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Description
The next two-parter of my own WWM series, showing the evolution and diversity of the first tetrapods. Both settings are swamps or rivers, so you can obviously see that I had no other choice for Dunkleosteus but to put it into the marine setting at the Gogo reef. Also, these are the last settings to primarily focus on aquatic animals. As vertebrates conquer the land, we no longer have any marine settings (sorry to disappoint anyone who was looking forward for eugeneodontids).

Late Devonian Canada, 375 million years ago (Fram Formation). Probably the most important Devonian discovery of this century is the "fishapod" Tiktaalik, being a perfect example for the kind of transitionary animal one would expect to see "sitting between" tetrapodomorphs like Gogonasus and the first true tetrapods. Unfortunately, there is barely any information about the formation where it was discovered, so like the Gogo Formation this setting has a couple of "foreigners". As a Frasnian setting, this part of the episode would end with the Kellwasser Event, which triggers the Devonian mass extinction.
Tiktaalik roseae: A 1.8 meter long benthic predator which unlike any of its vertebrate contemporaries has a movable neck and wrists. These features allow it to crawl out of the water to escape from other river predators or to travel briefly across the land in case its body of water dried up. Pose based on this skeletal illustration: www.earthhistory.org.uk/wp-con…
Laccognathus embryi: Measuring 1.8 meters, this benthic predator is Tiktaalik´s biggest rival. Both are ambush predators that spend a lot of time hiding at the bottom of the river bed, though Tiktaalik´s ability to expand its lifestyle onto the land gives it an obvious edge. Oddly enough, there seems to be the theory that Laccognathus was able to travel between bodies of water, too, so they may have been even more bitter rivals than you thought (of course, Tiktaalik with its more advanced features would eventually win this evolutionary race) . Pose based on ´s reconstruction: biarmosuchus.deviantart.com/ar…
Eusthenodon wängsjöi: There are so many nasty sarcopterygians, i wanted to feature one genus that probably nobody of you ever heard of, Eusthenodon. It is 2.5 meters long and known from Russia, Belgium and Greenland, the latter seeming close enough to Canada. Skull based on a skull reconstruction of Eusthenodon on Wikipedia, the body is based on Eusthenopteron.
Bothriolepis canadensis: While the genus itself doesn´t seem to be known from the Fram Formation, there are dozens of Bothriolepis species known from around the world (hell, even from the Gogo reef), so there´s no reason why these 30 centimeter long placoderms couldn´t show up in the rivers prowled by Tiktaalik, too. While it´s not as spectacular as the arthrodires of the last episode and literally resides at the bottom of the food chain, this armored fish is still successful enough to be noteworthy.
Stylonurus powriensis: I´m pretty sure there aren´t any eurypterids known from the Fram Formation, but I wanted to showcase that eurypterids did not immediately all disappear after the Silurian, so to expand the diversity of eurypterids beyond BBC´s Megalograptus and Pterygotus, here is Stylonurus. I would have already showcased this 1.5 meter long eurypterid in the Gogo reef setting if it wasn´t for all those noteworthy fish. Because this eurypterid has long walking legs instead of paddles, it can also leave the water to crawl around on land, where it is safe from all fish except Tiktaalik (though they wouldn´t try to attack a fully grown Stylonurus).

Early Carboniferous Scotland, 335 million years ago (East Kirkton Quarry). I didn´t want to have three Devonian settings that each jumped 5 million years ahead, so the first setting to feature actual tetrapods is already somewhere in the Carboniferous (the early Carboniferous also sems to suffer the same curse of obscureness as the Early Jurassic). This is another setting with a very hodgepodge cast. While the formation really exists, I shunted several actual residents of that formation to instead feature a bunch of personal favourites.
Balanerpeton woodi: After the Late Devonian "fishapod" Tiktaalik, we finally encounter an early proper tetrapod, and boy is it a generic one. This 50 centimeter long amphibian is the earliest and most common tetrapod in the East Kirkton Quarry assemblage, and that´s pretty much all there is to this one. There´s even a possible amniote known from this formation, Westlothiania, but because I didn´t want to jump from "fishapod" directly to "terrestrial reptile", I made this amphibian the focus of this episode.
Crassigyrinus scoticus: This 2 meter long predator is remarkable in being a derived tetrapod that has evolved back into an aquatic animal comparatively shortly after tetrapods managed to step out of the ater at all. While being a scary ambush predator, it still does not sit at the top of the food chain in this river... Skull based on this illustration: www.theclacks.org.uk/jac/crass…
Rhizodus hibberti: The one and only king of sarcopterygians. Measuring 7 meters in length, this apex predator is one the largest freshwater fish ever known. Rhizodontids are known for their huge tusks, but they also have very powerful supporting pectoral fins, so this guy will be able to crawl out of the water like some kind of crocodile. I wanted to give it a darker and more muted colour scheme as Deviantart´s Rhizodus gallery currently has a very high percentage of my yellow and green Rhizodus pattern (I even reused it for the Eusthenodon up there). Skull based on this illustration of a smaller relative: img.blog.163.com/photo/qRjYDup…
Hibbertopterus scouleri: Another animal known from the Carboniferous and known from Scotland, but not this very formation. There is actually a large "proper" terrestrial scorpion known from the East Kirkton Quarry, but I wanted to give this eurypterid some much-needed publicity. At 1.6 meters long it would be as long as my Pterygotus, but much heavier, and would be the final eurypterid to be featured in this documentary. Even though the eurypterids survived till the Permian, this really seems like the last species "interesting enough". There is actually a 1 meter wide trackway known from Scotland showing that despite its size this eurypterid definitely was able to crawl around on land, very slowly. Even underwater this thing must have been pretty slow, so its main food course are small aquatic organisms and carrion. Pose based on the reconstruction by Martin Whyte.
Stethacanthus altonensis: The obligatory early shark to show that early sharks were pretty low on the food chain of their time (this one measures just 70 centimeters). Stethacanthus is known from the Late Devonian till the Early Carboniferous, so this is another animal I technically could have included in the Devonian episode already. Pose based on Dmitry Bogdanov´s reconstruction.

Description
The next two-parter of my own WWM series, showing the evolution and diversity of the first tetrapods. Both settings are swamps or rivers, so you can obviously see that I had no other choice for Dunkleosteus but to put it into the marine setting at the Gogo reef. Also, these are the last settings to primarily focus on aquatic animals. As vertebrates conquer the land, we no longer have any marine settings (sorry to disappoint anyone who was looking forward for eugeneodontids).

Late Devonian Canada, 375 million years ago (Fram Formation). Probably the most important Devonian discovery of this century is the "fishapod" Tiktaalik, being a perfect example for the kind of transitionary animal one would expect to see "sitting between" tetrapodomorphs like Gogonasus and the first true tetrapods. Unfortunately, there is barely any information about the formation where it was discovered, so like the Gogo Formation this setting has a couple of "foreigners". As a Frasnian setting, this part of the episode would end with the Kellwasser Event, which triggers the Devonian mass extinction.
Tiktaalik roseae: A 1.8 meter long benthic predator which unlike any of its vertebrate contemporaries has a movable neck and wrists. These features allow it to crawl out of the water to escape from other river predators or to travel briefly across the land in case its body of water dried up. Pose based on this skeletal illustration: www.earthhistory.org.uk/wp-con…
Laccognathus embryi: Measuring 1.8 meters, this benthic predator is Tiktaalik´s biggest rival. Both are ambush predators that spend a lot of time hiding at the bottom of the river bed, though Tiktaalik´s ability to expand its lifestyle onto the land gives it an obvious edge. Oddly enough, there seems to be the theory that Laccognathus was able to travel between bodies of water, too, so they may have been even more bitter rivals than you thought (of course, Tiktaalik with its more advanced features would eventually win this evolutionary race) . Pose based on ´s reconstruction: biarmosuchus.deviantart.com/ar…
Eusthenodon wängsjöi: There are so many nasty sarcopterygians, i wanted to feature one genus that probably nobody of you ever heard of, Eusthenodon. It is 2.5 meters long and known from Russia, Belgium and Greenland, the latter seeming close enough to Canada. Skull based on a skull reconstruction of Eusthenodon on Wikipedia, the body is based on Eusthenopteron.
Bothriolepis canadensis: While the genus itself doesn´t seem to be known from the Fram Formation, there are dozens of Bothriolepis species known from around the world (hell, even from the Gogo reef), so there´s no reason why these 30 centimeter long placoderms couldn´t show up in the rivers prowled by Tiktaalik, too. While it´s not as spectacular as the arthrodires of the last episode and literally resides at the bottom of the food chain, this armored fish is still successful enough to be noteworthy.
Stylonurus powriensis: I´m pretty sure there aren´t any eurypterids known from the Fram Formation, but I wanted to showcase that eurypterids did not immediately all disappear after the Silurian, so to expand the diversity of eurypterids beyond BBC´s Megalograptus and Pterygotus, here is Stylonurus. I would have already showcased this 1.5 meter long eurypterid in the Gogo reef setting if it wasn´t for all those noteworthy fish. Because this eurypterid has long walking legs instead of paddles, it can also leave the water to crawl around on land, where it is safe from all fish except Tiktaalik (though they wouldn´t try to attack a fully grown Stylonurus).

Early Carboniferous Scotland, 335 million years ago (East Kirkton Quarry). I didn´t want to have three Devonian settings that each jumped 5 million years ahead, so the first setting to feature actual tetrapods is already somewhere in the Carboniferous (the early Carboniferous also sems to suffer the same curse of obscureness as the Early Jurassic). This is another setting with a very hodgepodge cast. While the formation really exists, I shunted several actual residents of that formation to instead feature a bunch of personal favourites.
Balanerpeton woodi: After the Late Devonian "fishapod" Tiktaalik, we finally encounter an early proper tetrapod, and boy is it a generic one. This 50 centimeter long amphibian is the earliest and most common tetrapod in the East Kirkton Quarry assemblage, and that´s pretty much all there is to this one. There´s even a possible amniote known from this formation, Westlothiania, but because I didn´t want to jump from "fishapod" directly to "terrestrial reptile", I made this amphibian the focus of this episode.
Crassigyrinus scoticus: This 2 meter long predator is remarkable in being a derived tetrapod that has evolved back into an aquatic animal comparatively shortly after tetrapods managed to step out of the ater at all. While being a scary ambush predator, it still does not sit at the top of the food chain in this river... Skull based on this illustration: www.theclacks.org.uk/jac/crass…
Rhizodus hibberti: The one and only king of sarcopterygians. Measuring 7 meters in length, this apex predator is one the largest freshwater fish ever known. Rhizodontids are known for their huge tusks, but they also have very powerful supporting pectoral fins, so this guy will be able to crawl out of the water like some kind of crocodile. I wanted to give it a darker and more muted colour scheme as Deviantart´s Rhizodus gallery currently has a very high percentage of my yellow and green Rhizodus pattern (I even reused it for the Eusthenodon up there). Skull based on this illustration of a smaller relative: img.blog.163.com/photo/qRjYDup…
Hibbertopterus scouleri: Another animal known from the Carboniferous and known from Scotland, but not this very formation. There is actually a large "proper" terrestrial scorpion known from the East Kirkton Quarry, but I wanted to give this eurypterid some much-needed publicity. At 1.6 meters long it would be as long as my Pterygotus, but much heavier, and would be the final eurypterid to be featured in this documentary. Even though the eurypterids survived till the Permian, this really seems like the last species "interesting enough". There is actually a 1 meter wide trackway known from Scotland showing that despite its size this eurypterid definitely was able to crawl around on land, very slowly. Even underwater this thing must have been pretty slow, so its main food course are small aquatic organisms and carrion. Pose based on the reconstruction by Martin Whyte.
Stethacanthus altonensis: The obligatory early shark to show that early sharks were pretty low on the food chain of their time (this one measures just 70 centimeters). Stethacanthus is known from the Late Devonian till the Early Carboniferous, so this is another animal I technically could have included in the Devonian episode already. Pose based on Dmitry Bogdanov´s reconstruction.