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Description
Episode two, "Whale Killer", set around the ancient Tethys Sea 36 million years ago. "New Dawn" was rough to revisit. It could easily go toe-to-toe with any Walking with Dinosaurs episode in terms of radical liberties/outdated science. But as we edge closer to the present, by the Late Eocene (Priabonian), most of the major landmasses have more or less taken on their familiar, modern-day forms, meaning Tim and Jasper are running out of excuses for putting prehistoric animals on the wrong side of the globe. Another positive I failed to mention in my previous post is that although WWB had a smaller budget than WWD (4.2 million versus 6.1 million), WWB has fewer offenses when it comes to prop recycling, which is admirable. You might fool the average smuck by repainting an allosaur and calling it a megalosaur, but you can't repaint a Hyaenodon and call it a sabretooth. Not to say that there is no prop recycling in WWB and when it crops up, it's pretty damn noticeable and detrimental.

Fortunately, this is not the case with our second example in WWB, them reusing the "Hybodus" model (sans the horns) for a small Late Eocene shark (Physogaleus apparently). Like most fossil sharks, Physogaleus is only known from teeth and some vertebrae, so their guess is as good as any about its anatomy. This leads us to the introduction of our feature creature, the early, serpentine whale Basilosaurus, and its introduction is certainly a memorable one, probably one of the highlights of WWB. Small note, I love how the narrator cites that the K-Pg extinction wiped out not only the dinosaurs but also the "giant" marine reptiles that patrolled our oceans, since at up to 18-20 meters , Basilosaurus was far larger than any sea predator that has existed since the end of the Triassic (though not in WW land ).

Unfortunately, despite the overall good plot, the episode's portrayal of Basilosaurus is its biggest shortcoming, and like with half of the cast in "New Dawn", this issue makes the main plot of this episode null and void, though at least here, detrimental issues are largely limited to the main character. Granted, there are other issues, the biggest one perhaps being the fact that this episode and the next one ("Land of Giants") focus heavily on Asian mammals from the upper Paleogene, but extensive research in the 2000s (some going as far back as the 90s) pushed back the geological ages of many fossil formations from the Eocene-Oligocene of Central Asia by about 5 million years, domino-style. This will be an issue for one bigheaded hoofed carnivore (though not the only one), but a similar issue concerns our little Egyptian predecessor Apidium. But I'm getting ahead of myself. The biggest issue with this episode is the main character.

A) Although it received a lot of recognition due to its appearance in WWB, and despite its great size and status as our ocean's largest killer during the Bartonian-Priabonian, Basilosaurus is rarely cited as one of the great marine predators of Earth's past, unlike pliosaurs, mosasaurs, megalodon, and the more recently described Livyatan. There's a reason for that, as its overall anatomy suggests that Basilosaurus wasn't anything close to the agile orca-like predator shown in this episode, quite the opposite. Basilosaurus was something of a work-in-progress in whale evolution, as its bones were hollow and likely filled with fluid (unlike the solid bones of modern whales), which made the animal more buoyant, the vertebrae at the tip of the tail suggest that it had small tail flukes, limiting its mobility when coupled with its insanely long body , and its general anatomy (including weak muscle attachments along the spine) paint it as a two-dimensional swimmer that was ill-suited for deep diving or long pursuit, quite restricted in terms of movement when compared to Dorudon, which is thought to have been an agile, diving, three-dimensional swimmer. This all points towards Basilosaurus being an ambush predator that hunted near the surface or in shallow waters, possibly even mangroves, the exact opposite of what's shown in the episode, maybe using its snake-like body to navigate through the channels.

It was widely distributed though, with fossils found across the globe (though some of those have since been reassigned to other basilosaurids) and we do have evidence of bite marks on Dorudon bones attributed to Basilosaurus, showing that it did indeed regularly hunt its smaller relatives, so it must have been doing SOMETHING right, albeit not in the fashion shown in "Whale Killer". And this is as good a place as any to mention...maybe not an issue but a discrepancy I noticed between WWB and WWD. While the former certainly isn't averse to showing nature's brutality as well (especially towards babies like the Gastornis chick and Smilodon cubs) it's not as raw and unrestrained as its predecessor, with all of the protagonist creatures getting a happy ending despite the odds. It works in some episodes like "Land of Giants", but it's especially egregious here and in "Sabretooth", more so here, since the entire premise of this episode is how severe climate change is affecting the world and the main Basilosaurus (who is pregnant by the way) struggling to adjust to it. If WWB wasn't holding back any punches, the main Basilosaurus would have certainly died at the end, the odds were just stacked too much against her. It would have been a tragic end but a fitting one for an episode all about change and animals struggling to keep up with it. In a lot of ways, "Whale Killer" is WWB's answer to "Death of a Dynasty", a story about how top-of-the-line predators are just as vulnerable as any other animal (minus the embellished extinction event) but cops out at the end.

B) Andrewsarchus is an obvious one, and it's quite unfortunate that 22 years later, we still don't have any more fossil material of it than we had in 2001 (other than possibly having its lower jaw with Paratriisodon). Here it's credited as the largest mammalian land predator, another example of WW endorsing an outdated mentality, i.e. that evolution has goals of some kind like creating record-holders. In reality, much like how there probably was no definitive largest sauropod or largest theropod, the same is true for the title of largest carnivorous land mammal. With an 83.5-cm skull, Andrewsarchus was likely pushing the size limit, but it would have been in the same league (if not outclassed) by giant entelodonts and short-faced bears (who also have far more complete material). Here, it's shown as a mesonychid, a group of hoofed carnivores distantly related to even-toed ungulates and who have traditionally been thought to be the ancestors of whales (as endorsed in the behind-the-scenes special) until it was discovered that whales were proper artiodactyls and most closely related to hippos. With that in mind, the brontothere segment being set in Pakistan was likely a nod to this place being a goldmine of early whale fossils (like Ambulocetus and Pakicetus).

The notion that Andrewsarchus mongoliensis was a giant mesonychid is linked to its purported status as the largest mammalian land predator, as its describer, Henry Fairfield Osborn, thought it was a mesonychid and used the smaller but more complete Mesonyx (found at Bridger) to calculate the size of Andrewsarchus by just scaling up Mesonyx, leading to the idea that Andrewsarchus was a 1-ton, 6-meter-long monster of a mammal, but not long after WWB aired, new phylogenetic studies recovered the enigmatic mammal as a cetancodontamorph, the same group that includes whales, hippos, and entelodonts, the latter potentially being the closet relatives of Andrewsarchus. Since early cetancodontamorph across the board have severe "bobblehead syndrome" (like early whales and entelodonts), the immense size attributed to Andrewsarchus is likely exaggerated, though it would still have been a very large animal, with its skull only around 6.5 cm shorter than that of the largest entelodonts like Dinohyus, which grew as big as bison.

The one skull we have of the animal comes from the Irdin Manha Formation , with the purported additional material coming from the similar-aged Luishi Formation, and although Irdin Manha was previously suggested to be Priabonian in age, the aforementioned pushback of land mammal ages in upper Paleogene Central Asia means it more likely represents the late Lutetian-early Bartonian (45-40 mya), which makes more sense, as the overall fauna of Irdin Manha isn't consistent with other sites in Central Asia known to represent the Priabonian (Houldjin Gravels, Ulan Gochu, Ergilin Dzo), housing many animals that are instead more indicative of a Mid Eocene date (some of the last mesonychids, oxyaenids, and uintatheriids, together with midsized brontotheres and tiny paraceratheres) and actually represents a transitional phase between the typical Holarctic wildlife from the Ypresian-Lutetian and the Priabonian-Rupelian (giant brontotheres, entelodonts, large hyaenodonts, nimravids, etc.). You can see how WWB was made during this transitional period regarding the aforementioned land mammal ages, as it puts Andrewsarchus together with Embolotherium, whose fossils are known from sites like Ulan Gochu and Ergilin Dzo, which have previously been interpreted as Rupeltian (Early Oligocene) in age, while Andrewsarchus coexisted with the smaller but still pretty big (1.5 ton) brontothere Rhinotitan .

Basilosaurus and Andrewsarchus are the two creatures who really show their age, and in the case of the former, it's quite detrimental to the story. The other animals hold up suprisingly well, though there are caveats and smaller issues. Apidium is another example of anachronism, as its fossil are known from the upper Jebel Qatrani Formation of Egypt (with fossils of the younger Apidium phiomense being especially common), and although it was thought to represent the Priabonian at the time, in 2006, the upper strata was reevaluated as Rupelian in age, making Apidium a contemporary of early Paraceratherium rather than Basilosaurus and Embolotherium, the same applying to many fossils of Arsinoitherium found there. Though the lower Jebel Qatrani still seems to represent the Priabonian, so other local simians like Catopithecus (the best preserved of the lower strata taxa) could easily replace it, and the lower strata also has fossils of Arsinoitherium. Fellow parapithecid Biretia comes from the even older Birket Qarun Formation (which underlies Qasr el Sagha). And although parapithecids are very basal simians, I think WWB still made them too overtly monkey-like. Still, their general portrayal is neat, seemingly based on the behavior of the proboscis monkey (one of the few extant simians to live in similar habitats).

The other three animals do come from the Priabonian; Moeritherium (known primarily from Qasr el Sagha, which overlies Jebel Qatrani, which also has some fossils of it) and Dorudon (another cosmopolitan basilosaurid), as well as Embolotherium, which is mainly known from a dozen or so skulls (up to 95 cm long), along with jaw material and sparse postcrania collected from Inner and Outer Mongolia, meaning we don't know much about its postcranial anatomy and have to largely rely on the similar-sized and contemporary Megacerops from North America as a guide. There are some potential issues with facial reconstructions, as some have argued that Moeritherium lacked a trunk altogether (though deducing the presence of trunks on any non-elephantiform mammals has proven tricky), making it look more like a hippo-hyrax (hyraxes are one of the proboscideans closest relatives after sirenians), and a recent theory suggests the ram of Embolotherium might have been encased in flesh and served as a resonator to produce vocalizations , but that's up for debate. Oh, and it's not properly credited by its genus name and is instead just called a "brontothere", because the latter sounds cooler. I don't agree with that practice (sensationalist slant).

Oh, and the narrator makes a rather odd comment about Moeritherium, claiming that at 200 kg, it's "too big" to be taken by any of the local sharks or crocodiles, and thus the mangroves are very safe for them unless a Basilosaurus shows up. Even as a kid, I found that strange, since a good-sized crocodile or shark could certainly take out a tapir-sized mammal, some of the largest sharks at the time, like Otodus auriculatus (with an estimated length of 9.5 meters), and even the 5-meter Dorudon, would be more than a threat to it. And then there's the massive madtsoiid snake Gigantophis garstini, which coexisted with Moeritherium at Qasr el Sagha Formation. Clearly there were plenty of predators that could and would have threatened it.

While not to the extent of "New Dawn", "Whale Killer" is still the second most problematic episode in WWB, mainly due to the portrayal of the titular beast and Andrewsarchus. The latter's role in the episode isn't unfixable due to its reclassification, as the more modern entelodont redux or hippo-wolf could still fit the opportunistic carnivore role, and it would be a very cool creature to include, but the real problem is the anachronism. It's currently placed (by default) in its own family (Andrewsarchidae) which obviously lacks any other members, and while one could use a hypothetical younger andrewsarchid (as the age gap isn't that great), it's worth noting that by the Priabonian, the old guard Holarctic predators, the mesonychids and oxyaenids, were almost entirely gone, replaced by large hyaenodonts, entelodonts, and nimravids, as confirmed by sites like Ergilin Dzo, which is where we first found fossils of Hyaenodon gigas, together with specimens attributed to Entelodon, and both were sympatric with Embolotherium (more on this in "Land of Giants), showing a clear shift in the predator guild of Asia.

Though obviously, the biggest issue is Basilosaurus itself, as the main one's story is essentially the reverse of what current evidence suggests the animal lived like. That said, four out of the six mammals are still in the right time period, and Apidium is easily replaceable, so this episode's setup is salvageable but it still would require a heavy rewrite in regards to the Basilosaurus's story (this might be a me thing, but I would have it end like "Giant of the Skies"... plus abortion). Since Basilosaurus would undoubtedly lose a lot of its badass credentials in this rewrite, perhaps the title should change ("Rise of Whales" or something) and the focus could be split between it and its smaller cousin Dorudon, maybe by contrasting the two and showing off their respective strengths and weaknesses. Moeritherium and Catopithecus pretty much fill the same roles as their original counterparts, though I'm split about the brontothere segment.

For the sake of "Land of Giants", I wouldn't use any of the more common predators from the Priabonian of Asia, and given that the theme of this episode is "extinction", the inclusion of Embolotherium makes sense thematically, as it was one of the last brontotheres (one of the most prolific victims of the Eocene-Oligocene transition), and so would the inclusion of Mongolestes, which coexisted with Embolotherium at Ulan Gochu, and is the only known Late Eocene mesonychid. You could also repurpose the Coryphodon from my previous rewrite and throw in its rhino-sized descendent Hypercoryphodon, the last pantodont (known from Houldjin). On the other hand, perhaps two mesonychids in a row would be too repetitive, so alternatively, the brontothere segment could be set in North America with Megacerops (Brontotherium) and the stocky, oxyaenid-like hyaenodont Hemipsalodon grandis (who is sufficiently different from Hyaenodon). Basilosaurus and Dorudon are also known from North America, so they could be shown crossing the Atlantic, or rather just the Dorudon and different populations of Basilosaurus being present on both sides.

Okay, the first two episodes were the hardest but it should be smoother sailing with the last four episodes, though they still have issues...

Description
Episode two, "Whale Killer", set around the ancient Tethys Sea 36 million years ago. "New Dawn" was rough to revisit. It could easily go toe-to-toe with any Walking with Dinosaurs episode in terms of radical liberties/outdated science. But as we edge closer to the present, by the Late Eocene (Priabonian), most of the major landmasses have more or less taken on their familiar, modern-day forms, meaning Tim and Jasper are running out of excuses for putting prehistoric animals on the wrong side of the globe. Another positive I failed to mention in my previous post is that although WWB had a smaller budget than WWD (4.2 million versus 6.1 million), WWB has fewer offenses when it comes to prop recycling, which is admirable. You might fool the average smuck by repainting an allosaur and calling it a megalosaur, but you can't repaint a Hyaenodon and call it a sabretooth. Not to say that there is no prop recycling in WWB and when it crops up, it's pretty damn noticeable and detrimental.

Fortunately, this is not the case with our second example in WWB, them reusing the "Hybodus" model (sans the horns) for a small Late Eocene shark (Physogaleus apparently). Like most fossil sharks, Physogaleus is only known from teeth and some vertebrae, so their guess is as good as any about its anatomy. This leads us to the introduction of our feature creature, the early, serpentine whale Basilosaurus, and its introduction is certainly a memorable one, probably one of the highlights of WWB. Small note, I love how the narrator cites that the K-Pg extinction wiped out not only the dinosaurs but also the "giant" marine reptiles that patrolled our oceans, since at up to 18-20 meters , Basilosaurus was far larger than any sea predator that has existed since the end of the Triassic (though not in WW land ).

Unfortunately, despite the overall good plot, the episode's portrayal of Basilosaurus is its biggest shortcoming, and like with half of the cast in "New Dawn", this issue makes the main plot of this episode null and void, though at least here, detrimental issues are largely limited to the main character. Granted, there are other issues, the biggest one perhaps being the fact that this episode and the next one ("Land of Giants") focus heavily on Asian mammals from the upper Paleogene, but extensive research in the 2000s (some going as far back as the 90s) pushed back the geological ages of many fossil formations from the Eocene-Oligocene of Central Asia by about 5 million years, domino-style. This will be an issue for one bigheaded hoofed carnivore (though not the only one), but a similar issue concerns our little Egyptian predecessor Apidium. But I'm getting ahead of myself. The biggest issue with this episode is the main character.

A) Although it received a lot of recognition due to its appearance in WWB, and despite its great size and status as our ocean's largest killer during the Bartonian-Priabonian, Basilosaurus is rarely cited as one of the great marine predators of Earth's past, unlike pliosaurs, mosasaurs, megalodon, and the more recently described Livyatan. There's a reason for that, as its overall anatomy suggests that Basilosaurus wasn't anything close to the agile orca-like predator shown in this episode, quite the opposite. Basilosaurus was something of a work-in-progress in whale evolution, as its bones were hollow and likely filled with fluid (unlike the solid bones of modern whales), which made the animal more buoyant, the vertebrae at the tip of the tail suggest that it had small tail flukes, limiting its mobility when coupled with its insanely long body , and its general anatomy (including weak muscle attachments along the spine) paint it as a two-dimensional swimmer that was ill-suited for deep diving or long pursuit, quite restricted in terms of movement when compared to Dorudon, which is thought to have been an agile, diving, three-dimensional swimmer. This all points towards Basilosaurus being an ambush predator that hunted near the surface or in shallow waters, possibly even mangroves, the exact opposite of what's shown in the episode, maybe using its snake-like body to navigate through the channels.

It was widely distributed though, with fossils found across the globe (though some of those have since been reassigned to other basilosaurids) and we do have evidence of bite marks on Dorudon bones attributed to Basilosaurus, showing that it did indeed regularly hunt its smaller relatives, so it must have been doing SOMETHING right, albeit not in the fashion shown in "Whale Killer". And this is as good a place as any to mention...maybe not an issue but a discrepancy I noticed between WWB and WWD. While the former certainly isn't averse to showing nature's brutality as well (especially towards babies like the Gastornis chick and Smilodon cubs) it's not as raw and unrestrained as its predecessor, with all of the protagonist creatures getting a happy ending despite the odds. It works in some episodes like "Land of Giants", but it's especially egregious here and in "Sabretooth", more so here, since the entire premise of this episode is how severe climate change is affecting the world and the main Basilosaurus (who is pregnant by the way) struggling to adjust to it. If WWB wasn't holding back any punches, the main Basilosaurus would have certainly died at the end, the odds were just stacked too much against her. It would have been a tragic end but a fitting one for an episode all about change and animals struggling to keep up with it. In a lot of ways, "Whale Killer" is WWB's answer to "Death of a Dynasty", a story about how top-of-the-line predators are just as vulnerable as any other animal (minus the embellished extinction event) but cops out at the end.

B) Andrewsarchus is an obvious one, and it's quite unfortunate that 22 years later, we still don't have any more fossil material of it than we had in 2001 (other than possibly having its lower jaw with Paratriisodon). Here it's credited as the largest mammalian land predator, another example of WW endorsing an outdated mentality, i.e. that evolution has goals of some kind like creating record-holders. In reality, much like how there probably was no definitive largest sauropod or largest theropod, the same is true for the title of largest carnivorous land mammal. With an 83.5-cm skull, Andrewsarchus was likely pushing the size limit, but it would have been in the same league (if not outclassed) by giant entelodonts and short-faced bears (who also have far more complete material). Here, it's shown as a mesonychid, a group of hoofed carnivores distantly related to even-toed ungulates and who have traditionally been thought to be the ancestors of whales (as endorsed in the behind-the-scenes special) until it was discovered that whales were proper artiodactyls and most closely related to hippos. With that in mind, the brontothere segment being set in Pakistan was likely a nod to this place being a goldmine of early whale fossils (like Ambulocetus and Pakicetus).

The notion that Andrewsarchus mongoliensis was a giant mesonychid is linked to its purported status as the largest mammalian land predator, as its describer, Henry Fairfield Osborn, thought it was a mesonychid and used the smaller but more complete Mesonyx (found at Bridger) to calculate the size of Andrewsarchus by just scaling up Mesonyx, leading to the idea that Andrewsarchus was a 1-ton, 6-meter-long monster of a mammal, but not long after WWB aired, new phylogenetic studies recovered the enigmatic mammal as a cetancodontamorph, the same group that includes whales, hippos, and entelodonts, the latter potentially being the closet relatives of Andrewsarchus. Since early cetancodontamorph across the board have severe "bobblehead syndrome" (like early whales and entelodonts), the immense size attributed to Andrewsarchus is likely exaggerated, though it would still have been a very large animal, with its skull only around 6.5 cm shorter than that of the largest entelodonts like Dinohyus, which grew as big as bison.

The one skull we have of the animal comes from the Irdin Manha Formation , with the purported additional material coming from the similar-aged Luishi Formation, and although Irdin Manha was previously suggested to be Priabonian in age, the aforementioned pushback of land mammal ages in upper Paleogene Central Asia means it more likely represents the late Lutetian-early Bartonian (45-40 mya), which makes more sense, as the overall fauna of Irdin Manha isn't consistent with other sites in Central Asia known to represent the Priabonian (Houldjin Gravels, Ulan Gochu, Ergilin Dzo), housing many animals that are instead more indicative of a Mid Eocene date (some of the last mesonychids, oxyaenids, and uintatheriids, together with midsized brontotheres and tiny paraceratheres) and actually represents a transitional phase between the typical Holarctic wildlife from the Ypresian-Lutetian and the Priabonian-Rupelian (giant brontotheres, entelodonts, large hyaenodonts, nimravids, etc.). You can see how WWB was made during this transitional period regarding the aforementioned land mammal ages, as it puts Andrewsarchus together with Embolotherium, whose fossils are known from sites like Ulan Gochu and Ergilin Dzo, which have previously been interpreted as Rupeltian (Early Oligocene) in age, while Andrewsarchus coexisted with the smaller but still pretty big (1.5 ton) brontothere Rhinotitan .

Basilosaurus and Andrewsarchus are the two creatures who really show their age, and in the case of the former, it's quite detrimental to the story. The other animals hold up suprisingly well, though there are caveats and smaller issues. Apidium is another example of anachronism, as its fossil are known from the upper Jebel Qatrani Formation of Egypt (with fossils of the younger Apidium phiomense being especially common), and although it was thought to represent the Priabonian at the time, in 2006, the upper strata was reevaluated as Rupelian in age, making Apidium a contemporary of early Paraceratherium rather than Basilosaurus and Embolotherium, the same applying to many fossils of Arsinoitherium found there. Though the lower Jebel Qatrani still seems to represent the Priabonian, so other local simians like Catopithecus (the best preserved of the lower strata taxa) could easily replace it, and the lower strata also has fossils of Arsinoitherium. Fellow parapithecid Biretia comes from the even older Birket Qarun Formation (which underlies Qasr el Sagha). And although parapithecids are very basal simians, I think WWB still made them too overtly monkey-like. Still, their general portrayal is neat, seemingly based on the behavior of the proboscis monkey (one of the few extant simians to live in similar habitats).

The other three animals do come from the Priabonian; Moeritherium (known primarily from Qasr el Sagha, which overlies Jebel Qatrani, which also has some fossils of it) and Dorudon (another cosmopolitan basilosaurid), as well as Embolotherium, which is mainly known from a dozen or so skulls (up to 95 cm long), along with jaw material and sparse postcrania collected from Inner and Outer Mongolia, meaning we don't know much about its postcranial anatomy and have to largely rely on the similar-sized and contemporary Megacerops from North America as a guide. There are some potential issues with facial reconstructions, as some have argued that Moeritherium lacked a trunk altogether (though deducing the presence of trunks on any non-elephantiform mammals has proven tricky), making it look more like a hippo-hyrax (hyraxes are one of the proboscideans closest relatives after sirenians), and a recent theory suggests the ram of Embolotherium might have been encased in flesh and served as a resonator to produce vocalizations , but that's up for debate. Oh, and it's not properly credited by its genus name and is instead just called a "brontothere", because the latter sounds cooler. I don't agree with that practice (sensationalist slant).

Oh, and the narrator makes a rather odd comment about Moeritherium, claiming that at 200 kg, it's "too big" to be taken by any of the local sharks or crocodiles, and thus the mangroves are very safe for them unless a Basilosaurus shows up. Even as a kid, I found that strange, since a good-sized crocodile or shark could certainly take out a tapir-sized mammal, some of the largest sharks at the time, like Otodus auriculatus (with an estimated length of 9.5 meters), and even the 5-meter Dorudon, would be more than a threat to it. And then there's the massive madtsoiid snake Gigantophis garstini, which coexisted with Moeritherium at Qasr el Sagha Formation. Clearly there were plenty of predators that could and would have threatened it.

While not to the extent of "New Dawn", "Whale Killer" is still the second most problematic episode in WWB, mainly due to the portrayal of the titular beast and Andrewsarchus. The latter's role in the episode isn't unfixable due to its reclassification, as the more modern entelodont redux or hippo-wolf could still fit the opportunistic carnivore role, and it would be a very cool creature to include, but the real problem is the anachronism. It's currently placed (by default) in its own family (Andrewsarchidae) which obviously lacks any other members, and while one could use a hypothetical younger andrewsarchid (as the age gap isn't that great), it's worth noting that by the Priabonian, the old guard Holarctic predators, the mesonychids and oxyaenids, were almost entirely gone, replaced by large hyaenodonts, entelodonts, and nimravids, as confirmed by sites like Ergilin Dzo, which is where we first found fossils of Hyaenodon gigas, together with specimens attributed to Entelodon, and both were sympatric with Embolotherium (more on this in "Land of Giants), showing a clear shift in the predator guild of Asia.

Though obviously, the biggest issue is Basilosaurus itself, as the main one's story is essentially the reverse of what current evidence suggests the animal lived like. That said, four out of the six mammals are still in the right time period, and Apidium is easily replaceable, so this episode's setup is salvageable but it still would require a heavy rewrite in regards to the Basilosaurus's story (this might be a me thing, but I would have it end like "Giant of the Skies"... plus abortion). Since Basilosaurus would undoubtedly lose a lot of its badass credentials in this rewrite, perhaps the title should change ("Rise of Whales" or something) and the focus could be split between it and its smaller cousin Dorudon, maybe by contrasting the two and showing off their respective strengths and weaknesses. Moeritherium and Catopithecus pretty much fill the same roles as their original counterparts, though I'm split about the brontothere segment.

For the sake of "Land of Giants", I wouldn't use any of the more common predators from the Priabonian of Asia, and given that the theme of this episode is "extinction", the inclusion of Embolotherium makes sense thematically, as it was one of the last brontotheres (one of the most prolific victims of the Eocene-Oligocene transition), and so would the inclusion of Mongolestes, which coexisted with Embolotherium at Ulan Gochu, and is the only known Late Eocene mesonychid. You could also repurpose the Coryphodon from my previous rewrite and throw in its rhino-sized descendent Hypercoryphodon, the last pantodont (known from Houldjin). On the other hand, perhaps two mesonychids in a row would be too repetitive, so alternatively, the brontothere segment could be set in North America with Megacerops (Brontotherium) and the stocky, oxyaenid-like hyaenodont Hemipsalodon grandis (who is sufficiently different from Hyaenodon). Basilosaurus and Dorudon are also known from North America, so they could be shown crossing the Atlantic, or rather just the Dorudon and different populations of Basilosaurus being present on both sides.

Okay, the first two episodes were the hardest but it should be smoother sailing with the last four episodes, though they still have issues...