In our 105th episode, we had the pleasure of speaking with Sean P.S. Gulick, a research professor for the Institute for Geophysics who has been studying the geologic processes and environmental effects of the Cretaceous-Paleogene Chicxulub meteor impact.

Episode 105 is also about Centrosaurus, a ceratopsian that had small hornlets on its frills.

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In this episode, we discuss:

• The dinosaur of the day: Centrosaurus
• Name means “pointed lizard”, got its name from having small hornlets on its frills (not from the nasal horns, which were found later)
• Ceratopsian that lived in the Late Cretaceous in Canada, and has been found in the Dinosaur Park Formation
• Lawrence Lambe found Centrosaurus along the Red Deer River in Alberta, Canada, then later Centrosaurus bonebeds were found in Dinosaur Provincial Park (some have thousands of individuals, of all ages), described Centrosaurus in 1904
• Possible they died while trying to cross a flooded river
• Bonebeds may also be from a watering hole that disappeared in a drought
• Centrosaurus may have the largest known dinosaur bonebed, one near Hilda, Alberta has thousands and is known as the Hilda mega-bonebed
• There are Styracosaurus on top of the Centrosaurus remains, so some people think Styracosaurus displaced Centrosaurus in the area
• No Centrosaurus fossils found outside of southern Alberta
• Type species is Centrosaurus apertus
• Part of a naming controversy in 1915, with Kentrosaurus (stegosaurid). Kentrosaurus got alternative names, but it didn’t matter since they’re spelled differently (and pronounced differently)
• One species, Centrosaurus brinkmani, was reassigned to Coronosaurus in 2012 (named in 2005)
• Probably traveled in large herds
• About 20 ft (6 m) long
• Had stocky limbs
• Had a single large horn on its nose that curved forwards or backwards, depending on the specimen you’re looking at
• Had two big hornlets that hook forwards over its frill, and a pair of small horns over its eyes
• Had a long frill, with large fenestrae and small hornlets along the edges
• As it aged, its ornamentation decreased
• Centrosaurus frills were too thin to be used for defense, so probably used them for display or species recognition
• Had jaws that could shear through tough plants (herbivore)
• Centrosaurus is part of the Centrosaurinae subfamily
• Large horned dinosaurs in North America with large nasal horns and brow horns
• Includes Pachyrhinosaurus, Avaceratops, Albertaceratops, Einiosaurus, Achelousaurus, and maybe Brachyceratops (dubious)
• Fun fact: The term “thagomizer” originated in a far side cartoon by Gary Larson, in his 1982 comic. Where a caveman pointed to the tail with and stated “Now this is called the thagomizer… after the late Thag Simmons”. According to New Scientist, the term was picked up after the paleontologist Ken Carpenter gave a presentation at SVP in 1993 about stegosaur tails where he described it as a “thagomizer”

This episode was brought to you by:

Permia. Permia is a prehistoric apparel and art brand, dedicated to creating collectible, scientifically accurate restorations of ancient life. There creations are available now on their Kickstarter page or Permia.com.

Artemesia Publishing. They not only publish award-winning dinosaur books, but also “coloring puzzles” which can be put together and then colored using markers, crayons, or colored pencils. You can get more information at apbooks.net and you can purchase the “coloring puzzles” at http://www.paleoartisans.com/Catalog/fuseaction/ListProducts/classid/152603.

For those who may prefer reading, see below for the full transcript of our interview with Sean Gulick:

Garret: All right. I know you’ve been doing a lot of interviews; I’ve seen a lot of things popping up on my Google alerts and things about your work.

Sean Gulick: Yeah, it’s been really—It’s being busy. I’m glad to see all the excitement.

Garret: Yeah, so what led you to drill into the peak ring instead of some other part of the crater?

Sean Gulick: It’s a great question. You could choose to, if you only could drill one place, in particular the impact crater, you could envision, you might draw in inside the center of that crater and try to hit the melt sheet that lies in the center, or you could drill in the trough around the edge of the crater that would have sort of the thickest section of material that infill the crater afterwards. But we actually chose to drill a landform, the peak rings, like a ring of mountains around the centre of the crater, because there have been no samples ever collected from the peak ring as an impact in part because Chicxulub are a little bit busy, only a large impact crater on earth with a clear peak ring that hasn’t been eroded away.

The next nearest place that you could say, figure out what a peak ring is made of, how they’re formed, would be to go to the moon. Obvious target there would be to drill into the peak ring, and you could get some of the other things on the way. So we could still get the sediments that burry the peak ring and worry about how life came back and the impact. We could get whatever the material that mantles the peak ring, that we can see in our physical data and of course we would get significant amount of the upper part of the rocks that make up a peak ring.

Garret: Great. I was kind of surprised when I saw that the Chicxulub crater was the only one that had a peak ring, but I guess it makes sense since it’s supposed to be like a one in two million, one in two billion years size asteroid or something? Some huge size for an impact and since it was pretty recent.

Sean Gulick: Yeah we should actually get one of that size every hundred million years.

Garret: Oh really?

Sean Gulick: Yeah, but the problem with the earth record is that 71% of our planet is oceans and beneath those oceans are oceanic plates which whenever by plate tectonics they are up against a continent. They’re going to lose the fight and they’re going to sit docked and be destroyed. So ocean basins are never older than about 200 million years. We have a very incomplete record for much of the Earth. And so that’s right now, we only know three very large impacts on earth, Chicxulub which is 66 million years, and then Sudbury in Canada and Vredofort [ph] in South Africa which are both around two billion years old. They eroded well below a depth that you would ever see their peak rings and Chicxulub is perfectly reserved.

Garret: That’s awesome. I remember from plate tectonics classes that most of the ocean is way younger than continents and I was kind of thinking, how much longer would the Chicxulub impact be there because it’s not really near a subduction zone, is it?

Sean Gulick: No, actually it would kind of locked out on this one. So it was a shallow swell locked out in the sense that we can observe it, and I guess locked out also in the sense that it caused the mass extinction. I don’t know if it could be here.

Garret: True.

Sean Gulick: At the time the Yucatan Peninsula was a shallow sea, it was a carbonate platform, so think of a bunch of limestone wrap off into the ocean if you will. So one side of a crater might have been two kilometers of water depth and the other side of the crater might have been really shallow, I would say 100 meters wound up. And after their impact, basin created the crater, then it was sort of a basin that was of the little bowl shaped thing with this peak ring in the middle that was probably on average about a kilometer deep. But it had a big hole to the North where there was no rim, so it was open to the ocean.

But it is on top of continental crust. It’s underneath that shell, underneath that peninsula, it’s actually continental crust. We don’t expect it to get subducted, it may later in the fullness of plate tectonics in time have a collision with something and have the record destroyed by it becoming a mountain range or something like that, but for the time being anyway given that the history of the last say only eroded 100 million years you can tell the peninsula has been a very pretty stable place technically speaking, and so a good one for preserving this record of this event.

Garret: Cool. How far East do you have to go before you get to the edge of the continental shelf?

Sean Gulick: From the impact of the crater itself?

Garret: Yeah.

Sean Gulick: It actually goes quite a bit further out. It’s another—it’s tens of kilometers further, depends in which direction you go. It’s almost 50 kilometers in some directions before you get to the edge of the shelf. It’s quite a wide kind of a shelf. The pier there is at that port of Brazil and it’s the longest pier in the world, so six kilometer long pier.

Garret: Holy cow.

Sean Gulick: Just in order to get to a water depth of about seven meters so they could [inaudible 00:05:02] about.

Garret: That’s hilarious. That’s like around Florida, they’ve got spots like that too I think where there’s quite a long stretch of shallow maybe not to that extreme though, that’s pretty crazy.

Sean Gulick: No it’s similar, Florida, the west side of Florida is also what they call a carbonate platform and as is the Yucatan. It’s a very similar kind of province. Yucatan just happens to be a bit flatter.

Garret: Cool. What have you learned so far from these core samples that you’ve taken?

Sean Gulick: Well it still very much early days, but we kind of have three primary goals. The first was to study the fossils in the sediments that bury the peak ring, the sediments within the basin in the center of the structure. When we started drilling approximately 50 million years ago in the age of the rock samples that we’re collecting which was at about 500 meters below the modern sea floor. And we collected so something like 115 meters or so of these lime stones that buried the crater, and so we could look at all of the fossils within those sediments and ask questions about how life recovered after the mass extinction event in the oceans in particular because that’s where we were recording in these lime stones and at ground zero of the event, so that’s pretty exciting. So that’s still ongoing work.

And then we also collected about 130 meters of basically broken up and melted rocks called [inaudible 00:06:33] or the geologic term is [inaudible 00:06:36] and there’s a lot of excitement in studying the sort of the hydrothermal systems inside there, as well as in the peak ring itself because there’s interest in whether or not an impact crater can create an ecosystem in the subsurface, sort of subsurface habitat for microbial life. So that’s ongoing as well looking for counting the cells that are found, extracting DNA, all that kind of stuff.

And then the last one, and the one that we’ve just published on is the simple question of how impacts work as a geologic process and how is it that when you initially create an impact that might be fairly deep into the subsurface that it results in these kind of lying flat craters like you see on the moon, but with these enigmatic features of topography within their centers, like these peak rings. And since we had little samples of the peak ring, the debate has been all centered around measuring weights and heights of crater rims and peak rings and making arguments about formation or computer models that simulate how you might create an impact to get these peak rings and that those communities have been debating for a long time, and we figured you could test it by simply figuring out what the peak ring is actually made of.

Garret: Yeah and I saw, I think as part of that paper you made a really awesome animation that showed how the ground shifted during the impact and immediately after, and it almost looks like a wave or something of just liquid and then you think oh that’s granite.

Sean Gulick: Right. That’s the big test, right? If the models that view the process are to be one where the velocities and the energies are such that the target temporarily behaves like a slow moving fluid, then the predictions of those would be first open up a hole and then in this case the hole would be 100 kilometers across by 30 kilometers deep, so a big hole. The side would then collapse in, or I should point out that hole would have sort of a uplifted rim all the way around it which should be the height of [inaudible 00:08:44].

That would collapse inward to the center of the crater just as the center is rebounding upward, possibly ten or 15 kilometers above the earth’s surface. And then that’s up rebounding center would collapse outward over top of the sides as they came in and created sort of this perched ring of mount rings that we call a peak rings, and that model predicts that the material that make up the peak ring should come from deep and indeed when we drilled it, we found granite that was probably from as deep a ten kilometers. So six miles down.

It was sort of a real win for one and member of the way of thinking about how impacts works, which in these ones that view them as a dynamic collapse process, things are moving again sort of like the slow moving fluid that allows all of that, but I just described happen in just a few minutes.

Garret: Yeah, that’s a really fascinating and watching that picture, I couldn’t help but just keep wondering like when is this going to solidify because you’ve got a little section highlighted where you drilled and it’s like how is that going to line up in a way that makes any sense while everything is just moving crazily, it’s really cool.

Sean Gulick: And the interesting thing there is it never actually is a liquid in the sense it isn’t melted, right? There is some melt that forms but the whole pile, the whole crust isn’t melted. The crust is just moving in a fluid manner. So it stays as a rock, it stays as a solid material but somehow loses its cohesion, loses its ability to stick together and thus can actually temporarily move in the way that that movie shows. And we think it’s got to be related to the pressures involved, so that blue patch in that movie is actually also tracking what kind of maximum pressures do we think that the rocks that eventually become the peak ring that experience. Because we can then again look at the cores and test it and in the cores we found pressures from ten to 35 gigapascals of pressure and which is something that eroded eight or nine thousand PSI, sorry eight or nine million [inaudible 00:11:00]. And so that’s maybe is that pressure that ultimately somehow weakens the target.

Garret: When you drilled was it really fractured rock because of that or was it still…?

Sean Gulick: Absolutely, great question. In fact it was—we were all—Owen and I were—in fact we had pink granite coming up or orange colored granite coming up. But then when you looked at the end of the cores when we first cut them open, split the sections apart, you could see they’re completely shot through with fractures and faults. Just in every orientation you can imagine and then we actually found true faults that showed evidence of movement where you could see crystal growth on the direction that moves.

Garret: Oh cool.

Sean Gulick: And then we found evidence all the way down at the crystal scale of high pressures. Things like the courts crystals had defamation, plains of defamation cutting through the crystals and things like biotype, the black mineral that you see in, it’s kind of mica was actually changed by the pressure wave. You could really tell this thing had gone through a layer, practically stressed, and the physical properties were fundamentally changed.

So not just was it fractured visibly, but if you measured the density of it, most geology students will tell you a continental crust should be about 2.65 grams per cubic centimeter and that’s because it’s made of granite, that’s the normal granite. Well these granites were more like 2.2 to 2.4, so they’re reduced in density, so they’re lighter than they should be, and they had lots more pore space, so instead of it being maybe one or two percent maximum pores to relative to the amount of rock in a given sample. These are something like 10% or higher pores relative to the rock. So somehow it opened up pore space, it opened up pores if you will in between the grains within the granite behind this process of shock and fracturing and movement.

Garret: Well from that video you could almost imagine it being like making whipped cream or something that’s folding in extra air while you’re sloshing it all around and cracking it apart.

Sean Gulick: It’s an interesting in air log, I kind of like that. And it’s a really important observation because when we think about several things, when we think about how planetary surfaces evolved places other than earth, where they are not protected by an atmosphere, we can envision if you have four billion or four and a half billion years of bombardments by impacts, that you’re going overall affect the crust of the target.

We know that impacts are bringing things up from deep, so it’s kind of recycling the crust a lot, and also you’re lowering the density and expanding the porosity and fundamentally damaging the surface. And so this fits some recent results of a gravity measuring to the moon called, grail, where they argued that the entire lunar crust was maybe 8% porosity on average which everybody thought that’s amazing. But I think it’s pretty clear that its impact is to blame for that kind of observation.

Garret: Yeah, there’s some kind of Swiss cheese analogy there that it is a skiff being made.

Sean Gulick: Well the other side that I guess got people excited is, if you’re making a whole lot of pore space, if you’re making in the subsurface and then you’re flushing it with hot fluids because the melt sheets right next door and it’s very hot vibrant vigorously probably sloshed place in the wake of an impact, then you now have created an interesting habitat in the subsurface for life, because all life really needs is a place to live, it needs some fluids and it needs a chemical exchange, and so there is a lot of interesting chemistry like we’re moving through these rocks. And so we can envision impacts are there for potentially really good habitat for life to live in the wake of an impact.

Garret: That’s really interesting to me because I always thought of the impact side as kind of like the ultimate sterilization process. But I guess if it doesn’t all melt, it doesn’t necessarily all get super hot or would it just be hot but temporarily and then with the ocean water and everything microbes could rush back in.

Sean Gulick: Yeah I think that’s right. I think it would be hot and it would actually stay hot for quite a long time but there are microbes that as long as it’s not too hot, right there are microbes that can live at very high temperatures. That [inaudible 00:15:31] say mid-ocean ridge kind of settings that are quite hot, we call them extremophiles, things that love extreme conditions. But we know they exist and we have hydrothermal minerals we saw in these course, so we know these hot hydrothermal systems were crushing through and so now the work to do is to seek to attract some DNA out of the cores and do cell counts.

And there’s some precedent to this. I don’t know if you know but the Chesapeake Bay, has a large impact crater beneath it called, the Chesapeake Bay impact crater. It’s 85 kilometers across, about 35 million years old and when they drilled into it, they actually found elevated counts of cells down in the subsurface of the crater at about 1500 meters depth, so close to a mile down which is pretty exciting result because that’s modern cells, its living cells, right? So this is a 35 million old crater, created some kind of ecosystem inside it, down in the subsurface. Then it evolved such that we still have LA or an ecosystem today that’s no longer being fed by the impact but was there because of the impact.

Garret: Wow, yeah that’s really interesting because I would have assumed that these extremophiles after it cooled, would kind of die out and it might go back to nothing but the fact that it maintained, it’s fascinating.

Sean Gulick: That’s a wonderful question and your instinct is what my instinct would also be that once you take away these chemical reactions that they’re sustained on and the temperatures and so on, why doesn’t that ecosystem die off. But if evolution finds a way and results in an ecosystem that can survive despite having been cut off from its original reason for being. Certainly any microbes where there are any on the asteroid itself are thought to be gone, not to be vaporized, and destroyed if there were any. Likewise anything right at the target, right at ground zero might well have died but not everything in all distance is away. So as long as there are some connection within the crust that microbes can move around in, then you can actually have a seeding of this habitat and subsurface. And that’s a question that needs a lot more research, and it’s one of our future goals.

Garret: Cool. So I know that after the impact really at the exact moment of the impact geologically speaking, it layered a layer of a radium all over the earth which is—this a really handy way that date things at the end of the Cretaceous. When you were drilling, did you find a bunch of the radium or would that have been further towards the actual impact site?

Sean Gulick: That’s another arena of study which is to look for any evidence of the asteroid itself within the course. But it’s not something you ever get an immediate answer on, a radium is it comes in parts per billion scale if you’re going to find it all and so that’s not—we don’t have an instrument on the drill leg or at the initial place where we split the material to look at something at that levels. So just to check, we have sent samples to 40 other labs around the world to see if there is any evidence of that, so jury’s still out on that one.

Garret: All right makes sense.

Sean Gulick: It is absolutely a link though of the asteroid impact to the end Cretaceous everywhere in the world outside the crater. You do find the radium anomaly 80 times background that says there was an event from an asteroid that took place right at the end of the Cretaceous coincident with the mass extinction of that.

Garret: Sure is handy, it’s almost like having a universal timestamp or something.

Sean Gulick: Well it’s an excellent marker of horizon if you will. Well this is in fact, this idea has just been used again recently, we’ve redefined the geological time scale to include the [inaudible 00:19:29] as a sub part of the [inaudible 00:19:31] and they use 1950 as the year basically bombs. Again this wonderful, horribly created but wonderful marker within the modern geologic record of a change in time, that is they’re arguing is going to be the thing that a geologist of the future could recognize as the beginning of the new era.

Garret: Interesting. Does that leave the same kind of marker, like could you find something in like Kansas from nuclear tests?

Sean Gulick: Really anywhere you go, you measure sediments from the 1950s and on, you will find evidence of bomb created isotopes that were not present prior to that, so a very clear marker.

Garret: It’s kind of freaky.

Sean Gulick: Yeah it is a little bit.

Garret: So a crazy fact I read and I wanted you to weigh in on it. There was a kind of a simulation done I forget which University did it, somewhere in the Midwest and they said that 48,000 cubic miles of material were shifted as a result of the Chicxulub impact, but it wasn’t that at all like moved to a particular spot I think some of it’s kind of like this peak ring formation where it kind of moved, left five feet and right three feet kind of thing.

Sean Gulick: Yeah and I suspect that that number is probably also now out of date. But the way to think about it is when you first—It had this 14 kilometer asteroid which is coming in at 20 kilometers per second impact the earth. It’s going to open up that hole, that sort of the instant transience cavity against 100 kilometers wide, but 30 kilometers deep, but in doing so, the uppermost few kilometers that get hit are going to actually vaporize, they go up into this big vapor plume, along with most of the asteroid, and then the next few kilometers are going to be actually ejected out of crater as particles.

And then the rest of it, what’s below that is the part that gets moved out of the way, rebounds up and collapses inwards. So besides that they were not ejected or vaporized can collapse them and we find that in the crater where we have sort of cotasious [ph] sediments, and limestones that vaporize have fallen into the crater, big slum rocks. Then the peak actually lies on top of those yet it came from very deep below the area that was actually ejected and vaporized. So that material has actually spread all over the world, right?

That whole digging of many kilometers down spread all over the world, but then in addition all the material that was displaced outwards and back inwards and can create the final impact or also moved. So it is an enormous area that was directly affected and we think we actually can image on our geo physical data faults that cut through the entire crust and we can even see it uplift at the crust mantle boundary and what’s called the Moho, by a couple of kilometers permanently raised upward inside of the crater.

Garret: Holy cow. And that’s interesting that it went up too.

Sean Gulick: Again it’s that rebound process. If you picture throwing a rock in a pond, what’s the immediate result, ripples go out, but the sides collapse, and then the center splashes up.

Garret: Yeah it’s interesting.

Sean Gulick: This is not quite water in motion, is it? It’s a slower moving fluid than that, but the same concept holds, it is a rebound effect, and it’s a bit [inaudible 00:23:12].

Garret: Cool. You mentioned the several kilometers that vaporized, is that what ended up being that kind of glass that was raining down or was that the layer that was ejected?

Sean Gulick: Most of the actual glasses is in the ejector, but you will find the spirals that are actually spherical in shape, they’re also made usually of some kind of glass but they’re round. Those are actually condensates, so those are actually the vapor plume that then condenses back as a spiral or as a ball and it rains down, so we have actually glass in both the ejected tektites and in the—which are materials that have travelled through the air as a semi solid versus things that went up as a vapor condensed and rain back down.

Garret: Those micro tech type things are ejector, and then the raining ones are a different category?

Sean Gulick: I didn’t say this is the way to think of the [inaudible 00:24:05]. They condensed from the vapor plume and you often hear things like spirals which are these again these little glass balls if you will.

Garret: Cool.

Sean Gulick: And there’s a terrible muddying of these terms that happen. So you always have to be a little bit careful when people use those terms because they cross the boundary between them quite often than their use. But the two processes are important. There are things that are literally fired out of the crater by the energy, 100 million atomic bombs of energy. And then there are things that literally vaporize as a plume that then we condense and rain back down.

And if you do simulations of this material arriving in a place like Natasha [inaudible 00:24:46] a colleague of ours has done a really nice one which shows the ejector arriving over Europe, 6000 kilometers away, and you can see that the ejector arrives sort of at the top of the stratosphere and then the heavier stuff like a the spirals are raining down fairly early, very quickly within hours, causing a heating of that, causing friction in the atmosphere that will set off wildfires and things like that and heat up the surface of the earth and that’s one of the kill mechanisms. But then all the finer stuff, the dust in this case even had sulphate that became a sulphate aerosol would be aftermath finer stuff, each one would then impede photosynthesis, and ultimately likely pretty much crash the [inaudible 00:25:29].

Garret: That’s a nuclear winter thing, right?

Sean Gulick: Right and it is unclear how long it would last in this case, there’s estimates months to years.

Garret: How far—was there stuff raining on the entire earth like these glass things, does that make it all the way around, what’s on the opposite side, I guess Russia? I don’t know what’s over there, oh India, right?

Sean Gulick: Well India wasn’t there at the time.

Garret: That’s true, it was still moving North.

Sean Gulick: Yes it would have been—it is a global boundary layer, in fact we think some of the ejected particles likely took more than one trip around. There’s nowhere that didn’t have material raining down from the sky or blocking the atmosphere about everywhere on the planet. Now they have been depending on this is again a research topic, depending on the angle that is hit, you can actually vary the amount of ejector in different directions and that may actually be very important, but because we don’t have a perfectly preserved surface from 66 million years everywhere, we can’t do that you wouldn’t say on the moon or Venus where you can actually see the spray of the ejector, use it to backtrack the direction of the impact. We don’t have that, so we’re trying to attack that question in other ways.

Garret: With it raining and obviously the condensation process, producing a lot of heat and then lighting things on fire, do you think the whole earth would have been engulfed in a flame?

Sean Gulick: That’s a good question. The debate is scattered wildfires versus worldwide wildfires. And there is soot that has been found in many boundary sections at the end of the Cretaceous. I think the debate went back to sort of scattered for a while and maybe it’s now moving back again to closer to the worldwide wildfires, but it’s very dependent on the interactions of the ejected material on the vapor plume with the atmosphere.

And so there’s a lot of specific debates about that. And that also leads to these questions about how hot the surface got for how long, was it a pizza oven for hours, was it a toaster oven for tens of minutes; these are differences and how efficiently it killed large land animals for instance.

Garret: The interesting thing to me with that too is when there are these depictions like I think the Natural History Channel, they were not too long ago where they showed basically the whole earth looking like Venus or something just like engulfed in this big fire mess. I can’t imagine anything surviving that, so it seems like it would have to be a little bit less severe than pizza oven for hours kind of mentality because how would you even have anything left.

Sean Gulick: Yeah and I think that’s an interesting point to make that you can’t have that go on for too long or you don’t have the 25% that did survive, survived. And there is an observation everything large died, both in the oceans and on land, but that actually everything larger about 25 kilograms were in extinct. But that that may well be simply because of the food needs not necessarily because of these initial effects like the firestorm. So there’s debate still on this. And the other big debate on the kill mechanisms is we know it’s uneven, the oceans, the surface oceans actually had about a 90% extinction rate versus rivers and streams only maybe 5%.

Garret: Really, I didn’t know it was that [inaudible 00:29:03].

Sean Gulick: It’s a really big difference depending on the ecosystem involved. And maybe a big difference, the carrion eaters may have done better than the primary predators and we don’t know enough of the details. What we do know is that large things went extinct and in places where we have very large numbers and can do the statistics like looking at the [inaudible 00:29:25] plankton that live in the ocean, these things, all the larger ones of those went extinct too and only the smaller ones made it through. In fact only four species, four actually made it, and all modern forms of all famous four which is a phenomenal concept to think about.

Garret: Yeah, that’s a really interesting because it—I had the simplistic view of like well the big things die because they couldn’t hide or something or the ones that were in burrows at the time happened to survive, but if you start putting plankton into that theory…

Sean Gulick: You can kind of extend it down there. The zooplankton eat the phytoplankton or some of them do. And the phytoplankton had about a 90% extinction rate, so maybe it is just the food chain that matters in that case, but it’s interesting that there is some connection, the body size, there’s also a connection to simplicity of the organisms, the complicated ones lived to the end of [inaudible 00:30:20] largely went out and maybe the ones that were more generalists made it, but these were all things that we really want to look at and understand a whole lot better. Why did the things that survived survive and then ultimately become the breeding stock if you will that caused evolution of all the modern organisms.

Garret: That’s awesome. I hope you find all the answers.

Sean Gulick: I’m going to keep working; more papers come this year I hope.

Garret: Great. I’ve read really conflicting things about the size of the wave, what do you think about that?

Sean Gulick: The tsunami?

Garret: Yeah.

Sean Gulick: Yeah so we have a large pile of broken and melted stuff up on top of the peak ring. So we are now investigating that, but certainly it seems like it’s at least that high in that face models that we looked at hundreds of meter high tsunami, how high precisely is still going to get molded. There haven’t been any modern models using what we now know the geometry of the crater debate, right, so you got to figure out how you—you got to create the initial wave but then a large part of tsunami comes from the water rushing back in, interacting with itself and rushing back out again.

And so to do that right, you’ve got to model it with the actual geomorphology, the actual shape of the crater, and that hasn’t been done. That’s again one of our upcoming tasks for the science part we’ll work on.

Garret: Interesting. Is there anything you want to share with the audience where they can check out your work?

Sean Gulick: I think if you guys are going to share that movie for them to take a look at, I think that’s a pretty exciting one to get a grasp of the processes involved. And also there’s going to be two documentaries coming up in the spring.

Garret: Great.

Sean Gulick: On Both BBC and on Noder. So there’ll be a chance to have a much longer discussion via those media.

Garret: Awesome. Is that based on your work drilling or is it on the findings?

Sean Gulick: Just on the drilling expedition yeah.

Garret: Awesome. Well I’ll look forward to it. Thank you very much for speaking with me. It was a fascinating discussion.

Sean Gulick: Absolutely, my pleasure. Thanks very much.