Two New Doctors

Don't know why I haven't said this earlier, but congratulations go out to two paleo community friends. Mark Witton and Manabu Sakamoto hit Level 80 in World of Dinocraft and were thusly ranked up to "Doctor." Now I'm going to start calling them about relieving my bellyaches. Well done, gents! You're fine until they release the next expansion: Wrath of the Tyrant Lizard King!

Paleo Predictions for '09

Well, I'm hopping on this bandwagon because it looks like fun. Ten things I believe (or would like to believe) will happen in the vert. paleo. world in the coming year. One of my predictions is totally a joke. Can you guess which one?

1) Zanno's prediction that therizinosaurs represent the basalmost maniraptor theropods (and do not form a sister group with oviraptors) will be validated by a basal new oviraptor, possibly from China, which shows a close relationship between Oviraptoridae and Paravia.

2) New rigorous studies on Silesaurus will show it to be the basalmost ornithischian dinosaur, rather than a non-dinosaurian dinosaurmorph.

3) An actual scientific description will be published on Dakota, that Edmontosaurus media darling (remember her?).

4) Fossil grasses will be discovered in Nigerian rocks of Middle Cretaceous age, thus giving Nigersaurus something to eat.

5) "Octoceratops" will recieve a 5-page description in Nature or Science at the end of the year.

6) A relatively complete noasaurid abelisaur will be discovered in South America. It will show broad similarities to Ceratosaurus and coelophyloids.

7) Large bones attributed to Therizinosaurus will be discovered. The bones will not be very exciting (things like isolated vertebrae and maybe a tibia) but will validate a therizinosauroid relationship. The animal will be compared to ground sloths in the following media frenzy.

8) More complete remains of Anchiornis will be described, including a mediocre skull, which will show a close relationship with Archaeopteryx.

9) A new Eocene whale will be found that has very reduced, but still functional, hindlimbs. Creationists will ignore the fossil or claim that it simply isn't a whale.

10) Jurassic Park IV will be officially announced, in memory of Crichton, but no further details will be revealed in 2009, aside from a possible male lead.

Christmas Swag

Oh, it was a good year. A mighty good year. My folks got me a Wacom Bamboo "Fun" tablet, so my digital art experiments can continue. This is the part where I beg Scott to show me the ropes in Photoshop Elements and Corel Painter, because brother, I don't know what the hell I'm doing. My wife and I bought a new PC, and it's fantastic apart from the fact that it doesn't support our scanner. It prints fine, but you have to scan from Paint, so much control is lost. My abelisaur discussion might be postponed until I iron this problem out. A new scanner might be needed...

But that's not all, kids. My brother-in-law, Justin, got me LittleBigPlanet, a game everybody should play. Everybody. If you're creative, and you like gaming, this is the game you need to buy a PS3 for. Even the narrator is great. How great? Well, I don't have a Playstation Eye, but I sat through the tutorial so I could hear him narrate it. He also got me a hilarious and very old "how to draw dinosaurs" book featuring a caveman, published in 1982 (so was I, actually). And here's a funny story for you: My birthday list to my in-laws included Tomb Raider: Underworld and Fullmetal Alchemist Season 2, Part 2. They sent me a gift card, which I used to buy both things. For Christmas, they sent Tomb Raider: Underworld and Fullmetal Achemist Season 2, Part 2! Hilarious! They also wisely sent a gift reciept, so today I returned both and got a big fat gift card in return, which I used to pick up Prince of Persia and...I'm gonna hang on to the rest for now.

But they also gave me a singing rubber duckie and a glass block with my wife's senior picture in it. Really awesome, my favorite present of the year. It will live on my office desk, and make everybody jealous. :-)

And whatabout my wife? We gave ourselves a PC and a trip to Maui, so it was just stocking stuffers for us. Gina gave me candy, The Dark Knight, a stuffed Godzilla, and Pixelblocks. These little blocks are the best thing since Legos for a gamer like me. Unfortunately, I didn't get one thing I really did want this year: a tuatara skull from Skulls Unlimited. I suppose with all the money I'm saving on PS3 games and movies, though, I might be able to afford it!

Merry Chanuchristmakwanzaka

It's snowing! It's cold! It must be Christmas in Alaska! Happy holidays, everybody.

Silesaurus gets a minor revision?

I'm not really sure how much work's been done on my favorite supposedly non-dinosaurian dinosauriform, but Dzik & Sulej (2007) suggest that initial reports (Dzik 2003) placed it just outside of the Dinosauria proper, but the new paper briefly describes new material and suggests that Silesaurus is the most basal ornithischian known. This is a position I generally agree with--the original ornithischian is not going to look like Lesothosaurus. It's going to look more like Eoraptor or Herrerasaurus, because those two dinosaurs retain more plesiomorphic features, whereas Lesothosaurus is more specialized than either. Does anyone out there have strong opinions either way? Seems like you could get a lot of descriptive text out of Silesaurus, but aside from these two papers, I haven't seen much.

Also, how do you pronounce the name? It seems like there are a lot of possibilities. It's always said "SIGH-ul-SORE-us."

References:

Dzik, J. (2003). A beaked herbivorous archosaur with dinosaur affinities from the early Late Triassic of Poland. JVP 23: 556-574.
Dzik, J. & Sulej, T. (2007). A review of the early Late Triassic Krasiejow biota from Silesia, Poland. Palaeontologica Polonica 64.

Point and Laugh

That's a painting in the background. It's not even a CG dinosaur. Having a photograph (the people on their boat) composited onto a painting is jarring and looks silly. That tyrannosaur looks a little fat, too, although I kind of like the cranial ornamentation. However, this is a Will Ferrell movie, and my tolerance for that actor is extremely low, lower even than Ben Stiller. Ferrell has been in exactly two movies where I liked his character: Night at the Roxbury and Stranger Than Fiction. I can't help but think that this movie will be nothing at all like the told TV show, which was insufferably corny. Some great stop-motion work, but damn.

This movie also looks suspiciously like this year's Journey to the Center of the Earth, starring Brendan Frasier. That movie also had a poorly-done tyrannosaur. Why does it always have to be a tyrannosaur?

Paleo Overload!

Geeze, I leave for one week and when I get back I have papers coming out of my ears! I have a big abelisaur post to accomplish, complete with my own pictures. No Google trolling for me on this one, seeing as they ARE my favorite dinosaurs. As if that wasn't enough, a big new deinonychosaur was dug up in South America named Austroraptor (described in the paper as a unenlagiine dromaeosaur, but it could be a troodontid). Then Varriccino et al. figured out that maniraptor theropods brooded their nests like modern paleognathid birds (ratites, tinamouses). Then Bill Parker throws me a curve-ball paper about a new non-avian theropod, Anchiornis, which a very tiny, has a really flexible wrist, and speaks to the problem of the homology of the "semi-lunate" carpal. So I've got a lot of blog posts to write!

By the way, Hawaii was fun, if for no other reason that I got to see my wife wandering around in her swim suit, which NEVER happens up here in Alaska. Disappointed by the lack of lizards on Maui, but we saw some really beautiful sights and went to some fantastic beaches. On the last day there, while running the clock before our flight back, we saw Seven Pounds, the new Will Smith movie. It is a downer.

Fish and Turtles

Today was aquarium today. The Maui Aquarium is a really first-rate aquatic zoo, filled with all sorts of swimming creatures, including hammerheads and giant rays! Sadly, all the pictures I took of the boneless variety came out blurry (they never stop moving), so alas, you will not see them here. Above is one of the cooler animals there--a frogfish, one of two species in the aquarium. The other was much smaller and wedged into a coral. There were also LOTS of unicorn fish:

I wonder why they're called unicorn fish? The horn seems to grow with the animal. The largest fish had the longest horns. In young unicorn fish, the horn is barely more than a wedge sticking out of the forehead. Very cool fish, though. In many tanks, small sharks swam right alongside the fish, and I wondered why the sharks didn't just chomp up their tank-mates! My favorite animals in the aquarium, though, were these guys:

Three-month-old baby sea turtles! ADORABLE! All three were very energetic and curious, very interested in the people passing by. Their tank was pretty big, but they all congregated around the front, eager to check everybody out. There were also adults in a nearby area:

It's a bird! It's a plane! It's an unenlagiine dromaeosaur!

So, kids, while here in Maui, two ridiculously awesome papers came out. One about Austraraptor, a new unenlagiine dromaeosaur from South America (above), and one about the brooding habits of maniraptor theropods. The raptor was published in Proceedings of the Royal Society of London (online), and the brooding one was published in Science.

I found the Austroraptor paper, but I can't get into the brooding male paravians. Does anybody happen to have it? Thanks!

Oh, and Maui? Today sucked, honestly. We traveled to South Maui for supposedly awesome malls, but there were none. Additionally, the traffic was horrible and the people obnoxious (one bystander shouted "go back home!"). We came back and went on a whale sightseeing boatride. Humpback whales--saw one breach, which was cool. Unfortunately, I spent most of the ride trying not to throw up over the side. I apparently do not function well on the open sea. Thus, my preference for swimming pools.

Mau, Day 3, Part 2

I think this is where they film Lost!*

*That's not true. They film Lost on...a different island. The one that begins with K. Same place they filmed Jurassic Park. Anyway, nice picture, right?

Maui, Day 3

Lava, lava everywhere, and not an ounce to drink! Today the wife and I traveled to something called the "Dragons Teeth" rocks, which really means big awesome lava flows! The "dragons teeth" of myth and lore are vertically-oriented spikes of igneous goodness which look kind of like the dental arsenal of a dragon's lower jaw. More impressive than those draconic spikes was the lava flow itself, which stuck out like a spit into the ocean. The formation begins high above the water line but constantly slopes downward, so by the time you get to the end, the frothy waves cover the rock with every undulation, leaving awesome little tidepools in their wake. We found fish (I believe they were sculpin), hermit crabs, and tons of snails.

After that, we went snorkeling. Or, more accurately, I went snorkeling while Gina read her book on the beach. The waves were pretty severe, and it took me a really long time to get out to calm waters. Once there, however, I saw a ton of pretty fish, corals, and urchins. Interestingly, all of the wildlife was concentrated around the giant igneous rocks that were scattered haphazardly out in the sea. In between the stones, the sandy ground was pretty barren. I brought my aqua-camera, and I hope I snapped some good pictures. Hard to tell when you're wearing goggles.

Maui, Day 2

I looked "chiton" up on Google Image Search. This is not a chiton. It almost looks like some kind of bloated sand-dollar given the distinct five-pointed ridges across its dorsal surface. That, plus the bulky arm-like processes that attach to the rock surface, makes me think it's an echinoderm. It's the strangest creature I've seen on the island so far. Today I saw an anole lizard scamper across a rock, two small white herons, and sandpiper. We traveled to a really beautiful part of the island called "Needle Rock," and I was horrified to realize that I'd forgotten my camera. We'll probably go back with camera in tow, because you guys really need to see this formation.

Maui, for those who haven't been here, is kind of like Racoon City--the walking dead parol every street and every shopping center. This is like a rich (old) man's Florida. Tomorrow, snorkeling, and I bought a waterproof camera specifically for such adventures!

The View from Maui

This is the view from our balcony. Pretty, don'tchathink? Rule #1 when traveling to Maui: Do not bring books, especially new, expensive books. The pages will warp, and you will cry. Solution: Wrap the book in a cloth or towel and stick it in the fridge at night. The dry cold of the fridge reverses the effects of the hot moisture of the island. Such is what I have learned from The Necronomicon, the singular tome I brought with me to Maui. Its pages are filled with ghastly, horrific stories which bring me much glee.

Today is quite cool, the temperatures briefly rising into the low 80's, and that was when the sun was shining. Right now, the skies are overcast, and neighbors warn of rain on the horizen--something I would very much like to see while I'm here. Of exciting wildlife, there is plenty. Colorful birds have taken the place of mainland pigeons, croaking and pecking around human colonies. Small yellowish geckos with giant red eyes cling to outdoor walls, soaking up precious sunlight. On the beach, sand-colored crabs with enormous eyes and tiny pinchers scuttle to and fro. The strangest sight has been organisms which cling to rocks beaten by the surf. They look something like mounds of outwardly-overlapping scales, purple and red. Where scale meets igneous rock, long pink scales fan outwards. Very strange creatures, hard to the touch and immobile.

Bye-bye, Alaska!

If you don't hear from me much in the next week, it's because I'm roasting on a beach in Hawaii. Sorry I didn't get my abelisaur post done--I promise I'll work on it while I'm there! (Ed. note: He's lying) I'll try to post pictures while I'm down there, though.

Ariados!

Scorpion-Eating Theropod?

Until I get on the ball (I've been busy the last few days), I'm going to point you in the direction of the Hairy Museum of Natural History if you want to find out about a brand-spanking new abelisaur named Skorpiovenator. No, it didn't eat scorpions. The authors named it after the deadly arthropods that infested the dig site! Skorpiovenator wasn't very big, but it has a very interesting skull! Abelisaurs are just plain cool, so check it out! And I'll work on my own post in the meantime.

R.I.P. J.P.4

No freaking way! I was totally looking forward to Jurassic Park 4: Dinosaurmaggedon. Thanks to Julia for pointing this out, though my day is now ruined.

How the Turtle Got Its Shell: Addendum

eBlogger does not like it when you try to screw with a long, image-heavy post. When you try to edit said post by, say, adding a new picture, the rest of the post goes to hell. Anyway, here is another fantastic picture by Matt Celeskey of Chinlechelys, showing the known shell fragments and what they represent. There's a little more to the skeleton, including some vertebrae, a bit of plastron, and cervical spines (like Proganochelys has). But the carpacial elements are the most telling bits.

PZ Myers Gets Mail

You know, people ask me, sometimes, why I don't like God. It's not GOD I don't like. After all, you can't prove God exists. Even if the sun failed to rise tomorrow morning, it would be a fallacy of equivocation to assume that meant God exists. There could be lots of reasons why the sun didn't come up. So I don't not like God. It's his followers I could do without. You never hear this kind of lunacy from non-Christian religions. You don't hear Buddists throwing the term "Marxist" around to describe scientists. You don't often come across a Jew who compares evolution to Nazism. One of the goals of modern Christianity seems to be the eradication of science (not just evolution), and it gets old.

People like Bonnie vote. They vote in droves, and are furthermore elected to public office. This worries me on a constant basis.

EDIT: How the heck did I forget about Ben Stein? I probably just blocked him out, as should we all, really. Okay, so there's ONE Jew who compares evolution to Nazism. And yeah, I didn't mention Islam, but there's a reason for that: I don't think the goal of radical Islam is the eradication of science so much as the eradication of Homo sapiens.

How the Turtle Got its Shell

Testudo hermanni in cross-section.

Turtles are weird. These are sauropsids with an armored shell enclosing virtually their entire body. The two halves of this shell—carpace on top, plastron on bottom—seem to have separate origins, and come together at a “seam” formed by osteoderms. Their elbows are backwards. Their vertebrae, having no mobility, have become elongated tubes connected to the underside of the carpace. The shoulder girdle sits vertically in the shell, seemingly within the ribcage, and in many turtles, the serpentine neck is able to retract into the shell. Other turtles are able to move their limbs into the shell as well. Skull shape varies wildly among turtles, but in all cases is an anapsid structure: like many basal sauropsids, the only fenestrae in the skull are for the eyes and the nose. While most modern turtles are semi-aquatic, at least one large group (the tortoises) are fully terrestrial and seem to like hot, arid climates. Other turtles are almost entirely aquatic—the sea turtles—who only come onto the beaches (with great difficulty) to lay their eggs. The retention of egg-laying is strange given that so many other sauropsid groups who returned to the sea gave birth to live young, including ichthyosaurs, nothosaurs, plesiosaurs, and mosasaurs. Turtles have outlasted all of those groups, having emerged during the Late Triassic and surviving well into the present day, yet the sea turtles never took a lesson from their live-bearing cousins. For over one hundred years, Baur’s Proganochelys (= Triassochelys) was the most basal turtle known. This Late Triassic turtle, about a meter long, was adapted to terrestrial life with a heavily armored shell, spike-covered tail, cranial spines, and smaller spikes coming off the neck. Unfortunately, Proganochelys told paleontologists little about the phylogenetic origins of Testudines.

The problem with turtles is that they have a ridiculously derived body plan, totally different from any other animal, either living or extinct. Plenty of other amniotes have armor, but none have a body enclosed within a bony, armored shell. Glyptodonts came close to turtles, as their dorsal vertebrae and pelves fused to the underside of their massive patchwork shell. Placodonts, early shellfish-eating sauropterygians, came very close to the turtles in terms of shell design. Within Placodontia, two groups evolved different shell types. The smaller cyamodontoids developed a two-part carpace, with a broad shell covering the shoulders and most of the body, and a second smaller carpace covering the pelvis. Cymodontoids did not have plastrons. Another placodont, however, Henodus, had an incredibly broad carpace and plastron. Both halves were wider than the animal’s skeleton, and would have stuck out laterally from the body. Unlike cymnodontoids, however, the carpace of Henodus was a single broad structure that ran the length of the animal from the shoulders to the base of the tail.

A trio of placodonts by Darren Naish. From left to right: Placodus, Placochelys, and Henodus.

Placodonts, however, developed their shells in a different way than turtles. While turtles build their shells from a combination of expanded ribs and a small number of interlocking armor plates, placodonts built their shells with hundreds of very tiny osteoderms, much like the mammalian glyptodonts. Still more problematic is the fact that placodonts are unquestionably diapsids—their skulls have eye, nose, ear, and temporal fenestrae. Remember that turtles do not have any holes in their skulls behind the eye.

So what are turtles? These shelled creatures have a wonderful fossil record post-origin point, much like pterosaurs and bats. However, their bodies are now so ridiculously derived that figuring out their relationships based purely on morphological comparison to other living groups of animals is an exercise in futility. Let’s use a more familiar example. Take whales, for instance. Let’s say that you were given the task of figuring out which living group of animals is most closely allied to Balaenoptera musculus (the blue whale) based solely on that whale. It would be easy to mark the whale as a placental mammal—it gives birth to live, developed young and nurses its babies. It’s endothermic, grows quickly, and moves its spine up and down instead of side to side. But after that, where would you position Balaenoptera among terrestrial mammals? Is it closer to lions than walruses, or perhaps cows and antelope? Hippos? Horses?

The skeleton of Balaenoptera musculus. Have fun with that.

The fact is, you need more basal forms. As any group of animals evolves, many of the features it once shared in common with other animals disappear. Balaenoptera lost its hind legs and teeth, retraced its nose to the top of its head, repositioned its eyes close to the jaw articulation, grew baleen along the gumline, and turned its forelimbs into powerful flippers. However, when you look at other whales, you quickly see that Balaenoptera (and other baleen whales) form their own cohesive group to the exclusion of others. Physeter, the sperm whale, does have teeth, as do belugas, narwhales, dolphins and porpoises. So those groups are more closely related to each other than to baleen whales. The more features a group has in common, the more closely related they are.

And now that we have a good understanding of whale evolution thanks to wonderful fossil evidence, we can see how the cetacean body plan evolved, from terrestrial carnivore (Pakicetus) to semi-aquatic opportunist (Ambulocetus) to four-flippered doggie-paddler (Rodhocetus) to vestigal-hindlimbed giant (Basilosaurus) to more-or-less modern toothed whale (Squalodon). We can even see now the transformation between toothed, predatory whale (Janjucetus) to a whale with both teeth and baleen (Aetiocetus) to modern baleen whales.

So what does that have to do with turtles? Well, modern turtles come in a wide variety of forms, from freshwater turtles to sea turtles to tortoises and enormous snapping turtles. Turtles are a monophyletic group—that is, all turtles share certain characters that indicate they all came from a single common ancestor. So even though snapping turtles look a lot different from matamatas, you can bet they both belong to Testudines. However, up until just this year, the earliest fossil turtle was Proganochelys, and it was already a more-or-less “modern” turtle. It already had the particular shell plate pattern you see in modern turtles and it already had a fully enclosed body with a large carpace and plastron fused in the middle. In some respects, especially its numerous spikes, Proganochelys did differ from modern turtles, but those features were probably unique to Proganochelys itself (or its family). So Proganochelys tells us very little about where turtles come from.

Gamera...I mean, Proganochelys!

That didn’t stop some authors, however, from trying to piece together turtle relationships based on Proganochelys. Baur himself compared sea turtles to ancient plesiosaurs, a view criticized by Williston as being based entirely on similarities in how the two groups swam. He wrote that neither could possibly be derived from the other, as they are both woefully disparate. Cope believed that turtles came from a group of extremely basal sauropsids (like Diadectes) which had small armor scutes along the back. The beast is now seen as an unspecialized “stem reptile” helping to span the gap between non-amniote tetrapods and sauropsids. In 1902, Jaekel suggested that turtles were related to the placodonts based on the fact that both groups have shells. The first major discussion on turtle origins, however, was written by Gregory in 1946, in which he turns his attention to the Permian pareiasaurs, a group of large, heavy-set anapsid sauropsids. He writes:

“When I turned my attention to the pareiasaurs, I was surprised to find that apart from their gigantic size they seemed on the whole to afford an excellent starting point for the chelonian line, both in their general construction and in many features of the skull, vertebrae, ribs, girdles, limb bones, hands, and feet.”

In addition to supplying a relationship between pareiasaurs and chelonians, Gregory dismisses captorhinid, seymouriamorphs, and placodonts as turtle relatives. He proposes that turtles started out as a “pug-like” branch of the pareiasaurs, perhaps related to Elginia. In 1947, Olson proposed a reorganization of Reptilia into two branches, the Parareptilia (basically anapsids) and Eureptilia (diapsids), and that turtles rested on the former branch. In 1969, Carroll allied turtles with the captorhinids. 1997 saw two opposing papers in the same issue of Zoological Journal of the Linnean Society. In one, Lee proposed that turtles were pareiasaurs. DeBraga & Rieppel, however, used a broad array of amniote taxa in a large cladistic analysis to find that turtles formed a sister group to Sauropterygia, just like Jaekel had suggested 95 years previously. This proved to be a very contentious idea, but support mounted. In 2005, Hill published a large phylogenetic analysis that included representatives from a very large number of amniotes, and found turtles to be a sister group to the Lepidosauria. Hill used integumentary characters in addition to skeletal elements, and he emphasized their importance.

But fossil evidence is still scant. Luckily, 2008 saw the discovery of who wonderfully important new turtles, one complete, one not so much, and new embryological evidence for how the shell forms in modern forms.

First came the discovery of Chinlechelys tenertesta, a very fragmentary turtle which, happily, preserved a cross-section of the shell. The shell is not fully fused to the underlying ribs, which are, themselves, still individualized. The shell is extremely thin (discounting the ribs), only 1 to 3 millimeters thick. Chilechelys shows that the overlying osteoderms on the back contributed to the shell separately from the expansion of the ribs. In modern turtle embryology studies, the ribs expand at the same time as the armor fuses to them. So it would appear that, according to Chinlechelys, the ribs expanded under the skin of an armored animal, and the armor later integrated into the bony ribs. The authors suggest a progression like this:

Chinlechelys suggests that armor was present in the terrapin ancestor.

Related to the question of rib expansion is scapular position. The turtle shoulderblade seems to sit within the ribcage, while in all other vertebrates, it is positioned dorsal to the thoracic ribs. At this year’s SVP, Lyson & Joyce demonstrated that once your remove the bony shell elements, which are not homologous to other tetrapods, and reduce the expansion of the ribs, it turns out that the scapular blades, while still vertically oriented, frame the neck and sit anterior to the thoracic ribs. Lyson & Joyce implied a relationship with basal amniotes due to the position and orientation of the scapulae. What’s important, though, is that the authors showed another important feature of how the turtle shell develops—the ribs expand, and those expansions are filled in and covered by unique ossifications. As Chinlechelys has shown, those ossifications are then fused with overlying dermal armor.

But wait—there’s more! Just a few weeks ago, word came down the pipe of a turtle older even than Proganochelys, a turtle known from a virtually complete, well-preserved skeleton! This turtle, Odontochelys semitestacea, an aquatic form that seemingly lacks a carpace. You read that right—Odontochelys doesn’t seem to have a carpace. Matt Celeskey, from the Hairy Museum of Natural History, was kind enough to let me use two of his beautiful illustrations of the critter’s skeleton. The first is a dorsal (top) view:

Dorsal view of Odontochelys

Let’s talk about that. Notice how the ribs are expanded, but not to the extend you see in modern turtles. Additionally, there are no costal plates or shields. The animal does preserve a row of small neural plates running down the back, a feature present in modern turtles. The skull is long but still anapsid, with a long neck and tail. The plastron is complete and remarkably large, with flared corners which seem to overgrow the width of the ribcage. But what about that plastron?

Ventral view of Odontochelys

There’s your fully-developed plastron! Aside from its flared, “combed” edges, the plastron is modern and surprisingly large. A ventral view of the skull gives a look at the dentition, with teeth in both the upper and lower jaws, premaxilla and maxilla. The authors of Odontochelys propose that this new turtle simply doesn’t have a carpace, that the plastron developed first, and that because Odontochelys was probably a semi-aquatic turtle, that turtles evolved in a marine environment. Furthermore, their phylogenetic analysis places Testudines firmly within Diapsida, and again supports a sister group relationship between turtles and Sauropterygia. In the “News & Views” section of Odontochelys’ issue of Nature, Reisz & Head suggest that Odontochelys lost its carpace due to its semi-aquatic lifestyle. They point to the fact that it has neural plates, so the carpace isn’t entirely absent. Indeed, what if Odontochelys had osteoderms that were not preserved? Actually, the modern soft-shelled turtle has both reduced its bony carpace and lost its dermal armor entirely. Leatherback sea turtles reduce the costal plates and shields, and ancient Archelon reduced its carpace to almost nothing but neural plates and ribs!

Notice also the flared "combed" plastron edges in the leatherback (middle) and Archelon (bottom). Odontochelys gives us competing hypotheses about the turtle shell. Either Odontochelys descended from a shelled ancestor, or it simply did not have a carpace, but its neural plates form the first part of the structure. Chinlechelys further muddies the picture, as it suggests that the ancestral turtle did have thin dermal armor--which is either absent or unpreserved in Odontochelys. What is exciting, though, is that Odontochelys, as the most basal turtle known, gives paleontologists a better opportunity to figure out the taxonomic position of Testudines among other sauropsids. Just like with whales, the most basal your taxon, the better your chances of figuring out who it is related to. A string of evidence from the last decade suggests that turtles are, in fact, diapsid reptiles related to Sauropterygia. So turtles really are close to placodonts, despite their differences in shell construction! Interestingly, if turtles are removed from Anapsida (or "Parareptilia"), that would mean that the only living sauropsids are diapsids! If turtles are pareiasaurs, they would be the sole representatives of a very ancient lineage, but it's looking worse and worse for the parareptiles.

We still don't have a Testudine Archaeopteryx, but it's been a good year for basal turtles. I can only hope that a shell-backed urvogal remains buried somewhere, awaiting discovery, and I look forward to reading about it! A special thanks goes out to, who provided those wonderful skeletal drawings. I tell ya--you kids and your digital media. You're zooming past dinosaurs like me who use traditional tools. This old dog's got to learn a new trick or two!

The most bizarre restoration of Odontochelys I've come across, from Wikipedia.

EDIT: I do plan on adding a reference list, but perhaps tomorrow. This post already took three hours to write (most of that is research). I'm also going to add another awesome drawing from Matt, so keep an eye out!

Wherefore art thou, Pelycosauria?

I love pelycosaurs. They're probably the most famous non-dinosaurian prehistoric critters. They're not even reptiles, though--they're basal synapsids. They're more closely related to you and I than to lizards and crocodiles. Pelycosauria used to be a coherent group featuring a variety of Permian forms that all looked fairly similar. So similar, in fact, that in at least one case, one distinct genus was considered the female of another genus! Pelycosaurs were largish, lizard-like critters with large skulls and mean, bladed teeth. There was at least one herbivorous pelycosaur, Edaphosaurus, a small-headed form that lived alongside uber-carnivore Dimetrodon.


Some pelycosaurs developed sails on their backs. In Dimetrodon, the sail was tall and roughly symmetrical from front to back, as its tallest point was in the middle. In Edaphosaurus, though, the sail was much shorter on the neck, and the neural spines were swept back, giving the sail a ramp-like profile. Additionally, the neural spines had cross-pieces of bone along its length. The sail would have looked spikey! But most pelyosaurs were sail-less, including basal form Ophiacodon.



Lately I've been hearing that pelycosaurs are not a coherent group. That is, Dimetrodon is closer to stem mammals than Edaphosaurus is. Instead of forming their own family, it would seem that pelycosaurs form a stepwise progression toward stem-mammals, just like rhamphorhynchoids form a stepwise progression toward pterodactyloids. I'm perfectly willing to accept that, but I'd like to know where this idea came from. Additionally, are there any taxa within the traditional "Pelycosauria" that DO form monophyletic groups? There are such minor groupings among rhamphorhynchoids, after all. So while "Rhamphorhynchoidea" is not a monophyletic group, Anurognathidae IS, and so is Rhamphorhychidae (Rhamphorhynchus, Scaphognathus, a few others). So are there any pelycosaurs that form a monophyletic relationship?

Anybody can Comment!

Finally, right? I think this must be a new feature to eBlogger, but I was just able to change the settings of "who can comment" from "registered users" to "anyone!" So if you've been itching to leave comments on the blog but have been unable to, your prayers have been answered!

In order to cut back on spam, though, I have implemented a word verification "test."

My Favorite Museum(s)

I know I'm cutting it close, but here's my Boneyard submission, better late than never!

My Favorite Museum (Royal Tyrell Museum of Natural History)
I haven't been to the RTM in a decade, but some of my most treasured memories rest in its hallowed halls. It was, in fact, the first museum I'd ever been to, probably when my age was still measured in the single digits. I don't remember the details, but I do remember the feeling of awe which said visit inspired. When I was fifteen or sixteen, I traveled there again and was greeted by some awesome displays. The building's exterior is decorated by plenty of life-size models of Albertan taxa including Pachyrhinosaurus (with curious double nasal horns), Albertosaurus, and Ornithomimus. The exhibits inside were even better. An entire room was dedicated to curious theropod dinosaurs. I forget the exact taxa, but there was a tyrannosaur, ornithomimosaur, dromaeosaur, and abelisaur. The main area had that famous Tyrannosaurus mount alongside a Triceratops, and Edmontonia and...I seem to remember a Stegosaurus, which doesn't seem right. Edmontosaurus too, of course. There was another room featuring Cambrian critters with beautiful glass displays featuring what appeared to be floating invertebrates!

That's all I remember of the museum. I hear they have a kickass ceratopsid exhibit now, so I really want to go back. If I do, I kind of want to meet Phil Currie (as I missed him at SVP)! Drumheller in general is a Mesozoic celebration, with sometimes strange-looking dinosaur sculptures dotting the town. My family travelled to Dinosaur Provincial Park last time we went to Calgary, but they were closed due to a power failure. There was a Styracosaurus statue in front of the visitor center. I know Traumador has a special place in his heart for RTM, and I don't blame him. It's really a wonderful place.

The Chicago Field Musem
I've also been here twice, once when Sue was first erected (ohhhh it was so cool) and again two years ago. Not a whole lot changed, from what I remember, but that's alright, because the Field Museum rules! Of course, you are greeted by Sue the T.rex when you walk in the door. I was actually disappointed last time I was there because her "wishbone" (proven now to be a pathological pair of gastralia) was not fixed. I would think the Field Museum would keep up with the literature and keep their most prized dinosaur up to date! I wanted to show somebody proof, but the copy of The Carnivorous Dinosaurs in the bookstore was shrinkwrapped. Perhaps next time! The Field Museum's dinosaur hall is great, if a little disorganized. Interestingly, Buitreraptor was in there, standing under a Deinonychus during my most recent visit. I also saw a full-scale Majungasaurus skull, and it was a lot smaller than I thought it was. Even better than Sue, though, I love the pair of Herrerasaurus sculptures that greet you to the dinosaur hall. One is a skeletal restoration, and the other is a life restoration by...I'm guessing Stephen Czerkas. I was surprised at how big the animal was. You think of basal dinosaurs as small, but Herrerasaurus would have no trouble overpowering a person!

You'd think the Alaska Museum of Natural History would be on my list, as I've done so much work there, but until they put some kind of plaque under that T.rex skull, acknowledging all the work Scott, Brian, Raven and I put into it, the AMNH stays off my list.

Special Shout-Out to Nick Gardner

I have to thank Nick Gardner, who as you may remember, hates theropods. He (and Will Baird, actually) has been hounding me about my mispeakings regarding Odontochelys and turtle origins. I have never understood the morphological basis for a diapsid origin for turtles, and grew up with the dogma that Testudines are the only living group of anapsids whose closest (extinct) relatives were the pareiasaurs like Scutosaurus.

Well, Nick pointed me in the direction of an important paper by Reippel & Reisz which gives said morphological basis. I would be remiss were I not to pass this information along:

Rieppel & Reisz (1999). The origin and early evolution of turtles. Annu. Rev. Ecol. Syst. 30: 1-22.

And I found an alternate, albeit much older opinion by William Gregory comparing turtles to pareiasaurs and placodonts. Although probably outdated, this paper contains absolutely wonderful illustrations. You don't see this anymore.

Gregory, W. K. (1930). Pareiasaurs versus placodonts as near ancestors of turtles. Bull. Am. Mus. Nat. Hist. 86: 275-326.

I will have more to say on this topic after fully digesting both papers. Thank again, Nick!