Saturday, November 26, 2011

Planet Dinosaur: The Great Survivors

Here we go, the sixth and last episode of Planet Dinosaur. The show took a break from maniraptors in the fourth and fifth episodes. The fourth episode showcased large Jurassic predators, specifically the allosaurid Allosaurus and a yet undescribed pliosauroid, the first discovered specimen of which has been nicknamed "Predator X". The fifth episode on the other hand discussed the giant sauropods Argentinosaurus and Paralititan, as well as their respective potential predators, the carcharodontosaurids Mapusaurus and Carcharodontosaurus. Maniraptors return in this last episode, however. Spoilers ahead.

One of the less desirable characteristics of Planet Dinosaur is that it's very theropod centric. Plesiosaurs and sauropods get some spotlight in the fourth and fifth episodes respectively and the giant pterosaur Hatzegopteryx gets good airtime in this one, but by and large it's theropods that get the main roles. If (the broadcast version of) Dinosaur Revolution should have been called "Saurischian Revolution", Planet Dinosaur probably should have been called "Planet Theropod". But then, as a maniraptor fan myself I can't complain too much.

The first maniraptor to make an appearance is Bradycneme. This maniraptor is known only from fragmentary remains. It was first thought to be a giant owl, but nowadays a troodont or alvarezsaurid identification is more common, and the show depicts it as a troodont. Once again the model is unsatisfactory. It's something of a shame that troodonts get the most screentime out of all maniraptor groups in this show when the troodont models are the most inaccurate. It was amusing though to see Bradycneme being shown while the narration was discussing threats to the sauropod Magyarosaurus, only to have Bradycneme attack... a lizard. The real threat is then shown to be Hatzegopteryx. Bradycneme also gets some airtime toward the end of the episode when the show does its obligatory K-Pg sequence, as another continuation of the "troodonts were probably the last non-neornithine dinosaurs to die off" meme, I guess. It was interesting to see a K-Pg setting not at Hell Creek.

Next up is the therizinosaur Nothronychus, which is shown browsing and using its claws to fight off predators (in this case a group of an undescribed tyrannosauroid taxon, nicknamed "Zunityrannus" in the show), as therizinosaurs tend to be. Although it is depicted with protofeathers, I felt the feathers were a little too contour hugging. Feathers we know of on Beipiaosaurus (which, granted, was much smaller than Nothronychus and probably lived in a more temperate environment) were very long and shaggy. It would have been nice to see bristle-like EBFFs (known on Beipiaosaurus and possibly some undescribed basal coelurosaurs) as well. The show points out that Nothronychus was a herbivore that descended from carnivorous ancestors, another good effort to include recent research.

It goes on to mention another group of herbivorous and omnivorous maniraptors, the oviraptorosaurs, and the giant oviraptorosaur Gigantoraptor makes a return. A pair of Gigantoraptor brood their nest and defend it from smaller oviraptorids (that also appeared in the second episode; I've been told that the accompanying book for Planet Dinosaur calls these Oviraptor) as well as the tyrannosauroid Alectrosaurus. This sequence was arguably my favorite of this episode; the one nitpick (besides the usual wing feather attachment issue) I have to make is that the smaller oviraptorids do the weird digging with their wings thing again. The movements and behaviors of the Gigantoraptor though are very reminiscent of large ground birds, particularly the leaping attacks they make towards the Alectrosaurus. At the end of the segment the show talks about how oviraptorosaurs are often found having been buried alive on their nests...

Then we come to the K-Pg segment that I mentioned earlier. I don't have a whole lot to say about it, other than the fact that it contains an anomaly that may be my least favorite part of the entire series. As the show talks about how the K-Pg event impacted different animal groups (Wikipedia regulars keep an eye out during the sequence, by the way; some of the silhouettes they use will look very familiar), it claims that 100% of "dinosaurs" became extinct, while 95% of birds became extinct... wait, what? It's almost understandable if they'd wanted to avoid the birds are dinosaurs thing for the sake of brevity, but the funny thing is they do get this right in the second episode! So much for consistency! I know that the whole "actually some dinosaurs are still alive today" is something of a cliched ending for dinosaur documentaries these days, but given the fact that this important discovery has not yet fully entered public consciousness, I don't think it's cliched enough. Only until birds being dinosaurs becomes as common knowledge as bats and whales being mammals would I suggest that it's remotely "safe" to drop opportunities to hammer home this fact.

So there we have it. I liked this episode, other than the ending, and as far as science communication goes the series as a whole is very good. (Any dinosaur documentary that can teach Mickey Mortimer something new has to be.) If you want a dinosaur show that actually incorporates science (and isn't Dinosaur Train), then be sure to check this one out.

Saturday, November 5, 2011

Planet Dinosaur: Last Killers

The third episode of Planet Dinosaur, this one deals predominantly with recent research on large predatory theropods from the end of the Late Cretaceous, namely the tyrannosaurid Daspletosaurus and the abelisaurid Majungasaurus. However, there is one maniraptor-centric segment featuring Troodon. Some spoilers ahead.

A flock of the Troodon are shown attacking the hadrosaur Edmontosaurus. Normally I'd complain, but this is actually one of the few situations where such a scenario would be acceptable: the Troodon are based on the giant Troodon teeth found in Alaska, and the Edmontosaurus is a juvenile, while an adult Edmontosaurus easily chases the Troodon off (though the juvenile still dies later on from its injuries). In fact, the reason the Troodon are in the episode is because they represent the top predators in a unique Late Cretaceous ecosystem that wasn't dominated by either tyrannosaurids or abelisaurids. Unfortunately, the plumage of the Troodon suffer from the same problems as that of the Saurornithoides in the second episode.

Another maniraptor, Rahonavis, makes a brief appearance in the Majungasaurus segment, though it doesn't do much except feed from a carcass. It uses the same model as Sinornithosaurus (from the second episode) and comes with the same strengths and flaws thereof.

Not that much to say for this one (at least regarding maniraptors). Still decent stuff.

Wednesday, November 2, 2011

Planet Dinosaur: Feathered Dragons

Besides Dinosaur Revolution, the other big dinosaur documentary that came out this year was Planet Dinosaur. Naturally, this invites comparisons between the two, but, aside from both being about dinosaurs, they are really very different shows.

Though with scientific basis (and for most part accurate dinosaur models), Dinosaur Revolution is an experiment in storytelling that was unfairly shoehorned into a documentary format. Planet Dinosaur, on the other hand, is a bona fide dinosaur documentary. And I mean bona fide dinosaur documentary! Instead of putting a lot of focus into story or unsupported speculation, the real highlights of Planet Dinosaur are the cutaway segments throughout each episode that (get this) explain the fossil evidence for the behaviors its animals are shown engaging in and the form and function of each animal based on actual scientific research. Science in a dinosaur documentary, people! Take note, this is how a dinosaur documentary should be done, or at least it's a step in the right direction.

It's not that Planet Dinosaur doesn't engage in the occasional wild speculation now and then. It does. It's not that it gets everything right. It doesn't. But the fact it uses science as a focal point instead of an occasional aside or a way to make itself resemble a documentary makes it worthy of being a true documentary.

The first episode of Planet Dinosaur, "Lost World", focuses on two giant African theropods, the spinosaurid Spinosaurus and the carcharodontosaurid Carcharodontosaurus. It was a good start to the series, but there were no maniraptors in it.

The second episode, on the other hand, showcases maniraptors almost exclusively, and this is the episode I'll review here. Some spoilers ahead, even though plot isn't a big deal in this show.

A recurring theme throughout Planet Dinosaur is that it discusses mostly very recent dinosaur discoveries (made within the last decade). This episode, titled "Feathered Dragons", covers the discovery that some non-avian dinosaurs had feathers. The episode is split up into several segments that each features a different maniraptor taxon and talks about a different function feathers may have served in these dinosaurs.

First up is the strange Epidexipteryx, a possible basal avialian. One of the first scansoriopterygids on TV! It is shown escaping from a juvenile Sinraptor by climbing into the trees and hunting for grubs using its long third finger and unique dentition. It also encounters a rival Epidexipteryx and engages in a threat display using its four long strange tail feathers. It looked to me as though the Epidexipteryx had pronated hands in a number of shots, and we see its eyeball swiveling in its socket as it hunts. Modern birds can't do this, and that's why they often need to cock their heads at weird angles, which, confusingly, the Epidexipteryx is also shown doing. Otherwise though I have very little to nitpick (I want to say "pun intended" here, but I'd be lying) about this segment, though that might be at least partly because there isn't much about scansoriopterygids that we can even be reasonably certain of at the moment.

Next we see a Saurornithoides brooding its nest. Not a fan of Saurornithoides model, which lacks pennaceous feathers entirely and has only a very thin covering of feathers on the body, plumage befitting of a compsognathid perhaps, but not of a maniraptor. When the Saurornithoides leaves its nest temporarily, the nest is raided by an oviraptorid (which isn't specifically named). Evidence for omnivory in oviraptorosaurs is brought up, though unfortunately the evidence they put forth for predation (the discovery of hatchling Byronosaurus skulls in a Citipati nest) may soon fall victim to science marching on. This is of no fault of the show, as this data is still unpublished and has only been mentioned in a DML post, but they might have had better luck had they used the lizard in the body cavity of Oviraptor. The generic oviraptorid engages in some strange behavior of digging the eggs from the nest using its wing claws, in spite of the long wing feathers attached to its hands (which it commendably has). Digging using the feet as in modern ground-dwelling birds might have been more plausible, and indeed there is evidence of such behavior in Mesozoic aviremigians. Another anomaly regarding the oviraptorid is that even though it has wing feathers, they attach to the third finger (instead of the second as they should be). In fact, this is the case for every aviremigian in this show (or at least the ones that are lucky enough to have been given wing feathers).

Either way, the Saurornithoides manages to chase off the oviraptorid, only to be eaten by a much larger oviraptorosaur, Gigantoraptor, and the spotlight shifts. The show explains that large maniraptors might have kept feathers for display purposes, which is something straight out of the Gigantoraptor description paper. It's interesting that both Dinosaur Revolution and Planet Dinosaur have a sequence on the speculative display behavior of Gigantoraptor. The different approaches the two shows have are readily apparent: the Dinosaur Revolution Gigantoraptor is extremely flashy and extravagant with heavily speculative soft tissue structures, while the Planet Dinosaur Gigantoraptor is altogether more conservative. Aside from the wrong wing feather attachment, I quite like the ostrich-like plumage of the Planet Dinosaur Gigantoraptor and I find it quite plausible.

Finally, we get a sequence featuring the Jehol biota. There's a bit of anachronism here. We see a Microraptor hunting the gliding lizard Xianglong, and then being hunted itself by a Sinornithosaurus. The problem is that Microraptor is known only from the Jiufotang Formation, which is slightly younger than the Yixian Formation that Xianglong and Sinornithosaurus come from. I won't hold this too much against the show, as it is a common mistake. (It's even been made in the technical literature before!) In fact, even knowing that Microraptor is from the Jiufotang, I still find it hard to disassociate it from the Yixian. The Microraptor and Sinornithosaurus models are excellent, and aside from the usual wing feather attachment issue are some of the best deinonychosaur models on television I've seen to date, at least in terms of plumage. The chase scene that unfolds as the Microraptor tries to escape shows off (one of) the (hypothesized) gliding posture of Microraptor well. The legs looked a little splayed to me, but the show appears to have been going for Dr. Xu Xing's hypothesis presented in "The Four-winged Dinosaur" on Nova, and in any case there appears to be some possible evidence that microraptorines could splay their legs slightly more than other dinosaurs can. The really strange part in this sequence is that Sinornithosaurus is also shown to be capable of gliding, which is one of the few baseless speculations this show indulges in. Gregory Paul would be proud, I assume, but it appears that the wings of Sinornithosaurus were not large enough for actually gliding with (which is why there's hardly been any technical papers discussing the flight of Sinornithosaurus, as there has for Microraptor).

The last part of the show also happens to be the worst science wise. It features a trio of Sinornithosaurus hunting a family of the ornithopod Jeholosaurus. That alone isn't anything bad, and they even get in some impressively up-to-date info, namely the sclerotic ring study (published earlier this year) that indicates Sinornithosaurus may have been cathemeral, being active at intervals both in the day and at night. Things go downhill though when the Sinornithosaurus bring down one of the Jeholosaurus... using venom. That's right, the dreaded venomous Sinornithosaurus hypothesis. Granted, the show does use cautious qualifiers when dealing with the idea, but the fact that the Sinornithosaurus are actually shown in a way that endorses the hypothesis will probably leave a greater impact on laypeople than the narrative language. Frankly, in my opinion such fringe hypotheses should preferably not make their way into these serious documentaries at all, or only be mentioned to be dismissed as fringe hypotheses.

The show concludes with the concept that some feathered dinosaurs are still with us today, which of course is always a good idea to reinforce. Besides the venomous Sinornithosaurus slip up, this was a decent episode. As a dinosaur enthusiast it's easy (and, to be honest, fun) to nitpick and criticize, but I'll bet that most of the information presented here will be new to the average viewer and will greatly help in bringing them up to speed with the many wonderful new dinosaur discoveries made in recent years.