"This is Earthend!"
This is what happens when worlds collide!
If any of you readers out there want to join me for a rousing round of zombie-killin', my PSN handle is "Sillysaur." We shall battle together...for great justice!
When Pigs Fly Returns is a paleo-themed blog featuring original art and occassional rants.
"This is Earthend!"
This is what happens when worlds collide!
If any of you readers out there want to join me for a rousing round of zombie-killin', my PSN handle is "Sillysaur." We shall battle together...for great justice!

Phylogenetics is kind of like the mythical hydra: for every gap closed by a new fossil, three new gaps appear. This makes paleontology very exciting, but it also makes the science easy to pick on by Creationists and other science-deniers. Why are three gaps opened instead of just two? Well, because we weren't around to see one species branch directly from another, taxonomy assumes that all common ancestors are unknown. All you can really do is say that Velociraptor and Deinonychus share certain features inhereted from a common ancestor. Even if Tyrannosaurus evolved directly from Daspletosaurus, it's just not something we can ever know. So because every animal in the fossil record (and in the modern world) exists on its own "sidebranch" to the main line of faunal evolution, then three gaps appear:
1) The gap between the new taxa and the common ancestor;
2) The gap between the common ancestor and its the next rung down;
3) The gap between the common ancestor and the next rung up.
Here's a simplified Dinosauria cladogram illustrating this point:

When I say "shared characteristics," I mean things like number of fingers or length of cervical ribs, things like that. Some of these relationships are based on very technical measurements and features. At any rate, the tree is designed to show that Sauropodomorpha is closer to Theropoda than either is to Ornithischia. That doesn't mean thatt Dinosauria is polyphyletic, it just means that Saurischia is a more exclusive group than Dinosauria. You could say that the features diagnostic of "Dinosauria" are entirely arbitrary, and you'd be right. The whole point is to show relationships, though. If we decide one day that silesaurids should be dinosaurs, the label "Dinosauria" would be moved one rung down to include Silesauridae, which is currently considered more or less an outgroup to the Dinosauria proper.
So what happens when a new fossil fills a critical gap in an otherwise poorly-known transitional series? Let's use dinosaurs and birds as an example. The relationship was realized back in Sir Richard Owen's time. In fact, he favorably compared the femur of Megalosaurus to that of an ostrich. Anyway, watch what happens when we toss Archaeopteryx between Allosaurus and Gallus:

Because Archaeopteryx shows features unique to it and exclusive to both birds and Allosaurus, it cannot be suitable common ancestor between the two outgroups. However, because it has more features in common with Gallus than Allosaurus, it must be closer to the chicken. But because it has its own unique suite of characters, it is not a suitable ancestor. So it split off from a theoretical ancestor between itself and Gallus. Now, we'll probably never find an actual ancestor-decendant relationship in the fossil record, but we can come darn close and make predications as to what features that ancestor should have. Eoraptor, for instance, is the basalmost saurischian dinosaur known. It's got a few unique characters (apomorphies), but on the whole it's a fine model for the common ancestor between Sauropodomorpha and Theropoda. That is, Eoraptor has lots of features common to both groups.
Here's a simplified theropod cladogram using manual digits as an example of this principle:
So when did theropods lose that fourth digit? More fossils are necessary for that answer. You'd have to find a theropod that, morphologically, falls between Herrerasaurus and Allosaurus (like Carnotaurus) and count its fingers (it has four). Then go farther up the tree to, say, Spinosaurus (who is between Carnotaurus and Allosaurus) and you see that has three fingers. So you've further narrowed the taxa gap for that finger to be lost. Likewise, when did tyrannosaurs lose their third finger? Basal tyrannosaurs like Guanlong and Eotyrannus have three fingers, but later ones like Gorgosaurus and Tyrannosaurus have two. Someday we'll find a tyrannosaur with two full fingers and the third finger has been reduced to a splint of bone (as the fourth one is in Herrerasaurus).
The same process has recently been done with whales. Whales used to be a total mammalian mystery. Aside from the fact that they gave birth to live young and nursed their babies, modern whales were far too derived to pinpoint a fossil ancestor. Because of their bizarre skeletons, shaped by a millenia of marine adaptation, comparisons to other modern mammal groups was virtually useless. The cladogram basically looked like this:
But then, paleontologists discovered Ambulocetus natans, and the whole cladogram changed. It just takes one fossil to demonstrate relationships between any two groups.

Aside from being a vicious shallow-water predator with whale-sized dentition, Ambulocetus had a unique ankle structure shared by it and the Artiodactyla, an enormous group that also includes goats, cows, hippos, pigs, and antelope (and more). But because Ambulocetus also had a very unique inner ear shared only by whales, scientists knew that it was a ridiculously basal whale. More finds would come later further solidifying the artiodactyl link (Rodhocetus) and show that early whales hauled themselves onto land to give birth (Maiacetus). The big mystery now is exactly how far back toward the origin of the Artiodactyla whales go, and also when they lost their hindlimbs (are there fossils that document this? Anybody?).
So now the whale cladogram is a lot clearer:
So with all that information in mind, I present to you Puijila darwini, a new basal pinniped that sheds light on the transition from mustalid-like carnivore ancestor to flipper-finned seal. Pinnipeds are a group of extremely diverse and successful mammalian carnivores. They include seals (eared and otherwise), sea lions, and walruses. Their closest non-marine relatives are bears and mustalids (weasels, otters). The ancestor of modern seals has been very difficult to nail down, though. The oldest known seal is Enaliarctos, which already has well-developed flippers. So there exists a big morphological gap between mustalids and seals. That gap has now been partially...um...sealed!
It's less than a meter in length and was found on Devon Island, one of those horribly cold islands above Canada near Greenland. Puijila has a seal's head, including the osteological correlates indicating large, sensative whisker pads. However, its body and feet are more like an otter in that it has, you know, feet instead of flippers. The fingers and toes are flattened, though, indicating extensive webbing (same correlates are in beavers, otters, and Casterocauda). And check out that bacculum! I would like to point out, however, that the feet and hands of Puijila are longer than any otter or beaver.

Look at that muzzle--I would not want to come toe-to-snout with Puijila, though it's small enough you could potentially kick a field goal with it. At any rate, a few more interesting points about Puijila. First, it was discovered well within the arctic circle, lending some credence to the notion that pinnipeds originated in the colder northern waters of the arctic. What's more, its swimming style was more toward pinnipeds than mustalids: quadrupedal "doggie paddling" rather than pelvic paddling. Puijila's long tail probably did very little in the water, and the limb-centric swimming style of Puijila could have easily developed into pinniped swimming, which is similarly dominated by the limbs. Finally, Puijila was not an oceanic swimmer. It preferred freshwater lakes and streams, which indicates that pinnipeds went through a freshwater "phase" before braving the deep blue sea. This is to be expected given other marine mammal's ancestral records (Ambulocetus, Pezosiren).
So what's the moral of the story? Puijila represents a good model for the common ancestor between it and modern pinnipeds, both morphologically and ecologically. It helps to close the distance between mustalids (and bears) and walruses, and future fossil discoveries may show other transitions, such as the loss of caudal vertebrae, the perpetual retraction of the hindlimbs, or the enlargement of manual digit I. So think of Puijila as a seal-headed, long-footed otter, and a virtually perfect representative of common ancestry. Feel free to put together your own cladogram!Oh, and here's a picture I whipped together from the description.


Lindworms, also know as "Chinese dragons" and "lungs" are medium to large-sized creatures with short, powerful forearms but lack hindlimbs entirely. Although secretive and rarely seen, it's clear that lindworms are totally flightless, having no wings to speak of. At first glance, that fact may imply their relationship with dragons, rather than wyverns, as dragons have both forelimbs and wings. However, preliminary genetic comparisons between a dead lindworm recovered from China (in press) and a living wyvern and dragon show that, in fact, lindworms are genetically closer to wyverns than dragons. The obvious taxonomic implications are that lindworms are stem wyverns, sitting somewhere below true wyverns on the archosaur family tree, branching off before wyverns developed wings.
Given their rarity, lindworms are rarely studied. In fact, the first named wyvern is Lindwyrmus nychognathus from Argentina, and it was described only recently (Farke, 2005). Although it features plenty of its own peculiar anatomical features, Lindwyrmus is generally viewed as diagnostic of the entire group. Most impressively, Lindwyrmus is semi-arboreal, rather than semi-aquatic as lindworms are usually thought to be. Farke noted that the bright-green lindworm curls its serpentine body on a branch as would an anaconda or constrictor. The arms are used to help pull the animal up through the trees and clamber across the canopy. While the body is bright green, Lindwyrmus has bright orange flaps of skin on the arms and along the spine. These structures are usually draped across the body or arms, but when aggravated, the lindworm can "flare them up" and create a striking threat display. In fact, the flaps are structured by thin muscular rods akin to the actinofibrils of pterosaur wings.
The skull of Lindwyrmus is very distinctive. There are two pairs of cranial horns which point posteriorally behind the eyes. Two small nasal horns rise from the tip of the snout. The skull is dorsoventrally flattened. Unlike most dragons and wyverns, there is no "lip" around the teeth. Instead, the teeth erupt from the underlying skin as in crocodilians. Most interestingly, however, is the pair of laterally-placed, spike-like mandibles that boarder the mouth. These mandibles are mobile in two places: at the point of articulation with the skull itself and immediately behind the spike-like process. This novel structure seems to serve two purposes: first, it greatly increases the effect of the animal's threat display, and second, the mandibles actually impale prey while the mouth grips it. Bizarrely, the main articulation of the mandibles is a cup-like depression in the jaw just above the mandibular joint, and the proximal surface of the mandible is a ball joint. However, in life, the mandibles are limited to fore and aft movement. Exactly what environmental forces combined to create the need for such a strange structure is not understood. Incidentally, while the mouth is closed, the mandibles are held forward, overlying the exposed teeth and framing the face.
Lindwyrmus subsists on small vertebrates almost exclusively, though Harrison (2007), on a trip to Argentina's jungles, witnessed a pair of lindworms feasting on a dead hog. He was unable to determine whether the lindworms actually killed the hog or were simply scavenging on it. Both he and Farke were unable to tell males from females, and Harrison commented that, generally, lindworms seemed to be solitary animals. Neither man saw juvenile animals, which is unfortunate. It would interesting to see whether juveniles and subadults also posess the strange mandibular array that adults do. Farke estimated the total length of an adult Lindwyrmus at "about twenty feet," though he left open the possibility that larger individuals existed.
Farke said a recent draconology conference that he intends to travel back to Argentina to further observe Lindwyrmus and hopefully find some juvenile animals. Other workers, perhaps inspired by Farke's work with Lindwyrmus, are traveling to Asia to track down other species of lindworm. Hopefully, this little-known branch of the wyvern family tree will soon be better understood!
Farke, A. (2005). The first description of a "lindworm," from the jungles of Argentina. European Journal of Draconology 106(2): 245-258.
Harrison, M. A. (2007). Observations on Lindwyrmus nychognathus (Farke 2005). Draconium 48(3): 402-405.
So last time I talked about Troodon and how it was Alaska's most common theropod dinosaur as well as one of the largest. Up here, Troodon was around twice the size of a southern Alberta Troodon. A new paper in Paleogeography, Palaeoclimatology, Palaeoecology (heck of a business card) by Fanti & Miyashita add some surprisingly twists to that story. The paper describes a high latitude vertebrate assemblage from a west-central Alberta. A host of dinosaurs are known from scrappy remains, but include such colorful animals as Saurornitholestes, Troodon, Pachyrhinosaurus, Hypacrosaurus, an ankylosaur, a hypsilophodont, and a tyrannosaur. Evidence of duckbill nesting grounds are included here, with lots of juvenile material and, perhaps not surprisingly, lots of Troodon (more on this in a minute).
What's more important is that lots of squamates and a turtle were found at the site, so the temperatures must not have dipped to the lows of Alaska's Prince Creek formation, where ectotherms are totally unknown. However, it's interesting that most of the dinosaurs in this new Wapiti Formation are also in Alaska (Hypacrosaurus is not). Even more interestingly, the two mammals tentatively identified at Wapiti are also in southern Alberta and Alaska (Didelphodon and Cimolodon). To me, this implies a fairly uniform group of fauna across the northwestern coast of North America during the Late Cretaceous.
But I'm here to discuss Troodon. Fiorillo suggested (in 2008) that Troodon may have grown larger the farther north is occurred, possibly because of its dominance in the carnivore guild thanks to its predisposition to surviving in a colder, darker climate. In fact, the Troodon specimens from Wapiti are comparable to those of southern Alberta and Montana, which means that Troodon did not get larger as a consequence of Bergman's Rule (animals at high latitudes get larger than their more southerly counterparts) but instead thanks to its dominance in the carnivore guild, as Fiorillo suspected. What kept Troodon going during those cold winter months? As it turns out, the presence of hadrosaur nesting sites in both Wapiti and Prince Creek may tell us something about what Troodon did in its spare time.
Ryan, et al. (1998) suggested that the association of baby hadrosaurs and Troodon in the Horseshoe Canyon Formation (where other dinosaurs are uncommon) could mean that Troodon actively targeted baby and juvenile duckbills. Given that Hypacrosaurus apparantly nested at Wapiti and Edmontosaurus nested in Prince Creek, and that both sites are covered with shed Troodon teeth lends credence to this idea. And, in fact, it might be telling that Troodon becomes a larger and larger faunal component the farther north you go while other theropods become more scarce.
The description of the Wapiti Formation also has broad implications for paleogeographical and paleoenvironmental studies. It might also be time to revisit the question of whether any of Alaska's dinosaurs migrated south--the Wapiti Formation isn't that far away, and it was temperate enough to support a range of ecothermic vertebrate fauna!
Also, give Lukaz Panzarin a hand on his absolutely wonderful illustration for the paper. I especially like the trio of pachyrhinosaurs on the left!




The king of tension is still the king of tension, but not a lot else. Silent Hill: Homecoming upped the ante from a graphical perspective but kept all the old PS2-calibur gameplay choices, and that really weighs the game down. Trying a hundred doors before you get to an open one is just annoying, and having to get up close and personal to dangerous enemies in order to deal damage to them (melee combat) just isn't fun. There is the option for gunplay, but ammo is still scarce. The player has new combat abilities including dodges (actually present in SH4) and counter-attacks, but in general, combat is an activity best avoided. Homecoming will be fun for series veterans, but newcomers will likely warm to RE5 or Dead Space before this latest Silent Hill jaunt. This is not to say that Homecoming is a bad game--it's just archaic. But in order to regain fans, the series will definately need to evolve.
Dead Space is already getting a prequel for the Wii called Dead Space: Extraction. Although technically a rail shooter, EA cautions that it will be unlike any rail shooter that's come before, and all of the abilities of the first game, including stasis and kinetics, will return here. The game looks absolutely incredible: EA has broken the "Wii" barrier for graphics. Interestingly, the Wii is also getting another RE game, a sequel to Umbrella Chronicles called Darkside Chronicles which will likely focus on parts of the RE storyline left out in Umbrella Chronicles (most of RE2, Code Veronica, maybe RE4). Finally, even Silent Hill is showing up on the Wii soon. A remake of the original PSOne game is on the way, called Silent Hill: Shattered Promises. It will not be a rail shooter, but aside from its remake status, details are scarce. Anyway, it's a good time to be a horror fan, as there are lots of choices right now!