Thursday, June 30, 2011

Happy Feet

After my first maniraptor movie review, Babbletrish suggested that I should do one on Happy Feet. I had not seen Happy Feet at the time, but, eventually, I did. Spoilers ahead!

I'm going to agree that seeing otherwise realistic penguins with human-like eyes and dancing like humans is rather... uncanny. I'm not someone who cares that much about graphics or whatever, so that alone might not have put me off this movie. But, truth be told, I felt that the other aspects of the movie were rather "meh". That, and I also thought the ending was slightly rushed and not all that believable. Why would a zoo just suddenly release a new animal celebrity back to the wild? How did the humans figure out that the penguins were trying to communicate with them and what they were trying to say? It's as though someone just put that forth as a random suggestion and everyone else just went, "Hey, let's go with that!" The one mildly interesting thing I found in this movie was how Carnivore Confusion was treated. For a moment you might think the leopard seal is a mindless movie monster, and then it talks. Strangely, the orcas of all things are the only animals (besides actinopterygians and humans, naturally) that don't display an ability to communicate with the rest of the cast.

For all its faults, I must confess that, tap dancing aside, this movie has penguin biology down rather well. Emperor penguins really do sing during courtship, and the males really do huddle together for months while incubating the eggs. (Though just so you know, real emperor penguins sound like this.) Also, penguins really do jostle for position when entering the water as a way of checking for predators. Adélie penguins really are plucky birds, and really do offer stones to potential mates. On the other hand, unlike emperor penguins, Adélie penguins don't breed on the ice, even though they live on it for most of the year. A lone Eudyptes penguin (I do not know exactly which species, if any, it's supposed to represent; I'm guessing one of the rockhopper penguins) also shows up in this movie. Eudyptes penguins are usually found on the subantarctic islands surrounding Antarctica instead of the ice, but given that this is just one individual I assume he's a special case. Some skuas get a few brief scenes (though I am, again, unable to identify their precise species), and from what little we see of them they appear to be portrayed fairly accurately.

Finally, this has nothing to do with maniraptors, but the elephant seals are implied to be herbivores. Really? Unless this was meant as a joke that never gets corrected in the film, it sounds like someone got way too caught up in the similarities between elephant seals and elephants.

Friday, June 24, 2011

Maniraptor Feathers Part VII: Are Feathered Maniraptors, Like, Totally Uncool?

 This will be the last post in this series for now.

I suppose it can be said that many objections to feathered maniraptors, however flawed, have at least some apparent basis to them. But all too often I see arguments that have zero reasoning behind them, arguments that amount to little more than, "I refuse to believe maniraptors had feathers" or "I don't like how feathered maniraptors look."

I don't think I even need to explain how wrong this kind of "argument" is. They're entirely subjective, for starters. My two cents on the issue? These look terrible.

Or, to quote Babbletrish, "Naked maniraptors look stupid."

More importantly, organisms living millions of years ago don't care what a few individuals of one freaking species think. There's nothing wrong with liking naked maniraptors, but how that influences the characteristics of real-life animals is beyond me. I am completely incapable of seeing why this concept is so difficult to grasp.

Maniraptor Feathers Part VI: Lizard-faced Monsters in Gorilla Suits

It is abundantly clear by now that all evidence points to the fact that non-avian maniraptors had feathers, and most objections to such are little more than attempts to cover up desperate denial that hold little weight if any. A common problem in serious reconstructions of extinct maniraptors these days is not that they lack feathers, but that they aren't feathered correctly.

As Andrea Cau puts it (after being garbled by Google Translate), many depictions of "feathered dinosaurs" don't actually depict "feathered dinosaurs" but "dinosaurs with feathers". They don't really show how these dinosaurs were feathered in life, but take a traditional scaly dinosaur and stick it in a suit of feathers. In other words, they're the equivalent of sticking a human into a gorilla suit and calling it a gorilla. I don't remember where I heard that analogy first, but it sounds apt to me.

This is supposed to be a chicken.

It's not just non-avian maniraptors. Even the de facto "first bird" Archaeopteryx runs into this problem a lot. In reality, we have a decent amount of data on the plumage of these dinosaurs, and they certainly weren't scaly dinosaurs stuck in feathered suits. I briefly described in Part I what we presently know about the plumage of each non-avialian maniraptor for which evidence of feathers has been found. Incidentally, at least one thing I said in Part I is now probably outdated. I talked about how protofeathers, plumaceous feathers, and pennaceous feathers are all known in maniraptors. That is still true, but not in the way I described. A new study has shown that the feathers preserved in the feathered dinosaur specimens are likely more complex than typically thought. A (dead) European siskin was crushed in a printing press to simulate the preservation of the feathered dinosaur specimens, and it turned out that crushed pennaceous body feathers looked like plumaceous feathers or protofeathers. So the "protofeathers" and "plumaceous feathers" found on the bodies of oviraptorosaurs, deinonychosaurs, and basal avialians are likely actually pennaceous feathers, and the protofeathers in more basal maniraptors and other coelurosaurs are probably plumaceous feathers, or at least multiple filaments joined together at the base instead of single filaments. That leaves only the bristle-shaped EBFFs found in Beipiaosaurus (and possibly some undescribed basal coelurosaur taxa) as the only known monofilament feathers in maniraptors. Incidentally, the "ribbon-shaped" wing feathers reported in the juvenile Similicaudipteryx are likely just developing regular pennaceous feathers, while the ribbon-shaped tail feathers in many Mesozoic birds really are ribbon shaped, but the ribbon-shaped part is probably a specialized calamus instead of fused barbs as usually interpreted.

Several common and persistent characteristics of gorilla suit dinosaurs routinely find their way into reconstructions, even those that are otherwise perfectly accurate. Inaccurate wing feathers are one. All modern birds have a fairly uniform wing feather arrangement: tertials attaching to the humerus, secondaries attaching to the ulna, and primaries attaching to the second finger. Non-avian maniraptors and basal avialians don't appear to have had tertials, but aside from that all evidence so far shows that oviraptorosaurs and deinonychosaurs had a similar wing feather arrangement. Other than Caudipteryx zoui and the juveniles of Similicaudipteryx, all oviraptorosaurs and deinonychosaurs with preserved wing feathers have secondaries, and all, so far without exception, have primaries. (More basal maniraptors, such as therizinosaurs, didn't have actual wing feathers, just long protofeathers on the arms.) Possibly by far the most common error in depictions of plumage in oviraptorosaurs and deinonychosaurs is the lack of primary feathers. Although some speculate that certain taxa might have lost the primary feathers, this is typical wishful thinking. There is no evidence that this was the case. Even in flightless birds with short, stubby forelimbs, primary feathers remain, though they aren't easy to see because they "blend in" with the body feathers. Nor is there any reason to suppose that wing feathers would have gotten in the way of catching prey, as the palms and claws of theropods do not point the same way as the feathers do. On a related note, there is no evidence that the fingers of deinonychosaurs were scaly, even though just about everyone reconstructs them that way. As far as we know, even the fingers of deinonychosaurs were fuzzy, although oviraptorosaurs on the other hand appear to have had scales or naked skin on their fingers.

Diagram showing how a deinonychosaur could've used its hands even with large wing feathers from Senter 2006. (A) shows two handed grasping with the wrists flexed. (B) shows obligate supination of the hand as the wrist extends. (C) shows one-handed grasping to the chest. (Wing feathers would have prevented two-handed grasping to the chest.)

Another common error in reconstructions of feathered dinosaurs is stopping the head feathers at the snout, or worse, having scaly, lizard-like heads. Most of these reconstructions are evidently inspired by the fact that in modern birds, feathers stop at the snout. However, modern birds have beaks. In beakless maniraptors (including many Mesozoic birds), the feathers appear to go all the way down the snout, leaving only some naked skin at the tip. Of course, there are variations on this. Beipiaosaurus appears to have had a naked face, and many modern bird clades have evolved naked faces. Even so, there is no reason think that any maniraptor re-evolved scales on previously feathered parts of the body, even if they might have secondarily lost their facial feathers. By the way, although it is common to speculate that carnivorous non-avian maniraptors had bald heads, this appears to be based on vultures, and as I discussed briefly in Part V, bald heads in vultures have more to do with soaring habits than with feeding behavior.

Fossil of Eoenantiornis buhleri showing feathered snout photographed by Laikayiu, from Wikipedia.

Finally, in paleo art, it's common practice to "show all work" and make sure all the skeletal features and proportions of a dinosaur can been seen in reconstructions. However, as Matt Martyniuk, Mickey Mortimer, and Dr. Darren Naish discuss in the comments here, restoring feathered dinosaurs means "obscuring your research". Just look at how much feathers can cover up skeletal features in modern birds! Fossils of non-avian maniraptors also show obscuring of skeletal features by plumage. (Take a look at the fossils of "Dave" or Beipiaosaurus I posted back in Part I.) Even in featherless dinosaurs, the presence of soft tissues would mean that they were far from the shrink-wrapped creatures commonly depicted in art.

Museum mount of Strix nebulosa showing extent of plumage, photographed by FunkMonk, from Wikipedia.

Wednesday, June 22, 2011

Maniraptor Feathers Part V: What About Big Maniraptors?

The idea that some extinct maniraptors may have secondarily lost their feathers because "they didn't need them" is one that currently has no evidence for, and in most cases comes from the ignorance of the vast potential functions that feathers have. However, there is one instance where this line of reasoning does at least appear to make sense, and that is when big maniraptors are concerned.

How big is a big maniraptor? Some would say Deinonychus was a "big maniraptor", but truth be told it really... wasn't. Although it was fairly large for a dromaeosaurid, it still wasn't larger than even the largest living maniraptor, the ostrich. A large ostrich can easily weigh more than a hundred kilograms, while Deinonychus has been estimated at around seventy kilograms.

Size comparison between several large aviremigian maniraptors (and a synapsid) by Matt Martyniuk, from Wikipedia. Notice Deinonychus sulking at the back out of embarrassment from being much smaller than the others.

There are several dromaeosaurids that were much larger than Deinonychus, however. Achillobator, Austroraptor, and Utahraptor are the largest dromaeosaurids known. Utahraptor has been estimated at five hundred kilograms and seven meters long, and Achillobator and Austroraptor were probably slightly smaller. Some rumored undescribed specimens of Utahraptor are allegedly even larger, but for the sake of simplicity we can probably ignore those for now.

Size comparison between Utahraptor ostrommaysorum (including an alleged undescribed specimen) and a human by Matt Martyniuk, from Wikipedia.

Large as they were, these large dromaeosaurids were dwarfed by several other maniraptors. The oviraptorosaur Gigantoraptor was more than eight meters long and weighed more than a ton. It was about the same size as the tyrannosaurids Albertosaurus and Gorgosaurus. Multiple therizinosaur taxa may have also rivaled or exceeded the biggest dromaeosaurids in mass, including Alxasaurus, Falcarius, Nothronychus, Suzhousaurus, Enigmosaurus, Erlikosaurus, Nanshiungosaurus, and Segnosaurus. The largest known therizinosaur (in fact, the largest known maniraptor) was Therizinosaurus itself. Some estimates put it as being around three meters tall at the hip and weighing as much as six tons. Given the strange, upright build therizinosaurs tended to have, it probably would've been a very imposing animal in life.

Size comparison between Therizinosaurus cheloniformis and a human by Matt Martyniuk, from Wikipedia.

The concept that large maniraptors may have lost their feathers is based on the fact that several large modern tropical land mammal lineages (such as elephants, rhinos, and hippos) have greatly reduced insulating integument, which sounds reasonable. (It's a bit less reasonable when other types of mammals such as humans, naked mole rats, or whales are brought up, given that their reduction of hair involves specialized lifestyles not known in any maniraptor.) These mammals have dispensed with a thick coat of hair because they are large enough to maintain their body temperature without insulation, and probably because they'd overheat with a typical mammalian coat.

On the other hand, there's reason to think that overheating was not quite as much of a problem for theropods as it is for mammals. For one thing, theropods typically have greater surface to volume ratio than mammals do. After all, Velociraptor was roughly the size of a coyote, but was longer than the average man is tall. Even among mammals, surface area to volume ratio appears to make a difference in determining how much insulating integument is reduced. Giraffes and black rhinos are in the same size range, but giraffes haven't greatly reduced their coats of hair, because their surface area to volume ratio is much greater than that of black rhinos. It's worth noting that the builds of elephants, hippos, and rhinos are all terrible for shedding heat, while this was not the case with theropods. Secondly, theropods have an air sac system that mammals do not, and greatly increases their ability to shed excess heat. Indeed, preliminary calculations by Andrea Cau suggest that not even the tyrannosaurid Tyrannosaurus would've been greatly inconvenienced by a feather coat, and Tyrannosaurus was significantly larger than all known maniraptors, barring Therizinosaurus. I suspect the largest coelurosaur with a coat of plumage of a given thickness would've potentially been larger than the largest mammal with an equally thick hair coat.

Besides, there are other reasons why elephants, hippos, and rhinos don't make ideal comparisons to most big maniraptors. Rumors notwithstanding, Utahraptor, Achillobator, and Austroraptor weren't anywhere close to the size of those big mammals. Modern mammals in their size range, even those in tropical environments, don't show a particularly marked reduction in hair. (Funnily, the largest known avian maniraptors were about as large as the largest dromaeosaurids, but rarely does anyone suggest that they lost their feathers. Such baseless differences between the treatment of non-avian and avian maniraptors is quickly becoming an Overly Long Gag.) That leaves only Gigantoraptor, Nothronychus, Suzhousaurus, Segnosaurus, and Therizinosaurus as the only known maniraptors in the size range of large terrestrial mammals with reduced integument covering. Furthermore, the hair loss in hippos (and likely the ancestors of elephants) may well have as much to do with their semi-aquatic habits as it does with size and build, while there's no evidence that any big maniraptors had semi-aquatic ancestors.

Cartoon of hypothetical dromaeosaurids with lifestyles that may lead to significant reduction of insulating integument. Tellingly, none of them are known to have existed.

There's more. Feathers, especially pennaceous feathers (which most maniraptors have) are excellent insulators. They prevent both heat loss from the body and overheating caused by ambient heat. We're biased in our typical view of insulation because we deal with high temperatures by sweating, which isn't too effective with thick clothing covering our skin, but in fact, male turkeys are more likely to overheat from high ambient temperatures than female turkeys are because of their bald heads. Even for us, wearing thin clothing that still allows for evaporation of sweat can actually help lower body temperature. That said, feather loss in some areas of the body in maniraptors can be beneficial under some circumstances. For example, ostriches have naked flanks, legs, and inner wings, and rheas have naked legs and inner wings. These birds can run very fast and probably generate a lot of heat doing so, but live in fairly arid environments and can remain active in hot weather. It turns out that the featherless parts of an ostrich or rhea can all be shaded easily by the bird's wings or the rest of the body, so the heat generated during the day is stored and then can be rapidly shed in one go. The bald heads of certain vultures have also been found to be important in thermoregulation (instead of being an adaptation to cope with messy feeding habits; indeed, the messiest vultures don't have the baldest heads, and most vultures have feathered heads). These vultures usually need to cope with rapidly changing temperatures while soaring, and can quickly facilitate or prevent heat loss by extending or retracting the neck. Even the bald heads of turkeys have a role in shedding metabolic heat.

So it's not improbable for some non-avian maniraptors to have had some naked parts of the body, either for display or thermoregulatory purposes, especially the neck. (Feathers in the neck region are genetically easier to lose than feathers elsewhere on the body, which explains why so many different bird lineages have evolved bald necks for various purposes.) In particular, large cursorial non-avian maniraptors that lived in arid environments may well have had an ostrich-like feather covering. Nevertheless, there is little reason to think that any maniraptor lost its feathers to the same degree elephants, hippos, and rhinos have lost their hair. Even in flightless birds with naked skin patches, the rest of the body still tends to be densely feathered. Indeed, wing feathers in aviremigian maniraptors don't have much to do with insulation and may well have been present in even the largest aviremigians. (They wouldn't have gotten in the way of predation. Might talk about that in a later post.) In fact, ostriches and rheas have even more remiges than flying birds because they no longer need to fly. They have remiges on both sides of the arm, while flying birds only have them on the same side as the ulna. Whether or not any extinct maniraptors had similar feather arrangement is unknown.

Restoration of Achillobator giganticus with plausible ostrich-like feather distribution by Matt Martyniuk. Derived dromaeosaurids weren't cursorial, but fulfilling two out of three requirements is close enough!

Sunday, June 19, 2011

Maniraptor Feathers Part IV: What Good are Feathers?

Another occasional objection that is raised regarding feathered maniraptors is, "Why would taxon A have feathers? It didn't need them!"

Which... isn't really an objection. After all, there is generally no evidence that the taxon concerned "didn't need feathers", even though there may be evidence from phylogenetic inference or even direct fossil evidence that it did have them. Besides, many animals (including many dinosaurs) are known to have some crazy structures for which their function isn't obvious, but that isn't really evidence those animals didn't have them. (Who can actually say, for example, exactly what stegosaur plates or Psittacosaurus bristles were for?) This ends up as more an argument from personal incredulity (i.e.: "I can't think of how taxon A would've used its feathers, so it didn't have any!").

Nevertheless, just as with stegosaur plates and Psittacosaurus bristles, it's still good to try and seek out potential functions for feathers in non-avian maniraptors. Fortunately, the function of feathers is somewhat easier to infer than stegosaur plates or Psittacosaurus bristles, as there are still feathered maniraptors alive today.

All living maniraptors are either flighted or have flighted ancestors, and a primary function of feathers in neornithines is to help them fly. However, no non-avian maniraptor was quite as adapted to flight as modern neornithines, even though some clades have been suggested to have been secondarily flightless and a number of small deinonychosaurs could've had some limited aerial capability. The presence of plumaceous feathers with no aerodynamic qualities in non-maniraptor coelurosaurs with no flight adaptations shows that feathers arose before flight in dinosaurs began to evolve. (That's right, plumaceous feathers were probably present in basal coelurosaurs. Might talk a bit about that later in the series.) As feathers are found in flightless coelurosaurs (including modern ones), they must also be beneficial in other ways. Feathers are exaptations; they were later adapted for flight, but that wasn't their original function.

Another major function of feathers in modern maniraptors (both flighted and flightless) is insulation, and feathers are important in both keeping maniraptors warm in the cold and keeping them cool in the heat. Plumaceous feathers found in basal coelurosaurs (as well as in basal maniraptors such as therizinosaurs and alvarezsauroids) likely had this function.

Many non-avian maniraptors didn't just have plumaceous feathers, however. Oviraptorosaurs and deinonychosaurs are both known have had pennaceous feathers. Pennaceous feathers are also useful for insulation, and asymmetrical pennaceous feathers (which are known in the dromaeosaurid Microraptor) are good for gliding and flying with. In addition, pennaceous feathers are also more useful than plumaceous feathers in visual communication, due to their wider display area and (possibly) greater range of colors that they can show. Some feather structures known in non-avian maniraptors, such as tail fan and the short primary feathers forming little "hand flags" in Caudipteryx zoui and the feather crests in Microraptor and Anchiornis, were likely for display purposes. (In the case of Anchiornis, the feather crest is known to have been orange, in contrast to the dark gray and black of the rest of the animal, which supports its use in visual display. Similarly, the wing feathers of Caudipteryx show a banded color pattern. Furthermore, the development of wing feathers in Similicaudipteryx signify that the wing feathers were more important in older individuals than in younger ones.)

Male Pavo cristatus in display using pennaceous tail feathers photographed by PRA, from Wikipedia.

The greater area of pennaceous feathers likely served another purpose, too. Several oviraptorid and troodont specimens have been preserved brooding on top of their nests with the forelimbs extended over the eggs. The wing feathers that were likely present in these taxa would have helped cover the eggs while the dinosaurs were brooding.

Fossil of Citipati osmolskae brooding on nest photographed by Matt Martyniuk, from Wikipedia.

Some flightless birds have yet another use for their wings. Rheas and ostriches flick their wings out to the sides while running to help them make quick turns. Cursorial flightless non-avian maniraptors may have done the same.

An interesting idea that's been proposed in the last decade is Wing-Assisted Incline Running (WAIR). Many birds, particularly those that are primarily terrestrial or too young to fly, can escape from predators by flapping their wings to help them run up inclined surfaces such as tree trunks. This behavior was first observed in chukar partidges and has been documented among many neornithine groups. It's been suggested that small non-avian maniraptors with well-developed wing feathers may have also used WAIR and that it contributed to the evolution of flight. Other researchers, however, argue that the restricted forelimb movement in non-avian maniraptors wouldn't have allowed them to perform WAIR. (Non-avian maniraptors couldn't lift the wings above their backs. Indeed, not even confuciusornithids could!)

Friday, June 17, 2011

Pokemon Best Wishes: Fossil Revival! Ancient Mysterious Bird Archeos!!

A quick diversion from the maniraptor feathers series (which will be continued shortly).

As those of you who are Pokemon fans know, in the newest generation of Pokemon (Generation V), there are two Pokemon out there based on basal paravians, Archen and Archeops. (I know that "Pokemon" needs an accent mark in it. But I'm only a pedant when it comes to dinosaurs.)
Art by Ken Sugimori, from Bulbapedia.

Art by Ken Sugimori, from Bulbapedia.

I could do without the lizard heads, but they're pretty cool Pokemon. There've been plenty of Pokemon based on modern maniraptors, but the fact that we finally have some deinonychosaurs/archaeopterygids is great.

It so happens that these Pokemon were recently featured in an episode of the Pokemon anime. It can be watched here. Warning: there will be spoilers ahead for episodes that haven't been aired in English.

The episode just starts out of nowhere and we're immediately shown a Plume Fossil.

Fennel is very excited about resurrecting the fossil... I'd probably be pretty excited as well, especially given the fact we don't live in a world where you can just hand a scientist a fragmentary fossil and he or she can revive it for you in a matter of seconds.

They resurrect the fossil by hooking Musharna up to a machine. Okay...

It lives!

It's quite hyper and immediately goes around attacking people and running into stuff.

It also leaves behind some prehistoric seeds that were resurrected alongside it.

What an un-maniraptoran sleeping posture.

It uses Screech!

Which somehow causes the seeds to grow...!?

A few problems though. First, it evidently doesn't like modern Pokemon food.

Second, it's not much of a flier. Which is Truth In Television. (To be perfectly realistic, it probably wouldn't be able to get off the ground at all by flapping. But this is Pokemon.)

It can do WAIR (Wing-Assisted Incline Running) though! Neat.

Ash decides to help it out by sending forth fellow paravian Tranquill.

Watch and learn, inferior maniraptor with only incipient flight adaptations.

Iris also helps by sending out her flying synapsid. (No, really. It can actually fly. This is Pokemon.)

Emolga is more interested in trying out Attract though. Just in case she needs to steal apples from this thing in the future.

It... doesn't work. Looks like Archen is also female.

Fluffy mammal, nom nom.

Emolga is not amused. Volt Switch!

It malfunctions as usual, sending out Cilan's Stunfisk.

Emolga gets to spend the rest of the episode lazing around in a tree. Just the way she likes it.


Pancake fish, nom nom.

Too bad it happens to be an electric fish.

With help, Archen is making progress with her flying lessons.

Meanwhile, Archen's screeches throughout the episode have really made an impact on the plant's growth.

It even bears fruit!

These Archen does like to eat.

And when she needs more, she can just give a shout.

All of a sudden... (New evolution animation, w00t!)


It flies!

But then...

Team Rocket! Dun dun dun.

They decide to attack the plant... for reasons, I guess.

Everybody attack! (Funny that Fennel is being more proactive than the main characters who aren't named Ash.)

Team Rocket goes blasting off- Wait, this is the Best Wishes series. Team Rocket is actually competent.

Ash has Roggenrola and Oshawott deal with the ghost... fire... energy... stuff enveloping the building.

Good thing Archeops isn't a pushover. It removes the net with Dragon Breath.

Team Rocket retreats. (They don't blast off anymore.)

Unfortunately, the heroes couldn't save the plant, meaning Archeops's food source is gone.


Wait a minute, what? Aren't they supposed to be extinct? Didn't you make a big deal out of resurrecting one? Never mind...

So Archeops goes off to join her own kind, who presumably know how to survive in the wild in present day. (To be honest, part of me was hoping that someone would catch Archeops. But considering that Ash in particular is overloaded with Pokemon at the moment to begin with...)

Not bad for a Pokemon episode overall, in spite of some very strange plot devices.