Sunday, June 12, 2022

Prehistoric Planet

The talk of the town (or at least of the online paleontology community) lately has been Prehistoric Planet, a new documentary series now available for streaming on Apple TV+. This show has been eagerly anticipated ever since it was first publicly revealed in 2019 to have been in production, not least because paleontology documentaries have been thin on the ground in the last decade. The dearth of content has been especially true regarding series that portray prehistoric life as though it had been filmed in the wild, a premise popularized by Walking with Dinosaurs in 1999.

Despite the inevitable comparisons to Walking with Dinosaurs, however, Prehistoric Planet borrows more from recent BBC documentaries that focus on the modern biosphere, such as The Blue Planet, Planet Earth, and their sequels. Regular viewers of nature documentaries will likely notice stylistic choices and even specific film sequences in these shows that inspired elements of Prehistoric Planet (including its title). Unlike Walking with Dinosaurs, the series is organized by habitat, with each episode being composed of several vignettes that take place in multiple locations, instead of revolving around an extended narrative about one specific individual animal or ecosystem. In addition, all of the segments in Prehistoric Planet are set within a fairly narrow window of geologic time (the Maastrichtian Age of the Late Cretaceous), not spread across the entire Mesozoic.

Now that the show has been released, it appears that most responses to Prehistoric Planet have been overwhelmingly positive, and the acclaim is well deserved in my book. The considerable advances in both technology and paleontological science since Walking with Dinosaurs are more than evident throughout the series, and others have already commented repeatedly on the spectacular visual effects as well as the naturalistic, scientifically plausible depictions of extinct animals. Instead of heaping on more of the same (albeit justified) general praise, I'd like to take a closer look specifically at the show's portrayals of maniraptoran dinosaurs. This is a maniraptoran blog, after all.

There is quite a bit to cover, for maniraptors are featured extensively in Prehistoric Planet. Most exciting to me was the fact that there is a whole segment dedicated to an alvarezsaurid, namely Mononykus from the Nemegt Formation of Mongolia! This sequence has to rank among my favorites in the show, not only because I am extremely biased in favor of alvarezsaurids, but also because I was very impressed by how much scientific knowledge about alvarezsaurid biology it incorporated. Traveling for long distances on foraging excursions? Sensitive hearing for detecting prey? Using the specialized thumb claw as an excavation tool? Feeding on wood-dwelling termites instead of mound-building ones? Whereas some segments of Prehistoric Planet revolve around behaviors widespread in modern animals that were transplanted onto select prehistoric species as (generally reasonable) speculation, almost everything Mononykus is shown doing was based directly on research into alvarezsaurid anatomy, function, and ecology.

What's more, this depiction of Mononykus appears to have resonated strongly with audiences. From what I've seen, it's probably fair to consider Mononykus one of the breakout stars of Prehistoric Planet, with even executive producers Jon Favreau and Mike Gunton identifying it as one of their favorite dinosaurs in the series. Alvarezsaurids have made a surprisingly large number of documentary appearances considering their relative obscurity (BBC's Chased by Dinosaurs in 2002 and Discovery Channel's Dinosaur Planet in 2003 come to mind), but none of those previous shows spent much time highlighting what makes these dinosaurs strange and interesting. Thanks to Prehistoric Planet's approach, it seems that Mononykus is well on its way to becoming a household dinosaur name, and I couldn't be happier about that.

Paleoartist Ilari Pätilä has proposed calling the Mononykus from Prehistoric Planet "Dolores", after a character from the Disney film Encanto who has the power of super-sensitive hearing. I approve, though the production team behind Prehistoric Planet reportedly has their own internal nickname for her.

Therizinosaurs are represented in Prehistoric Planet by the largest of them all, Therizinosaurus. Another maniraptor known from the Nemegt Formation, Therizinosaurus first appears in the background visiting a watering hole alongside other Nemegt dinosaurs (including Mononykus), but is not acknowledged by the narration at this point. A later scene, however, features a group of juvenile Therizinosaurus as its protagonists. This segment has the distinction of being, to my knowledge, the only one in the series for which visual elements were neither given away in promotional material nor publicly described by reviewers who'd seen the show early, which made it especially enjoyable to watch for the first time.

The way in which the Therizinosaurus are shown using their beaks and claws for feeding is supported by published research on therizinosaurs, as is their precocial nature. Their attempt to reach a bees' nest for honey by climbing with their beaks, claws, and flaps of their forelimbs is more speculative, but well within the realm of possibility. It is furthermore a fun potential nod to a discredited hypothesis that therizinosaurs might have had arboreal ancestors, while at the same time showing that most flightless Mesozoic theropods probably weren't particularly good climbers (which might not have stopped some from occasionally trying to climb anyway).

A juvenile Therizinosaurus has a go at wing-(and-beak-and-claw-)assisted incline climbing.

Despite their efforts, the young Therizinosaurus are quickly dissuaded by bee stings. They are eventually rewarded, however, when an adult Therizinosaurus shows up. Undeterred by the bees, it knocks the nest to the ground with a single swat from one of its clawed hands, and leaves behind enough leftovers for the youngsters to savor. This was a great way to convey the power and majesty of the adult Therizinosaurus without placing it in a stereotypically violent scenario. There is a minor error in the narration for this sequence: the adult is mistakenly described as 30 ft tall instead of 30 ft long. That being said, lead scientific consultant Darren Naish has pointed out that it is not inconceivable for a large Therizinosaurus to have been able to rear to heights approaching 30 ft.

Oviraptorosaurs appear in the form of the tall-crested Corythoraptor from the Nanxiong Formation of China. They do not play a major role beyond serving as would-be prey for the tyrannosaurid Qianzhousaurus, but they have a lovely design that makes it clear that just as much research and care went into their depiction as for those of the other computer-generated creatures in the show. In fact, the segment that they appear in is perhaps among the most aesthetically pleasing and atmospheric in the entire series. It was also neat to see the Corythoraptor feeding on ginkgo fruits and using their wings for balance while running, in a manner similar to ostriches. (As an aside: I'm not a stickler for the pronunciation of scientific names, but as someone who knows Mandarin, hearing narrator Sir David Attenborough pronounce Qianzhousaurus correctly was a plus.) 

A flock of foraging Corythoraptor makes for pretty dinosaurs in a pretty forest.

The function of feathers in flightless maniraptors is spotlighted dramatically in one of two segments starring the dromaeosaurid Velociraptor. Strictly speaking, the "Velociraptor" in Prehistoric Planet were based on indeterminate velociraptorines from Maastrichtian fossil deposits, with Velociraptor proper having only been found in the Djadochta Formation and possibly the Wulansuhai Formation, which are generally considered Campanian in age. As others have noted, however, there is enough ambiguity in the dating of Late Cretaceous rock units from central Asia that the Djadochta and Nemegt Formations may in fact have been laid down in different environments that coexisted at approximately the same time. In any case, the presence of Velociraptor-like dromaeosaurids in the Maastrichtian of central Asia is readily justifiable.

Velociraptor is introduced with a pair of them trying to prey on an unspecified lizard, which is in turn feeding on carrion flies drawn in by some dozing Tarbosaurus (an obvious homage to footage of agamid lizards hunting for flies near lions, as shown on BBC's Africa in 2013). Where Velociraptor truly gets to shine though is in its second appearance, which depicts a trio stalking azhdarchid pterosaurs on a sheer cliff face, perhaps partly inspired by fossil evidence that Velociraptor at least fed on azhdarchids occasionally. The Velociraptor are portrayed as agile hunters, using wing-assisted locomotion to boost their jumps, control descents, and even survive dangerous falls on difficult terrain. These maneuvers are reminiscent not only of locomotor strategies seen in modern birds, but also observations of polar bears and especially snow leopards hunting on cliffsides. Somewhat surprisingly, the famous "raptor prey restraint" model (which proposes that dromaeosaurids used their wings to stabilize themselves while restraining prey with their feet) is not explicitly shown in Prehistoric Planet, though this may have been deliberate given that the bloodier aspects of predation are noticeably downplayed in the imagery of this series.

This may not be the version that mainstream popular culture is most familiar with, but Velociraptor was undoubtedly a skilled predator.

Another dromaeosaurid that shows up is an unspecified polar species, presumably based on dromaeosaurid teeth from the Prince Creek Formation of Alaska. A group of these dromaeosaurids is featured cooperating to hunt hadrosaurids larger than themselves. Dromaeosaurids being shown bringing down unrealistically large prey items is a long-standing pet peeve of mine, but here the predator–prey relationship is portrayed much more believably: it is stated that the polar dromaeosaurids are targeting juvenile hadrosaurids rather than adults, and the one they eventually feed on is not directly killed by them, instead dying from being swept away in its panic by a fast-flowing river.

Even in depicting an animal known only from fragmentary remains, Prehistoric Planet draws heavily from fossil evidence. The polar dromaeosaurids have a frond of tail feathers restricted to the back half of the tail and with two especially elongate feathers at its tip, probably inspired by the tail feathering found in one specimen of Microraptor. One is also shown sleeping in a curled-up pose, based on the posture preserved in two specimens of the troodontid Mei, and leaving functionally two-toed tracks in the snow, based on actual fossil trackways made by dromaeosaurids.

A soundly sleeping polar dromaeosaurid.

Two separate but thematically similar segments portray possible interactions Mesozoic paravians might have had with wildfires, modeled after interesting behaviors exhibited by modern birds. One features a third dromaeosaurid taxon, Atrociraptor from the Horseshoe Canyon Formation of Canada, picking up a burning stick to fumigate its feathers, in an allusion to similar activities that have been documented in corvids. In another, an unspecified troodontid (presumably a member of the taxonomic tangle that is the Late Cretaceous troodontids of North America) actively spreads burning vegetation to drive prey into the open, as has been reported for some Australian kites and falcons. These scenarios are speculative, and it seems unlikely that direct evidence for them could ever be ascertained from the fossil record, but dromaeosaurids and troodontids were probably versatile predators with relative brain-to-body ratios within the range of (albeit not exceptionally large relative to) those seen in modern birds, so it's certainly not out of the question that they could have practiced such behaviors.

An Atrociraptor reaps the rewards of a forest fire.

There is one major group of maniraptors that gets the short end of the stick in Prehistoric Planet, however, and it's avialans. They are not completely absent: enantiornitheans show up in a few scenes and various bird-like forms are sometimes visible as set-dressing in the background or in wide shots, but they never feature as protagonists in the individual segments nor even as the focus of any close-ups. In fact, if I had any notable criticism of the series, it would be the apparent neglect of the smaller tetrapods in Late Cretaceous ecosystems. Only a single mammal species appears on the show, unmentioned and unnamed, and its sole role is to be killed by the aforementioned troodontid. It also nearly beggars belief that a time-traveling documentary crew would film a whole episode on freshwater habitats in the Maastrichtian and fail to include any footage of crocodyliforms or turtles.

In practice, of course, resources to create and animate digital models of prehistoric life for a series like this are limited, so it is understandable that the production team prioritized particularly strange and spectacular fauna over more "mundane-looking" ones. I would contend though there likely is substantial audience interest in learning about the origins of modern animals, which increased spotlight on taxa more closely related to extant forms would have provided opportunities for. Furthermore, the Mesozoic diversity and disparity of "microvertebrates" is regularly underappreciated. Leaving aside recent Maastrichtian avialan discoveries like Asteriornis and Falcatakely, which were almost certainly published too late to be incorporated into the show, it probably would not have been difficult to come up with engaging storylines featuring the bizarre, island-dwelling Balaur or enantiornithean nesting colonies (both of which, as a bonus, have been the focus of Darren's own research).

Even without adding or replacing any of the existing narratives in Prehistoric Planet, I would have liked to see at least some split-second close-ups of the enantiornitheans, considering that the team had evidently gone to the trouble of making digital models for them. Such "incidental" shots are a regular component of modern wildlife documentaries and probably would have made the ecosystems portrayed feel even more vibrant and immersive. As it is, the show already spends time (and occasionally narration) on shots of crustaceans, fishes, fungi, plants, and other organisms in "non-starring" roles, not to mention an entire segment on ammonoids (arguably one of the highlights of the entire series), so I have no doubt that a few extra seconds of microvertebrate footage could have been used to great effect.

Probably the closest we get to an in-focus shot of an enantiornithean on Prehistoric Planet: one is perched in the upper right corner here as the giant ornithomimosaur Deinocheirus prepares to use its tree as a scratching post.

Another concern about Prehistoric Planet I've seen from some viewers is that it generally does not clarify which aspects are speculation and which are based on direct evidence. This is not a new discussion regarding paleontology documentaries of this sort; very similar arguments were had with respect to Walking with Dinosaurs. To their credit, Walking with Dinosaurs and its sequel series Walking with Beasts had tie-in websites with extensive sections explaining the scientific backing behind their creative decisions, and the former also had a companion book on the same subject (co-authored by Darren, as it happens). Prehistoric Planet, meanwhile, currently has 5-minute videos (available for free on the Apple TV YouTube channel) accompanying each episode that feature interviews with paleontologists and delve into the science behind the series. These "Uncovered" videos, as they are called, are quite good for what they are, but each of them focuses only on a single narrow topic (e.g., how we know Velociraptor had feathers), leaving a great majority of what is shown in the episodes unaddressed. The production of additional "Uncovered" videos is allegedly being considered, and I very much hope that it comes to pass. If anything, a lack of transparency does a disservice to the tremendous amount of thought and research that clearly went into this show.

These critical comments, however, do not undermine the excellence that Prehistoric Planet has achieved. The series is outstanding in nearly every way possible, setting a new and extremely high standard for works of this genre, and the fact that my biggest issues largely amount to a desire for more is very much a testament to its success. Given the positive reception so far, I feel hopeful that we will eventually see future seasons of Prehistoric Planet and, with luck, maybe even a whole new age of paleontology-inspired media.