Thursday, January 31, 2008

There's an Alces in my backyard

A mid-sized female moose crosses my neighbor's yard

I don't think there are too many places in the world where you can say that you're annoyed that an ice-age holdover is in your yard. Here in Anchorage, Alces alces gigas is extremely common. They get huge very quickly, the mothers become dangerously protective of their babies during the summer, and the males grow enormously broad antlers during the spring. Our moose stand around 7 feet high at the shoulder, and you can't go into a wooded area during the summer months without coming within twenty feet or less of one. Usually, moose in the Anchorage Bowl have become fairly docile. This is not to say they approach people, but they tolerate our presence.

Females become very aggressive when they've got calves by their sides. Whenever I see a calf my mind flashes "where's the mom?" She could be charging at me. My wife has been charged three times (only once by an irate mother), and I've been charged once. There's really no feeling like seeing an enormous artiodactyl bearing down on you, with death on its tiny mind. As we learned, most charges are fake-outs, and the moose will suddenly veer off in another direction before you get squashed. This is not to say that a moose will always do that--we've just been lucky. It's probably a good idea to find some tall trees to hide behind, or scrub pines if you're around skree rocks.

But they are awesome creatures, and my favorite Alaskan mammal. There are countless stories I could tell about moose sightings, but I'm just going to tell two right now.

1) My wife and I were hiking around a mountain base two summers ago. At one point we were forced through some thicket, with a narrow bridge crossing a long-dried-up streambed. The streambed provided the only relief from the thick foliage. When we stepped onto the bridge, what should I notice to our right but an enormous bull moose, antlers fully grown. This was a bull in the prime of its life. After that summer, I'm sure it's antlers would start getting a bit smaller year by year. It was big, healthy, and thankfully for us, did not care about humans. This bull was literally mere feet away from us. If I had a carrot, the beast would have taken it from my outstretched hand. Gina and I actually saw over a dozen moose that day, including a good-sized group complete with sparring males. We stumbled across a resting female and preyed that our dog wouldn't bother it. I, perhaps stupidly, wandered into some thicket after hearing what sounded like something large tromping through it (it was a big cow), and then of course there was that giant male.

Your heart kind of skips a beat when you see a huge bull that close. Although he clearly noticed us, he didn't seem bothered by our presence. We, of course, kept on walking lest he change his mind. That was too cool for words, though, and I have not been so close to a moose since. Nor, perhaps, would I want to be.

2) Just after Halloween this year, Gina gets up at like 2 a.m. to get a drink of water when she sees a large shadow move across the kitchen window (which does not have a shade). Probably because it's 2 a.m., she yells for me, perhaps thinking it's a robber or something. I stumble out of bed and peek out the window, and come face to face with one of the neighborhood regulars munching on our tiny pumpkins, which were set out on the stoop for Halloween. The moose is as happy as can be, because food is kind of scarce during the winter (and twigs must get pretty old). After she consumes all five pumpkins, she just wanders off, and I give Gina a hard time for being freaked out by a moose outside.

Now it's almost 2 a.m. right now (I honestly don't know why I'm still awake) so I'm heading to bed! But remind me sometime, if I forget, to tell you about the time Gina and I (and the dog) were aggressively charged my a mother moose. That experience kind of scared me straight about Alces alces, and I approach them now with extreme caution, even though many of them probably don't care that I'm there.

Sunday, January 27, 2008

Behold: The Boneyard!

Don your digging cap, and head over to The Dragon's Tales for a hefty dose of The Boneyard XII, which has little if anything to do with Albertosaurus. Although that genus is known from extensive bone bed remains...

Thursday, January 24, 2008

Ontogenic flight model for theropods? Awesome!

I'm hoping that one of you out there in Readerland has this paper:

A fundamental avian wing-stroke provides a new perspective on the evolution of flight
Kenneth P. Dial, Brandon E. Jackson, & Paolo Segre

It's in this week's issue of Nature. Looks like Dial is taking his WAIR model a step further, and after reading the abstract of this newest paper, it looks good! I must blog about it!

EDIT: Thanks to Neil and Jerry for so quickly sending the paper (and the videos) my way. From the looks of the paper, both the ground-up and trees-down hypotheses are correct. chukar partridges run up an incline, then fly (or glide) down to the ground! Expect a large post on this study later today, perhaps with a more non-avian version of Dial et al.'s Figure 1. :-)

Wednesday, January 23, 2008

Julia's Cetiosauriscus


Not too terribly long ago, Julia offered to send me any JVP articles I might want since I stopped getting access to the journal. I don't think she knew what she was getting herself into, and my request topped out at somewhere around twenty articles. And now, I think she just sends me stuff she thinks I'll like lest I bug her about it. :-)

But as thanks, I offered to draw her favorite dinosaur. Not surprisingly, the Ethical Palaeontologist wished upon Cetiosauriscus, and so, many weeks later, this picture was completed. Could I improve upon it? Sure, but I don't want to drive myself mad. I feel slightly bad that I recently went on a big rant about how artists shouldn't be restoring animals known from fragmentary remains. In detailing this eusauropod, I fell victim to that complaint. Cetiosauriscus is known from basically the back half, and an arm, so the neck, back, and head are completely made up! Julia suggested Omeisaurus as a reference (oh my!), but with a fatter overall structure.

So there it be: Cetiosauriscus. I'd give it a species name, but according to Julia and every resource I've read online, the animal's taxonomic history is something of a nightmare.

Tuesday, January 22, 2008

If you didn't know it before, you know it now

Dinosauria is defined as:

The most recent common ancestor of Triceratops horridus and Passer domesticus, and all its descendants.

Fun fact! Before birds were confirmed to be dinosaurs, Passer was replaced by Allosaurus!

This, of course, assumes that Ornithischia + Saurischia = monophyletic clade. I'm still iffy on that proposal, for reasons I've gone into before. Still, if you're ever on Jeopardy, and that's the answer, you can buzz in and say "Dinosauria!"

Thanks to Jerry for pointing out that sparrows are not the same as pigeons. :-)

Monday, January 21, 2008

Spoilerific Review of "Cloverfield"

J. J. Abrams is known for several things. Most famously for Lost, I suppose, an ABC show whose season breaks are so long viewers wonder if it's been cancelled. He also botched Mission Impossible 3 and he's rebooting the Star Trek franchise later this year. But most recently he's produced Cloverfield, a movie known best for its viral marketing campaign. Viral movies have, in the past, succeeded (Blair Witch) and failed (Snakes on a Plane). I have a feeling that Cloverfield will undoubtedly succeed, but that doesn't mean it's good.

I should mention right off the bat that this review is packed to the brim with spoilers. If you haven't seen Cloverfield and don't want anything spoiled for you, don't read any further. However, you should also know that the film's synopsis could be written in about a paragraph, there are no plot twists, and you rarely see the monster that is terrorizing Manhatten Island(which I have named "Das Beastie").

Cloverfield is, admittedly, unique for a number of reasons--one might even say innovative. While most monster movies focus on the monster itself (Godzilla series, Godzilla 1998, King Kong, The Beast from 20,000 Fathoms, I could go on...), Cloverfield tells the story from a bystander's perspective. The only other monster movie that's attempted this viewpoint that I've seen is Gamera: Revenge of Iris, in which a ten-minute sequence depicts Gamera's reckless attack on a Gyaos "bird," destroying half of Tokyo's Shibyua district in the process. Cloverfield is also filmed via hand-held camcorder like The Blair Witch Project, which gives a real sense of scale to the destruction as well as a "you're right there with them" feeling to the movie. The monster itself is fairly unique, and while obviously inspired from several beasties in the past, looks nothing like your standard reptilian behemoth.

The plot is nothing special. The first twenty minutes of the film introduce the five major characters at a party, and one of the characters (nicknamed Hud, surely a reference to Heads-Up-Display) is interviewing people with the camera. An earthquake (or something) momentarily shakes up the party (HA!) and a local news story reports on a barge being overturned in the bay. Everybody runs to the roof because they want to see the overturned ship, only to see a building explode on the skyline. Everybody runs downstairs and then, for reasons unknown, into the streets, where Hud briefly catches a glimpse of a giant vertebrate passing behind a building. Stomps are heard. People scream. The camera shakes madly as Hud runs around.

That's where the trouble starts, at least for me. I imagine this sort of movie would not be difficult to watch on a small TV screen, but in the theater, the constant shaking and motion of the camera may leave you feeling dizzy or at least lightheaded. I ended up with a migrane headache and a feeling of imbalance that lasted until the next morning. None of my friends experienced this motion sickness, though, so it might just be me. If you get motion sick, though, avoid Cloverfield, at least in the theater.

Rob, one of the main characters, decides to find his way to midtown to save his ex-girlfriend, Beth. As his friends warn him, Rob would be crossing the path of Das Beastie, but for reasons I can't quite understand, he cares not. For reasons that make less sense, his idiot friends decide to go with him. Hud feels a duty to film the entire event, even stuff that doesn't make any sense to film, like a pitch-black subway tunnel or running up several dozen flights of stairs. What Hud does a terrible job of filming is Das Beastie itself, who shows up several times (it appears to be following out heroes), but Hud always manages to look at his friends instead of the monster. There are some close-ups, but I would have preferred full-body shots. As it turns out, Das Beastie is hardly in the movie, and when you see it, you just get glimpses. There was a scene late in the going where Hud and his friends are trying to cross a collapsed building, and the monster is coming right for them, in plain view to the left. Hud glances at it, then insists on making sure his friend Lilly's butt is still safe. DUDE! LOOK TO THE LEFT! YOU IDIOT!

Innovative though the camerawork may be, Cloverfield never rises above the standard genre scares. Das Beastie shakes off spider-like parasites which immediately attack innocent bystanders. This is a kind of cool biological trait, but it amounts to a "surprise" encounter with the spiders in that pitch-black subway tunnel, which I could see a mile away. "Hey, a pitch-black subway tunnel. We'll be safe there, right? Oh, it's so dark. Here, turn on the camera's night-vision (because cheap handheld cameras have night-vision). OMG! Spiders! Run!" And of course, the spiders did not attack at any time before they were seen. It would be in bad taste to attack prey that doesn't know you're there. If the spiders bite you, you eventually explode.

Then there's the "monster attacks, to nobody's surprise, the helicopter that Hud and his camera are on," the "everybody survives expect the pilots only to have one more encounter with the monster" scene, and the typical soap opera subplot crap that tires a movie like this out. Why would you film that, Hud? That's the other problem. At a certain point, I would just drop the camera and run--perhaps when Das Beastie is standing right over me, considering its next meal, or when the spider things are attacking the ugly girl. No, I'm just gonna film it. I'll let the cute girl help.

If you've had any interest, you've probably looked for pictures of Das Beastie on the Interweb. You'll usually come across concept art, like the big whale thing with lots of flippers. But the second I got home from Cloverfield, I sat down to draw its insidious form. What you are about to see may shock you, and I have been told from several people who saw the movie that it's essentially accurate. There may be an extra elbow joint in the arms, and the face might be a bit flatter, but...Behold! Das Beastie!



Terrifying, no? Those little paddle-arms bring to mind the Alien Queen. Actually, the whole animal seems like more of a bunch of concepts than a finalized build. Also, the hindlimbs are never really seen--I'm just guessing as to their form. There definately are hindlimbs, and they're a lot shorter than the forelimbs, but...yeah. Anyway, now let's talk about Das Beastie, and the other movie monsters it obviously takes inspiration from.

First off, the head is straight from the creatures in Gears of War. This is especially obvious near the end when it's being bombed, and also when it's staring Hud in the face. It is unique in having soft-tissue inflatable sacs around its temples, which indicates when it inhales and exhales. That's kind of cool. The teeth, tongue, and eyes all scream Gears, though. The tiny mitted vestigal arms smack of the Alien Queen, and the monster's overall arm-centric form may be a nod to King Kong, although that's just a guess. The creature is not textured well, and it seems to have an entirely smooth, perhaps moist skin. Assuming it came from the ocean, it may be originally amphibious. Aside from its sheer size, Das Beastie doesn't look especially threatening, and one wonders how much time Abrams et al. spent on the design. The spider-creatures look more threatening, but definately familiar. There are pieces of the insects from Starship Troopers there, the Splinter bugs from Metroid Prime 2, and the Chimerae from Resident Evil: Umbrella Chronicles. They have a decidedly leggy appearance and a high-rising head, which is kind of cool, but we've seen it before.

But what really irritated me about Cloverfield is exactly what makes it unique. There are no scientists or army generals explaining things away. Nobody knows the monster's motivations. Hud muses to himself as to Das Beastie's origins, but that's all we get. If you stay past the credits, you find out that, like Godzilla (not GINO), Das Beastie is impervious to all weaponry. Did it come from space? The ocean? Some island in the Pacific where a tribe worshiped it as a God and fed it a virgin sacrifice every year until one time they forgot and Das Beastie went on a rampage? Why attack New York? Was it a government-created biological weapon gone awry like in the short-lived TV show Surface? We get nothing, and that really frustrated me. I can only hope that the DVD will include more information about Das Beastie (including a name for it). The director has mentioned in interviews that a sequel may be on the way, and may come in one of two forms (if at all): Another movie shot by somebody else the same night, or an entirely new movie exploring the monster's origins and motivations. Guess which one I'm hoping for?!

Now, two of my friends are absolutely gung-ho about Cloverfield. They loved it, and really felt like they were a part of the action. They did not get motion sickness, and felt that the entire experience was very intense. They are not, however, big monster-movie fans. Thus, they are immune from references to previous kaiju films and genre-specific cliches.

So you may actually enjoy Cloverfield. You might like it a lot, but I couldn't stand it. Aside from the interesting perspective switch, Cloverfield fails to be original in any meaningful way, and may in fact give you motion sickness. Take this monster flick with a grain of salt, and maybe wait for the DVD.

P.S. For both this post and the spinosaur one, I cannot click on my pictures. They will not open in a separate window. Are the pictures too big, or is this a Blogger problem?

Thursday, January 17, 2008

Feeding Adaptations and Strategies of the Spinosauridae

The Spinosauridae is a small family of basal tetanuran neotheropod dinosaurs. Although the group is only known from the Cretaceous period, its origins most likely lie in the Late Jurassic. Spinosauridae is not a diverse clade, consisting of between four and six genera, and possibly as few as three. The group's rarity may in fact be due to its specialized lifestyle. The long, superficially crocodilian snout that defines Spinosauridae has been suggested to support a largely piscivorous diet. Gut contents from the type specimen of Baryonyx walkeri, however, indicate not only that these animals ate fish, but larger terrestrial prey as well. A recent study of Baryonyx's snout indicates that, like the modern gharial, spinosaurs may not have been able to attack large prey with their mouths without risking signficant injury. Rather, I suggest that spinosaurs subsisted mainly on fish but could have easily taken small prey. Spinosaurs also seem to be well adapted to scavenging, especially the more inclusive Spinosaurinae.

The taxonomic history of the group is fairly convoluted, with many taxa based on extremely fragmentary remains. For simplicity's sake, I will here by following Sues et al. (2002) in referring to Suchomimus tenerensis (Sereno et al. 1998) as Baryonyx tenerensis. Further, I agree with Dal Sasso et al. (2005) and Sereno et al. in considering Spinosaurus maroccanus (Russell, 1996) a junior synonym of Spinosaurus aegypticus (Stromer, 1915). Many workers have considered Angaturama limai (Kellner & Campos, 1996) as a junior synonym of Irritator challengeri (Sues et al. 2002) and that, indeed, the two taxa may simply belong to the same specimen (Charig & Milner, 1997; Sereno et al., 1998; Buffetaut & Ouaja, 2002). Thus, I will only discuss three genera and four species herein: Baryonyx walkeri, B. tenerensis, Irritator challengeri, and Spinosaurus aegypticus.

When Baryonyx walkeri was first described in 1986 (Charig & Milner), the comparison to gharials was immediately clear. In fact, Taquet (1984), investigating Stromer's myserious Spinosaurus, made a similar analogy regarding the giant theropod's dentary. Charig & Milner suggested that Baryonyx led a mostly piscivorous lifestyle, stalking riverbanks for fish. The gut contents of Baryonyx included fish teeth and scales, the humerus of a juvenile Iguanadon, and a small phalanx. Clearly, Baryonyx was at least partially piscivorous, but the ornithopod remains indicate that it also consumed larger terrestrial prey. But the question is whether it actively hunted that prey or scavenged it. The fragmentary nature of B. walkeri did not help to illuminate its lifestyle. Only in 1998, when Sereno et al. described B. tenerensis, did Baryonyx's anatomy, as well as Stromer's Spinosaurus aegypticus', become more clear.

Skull of B. tenerensis in lateral view based on Sereno et al. 1998

The vast majority of B. tenerensis' snout was recovered, showing for the first time just how long and narrow the structure really is. Additionally, the external nostril is recessed relative to its position in other theropod dinosaurs. The "terminal rosette" at the distal end of the snout is more obvious and better preserved in B. tenerensis. Interestingly, the giant gharial-like crocodilian Sarcosuchus imperitor (Broin & Taquet, 1966) lived alongside B. tenerensis and may have competed with it for food.

Sereno et al. (1998) divides the Spinosauridae into two distinct groups: the Baryonychinae, which includes the genus Baryonyx, and the Spinosaurinae, which includes the genera Irritator and Spinosaurus.


Skull of Irritator challengeri in lateral view based on Sues et al. (2002) and Dal Sasso et al. (2005).

Despite sharing obvious similarities, the Baryonychinae and Spinosaurinae are surprisingly different. Baryonyx has more teeth in its jaw than either Irritator or Spinosaurus, and those teeth are smaller and more recurved. In fact, spinosaurine teeth conical, tapering evenly toward their apex, and lack serrations. Baryonyx has very fine serrations on the anterior and posterior keels. The "terminal rossette," first pointed out in B. walkeri, is far more obvious and accented in spinosaurines. The spinosaurine premaxilla has fewer, but larger, teeth, and the matching area of the dentary has similarly large and reduced dentition. While Baryonyx's teeth continue along the maxilla nearly to its terminal end at regular intervals, the maxillary teeth of Irritator are small, unevenly spaced, far reduced in number, and end cranially to the antorbital fenestra. While it would be tempting to say that the Spinosaurinae is a derivation of the Baryonychinae rather than a sister group, the occurance of Irritator in Lower Cretaceous strata casts doubt on this hypothesis. Whatever their relationship, the two families were clearly pursuing different methods of obtaining food.


Skull of Spinosaurus aegypticus in lateral view based on Dal Sasso et al. (2005).

Spinosaurus shares more in common with Irritator than with Baryonyx, while developing some unique features of its own. The snout's terminal rosette is extremely long. The secondary bony palatte, a bony structure evolved independantly among spinosaurs, is large and dominates the ventral portion of the premaxilla and maxilla. Spinosaurus' external nostril is unusually small, not boardered at all by the premaxilla, and set far back on the snout. While the anterior portion of Irritator's skull rises sharply toward the orbits, Spinosaurus' skull remains on a fairly steady and shallow upward slant toward the orbits. The large crest of Irritator, which may have been a soft tissue structure, is underdeveloped in Spinosaurus, whose nasal bones fuse and fan upwards, producing a fluted crest. In the Spinosaurinae, the eyes were set high on the skull, while in the Baryonychinae, the eyes were set along the same plane as the external nostrils.

Premaxilla/maxilla in Spinosaurus (top) and Baryonyx (bottom) in ventral view, showing distinct secondary palate (dark blue). Redrawn from Sereno et al. (1998) and Del Sasso et al. (2005). Contact between left and right halves of the palate in Baryonyx extended a bit farther than restored above.

I mentioned previously the notion that spinosaurs have traditionally been considered crocodile analogues. Indeed, as you will recall, the type specimen of Baryonyx walkeri was found to have fish teeth and scales in its belly. When B. tenerensis was originally described, Sereno et al. named it "Suchomimus," literally, "crocodile mimic." Certainly the long and narrow snout of Baryonyx led to such comparison. And yet, until just recently, no test had been done to determine the authenticity of such intuition. Rayfield et al. (2007) used a comparative biomechanical analysis to test stresses applied to the skulls during biting for three taxa and one generalized theropod dinosaur. The type of Baryonyx walkeri was used, as was a modern gharial and alligator. The bite force analysis for B. walkeri was almost exactly the same as for the gharial. The authors suggested that spinosaurs evolved their own secondary palate to resist torsion stresses. The reduction and recession of the antorbital fenestrae also confer greater strength to the snout. In other words, the crocodile analogue is quite appropriate, although we should perhaps being calling them "gharial-mimics."

Gharials are, of course, specialized piscivores. Their extemely narrow jaws, complete with interlocking teeth, are easily whipped through the water to snatch a fish or swimming tetrapod. However, larger prey, especially struggling prey, poses a risk to gharials, whose thin snouts can be damaged by too much stress and torsion. Alligators and crocodiles, whose snouts are far broader, are able to tackle much larger prey without risk to their skulls. The convergent gharial-like shape of the snout in spinosaurs is almost certainly an adaptation to piscivory, although to what degree is contentious. Also, the mode of prey capture is mysterious. As Charig & Milner pointed out, B. walkeri contains no obvious aquatic adaptations. Aside from its head and hypertrophied thumb claw, the body of B. walkeri is that of a basal terrestrial tetanuran. The more complete remains of B. tenerensis confirm this. While not much of Spinosaurus' postcranial skeleton is known, its skeleton, too, seems distinctly "theropodian." Of note, Spinosaurus displays unusually lengthened (and widened) neural spines along its dorsal vertebrae.

Many illustrators, including Paul (1988) have restored B. walkeri as a bear-like piscivore, standing on the shoreline and using its enlarged thumb claw to bat at and "spear" fish from the water, as well as darting its gharial-like snout into a group of fish. The exact manner in which spinosaurs obtained their fish will probably never be known, but there are other possibilities. Despite not having any obvious skeletal adaptations for an aquatic lifestyle, many vertebrates, including bears, stalk their slippery prey in other ways. Bears do not simply stand on the shore and wait for a fish to jump toward them. Rather, bears will often run headlong into a stream or lake to actively pursue salmon. This is especially true during yearly salmon runs in Alaska and Canada. One can easily imagine a group of Baryonyx crowding around and in a river while a high concentration of fish swam through it. One questions whether or not Baryonyx would have been able to pluck a fish from its giant thumb claw with its jaws. Its arms, while robust, were not exceptionally long. Bears use their large paws to bat fish from the water onto land. The giant thumb claw of spinosaurs may have had other uses, such as defense from predators (more on that later) or intraspecies conflict.

Many modern fish-eating birds, such as herons, storkes, and pelicans stalk fish by standing motionless in the water, their heads held just above the water surface. When a fish swims close by, the bird snaps its head into the water and plucks the fish up. With their serpentine necks and long snouts, one can easily imagine a spinosaur doing the same thing. Some birds create shadows over the water with their wings, which fish are drawn to. While spinosaurs did not have wings, their size, and perhaps the sails of spinosaurines, may have helped in this regard. One wonders if perhaps spinosaurs hunted fish like modern gharials do--by lying in the water and scooping up fish as they pass. However, crocodilians have the advantage of telescopic eyes and noses, which at least Baryonyx lacks. Baryonyx's naris, while recessed, is fairly close to the end of the snout. Where its nose higher or farther back on the skull, the animal could leave its mouth in the water, agape, and still breathe. This was not the case, however, and more likely Baryonyx a more avian or ursine approach to its piscivory.

But what about larger vertebrate prey? Again, the original B. walkeri material contained a small Iguanadon humerus in the gut. Whether the carnivore actually killed the ornithopod will never be known, and the fact that it was a juvenile Iguanadon is more problematic. Could Baryonyx kill a juvenile but not an adult? Could Baryonyx's long skull withstand the stress and torsion of a struggling genusaur? And why was only a humerus found? I am not sure how capable a predator Baryonyx would have been--at least among large tetrapods. The long snout and terminal rosette of Baryonyx certainly would have its advantages for scavenging carcasses--the entire head need not be lodged in the prey's body cavity, and the premaxillary notch may have been useful in plucking meat from the carcass with a minimum of tough bones coming along with it.

But as we've seen, Baryonyx was clearly doing something far different than Irritator and Spinosaurus, so what of them? If we peg Baryonyx as a mainly piscivorous, potentially scavenging aimal, what can we say of the spinosaurines?

A collection of line drawings showing Spinosaurus aegypticus intimidating rival predators from a carcass (top), scavenging up to its nostrils (bottom left), and engaging in a unique mode of piscivory (bottom right).

What is immediately apparent to me of the spinosaurine skull is that the orbits have recessed caudally, but moved upward. While less severe in Spinosaurus, the skull slopes upwards from the snout moreso than in Baryonyx. Furthermore, the number of teeth is reduced, and those teeth tend to be larger and more spike-like in the spinosaurines. The snout of a spinosaurine is long, but not as long proportionatelly in relation to the total length of the skull as in Baryonyx. The external naris is recessed and shrunk down, moreso in Spinosaurus than in Irritator. The large distal portion of the dentary is nearly square in lateral view, and beyond that, the entire lower jaw is deeper than Baryonyx. The spinosaurines were clearly doing things differently than Baryonyx, but how?

First, I believe that spinosaurines would have been very effective scavengers. While they certainly had more bite force than Baryonyx, I doubt that even Spinosaurus would have been very effective in taking down the resident sauropods and ornithopods that shared its habitat. At least, not the adults. For predatory purposes, Spinosaurus and Irritator may have hunted sick, injured, or juvenile animals, but may have preyed on much smaller fauna in between carcasses. The huge sail and body size of Spinosaurus may be explained as a way to intimidate other carnivores away from a carcass. Even the large carcharodontosaurs that shared Spinosaurus' habitat must have reconsidered a kill after seeing an even larger carnivore approach it, complete with an enoromous, flash sail on its back! Spinosaurus was well-equipped (moreso than Irritator) to empty a dead animal. With its recessed nostrils, Spinosaurus would have been able to explore a dead body without worrying about breathing. The eyes, which were high on the head, would have been able to scan the horizen for potential threats while feeding.

Surely Irritator and Spinosaurus had not abandoned their piscivorous ancestry, and both animals show further adaptations for fish-feeding. Unlike Baryonyx, the recessed external naris of both genera would have allowed the animals to stalk their aquatic prey with their mouths partially in the water. Should a fish swim in between their teeth--SNAP--free meal! Perhaps a long pink tongue would have come in handy for attractive fish. Snapping turtles do it; why not Spinosaurus? Wouldn't it be an awesome sight to see several adult Spinosaurus back-deep in a river, with only the tops of their heads and giant sails in sight? It would be good to know whether spinosaurs displayed any degree of osteosclerosis, as that could indicate how much time it spent in water. If Spinosaurus, Irritator, or Baryonyx were bottom walkers, it would be much easier to decipher their feeding strategies.

Spinosaurs seem to have evolved to take over a small, but successful niche during the Cretaceous period. They may have lived in areas where crocodilians of similar habit did not exist, thus allowing such a specialization to occur. At least one giant crocodilian, Sarcosuchus imperitor, lived alongside Baryonyx tenerensis, but whether they hunted the same prey may never be known. While the Baryonychinae may have hunted much the way modern bears do and preferred piscivory over terrestrial prey, the Spinosaurinae seems equally suited to both piscivory and scavenging. Both groups probably hunted smaller vertebrate prey as well. In fact, Buffetaut et al. (2004) described a pterosaur vertebra with a spinosaur tooth embedded within it. Although the group does not appear to have been terribly diverse, further study of known specimens, as well as discovery of new ones, will surely elucidate more information on these strange and wonderful animals.

References

Charig, A. J. & Milner, A. C. (1986). Baryonyx, a remarkable new theropod dinosaurs. Nature 324: 359-361.

Sereno, P. C., et al. (1998). A long-snouted predatory dinosaur from Africa and the evolution of spinosaurids. Science 282: 1298-1302.

Sues, H. D., Frey, E., Martill, D. M. & Scott, D. M. (2002). Irritator challengeri, a spinosaurid (Dinosauria: Theropoda) from the Lower Cretaceous of Brazil. Journal of Vertebrate Paleontology 22(3): 535-547.

Dal Sasso, C., Maganuco, S., Buffetaut, E. & Mendez, M. A. (2005). New information on the skull of the enigmatic theropod Spinosaurus, with remakrs on its size and affinities. Journal of Vertebrate Paleontology 25(4): 888-896.

Rayfield, E. J., Milner, A. C., Xuan, V. B. & Young, P. G. (2007). Functional morphology of spinosaur 'crocodile-mimic' dinosaurs. Journal of Vertebrate Paleontology 27(4): 892-901.

Buffetaut, E., Martill, D. M. & Escuillie, F. (2004). Pterosaurs as a part of a spinosaur diet. Nature 430: 33.

Russell, D. A. (1996). Isolated dinosaur bones from the middle Cretaceous of the Tafilalt, Morocco. Bulletin du Museum National d'Histoire Naturelle, Paris 4(18): 349-402.

Buffetaut, E. & Ouaja, M. (2002). A new specimen of Spinosaurus (Dinosauria, Theropoda) from the Lower Cretaceous of Tunisia, with remarks on the evolutionary history of the Spinosauridae. Bulletin de la Societe Geologique de France 173: 415-421.

Kellner, A. W. A., & Campos, D. A. (1996). First Early Cretaceous theropod dinosaur from Brazil with comments on Spinosauridae. Neues Jahrbuch fur Geologie und Palaontologie, Abhandlungen, Stuttgart 199: 151-166.

Stromer, E. (1915). Too long to type. Das Original des Theropodes Spinosaurus aegyptiacus...too long to type 30: 1-22.

Charig, A. J. & Milner, A. C. (1997). Baryonyx walkeri, a fish-eating dinosaur from the Wealden of Surrey. Bulletin of the Natural History Museum, London, Geology Series 53: 11-70.

Taquet, P. (1984). Une curieuse specialisation du crane de certains Dinosaures carnivores du Cretace: Le museau long et etroit des Spionsaurides. Comptes Rendus de l'Academie des Sciences, Paris 2(299): 217-222.

Broin, F. & Taquet, P. (1966). Decouverte d'un Crocodilien nouveau dans le Cretace inferieur du Sahara. Comptes Rendus de l'Académie des Sciences à Paris, Série D(262):2326-2329

New Blog, as well as an Announcement

Scott, of Coherent Lighthouse, our mutual friend Brian Lyons, and I will be producing and displaying our own art show later this year in Palmer, Alaska. The theme is "The Archosauria," and, predictably, will highlight the great diversity of this massive clade. Our taxa list has been finalized, so no suggestions, folks!

You know, unless it's a good one, in which case I'll consider it. But nothing beats Effigia, people. Nothing.

At any rate, Scott has bit the bullet and signed on to Blogger, despite my flagrant arm-waving and general ballihooing. Check out the new link to the right. As I've said before, the man is one helluva an artist. Also new to the blogosphere is Brian, whose new blog, "The Wild Worlde of Wonder," is also new to by blogroll. Check it out as well!

Up next: Giant post about spinosauroids, with lots of original illustrations! Wheee!

Saturday, January 12, 2008

The Boneyard XI

The Boneyard? It's back! Laelaps' premier blog carnival makes its second appearance on my humble blog, and more than a month has passed since its last iteration. Here now, dear readers, are this edition's submissions!

The big news this last month was Indohyus, a new basal artidactyl that forms a sister group to whales. Several bloggers put their thoughts to keyboard. Of course, Brian starts thing off nicely as he shakes the cetacean family tree. The Hairy Museum of Natural History also chimed in, as did Pondering Pikaia, The Loom, Greg Laden's Blog, and of course, When Pigs Fly Returns.

Amanda from Self-Designed Student has some excellent offerings this time around, including a beautiful Triceratops painting and a cautionary tale about the Irish Elk, which is neither Irish or an elk.

Julia, that most Ethical of Palaeontologists, has some fine posts up this month. There's the funny, but also sad question about Carcharodontosaurus, some humorous dinosaur misconceptions, and a "Merry Christmas" via giant freaking rat.

My buddy Darren Naish has taken a break from anurans lately to focus on...well, salamanders. I sense a new series! There were also those those two posts about caecilians, the strangest living amphibians of all. He also dissects claims that pterosaurs are alive and kicking. Rubbish, I know. But perhaps his most entertaining posts have been the castration of a terrible book, How (not) to Keep Dinosaurs, and then, perhaps, how to really keep dinosaurs.

Speaking of pterosaurs, you'd all do well to check out David Hone's entertaining pterosaur-related blog, in which Dave does a whole lot of good-natured ribbing, but you'll learn more than you care to about pterosaur, archosaurs, and the world of paleo publication that you ever did before! And ask questions, because he eagerly answers them!

If paleo isn't your thing, Christopher Taylor has blessed us with Circus of the Spineless a blog carnival dedicated to invertebrates in all their glory. He also has a great post about the perils of modern taxonomy.

Will Baird gives us the low-down on Cretaceous glaciation. There's also a teaser for a post that will never come to fruition! Politics are great, Will, but get back to the paleo!

Manabu Sakamoto guides us through the process of drawing a gorgeous Allosaurus fragilis. Nicely done, Manabu. Wish I had those mad skillz.

Phew. If I type target=_blank>one more time I'm going to kill somebody! But I must press on!

My own offerings are quite meager this month. I was stuck in Kansas for two weeks without access to a scanner, so I wasn't very motivated to do some big uber-post. But I do have one or two posts of note. Mike Skrepnick and I had a discussion about restoring dinosaurs. I offered my opinion on the Stygimoloch, Pachycephalosaurus, Dracorex debate, and I wrote about what I do and do not want to see in the inevitable Jurassic Park 4: Dinosaurmaggedon.

And then we get to the Boneyard's founder. The man has way too much time on his hands, because he makes all of us paleo-bloggers look like lazy bums ever week! Despite this, his writing style is sharp, entertaining, often witty, and always enlightening. It's difficult to pick just a few key posts from all of Brian Switek's lovely prose, but I'll give it a shot.

We all like spinosaurs, right? Well, is that crocodile analogue worth its weight in fish? turns out, it might be! Brian offers an excellent rebuttal to a recent axe-grinding author who claimed that, obvously, Psitacosaurus' quills are not analogous to protofeathers. Although, after reading the paper itself, the reason is not exactly clear. He also discusses evolution's arrow, or lack thereof.

There it be, folks. Enjoy the Boneyard, and if I get any more submissions today or tomorrow, I shall add them, just because I care.

Thursday, January 10, 2008

Reconstructing Dinosaurs with Mike Skrepnick

A lot of you responded strongly to this post, in which I chided the media for demanding a full restoration of an animal known only from a hand and part of a foot. That beast was Hagryphus, and I asked my readers their opinions on restoring animals from scrappy remains. Mike Skrepnick and I had a chat about it over the email, too. I'm going to copy and past that conversation here, interspliced with some beautiful pictures that Mike graciously let me post here, possibly for the first time.


Zach (me): What do you think of restoring an animal from less-than-spectacular remains? Not just Hagryphus, but even a beastie like Masiakosaurus, who is known from otherwise pretty good remains, but the entire skull is missing?

Mike: In terms of "reconstructing dinosaurs based on scrappy material", I think its a "double edged sword" of sorts. . . ( a lot of the following, I'm sure you're familiar with, but is essentially my perspective on the subject, and observations on paleo art in general )

ON ONE HAND, it can call for an inordinate amount of speculation on the part of the artist, as you are implying anatomical features ( in a worst case scenario based solely on speculation / fantasy ), rather than at the very least an "inferred" look ( in cases where some elements are diagnostic and can point you in some general direction, Hagryphus being a case in point ). If you consider the problem of extinct vertebrate reconstruction from a more universal, objective perspective, it is clear that even in relatively well known taxa, a fleshed out reconstruction is still very open ended, in terms of soft tissue anatomy, integument, coloration, etc. . .

consider the following. . .

- evidence for dewlaps, skin folds, etc. . . as in hadrosaurids, where some of the mummified remains can be very suggestive, although not representative of all members of a clade

- specimens in which scalation / tubercles / dermal armor - ossicles / scutes, etc. . . are preserved as fossil elements / impressions, even revealing patterns of organization (ceratopsian rosettes, flank and underbelly linear arrangements in some lambeosaurines, etc. . . ), but often only in small areas of skin preservation. To date, I think the Brachylophosaurus "Leonardo" has the best overall "map" of differentiation observed in a single, intact body, but in most when left with only small, tantalizing areas of dermal structures, what to do in terms of the rest of the outer appearance ?

- theropod "lips", don't even get me started on this one. . .

- if the proximo / caudal bristle-like "mane", recently discovered in psittacosaurs ( by virtue of one chance discovery ) can give us such a dramatic change in the look of an otherwise, well known genus, what does it imply in terms of our understanding of the actual appearance of dinosaurs in general ?

- not so very long ago, ( 1996 when Phil and I were in Beijing, and the first North Americans to see the now infamous type of Sinosauropteryx with filamentous feathery "halo" preserved intact ), we were witness to a paradigm shift in the science, that has changed the course of vertebrate paleontology in a significant manner. Prior to that, suggestions of the bird - dinosaur relationship posited by Ostrom, Bakker, and Paul, were not nearly as defined, as our understanding is getting to be now ( I remember alot of us looking at Greg's feathered dromaeosaurs with a certain initial skepticism prior to the entry of "Sino" and subsequent feathered theropods, but in hindsight seems pretty certain his intuitive observation was right all along, and has been fully vindicated in his "artistic assertions".

- another leap by an order of magnitude is in coloration ( which we've discussed previously ), modern analogs, being in my opinion the best guide / reference in this respect, but still subject to conjecture. You know the old story " short of a time-machine. . . "

- extrapolating further still, what about postulating on traits and behaviours, environments, ecosystems. . . paleo botanical specimens, references and data are even more dodgy than that encountered in animal remains. I've often experienced far more frustration in attempting to reconstruct plausible environments / placing dinosaurs in context, than in dealing with the dinosaurs themselves.

- if, in only a century we've gone from the "cutting edge" science of Marsh and Cope ( that insisted upon seventy - eighty foot long sauropods largely restricted to life in ponds and lakes to help float their mass, incapable of supporting their weight on dry land ), to current day advances that reveal truely enormous titanosaurs that moved freely about, wide experimentation in small theropod flight mechanisms, alternate metabolic regimes, etc. . . What does the future of paleontology hold in store? How much of what we now understand, will be overturned, reinterpreted, replaced by new information through technological advancement yet to be invented / discovered ? Perhaps at this stage, it will progress in small increments of "fine tuning", but I wonder what dinosaurs will look like by 2108?

ON THE OTHER HAND. . . if we in some cases have only tenuous material to work from and choose as a result of limited data, not to address a "reconstruction" until better specimens come to light. . . how long might we wait ? Paleontology, by virtue of the very nature of the science, calls for a certain amount of "imagination" ( a reason why I think many involved in this pursuit, also have a penchant interest in science fiction, fantasy, etc. . .) It's a sort of "new frontier" science, in reverse.

For now "paleo art" is still in the largest sense "Art". . . a vehicle by which we can try to grapple with extinct worlds in a manner that complements the formal description of specimens within the literature, and is a conduit that makes the hard science accessible to the general public. The point of restoring extinct taxa visually ( whether from a handful of isolated elements or fully articlulated pristine skeletons ) is by a matter of degree, an attempt to hypothesize appearance. . . and however imperfect, it's the best we can do with what we have. In my own musings ( on my better days ), I like to think I'm for the better part "getting it right". . . as an advocate for ancient life whose "voice" is at best, a distant "echo" in the fossil record, the process of interacting with academics and interpreting information through the medium of paint remains an intriguing challenge.


Zach: I agree on all counts. And it really is fascinating that the entire face of the Dinosauria has been turned on its head over the last twenty-five years. It's so exciting, too. But it's also frustrating! We'll never know all there is to know about our favorite saurians. And that really is where paleoartists like you (and to a lesser extent, me) come in. We fill in the gaps as best we can, although there are times where the most tantalizing bits are just out of reach!

Mike: The interesting juxtaposition is. . . that art is inherently a subjective manifestation of the artist, while paleontology requires detached objectivity in analysis of the data. The function of the paleo artist is to attempt to successfully straddle the nether regions between both disciplines, producing a result that will both survive scientific scrutiny and satisfy our natural curiosity.

The man has some good points! Paleoart really is about trying to find that balance between objectivity and creativity. And clearly, Mike knows his stuff. Look at these beautiful pieces! For the curious, that's "Black Beauty," a gorgeous Tyrannosaurus on top, Corythosaurus in the middle, and Acrocanthosaurus down here. And hey now, that Corythosaurus is standing in the same spot that a Tyrannosaurus took down a Triceratops on the cover of Dinosaur Imagery! I just noticed that.

Again, dear readers, feel free to make your own points in the comments section! And I may have to blog about how I reconstruct dinosaurs, so you can all give me tips!

P.S. The Corythosaurus landscape is not really the same as T.rex vs. Triceratops. I just thought they looked similar enough to make a passing reference. As Mike pointed out to me, nine million years separate the helmeted lizard from the tyrant and the three-horned face.

Tuesday, January 08, 2008

The Triumphant Return of...The Boneyard!

Get those submissions in, people, either through the comments here or email. After an overly-long absence, The Boneyard is coming back full swing here on When Pigs Fly Returns. Surely you've all managed to write something awesome over the last two months! Let me know of your submissions, and they shall be included. I hope to have the new edition up by Saturday, so get crackin'!

Monday, January 07, 2008

Indohyus: Awesome, but not a Whale


Blogging on Peer-Reviewed Research
A note on this restoration: It is tentative. Until I get the damn Wacom tablet working again, you'll have to do with this hairless, B&W version of Indohyus. When my technology decides to work for me, I will replace this shoddy line drawing with a much improved, fuzzy, colorful animal. But I'm going into blogging withdrawl, having not done so intently since Christmas. I apologize to all six of my readers, because I've been promising a post about Indohyus for awhile.

For those paleo-bloggers among you who have been living under a rock for the past few weeks, there's a new ancestral whale in town. You didn't think it could get much more basal than Pakicetus, did you? Honestly, it can't, but Indohyus (Thewissen, et al. 2007)* comes darn close. New fossil material from the quite old genus shows that the Raoellidae, the family to which Indohyus belongs, shares quite a few features in common with early and modern whales. As I will illucidate further on, this does not mean that Indohyus is actually a basal whale.

About the size of a racoon, Indohyus a lithe, gracile little animal. At first (or second, or third) glance, this raoellid looks absolutely nothing like the superficially crocodilian Ambulocetus or foxy Pakicetus. Truthfully, Indohyus has no modern analogue, which may be why the media has been so hard-pressed to compare it some extant animal for their readers. In a now infamous flub, Seth Borenstein of the Associated Press, in a stumbling attempt to explain what Indohyus looked like for those of us who couldn't just look at the accompanying image (by the excellent Carl Buell), suggested that it resembled "a long-tailed deer without antlers or an overgrown long-legged rat." Deer don't look much like rats, Seth.

Comical analogous snafus aside, the point is that Indohyus is suspiciously devoid, on the surface, of any features that would identify it as a potential cetacean ancestor. Probing deeper, however, Thewissen, et al. have found several subtle clues to its common ancestry.

First and foremost, little Indohyus' middle ear features an extra "wall" of bone called the involucrum, which helps whales hear underwater. Mammals are able to hear underwater thanks only to the vibrations of the skull bones (so our underwater hearing is severely dampened). Sound waves hit the whale's involucrum, and the waves are amplified and directed toward the ear canal. Modern cetaceans have managed to evolve melons and echolocation which further amplify sound waves via both the melon and the lower jaw. The involucrum is merely the first step in what will eventually be a very complicated method of hearing underwater. In a way, it's not a whole lot better than the basal mammalian condition--the involucrum merely amplifies the skull vibrations brought on by underwater sound waves.

In fact, Thewissen et al. aren't even that excited about the involucrum. Rather, they focus on the fact that Indohyus was an aquatic wader or bottom-walker. The bugger displays osteosclerosis, which is a fancy word for "thick limb bones." Osteosclerosis is not a unique feature to whales. Virtually all aquatic vertebrates evolved it due to the rigors of a marine lifestyle. In terms of bone thickness, Indohyus falls somewhere between hippos (which are bottom-walkers) and Ambulocetus (a swimmer). Because Indohyus' gracile limbs were not well adapted to a swimming lifestyle, Thewissen et al. interpret Indohyus as a bottom-walker.

The chemistry of Indohyus' enamel was studied to try and figure out its diet, but the authors could only conclude that Indohyus' diet must have been quite different from Pakicetus and Ambulocetus. Omnivory or herbivory are suggested, although the authors lean away from aquatic foraging toward the end. Thewissen, et al. suggest that Indohyus lived a lifestyle comparable to the muskrat, who spends most of its day in the water, coming ashore to sleep and eat its leafy greens (although the muskrats here in Alaska are strictly carnivorous).

Now, on to the phylogeny. I'm stealing Carl Zimmer's excellent cladogram, which shows exactly how Indohyus relates to whales (as far as we know) and why it's NOT on the direct cetacean lineage. Sorry, Carl!

What Indohyus and its raoellid cousins represent, kids, is an outgroup. Indohyus : Cetacea :: Silesaurus : Dinosauria. Need another example? Okay, I can do this all day. Herrerasaurus : Saurischia :: Indohyus : Cetacea. Want a non-dinosaurian comparison? Well, too bad. At any rate, Indohyus is too specialized to be a proper ancestral whale. Also, raoellids were around at the same time as the first cetaceans. Indohyus was not some ancestral whale. Rather, the Raoellidea shares a common ancestor with the Cetacea, and that common ancestor had an involucrum and was probably semi-aquatic by way of osteosclerosis.

The "Y" node on Carl's cladogram with Indohyus on one end and the branching Cetacea on the other is an unnamed clade. I humbly submit "Cetaceaformes" or some similar term.

The realization of Indohyus' cetacean features further calls into question the genetic evidence favoring a hippo/whale grouping. It may be that hippos still are related to whales, but in a (hippos + Cetaceaformes) way. We really need some basal hippo fossils. It could be that an aquatic nature was basal among some hypothetical hippo/Cetaceaformes ancestor (I don't even want to think about what that clade would be called), and that the invoculum is a novelty for Cetaceaformes. Now I'm rambling.

But that's Indohyus. An awesome little animal, to be sure, but I don't want people getting the wrong idea about its relationship to whales. It is NOT a whale, but an outgroup to whales.

* Was anyone else annoyed that Thewissen, et al. did not reference the species anywhere in the paper? According to the always-reliable Wikipedia, Indohyus consists of two species, I. major and I. indirae. It's possible, if not probable, that the two species are synonyms of each other, but I would have liked some explaination of Indohyus' taxonomy in the paper. It wasn't clear whether Thewissen, et al. was describing a brand-new creature (as the news items would lead one to believe), new material from an existing taxon, or a new taxon from somebody's basement.

Sunday, January 06, 2008

I Blame the Apparatus

I've been back in town for a few days now, scanner at the ready. I've got a McLarge Huge post about Indohyus, early whales, and what the former means for the latter. I drew a picture of Indohyus that's a bit different than Carl Buell's interpretation, but my Wacom tablet is on the fritz, so I can't color the little bastard or put hair on him. And since I'm fairly certain, given Indohyus' limb anatomy, that it wasn't hippo-like, so I'd like to put some hair on it.

But good things come to those who wait. Actually, some of you might know the answer to my Wacom woes. Here's the deal: I haven't used the Wacom for like six months. I plugged it in today, and the damn thing starts registering a line (on Corel & Photoshop) before the pen touches the tablet. That little green light that's supposed to light up when the pen hits the tablet? It's green a few centimeters before that. I also cannot "click" things by tapping the pen to the tablet. Clicking doesn't work, and the drawing is screwed up. If anybody knows how to right these wrongs, please speak up!

Tuesday, January 01, 2008

New Art Project

Many of you probably aren't aware of this, but I'm a huge fan of H. P. Lovecraft's horror stories. His "Cthulhu Mythos" (not his term) is wonderfully alien, and Lovecraft has managed to create a ghastly world apart from our own without relying on traditional or cliched means. For fans of the macabre genre, Silicon Knight's excellent Eternal Darkness is a gaming homage to Lovecraft's work. The ill-fated Call of Cthulhu, while hard to find, manages to remain true to the source material (although creature designs are fairly standard). The fantastic comic "Hellboy" also aludes to Lovecraft's stories at every turn.

But enough about that. I've been putting this off for awhile, but I think I might start a new art project, focusing on the various beasts and horrors of Lovecraft's black universe. I'll start big--with Cthulhu himself. So you might not see too many of my dinosaurs in the next few weeks. But that's okay, because hopefully my Lovecraftian beasties will haunt your nightmares instead!