- Welcome, I'm Nicole Perna, the Director of the J. F. Crow Institute for the Study of Evolution and it's my sincere pleasure to introduce today's speaker, David Lovelace from the UW Madison Geology-Museum.  David is a research scientist at the museum, but he's also involved with a lot of outreach activities there and for the Crow Institute, in general. I'm going to tell you a little anecdote about an activity I did with David this past June because it'll give you some sense of where he's coming from. So, in late May, we got an email from a middle school teacher from Sun Prairie asking us if we could put together a panel of four evolutionary biologists to spend an entire day with the middle school biology classes, helping to give them some feedback and evaluate a project they'd done where the assignment was to design a prehistoric park. So, I said, "Sure. Why not?" Because we hate to turn away anybody that comes to us asking for STEM education. Lo and behold, we agreed and then I hit send on the email, and I thought, "Well, where am I going to find "four people with about one week notice?" So, I looked around, I started quite literally at home, signed up my husband and figured I could apologize for that later. Then I looked around my lab and I signed up my post-doc. And then I said, "Well, three evolutionary geneticists "is not a real good representation of the whole breadth "of evolutionary biology. "We really need somebody who knows something "about fossils." So I wrote to the geology museum and they passed the invitation along to David and, within hours, he had agreed to do this as well, with really no more information than what I've given you. Flash forward a week and we show up at the school, and it turns out we are literally going to listen to five hours' worth of presentations from five different classes, each of which has been tasked to take five transitional fossils, assume they have DNA from it, bring them back to life and design a theme park. And the students spent several weeks and came up with these very elaborate plans. So they had a team dedicated to the research, a team dedicated to business and marketing, a team dedicated to educational outreach, for each of the five classes. And then a team dedicated to building these enormous, three-dimensional models. We walked in and there were about five of these large six-by-six models complete with hotels and enclosures and this, that and the other thing. Each class gave a presentation and this panel, which I would have found intimidating if I was in middle school, sat there and asked them a bunch of questions. So the geneticists, we asked kind of predictable questions, things like, "What have you done to ensure the safety "of the animals? Veterinary care and welfare "of the park-goers?" And they had good answers to all that. My husband Jeremy contributed this important question, "Why do soft pretzels cost so much "at the concession stand?" (audience laughs) But David had the real meat of it and I really admired the way he very gently brought the students around to question their own design in important areas, such as "Well, you chose an animal that's very small "to be the surrogate for this DNA "but the animal you're trying to grow "is really, very large." He would bring them around to that realization on their own. Along with that, one very important, maybe even the enduring lesson from the whole thing, is not all fossils are dinosaurs. (laughs) And so, today David will talk to us about some actual dinosaurs with his talk Shaking the Dinosaur Family Tree: a New Look at an Old Story. (audience applauds)  - All right, so how's everybody doing today? Awesome, so what I want to talk about centers on a paper that came out earlier this Spring by Baron and two colleagues. It kind of revolutionized the phylogeny of dinosaurs and how we think about them. What I want to do is kind of go through, first of all, the history of dinosaurs. Where'd they come from, what are they? And kind of walk through that, talk about the different clades, what we know about them a lit  And then we get the theropod line, and the sauropod line. And what we're really going to try to focus on for much of this talk, I'll explain the groups here, but we're going to be looking at the base of the dinosaur family tree. We're going to be looking at the trunk down there. To start with, down at the base, we need to first figure out where did dinosaurs come from. What are they related to? So, Archosaurs, is the major clade that we're talking about and all of those animals include the Crocodylians, the Crurotarsans and the Crocodylomorphs as a crown of that clade. You have Pterosaurs, so the winged reptiles, the flying reptiles. You have Proto-Dinosaurs, the Dinosauromorphs and then, true Dinosauria. We're going to be focusing on this part of the tree. But, to start off with, what are Archosaurs and how are they differentiated from the other animals? The big thing here is that, at this point in the evolution of this group, they go from this sprawling gate of all other reptiles at the time, they go to a semi-erect posture, they bring their legs down under them, they narrow their body plan, they elongate it. A lot of this seems to be in response to an increase in metabolism. They're moving a little bit faster, they're doing more, they're more active. That increase in metabolic heat requires them to narrow their body to reduce their profile effectively, to shed heat, not  absorb so much heat. So they're changing at this point in time, they're starting to evolve into this kind of warm-blooded. They interlock their gastralia so they can breathe with their ribs. The Crurotarsi, these are the Crocodylians, and then we have an extinct group, Phytosaurs, which are very similar ecologically, set at the base of the Crurotarsi and Crocodylians at the crown. Scleromochlus, this is kind of cool, so notice so far, everything that we talk about at the base of the dinosaur family tree is about this big. So when we think dinosaurs, most people think pretty big. Right? Sauropods, large theropods. Most of the small stuff, down at the base of the tree, are very small. Scleromochlus is probably the ancestor of Pterosaurs, which are a group within Ornithodirans. These are the flying reptiles and they have very small ancestors, a lot of the first ones are very small. They'll also then get up to be the size of Cessnas. So it worked for them. But, interestingly, most of these that had flight, certainly had flight capabilities, they were using those big, springy legs that we see in Scleromochlus, they had these huge things, they think they're saltatorial, they were bouncing. They actually use that bounce to become airborne. So these large, huge things like Quetzalcoatlus are probably launching from the ground, not flapping their wings to get up into the air. So there's some interesting characters that we're looking at the base of the tree, they're very long-legged, very long-armed and the earliest dinosaurs, whenever you look at their skeletal structure, look very similar to the slightly-more-derived true dinosaurs, except in the pelvis. One of the defining characteristics of dinosaurs, here you go, here's the million dollar thing, when somebody says, "What's a dinosaur?" You can say, "any animal that has a perforated acetabulum!" (audience laughs) If you have a hole in your hip, you're a dinosaur. Birds have a hole in their hip, so, right, they're dinosaurs. Hey, cool. The typical mammal structure in many reptiles, the head of the femur is a ball, and it sits in the socket and that's the hip joint, within dinosaurs, that perforated acetabulum, that hole, meant that the hook of the femur, the femoral head, would sit inside of it and the ilium would rest right on top of it. That was their motion. Now, one of the advantages of that is it locks the leg in to an anterior-posterior motion very well. It gives you a lot of structural stability whenever you go to being truly bipedal and you weigh a lot. The problem is that they can't do the splits. Well, they can, but they can only do it once. (audience laughs) So there are some limitations to th  So Ornithischians, one of the things we'll be looking at, at least in part, is really low down in the tree, is this critter Pisanosaurus. It's a relatively incomplete skeleton, but it's got enough material there, certainly in the cranium, to try to figure out where this animal goes. But it's this guy. This is one of the major ones that's kind of messing with the tree. You can imagine, as you get down to the base of a tree, there's a lot of problems trying to distinguish groups. That's where all the trouble lies. We had no data for a long time, so it's really easy. We have three very clear clades. However, whenever you get more and more information, especially at the base of the tree, it becomes not so clear. That's one of the animals we're going to look at. So here's Pisanosaurus, one of the features of it is, a very similar group Kulindadromeus has been found with feathers, or at least dermal insulation, protofeather-like structures. And it has a very Ornithischian-like beak, so there's a lot of structures within the mandible that are considered basal ornithischian. Heterodontosaurus, one of the interesting things, the Heterodontosaur dentition, that means it has different dentition, so it actually has really sharp canines and incisors, grinding surface-like posterior teeth. Very unusual for archosaurs. Archosaurs have like one type of tooth, it's sharp and that's it. We're starting to see diversification within the group in different diet and feeding habits. Eocursor, one of the new 2007, another new basal dinosaur, several dozen have been found within the last dozen years. Basically every year we get a new dinosaur coming out here. So Thyreophora, these are within that group, the Stegosaurs, the armored, the plated dinosaurs, we have the other armored dinosaurs, the Ankylosaurs. Again, these were much more derived and this is what Huxley was working with. This is what he was describing initially. Same with the Ornithopods, right? It's a very diverse group of crested dinosaurs, the duckbills. And then, lastly, within the Ornithischian, the famous Ceratopsians. So the Ceratopsians basically had a very similar body form, but they go completely wacky with their cranial ornamentation. Triceratops is actually one of the most boring of the Ceratopsians with just a mere three horns. I mean, they're only like a meter long, the horn. But the other ones had like 13, 20 ... They get awesome, but very derived, right. So, moving over from the Ornithischians as we know them, we're going to jump into the Saurischians. These, again, the Theropods here, which are the meat-eating dinosaurs, here we get up into the Tyrannosaurs. Then you get into really cool Edward Scissorhand-like Therizinosaurs and then up into the group, the Maniraptorans that lead to the evolution of birds. So here's birds, the crown group of Therapoda. Again, classic Tyrannosaurs and small, little theropods, Coelophysis there. Meat-eating, bipedal, almost all meat-eating, there's a few herbivores that throw things wacky. But, they have an avian-like breathing system and they're pneumaticized all over their body, very interesting structures. Similarly, the sauropods also are hypothesized to have this avian-style breathing system, as well as large pneumatic structures; one of the reasons that these have been united for so long. So Saurischia, these really large, long-necked, long-tailed dinosaurs, Brachiosaurus, Brontosaurus, which actually, for most of my career, I've been say, "it's not Brontosaurus, it's "Apatosaurus, it's a nomenclatural mess-up." Yeah, it turns out that now all the phylogenies are showing that it actually is true, so we can reinvigorate Brontosaurus. (audience laughs) So, who knew? Now Herrerasaurus. So we have Pisanosaurus, that little dude, as kind of messing around with the base of the tree, Herrerasaurus is the other one and it's been messing with Saurischia for a long time now. Herrerasaurus is a basal dinosaur, for sure, but it jumps back and forth between theropod and sauropod. We can't tell what it is. You look at one suite of charact  So that character, when we plot those, that really is one of the strong characters that unites this, it's unique to sauropods and theropods. Things are mapping all over, what's driving this? And, of course, cool things, right? Planets are really cool. And dinosaurs. So we got really envious when Pluto got all the attention for being kicked out of the solar system. So somebody had to come up with it and that's where Baron et al decided, "Hey, let's shake up the dinosaur family tree." So they ran a series of analyses and they actually are pretty robust analyses, they looked at a very large swath of Dinosauria. So they had a very broad inclusion throughout the tree and focused, though, on including these all the new dinosaurs from the Triassic, from the beginning, the dawn of dinosaurs. So whenever they started including these dinosaurs, this is what led to shaking things up. But they ran into a major problem. Back in the 60s and 70s when the vertebrate paleontologists are kind of having this dinosaur revolution, one of the things that came out is that we learned about this thing called cladistics. I don't know, botanists had been using it a long time and they were kind of laughing at us, so we thought, "Well, hey, we ought to try this out," and started applying cladistic analyses, coming up with phylogenic hypotheses, testing, these things. When you did that, we went from a field in vertebrate paleontology where were diagnosing these morphospecies, right? We don't have the same ability to look at species as you do in the extant, so we're just using morphologic characters of the bones, that's all we had. This is a description, what is Crocodylia? Well, it has all of these characters. If you have all of those characters, you are probably a Crocodylian. But whenever you go to the field, we find a fossil, we look at the characters, you don't want to list this every single time and say "this defines a crocodile." So what is a crocodile? You still use all this information, but we're using phylogenetic taxonomy, phylogenetic nomenclature. We're taking all this data, putting it into cladistic analysis and anything within Crocodylia is then defined as the last common ancestor of these, Gavials, Alligators, and Crocodiles. So, Crocodylia is anything that includes these three animals, these critters. So, if you're outside of that, you're not a crocodile. It was a very simple way to describe things. It simplifies the description and the diagnosis of the animal and how we discuss it. Any time new characters arise, it doesn't mess with the tree. It didn't do-- It makes it easier for us, but it also adds some issues because, here we go, here's Dinosauria. It has been defined for a long time now as all descendants of the most recent common ancestor of birds and Triceratops. So it's the inclusion of anything that includes birds all the way to Triceratops. Anything in there is a dinosaur. Great, and it's monophyletic. Great, it makes everybody happy. Saurischia, same thing, it is anything that includes pigeons and Saltasaurus but excludes Triceratops. So Saurischian is a clade within Dinosauria and similarly Ornithischia is Triceratops but does not include pigeons or Saltasaurus. So that's how we describe and define these major clades. However, when this paper came out, here's what we had nice, monophyletic Dinosauria, Ornithischia, theropods and sauropodomorpha, these comprise the Saurischia. The problem was this new phylogenetic hypothesis basically shifted the base of the tree and it threw theropods out of their inclusion in Saurischia, or at least their tie to sauropods, and said that they were more closely related to Ornithischians. The problem is that created a paraphyletic group, which, in phylogenic nomenclature, they didn't really like that much. So, enter Herrerasaurus. We had to redefine everything. The authors had to redefine everything and so they got rid of the definitions of Ornithischia and introduced Ornithoscelida and changed the definitions of Saurischia and Ornithopod. So these are the new definitions of these animal