod is also made to the use of the portal grenade in the previous mission after Drew draws out another one in preparation for use and it is recognized by Jack and Leon remembers having been told about the device secondhand.
- Divided into Disaster: Drew's decision to have Leon and Jack accompany him on the mission this time while leaving Alice and Adrian at the park ultimately proves very ill-fated. For without either of the two usual voices of reason around to reign in Jack and Leon, the latter two's Teeth-Clenched Teamwork reaches the point that they very nearly allow Drew to get killed or maimed by the dunkleosteus by being too distracted in their arguing.
- Drama Bomb: Through a mixture of the clashes between Leon and Jack, Drew's almost getting killed (or at the very least maimed) because of said clashes, and Leon and Jack's all too appropriate punishment at the very end of the episode, this episode proves easily one of the more dramatic ones.
- Dramatic Thunder: Flashes of thunder and lightning help to emphasize dramatic moments over the course of a storm that unfolds in the mission's climax.
- Fantastic Fauna Counterpart: The dunkleosteus are described by Leon at the very beginning of the episode as 'the great white of the Devonian seas', and they do display some relatively shark-like behavior. Similarly, the titanichthys are portrayed as giant filter feeders similar to modern basking sharks and baleen whales (with the comparisons to the former modern animal even lampshaded by an aquarist back at the park). Furthermore, despite engaging in at least one shark-like behavior immediately after a failed biting attempt, the onychodus also behave remarkably similar to moray eels. And just like back in South of Heaven, the dimetrodon are shown to behave in a lot of ways similar to alligators.
- Feathered Fiend: Despite Adrian's best efforts, the rescued teratornis pair so far still prove very difficult to work with.
- Fiendish Fish: The carnivorous fish encountered all prove very dangerous animals, with the dunkleosteus in particular very nearly killing or maiming Drew.
- Gentle Giant: The titanichthys are fairly easygoing animals over the course of the team's encounters with them.
- Jerkass Has a Point: Both Jack and Leon act incredibly rude and meanspirited to each other over the course of their clashes. However, as described in Both Sides Have a Point above, they also both bring up immensely valid points against each other in the process.
- Kick the Dog: Leon and Jack both verbally commit this against each other; with Jack downplaying Leon's efforts at rescuing Yolanda from the crassigyrinus in South of Heaven by virtue of Andrias playing a much bigger role in the two of them being able to successfully get out of the pit in time to avoid getting mauled and once again bringing up his supposed lack of skill or competence as well as his almost certainly having only been hired via cronyism on Drew's part while Leon calls him several mean names and implies that he considers Jack to be a reckless idiot with zero regard for personal safety.
- Laser-Guided Karma: Leon and Jack's Teeth-Clenched Teamwork ultimately comes back to bite them hard when one particularly ill timed squabble between them very nearly gets Drew killed or maimed by the dunkleosteus, resulting in him having them both suspended from active duty on the rescue team as punishment.
- Let's Get Dangerous!: When a powerful storm comes upon the Ancient Mariner, the usually laidback and carefree Captain Stavros shows off his more serious and authoritative side as he and Kira work to get the crew straight to work on ensuring that they keep the ship steady and afloat long enough for the rescue team to finish their mission so that they can then use the portal to safely return home.
- The Load: Leon's apparent status as this is once again given heavy focus in this episode, much to his displeasure.
- Mythology Gag: Multiple events in this chapter are based immensely heavily upon the events of Prehistoric Earth episode Life in Transition (while ironically sharing a name with a Prehistoric Earth episode that occurred even earlier in that story).
- Negated Moment of Awesome: Retroactively applied by Jack to Leon's assistance in rescuing Yolanda back in South of Heaven over the course of their final clash in this episode. For as Jack pretty heavily implies, as much as Leon managed to delay the crassigyrinus in their efforts at mauling Yolanda, he and Yolanda would still have both all too likely been doomed to get mauled to death and eaten by the temnospondyls if Adrian hadn't managed to release Andrias the proterogyinus into the crassigyrinus pool to scare them off long enough for a sufficient means of proper escape to subsequently be provided.
- Oh, Crap!:
- Jack and Leon subtly experience this at the episode's beginning when they properly realize that they've been assigned to directly work together alongside Drew without Alice (who'd previously proven a reliable mediator for them the last time they became at risk of letting their personal enmity get in the way of their work) around to rein them in.
- Drew undergoes one (albeit, more of an annoyed one than a horrified one) when he notices Jack missing his cue in the plan for rescue of the first encountered titanichthys.
- The entirety of the rescue team get an epic one much later; with Drew getting one when he ends up caught off guard, surrounded, and effectively trapped by a foursome of dunkleosteus and not immediately pulled back up to safety and Jack and Leon both getting one in unison when they realize that they've accidentally allowed Drew to find himself in such a dangerous situation as a result of their squabbling.
- Pay Evil unto Evil: For what little credit he deserves on as much, the majority of Leon's Jerkass moments against Jack were done in response to a similarly mean-spirited action the latter committed against him first.
- Punctuated! For! Emphasis!: As Leon states once Drew has managed to get him and Jack to settle down from a then recent scuffle and attempt to stay civil for at least long enough to finish the mission:Leon: As. You. Wish. Drew.
- "Reason You Suck" Speech: Leon and Jack both subject each other to this over the course of their squabbles, with Jack once again making it clear that he views Leon as just a useless walking textbook with no talent or natural skill beyond animal knowledge and operating a noise broadcasting device to back up his being hired to work at Prehistoric Park while also calling him out on being too much of a humorless stick in the mud and for seemingly only being hired at all due to cronyism on Drew's part and Leon calling Jack out on his constantly charging blindly into situations without thinking or planning in seemingly complete disregard for personal safety and seemingly always treating potentially dangerous and life threatening missions like they're just games to be played and enjoyed.
- Religious and Mythological Theme Naming: The 'dominant female' of the rescued dimetrodon is revealed to have been named Otrera, after the first queen of the Amazons in Greek mythology.
- Shipper on Deck: Kyle and Linda both prove themselves to be this for Otrera and Rommel the dimetrodon pair.
- Slippery as an Eel: The onychodus demonstrate some very eel-like hunting behaviors (and even look a lot like eels in physical appearance while also having a few other bodily features in common with sharks and coelacanths).
- Surprisingly Realistic Outcome: As demonstrated by how even the researchers are stumped at first as to why the dimetrodon are starting to behave more aggressively than they initially were, being the resident experts on a specific subject won't automatically guarantee that you'll know everything about said subject, especially not when the majority of one's knowledge is based upon years worth of speculation over fossilized remains instead of actual observations on the subject alive and in the flesh. Therefore, it takes a decent amount of time carefully observing the dimetrodon and carefully considering all possibilities available from the closest available modern day animals that could serve as a counterpart for comparison before the reason behind the dimetrodons' heightened aggression in this episode is finally discovered.
- Teeth-Clenched Teamwork: Much like in Life in Transition back in Prehistoric Earth, Jack and Leon's tensions and antagonism between each other reach boiling point in this mission. And also like in that episode of Prehistoric Earth, it ultimately comes back to bite them when a particularly ill timed moment of this very nearly results in Drew getting either killed or at the very least losing an arm.
- Threatening Shark: The true prehistoric shark species present (stethacanthus and gogoselachus) aren't portrayed as being too dangerous over the course of Drew's encounter with them (let alone the moment he rescues them). However, the dunkleosteus prove more than dangerous enough to fulfill the spirit of this trope (with the fact that they somewhat behave and get described similarly to great white sharks further strengthening the matter).
- Took a Level in Badass: Leon, in a roundabout way, once again proves himself to be accomplishing this over the course of his clashes with Jack. Unlike in some of his previous unpleasant interactions with Jack in this story (plus his clashes with Jack in Prehistoric Earth's equivalent of this chapter), in which he seemed largely heavily outmatched by Jack in several ways, he is able to actually hold his own against Jack much longer and even successfully use Jack's seeming reckless idiocy, inability to take things seriously, and tendency to seemingly use his insanely good luck as a crutch against him in the exact same way that Jack uses Leon's own seeming lack of natural skill or talent and overreliance on noise broadcasting devices against him.
- Ungrateful Bastard: Leon paints Jack out as this over the course of their final clash by pointing out how, in the three weeks that unfolded between this mission and South of Heaven, Jack never thanked him for helping to rescue Yolanda (who is just as much a friend of Jack's as she now is to Leon) from getting mauled and eaten by the crassigyrinus.
- Vile Vulture: Despite at least one or two months having passed since their rescue, Rocco and Laverne the teratornis still remain highly aggressive, which has left Adrian hired to try to train them into toning this aspect of their personalities down. So far, the emphasis is on try.
- What the Hell, Hero?: Jack and Leon both give each other one of these over the course of their clashes, with Jack calling Leon out for implying that he didn't meaningfully contribute to the rescue effort despite him having successfully rescued 1/3 of the haul that had been successfully rescued at that point all by himself without a chaperone while Leon calls Jack out for his seeming hypocrisy in criticizing him for relying too much on use of noise broadcasting devices in his work when Jack himself seemingly relies too much on his own insanely good luck as well as for his seemingly taking Yolanda (a close friend to the both of them at this point) for granted and never thanking him for his help in saving her from getting eaten by the crassigyrinus. And then they both fall victim to a savage one from Drew at the end of the episode when their final clash very nearly results in him getting killed (or at the very least getting an arm bitten off) by the dunkleosteus.
