I Think it Moved

Well, it's been a long time coming, but here it be: the newest comic! I hope you enjoy it as much as I enjoyed drawing the third panel. I know that I keep saying that I'm not obsessed with the weenis, but I'm beginning to have my own doubts! But honestly, that Throbicok is one bad-ass Pokemon. Incidentally, Dikidik/Throbicok is my third original Pokemon lineage, the first being the Chili's Bodangle (and it's Basic form, Dangleberri), and the second is a sort of ode to the Rudolph the Red-Nosed Raindeer yeti. Scary looking dude.

I'm moving tomorrow. Again. Gina and I sign the closing documents in the morning, and we start moving boxes over in the evening. By Monday, we should hopefully be completely moved in. What of our current condominium? We're renting it out so as to not pay the dreaded Double Mortgage. That would be a killer, especially given my current precarious job situation.

I'm going to try and go back to a regular comic-posting schedule (once a week). Next Monday I might actually re-post all of the comics I've done up to this point, given that this is a "new" blog and that only two other comics (aside from this one) have been posted here. We'll see, though. I have lots of stuff I'd like to share in the next several weeks.

Early Representatives of the Dinosauria Compared

Despite their popularity and a wealth of good material, the origins of the Dinosauria are still somewhat murky. This is not to say that paleontologists don't know where they came from--not at all. Dinosaurs are dinosauriform ornithodirans more derived than Marasuchus. The stepwise progression from Lagerpeton to Marasuchus to Psuedolagosuchus (and maybe Silesaurus) to Dinosauria well supported and has withstood every cladistic analysis I can think of that deals with the issue of dinosaur origins.

What's not so fully understood is the most basic split between the two major dinosaur clades. On one end, the more basal Saurischia, which retained the tri-radiate pelvis of its ornithodiran ancestors, as well as the carnivorous appetite and bipedal gait of its forebearers.

On the other side, the ornithischians were slower to diversify (if Eocursor's authors are right) but that could be thanks to their much more derived skeleton. These were herbivores through and through. And while theropods were carnivores, prosauropods may have been omnivores, and sauropods were growing to enormous sizes off the ferns of Pangea, ornithischians were having a tough time finding their niche. Right off the bat, ornithischians reworked their skeleton to include a sizeable gut, quara-radiate pelvis, and a unique predentary bone which capped the lower jaw.

I have reproduced two skulls here. Eoraptor (top) after Sereno's description with bits and pieces from Paul (2003), and Lesothosaurus after The Dinosauria, 2nd Edition, which is three or four years old now. Even the basic skull structures of these two animals are strikingly different, which seems so bizarre to me, given that both are the most primitive members of their respective groups--the closest on both sides of the Dinosauria to the common ancestor*.

The most notable difference (to me) is that in the ornithischians, the quadrate articulates with the surangular, unlike the case in Eoraptor and sauropodmorphs, in which the quadrojugal is the articulating bone. Exactly how this difference affects function, I'm not sure. In Archaeopteryx, however, the quadrojugal has been reduced to a small L-shaped splint between the jugal and the quadrate, and the quadrate articulates with the surangular. Another major difference is that the general construction of Lesothosaurus' skull is far more robust than Eoraptor's. Just look at a simple bone like the jugal (light blue). In Eoraptor, it's thin, but in Lesothosaurus, it's an enormous bone. Ornithischians also quickly began closing off the antorbital fenestra--the hole between the orbit and naris. In advanced ornithischians like thyreophorans and cerapods, the hole closes off completely.

Ornithischians also developed a strange "prong" of bone off the prefrontal (I can't remember the exact name--it's always "pap" in descriptions). This prong would have sat just above and in front of the living animal's eye, giving ornithischians a sort of "eye shade." Ankylosaurs eventually lose the prong, and hadrosaurs reduce its size, but exactly what purpose an eyeshade served is beyond me. Whether any workers have published on this question, I do not know (but I'd like to! Anybody?!). The nasals are large and wide in Lesothosaurus, but not so much in Eoraptor. The nasal bones rise in importance for many later theropod groups including abelisaurs and various tetanurine lineages, but their prominance is never questioned among the cerapoda. Ceratopsians and lambeosaurine hadrosaurs put an evolutionary premium on the nasal bones.

Since there's a loss of the antorbital fenestra, the lacrimal bone is large in Lesothosaurus and serves to wall off the preorbital region of the skull. In Eoraptor and many later theropods (and some early sauropodmorphs), the lacrimal is L or T shaped and twisted along its waist.

On the mandible, theropods and sauropodmorphs kept the strong mandibular fenestrae of their ornithodiran forebearers, but this hole, like the antorbital fenestra, simply shrinks and then closes off completely in ornithischians. Ornithischian dinosaurs developed a upward flange on the surangular that I find analogous to the large flange for muscle attachment in mammal jaws. The ornithischian flange is nowhere near as large (proportionately), but the fact that the two flanges developed in essentially the same place may have to do with chewing food. Since theropods and sauropodmorphs swallowed their food whole, a flange never developed.

It is interesting that Eoraptor and Lesothosaurus both display heterodonty, although they are reversed respective to each other. Eoraptor has spade-shaped teeth in the premaxilla and more traditional slicing teeth in the maxilla, while Lesothosaurus has pointed teeth in the premaxilla and spade-shaped teeth in the maxilla. Rather than indicate omnivory in Lesothosaurus, the sharp premaxillary teeth may simply compliment the animal's predentary bone in cropping vegetation. It's entirely possible, however, that Eoraptor occassioned plant matter from time to time. Some prosauropods, including Anchisaurus, have been regarded as omnivorous given their subtle heterdont conditions.

The wealth of differences present in the skulls of Eoraptor and Lesothosaurus are somewhat disturbing, given their supposedly "primitive" conditions. One would not expect to see an animal as obviously derived as Lesothosaurus while its near-contemporary, Eoraptor, retained so many ancestral features. Furthermore, Eocursor (see previous post) suggests that the ornithischian radiation did not explode until the Triassic/Jurassic extinction event opened up herbivorous niches previously unavailable to ornithischian dinosaurs. This suggests that ornithischian evolution went through a considerable "lag" period where diversity was very low. But the contradictory evidence is Lesothosaurus, who, if a primitive ornithischian, reveals that ornithischian evolution was fast, and that these animals were able to diversify beyond the ancestral condition in only a few million years.

I suppose the question I'm dancing around is this: "are ornithischians really Dinosauria?" Is the old thinking right, and the new thinking wrong? Supposedly the Dinosauria is united by a suit of postcranial characters, but I can name two right now that have been struck from the list thanks to Eoraptor, Herrerasaurus, and Saturnalia. It's also strange to me that those three animals, while derived in their own ways, still obviously retained more primitive ornithodiran characters, and they are all closely related to each other.

Lesothosaurus, on the other hand, looks like it's been around for awhile. The pelvis and ribcage have been completely rebuilt, the skull is amazingly different, and it's got a whopping five sacral vertebrae, unlike two or three in primitive saurischians (two in Marasuchus). Plus, if ornithischian dinosaurs were having a hard time in the beginning, as Eocursor suggests, then wouldn't that pressure have been there when ornithischians were first getting started? How would the group even get so far as a quadra-radiate pelvis if aeteosaurs were keeping them down? No, it seems like Lesothosaurus alone is evidence that the ornithischians have a longer evolutionary history than we think. Unless the split between the Saurischia and the Ornithischia occured much earlier than we think it did (maybe Middle Triassic?), I think the possibility exists that Dinosauria is a paraphyletic group, and that the Ornithischia originated a bit further down the Ornithodira tree**. Perhaps, in that sense, Silesaurus really is a key figure in the Ornithischia. Instead of trying to pigeon-hole it as an early dinosaur, maybe it's just a derived ornithodir which began a great bird-hipped herbivorous lineage.

*Actually, if you consider Dzik's little-known Silesaurus to be an incredibly primitive ornithischian, like I do, then here's it's skull. White areas indicate unknown material. For simplicity's sake, I'm not going to consider Silesaurus in my discussion here, but it's an interesting animal to consider. For more on this little upstart, see this post.

**Of course, what would probably happen is that "Dinosauria" would simply be moved down a few nodes to incorporate both the Saurischia and the Ornithischia, regardless of where Silesaurus eventually winds up. The union of the two groups is at the heart, after all, of our concept of the Dinosauria.

Giant oviraptorid and the "dawn runner"

Oviraptoroids were pretty small animals. The largest, Hagryphus, a North American form, stood about as tall an emu. That was considered huge for oviraptoroids--I mean, the next largest was Oviraptor itself at a whopping 5 feet long. Well, today's Nature issue reveals a new enoromous oviraptorosaur from the Gobi: Gigantoraptor (aptly named). The picture at left shows just hot large this monster was. The white bones indicate known material, as usual. Most of the news stories covering Gigantoraptor are focusing, ad nauseum, on whether or not it had feathers. Well who really cares? Oviraptoroids are not on the direct lineage to modern birds, and this animal certainly wasn't flying. This was an animal that could have taken on Therizinosaurus and Tarbosaurus if it felt like it. Feathers don't seem all that important. And yes, I know what you're thinking--the arms of Gigantoraptor are distinct from those of Deinocheirus and Therizinosaurus. Darnit!

And then, if you head over to the Proceedings of the Royal Society B's website, you can download Eocursor's disappointing short description. It's important because it's the most complete known ornithischian from the Late Triassic. It's skeleton is 25% complete, including a complete pelvis and leg, as well as a mandible and pieces of the pectoral girdle and arm. According to the authors, Eocursor is more derived than the heterodontosaurs and forms an outgroup to the Genasauria (Thyreophora + Cerapoda). The implications here are fairly severe: knocking the heterodontosaurs down to "most basal ornithischian" effectively knocks the idea of a monophyletic "Heterodontosauriformes" (Heterodontisauridae + Marginocephalia) down. Also, the authors assert that ornithischians as a group did not proliferate until the Early Jurassic, after the Triassic-Jurassic extinction left a bunch of herbivorous niches open.

So while saurischians got an early start, what with their carnivory (theropods) and hugeness (sauropodiforms), ornithischians were living in the shadow of the more prolific herbivorous archosaurs and therapsids like dicynodonts and aeteosaurs. It wasn't until those groups bit the big one that ornithischians were able to max out their potential during the Jurassic era.

So, two interesting finds to report today. And one of them is free online! Now, if only Nature would wise up. Looks like I've got to make a trip to the UAA library...

Hunt the Wumpus--For Real!

Now this is interesting. Don't know if it's legit, but, hey. So as some of you may know, I work primarily in the offices of an engineering firm here in Anchorage. This firm has a lot of North Slope projects, and workers usually spend two weeks there, two weeks home. The thing is, it's not like operations stop during the winter. And might I mention that the winter on the North Slope lasts much longer than here in Anchorage. They are above the Arctic Circle up there. They are a mile away from the Arctic Ocean. They stay inside and don't come out.

So anyway, one of my friends who works up there, Dean, was at Corp. yesterday (where I work) to talk about some worker's comp related thingamabob. We talked for like twenty minutes, but he mentioned that one of his friends had seen a "monster" during the winter up there. This other friend, Steven, tried to take a picture of the creature through the window, but his first attempt came out reflecting and the second attempt just caught the animal's side and back. It had to be a white creature, didn't it? Steven further claimed that blizzard conditions further prevented good camera work. At the end of this story, I told Dean that Steven was either making it up or was "smoking crack," which is of course illegal on the Slope. But Dean told me that he has proof in the form of a sketch that Steven etched out on a nearby piece of paper.

How Dean obtained this piece of paper, considering the two weren't working the same shift, was a question I failed to ask. Anyway, I told Dean to send me a PDF of the picture, and said picture arrived in my inbox today.

I copy it for you above. Another question that pops into my mind is why it's all crumpled up. It's as if Steven made a sketch, didn't like it, and threw it out, or it was thrown out by somebody else. Maybe Steven drew the initial creature, then, upon showing the sketch to other people, excitedly drew a horrible, horrible map designating the monster's last known position on the lower-left (nice job keeping the map separate from the creature, Steven). Anyway, Steven also managed to get a footprint down, although there's no scale bar or human print for scale.

In fact, the whole picture seems kind of vague to me. The top-heavy humanoid form could simply indicate a Slope worker wearing a white parka. Why there are claws on the hands are beyond me, and I question how well Steven could see this creature if, in fact, it was walking out in the middle of a blizzard. The feet are black because I guess the snow was high enough that he couldn't see any feet, but the footprint drawing seems to indicate a vaguely humanoid build, albeit with four large toes/claws. According to Dean's brief description, Steven thought the beast hairy and with "glowing orange eyes." Well, cat eyes glow too, but it's because they're reflecting light. That's probably what was happening here.

Hell, it could have been a Slope worker in a white parka with goggles on. If he had dark gloves on, I can see some moron thinking that the individual fingers represented talons.

But let's pretend for a second that the creature is real. Steven is apparently calling it a "Wumpus," not so much because "Wampa" was taken but because his favorite video game is the Atari's Hunt the Wumpus, which itself is supposedly a yeti-like creature. So that's kind of cool, but back to the "what if it's real" thing. If the Wumpus is to be taken seriously, we'd have esssentially a North Slope yeti, or perhaps bigfoot, but adapted to the colder Arctic climates. This would include, of course, a thick layer of white fur, like a polar bear. One wonders why the Wumpus doesn't just freakin' hibernate like every other North Slope mammal.

The strikes against this claim seem a bit severe. Still, I'm happy that Dean showed me the picture because it displays how nuts people can become up on the North Slope in the middle of winter.