 All right, thanks, Bill, and thank everyone for coming. Just want to make sure that everyone can see the slides, because on my computer, it takes a few seconds for this slide to show up. OK, my name is Shu Haishao, and I'm a painontologist at Virginia Tech in Blocksburg, Virginia. Can we go to your next slide, Bill? So I said I'm a painontologist, but I'm also a geologist. So I travel around the world and to do field work, which is a big part of my research. So I've been almost all the major continents. And one of my favorite fieldside was the northern side area. So the northernmost pane on the map. The next. So this place is called Tixie in Siberia. And it is literally the end of the world. If you keep going, keep going to the north, and the people you hit, the Arctic Ocean, this is a Tixie, it's a military base of Russia. And the heyday of Cold War, this is a large military base, where some of the largest helicopters are stationed there, and the Russians watch the Americans and the Canadians across the ocean. It's very tough both physically and politically to get there. Next, in Tixie, for example, this photograph of me having lunch in the field, about 50 miles, 100 miles south of Tixie. There's an inland from the coast. There's a lot of mosquitoes. And some of them are really big. We have to wear a beekeeper's net during work or during lunchtime to just keep the mosquitoes away. Next. And so if you take a look at what we have for lunch, this is some onion soup. But there are maybe two dozens of mosquitoes in a bowl. Because when you cook the soup, the mosquitoes sense CO2 and heat. So the plume of heat and CO2 from the stove attract a lot of mosquitoes. So there's always a small tornado of mosquitoes above the stove. And when you lift the lid, all the mosquitoes just dive into the pot. And they became part of your delicacy. But even so, we would still prefer the dead mosquitoes than the live one. The taste, not too bad. I mean, it tastes pretty good. But the dead mosquitoes are a lot better than the live one. Because when you walk, there's a plume of mosquitoes behind you, because you breathe up CO2, and the mosquitoes just following you. But when you stop to look at the rocks, they all come in front of you. And blocking the view of you, particularly when you try to look at the rocks, it's not that you have a plume of mosquitoes. So when I tell this field story to my friends, my parents, and then my son, they always ask me why you go to places like this, the Iberia, and also did some fieldwork in Africa, in the Himalayans, Australia, China, and in the Gobi Desert. So I went to this place because I was inspired by a quote from Charles Darwin, more than 160 years ago, to be exact. So in his book on the origin of life, Origin of Species, he wrote, consequently, if my theory, if his theory of natural selection, if my theory be true, it is indisputable that before the Lowes, the Cambrian stratum was deposited, the world swarmed with living creatures. And by that, he earned animal life. And of course, at that time, in the 19th century, there weren't any animal fossils predating the Cambrian period. So it was a problem for Darwin. But he very quickly dismissed his problem by recognizing that the geological record is incomplete. So he kept the writing. I look at the natural geological record, asked a history of the world imperfectly capped. On here and there, a short chapter was preserved. And on here and there, in each chapter, a few lines preserved, a few pages preserved, in each line, there's only a few words preserved, so on and so forth. So maybe the entire pre-Cambian animal record, fossil record of animals, was not preserved. Next. So before I go on to talk about what we now know about the pre-Cambian fossil record, I want to just introduce you to you the geological time scale. So what is shown here is the 4.6 billion years of the Earth's history, which is divided into the big chunk of time, the Hadian from 4.6 to 4 billion years ago, the Achaean from 4 to 2.5 billion years ago, and the protozoic from 2.5 to 0.5 billion years ago, roughly, actually 0.54 billion years ago. The later part of the protozoic, next, is divided into some final geological intervals that are known as the Tonian, the Cryogenian, the Ediacaran, and the Cambrian. So the Cambrian is where the abrupt appearance of animal fossils in the geological record happened. And that is known as the Cambrian explosion. And that was what kept Darwin worry about the fossil record. And he thought that any animals lived in the pre-Cambian time period were not preserved. So today, we are going to look at the Tonian, Cryogenian, and the Ediacaran period, and ask the question whether there's any choices of animals in this geological time period before the Cambrian. Next. OK, so there are two different ways to answer this question, whether there's animals before the Cambrian. One is to use the molecular data to look at things like DNA and protein sequences of all living animals and then compare their differences and their similarities among different animals. And you can infer when two animals split from their last common ancestor by studying the similarity or differences in their homologous DNA or protein sequence. And if you do that for a large number of animals, you can do two things. You can first put together a sort of famine tree. So who is more closely related to who? And two, you can also put a timescale against the famine tree. So in this slide, the left part is a geological timescale. So I have Tonian, sort of brownish, the Cryogenian, blueish, and the Ediacaran, sort of a beige color. And then Cambrian in a dark green. OK, on the right side of the slide that shows the famine tree that is scaled against the geological time using a molecular clock method, just comparing the similarity and differences of the biomolecule sequence of different animals. So clearly, the molecular clock seems to show that animals first diverged in a Tonian period. That is to say between Bainian and 720 many years ago. So some of the earliest animals split from each other, particularly perhaps Sponges. It's one of the animal group that split very early during the evolutionary history of animals. And then it's not until the Ediacaran period when a large number of animals split. And when you look at the fossil record, we now know a lot more than what Darwin knew in the 1800s. We now know that by the time you get into the Ediacaran period, macroscopic animals evolved, mobile animals evolved. There were also animals that were able to fat actively or bury into the sediments. And some of them were able to prey on other animals or other organisms. And a few of them actually evolved by mechanized skeletons. And this is critical. This is very important because all the fossil record of animals in a Cambian and a younger geological period are dominated by animals with skeletons. And that's shells and bones and things like that. Whereas most of the fossil that I'm going to show you today, that predate, the Cambian period, they don't have skeletons with the exception of maybe a few. So that's what we know today based on the fossils and the molecular clock. We now know there's a conclusive, there's a very good evidence suggesting animals evolved at least in the Ediacaran based on the fossil record. But the molecular clock tells us that there should be animals even earlier in the Chryogenian or even in the Tonian. So that prompt the paleontologists to look at the geological record. So we're going to go to the next slide to see whether there is or whether there are any animal fossils in the Tonian and Chryogenian period, as the molecular clock suggested. Now, the Tonian fossils of animals are really very controversial if there are any. Here's one group of fossils from the Tonian period in China. Some of them were very simple in morphology. So at the top row, you have these discoidal fossils, just about a millimeter, two millimeter in size, in diameter. This look a little discoidal structural. And all these five pictures are actually of the same specimen. And we look at the specimen using different methods. Light microscopy, so just look under the microscope. And a scanning electron microscopy using different electron mode. And what I want you to see to look is the panel to the upper right. So it's the same specimen. And on that panel, you can see many small circles, almost like a honeycomb structure. And each of this circle is a cell. So imagine you take a ball of cells, so perhaps hundreds or hundreds of cells that making a big ball, millimeter, two millimeter in size. And then squash it on the ground. And that is what it is. This is a fossil that was interpreted as animal fossils. But there's no diagnostic features to say that this one has to be an animal. I think it could be, but isn't any diagnostic feature other than it is multicellular. I think an alternative interpretation is that perhaps it is a multicellular algae, colonial algae. Yes. The bottom part of this diagram shows another cryo-tonian fossil that is a sort of tubular-like structure. And this has something that is suggestive of animals. It actually has, some of them shows a terminal opening. And some of them shows a sort of transverse annulation, kind of like worm annulations. So this has also been interpreted as animals. And again, I think it is a possibility. It's a tubular structure. It seems to have a mouth-like opening. And it seems to have some annulation. But there's another equally possible interpretation. And that is a group of green algae, or seaweeds, that can build tubular structures just like this. And they also have this transverse annulation. And they actually form segments that articulate, kind of like your sausage that have this segment, like polished sausage that link together. Yes, it's kind of segmentation. But it's not the kind of segmentation as the atherpods annulate. So we have some tantalizing evidence here, but nothing conclusive, nothing diagnostic. So let's go to next. In a cryogenium, the cryogenium is characterized by pervasive, and a long-lasting, and a global glaciation. So this is where the snowball of glaciation happened, a big ice age. Much of the ocean was frozen to ice. And according to some geologists, the entire ocean was frozen from pore to pore. So even equatorial ocean was frozen to ice. So there aren't many fossiliferous rocks in a cryogenium. But in our mom, there's a set of cryogenium rocks that contains molecular fossils. And there's a particular group of molecular fossil called 24 isopropylcholesting, or 24 IPC, or short. So in the upper right, I have some of the molecular structure of 24 IPC. And it is, yes, cryogenium is the snowball Earth era. So on the upper right, I have the structure, molecular structure of 24 IPC, and it's a precursor. And this precursor, according to some geologist, is uniquely derived from a group of animals called spones. And they occur, these 24 IPC molecules, occur in abundance in the cryogenium rocks. So both cryogenium and the cryogenium. So on the left side, you see the geological timescale, the cryogenium, the ideocrine, and the vanerozoic. And that spindle diagram shows the abundance of 24 IPC. And that would suggest that spones evolved in cryogenium. So to the next. But this is not universally accepted. In fact, just a few weeks ago, there is a group of organic geochemists from Germany and Australia and several other places. They concluded that this precursor of 24 IPC is not diagnostically sponge. So sponges can produce the precursors of 24 IPC. But some other protest can also do this. So again, the presence of 24 IPC is consistent, but not diagnostic of cryogenium animals. OK, so let's move to the next slide. And in this slide, I want to show some ideocrine fossils. So on the left, you have the geological timescale, the cryogenium at the bottom, and the ideocrine, and then the cambium at the top. Now, I just mentioned that the cryogenium is the era of Snowball Earth. So the last Snowball Earth event, as known as the Mary Norn Snowball Earth, ended up the set of rocks and failure that we caught at the Snowball Earth event. And as soon as the Snowball Earth event ended, this is the beginning of the ideocrine period, which is about 635 many years ago. Next. So in the ideocrine period, there is quite a number of fossils. A lot more than it was zero in Darwin's time. But today, we have a bunch of fossils. I'm going to show you a few of them. So this is a fossil that came from the ideocrine period, a set of rock known as the Doshan Tor Formation in South China. The Doshan Tor is 635 to 551 many years old. And it contains this, also, a ball of cells. But this is a lot larger. And it has some, what I think, it's more suggestive evidence for animal affinity. But still, it's not universally accepted. I talk about this a little bit more later. And move to the next. So this slide shows another set of fossils, slightly younger. So about 575 to 560 many years old. So perhaps a bit younger than the Doshan Tor, but perhaps also overlap with a big chunk of the Doshan Tor. From Canada and the UK, England. There's a set of fossil that is much larger. This one looked like a piece of leaf. It belongs to a group of fossil known as the Avalon assemblage. But it's not a plant fossil, although it looked like a piece of leaf. It's not a plant fossil. If anything, it is perhaps more related to animals than anything else. Next one. So younger than the Avalon is the White Sea assemblage. That's named after White Sea in Russia. And the similar fossils are also found in Australia. On this cover of nature, there's a picture of a fossil called sprigina. This is a very interesting fossil. It has a left and right side. It has a head and a tail. It does look like an arthropod. Yes, it looks like an arthropod. Whether it is an arthropod or not, it's certainly not a modern type of arthropod, because it does not have any appendages. It doesn't have legs. And it doesn't have jointed legs. And that's a hallmark of modern arthropod. If anything, it might be something that is related to arthropod, maybe the cousin of arthropods that went extinct. So this is about 560 to 550 many years old. It has a left and right and head and tail differentiation. And nothing other than animals have this kind of differentiation. And the Avalonian animals is a special group of animals called bilateria, which we're going to talk about a little bit more later. So move to the next slide. And toward the very end of the Ediacrine period, you've got fossils like this. There's something called pteridinium. And not only pteridinium, but it's in this very light stage of Ediacrine, the last 10 many years of the Ediacrine period from 550 to 560, so 550 to 540 many years ago. Animals began to make skeletons. And although the diversity, the number of taxa that have skeletons are very few, maybe a handful at most. But they began to look like some of the phanerozoic and younger animal fossils in the sense of skeletonization or mineralization. OK, move to the next slide. And once you cross the Ediacrine-Cambian boundary, you get things like this. This, of course, is anomalocris from the Burgess Shale in Canada. At a hill, you do see things that are more convincing. And more familiar to what we now know as animals, it's got appendages or limbs or legs. It's got joint legs, for example, the frontal appendages. It has sacraments. So it's clearly some sort of orthopath. So there's a big difference between Ediacrine and a Cambian. OK, let's move to the next slide. So what we can say now is that we do have a lot of fossils in the Ediacrine period. Some of them are suggestive of animals. But to understand these fossils from the Ediacrine period and to make sense of these fossils from the Ediacrine period, we need to be able to put them in the famine tree of animals. And Darwin recognized this in the 19th century. So this is a quote from Darwin in 1837. So this is a year after he came back from Beagle. So he came back in 1836. And he wrote this. He drew a little diagram now known as the I think diagram. So he wrote, case must be that one generation then should be as many living as now. To do this and to have many species in same genus as is requires extinction. And that's very, very important recognition. So he further wrote below the diagram, below the little tree. Thus, between A and B, if we can see the tree, he labeled a few twigs as A, B, C, D. So between A and B, a mass gap of relation. So a mass gap of relation. B and C define as the gradation. B and D, rather greater distinction. Thus, genera must be formed bearing relation to ancient types with several extinct form. So to illustrate what Darwin meant, I have these little dots here. There's columns and rows of dots. So Darwin's idea is that natural selection and evolution should be slow and gradual. And species split into more species, again, slow and gradual accumulation of differences. If you think the biological space as a two-dimensional space, the morphological space, when would natural think that if evolution is gradual and slow and continuous without extinction? If there was no extinction, then the space will feel more or less equally or uniformly with species that are distinct from each other by more or less similar kind of distance. But if you consider extinction, so if you move to the next slide, and you randomly remove some of the species, and then you get this group of dots that can be separate from each other and they form little islands. Actually, what is shown here, the dots are the extinct species. So the surviving species are between the extinct species. So if you have extinction, then you create gaps between the islands of species, which makes the genera. So this is what Darwin was trying to explain. Now we see all the genera that they are different from each other, each genus is made of species. And that's because of extinction. And extinction creates gaps. And if falling these gaps requires fossils, because we are studying extinct species. Let's move to the next. This turns out to be a very important recognition. Two things here, one is putting organisms, organizing organisms in trees. And the two is extinction and the gaps. Actually, a little before about the same time, this is 1840 by Edward Hitchcock. He was not an evolutionist. He was a creationist. And yeah, so it doesn't assume all parts of the mortal space must be filled. Yes, that's right. But randomly, it should be even a field, or, more or less, equal a field if extinction is gradual. Now, in 1840, Hitchcock published this tree of life. So he had plants on the left. He had animals on the right. So the flowering plants have the coin and mammals, the king. And he also saw the big morphological gap between animals and the plants. And instead of explaining this gap in terms of extinction, he saw this as evidence of creation. He had no way for him to breach this gaps. Particularly, the fossil record was very sparse. And he saw this evidence of random creation of different species, certainly different groups of animals and the plants. But Darwin's recognition of the trees, or organizing species in trees, and recognizing the importance of extinction, was a breakthrough back in the 18th century. So let's move to the next slide. Yes, someone commented, yeah, many predalvanians. And that's what many predalvanians were religious scholars and they recognized geological errors and extinction. But they thought that is evidence of separate creation. Yes, that's what Hitchcock thought and others did, too. So nowadays, of course, we have a more sophisticated tree than Darwin had in the 19th century. This is a version from more than 20 years ago, 1997. This is a tree of all life, including three major groups or domains of life, bacteria, archaea, and eukarya. And all the animals, there are millions of species of animals. There are probably tens or maybe hundreds of millions of animal species that lived one time or another on the Earth's history. The point of the wine is represented on the tree, and that's Homo, that's our genus, Homo sapiens. So that's a breached version of the tree of life. And the next wine, next slide, is a little more complete. But still, this wine includes many more species than the previous wine. But still, this is a very small sampling of all the living species. So you have the mettozoans here that is represented not by just wine species or wine genus or Homo, as we did in the last slide, but by maybe a couple of hundreds of species in this tree. And if we look at the tree of animals in the next slide, you know, there are millions of animal species, but this slide, just to show you the skeleton of the animal family tree. So we have a lot of animals that have a left and right side, a dorsal and eventual or, you know, a belly side and a back side and a head and a tail end. And this kind of animal, that includes the most majority of animals that we see today, including us, including butterflies, elephants, and fish, and many, almost all the animals that you're familiar with. They all have a left and right side, head and tail and a back and a belly side. And they make the group called bilaterians. So these bilaterians are the dominant animal group that is living today and also in the past. Let's move to the next slide. But animals are more than just bilaterians. Animals also include, in addition to bilaterians, also include niderians. That is jellyfish, sea anamones, bulls and fossil raccoe. They don't have, strictly speaking, they don't have a left and right side. They don't have the kind of belly and the back side. Go to the next slide. And a bunch of others. I'm gonna quickly, you know, show a couple of them here. Spongs is another group of animals that don't have a head and a tail back in the belly and the left and right. Those are very simple animals. Those are perhaps the, some of the illicit branch. Well, family tree. What is the most closest, the closest to living relative of animals? Go to the next slide. And you see here, they are something very simple. Something called chorionoflagellates is a single celled organism. And another group of organisms called mesomycetazoans. They are colonial. So there's a big difference, morphological difference between animals and their closest living cousins, the chorionoflagellates. There's an immense morphological gap between chorionoflagellates and even the simplest animals, the spongs. So some of the gaps are listed here in the next slide. For example, all animals, including spongs, have cell adhesion proteins to keep the cells together. They are all multicellular organisms. They all have cell differentiation. So not only this, they have many cells, but the cells are differentiated into different groups of cell, different types of cells that have different functions. And all animals have germ sequestration. That means that the reproductive cells are sequestered during the ontogeny, sometimes very early ontogeny, or the development of animals. And the only function is to do reproduction. And also all animals have apoptosis, or programmed cell death. So some cells are lived just to die for the purpose of the entire individual. And all animals have embryogenesis. They have an embryonic stage in their development for ontogeny. All animals have pattern formation, or most of them have pattern formation. That's what makes the left and right side different. The head and tail are different. Valley and the backside are different, for example. And if the list can go on and on, none of the coinoflagellates have these features. The coinoflagellates might have some genes that can do the things, but the genes don't actually do these things as they do. So there's an immense morphological gap between the coinoflagellates and animals. And everything here together are called the holozoans. So animals plus coinoflagellates, plus mesomycetazoans. So in order to understand the origin and the early evolution of the animals, we need to understand the gap. And in order to fill the gap, we need to look at the extinct transitional forms that can help us to fill the gaps. Because as Darwin showed, is extinction that result in these gaps. And now to reconstruct these steps of evolution toward animals, we need to go to look at the fossil record, okay? So why is the anticipation if we go to look at the fossil record, particularly if we want to fill the gap between coinoflagellates and animals, we have to recognize that this intermediate form or transitional form or transitional animals, they're kind of half animals or maybe 95% animals or maybe 5% animals. They're not the kind of animals like what they expect to see in modern animals and dog animals. They have some, but not all the features that are present in living animals. So that pose a significant challenge. If we find them, how to recognize them, and sometimes they even evolve their unique features. So I have three dots here, the blue dots and the pink dots and the red dots. So this transitional and extinct animals, this 50% animals, this 90% animals. What we call STEM group animals in a technical term. So sometimes I use the term STEM group animals. That means they're transitional between coinoflagellates and animals, but they're on the animal side rather than on the coinoflagellates. Question here, doesn't punctuate equilibrium predict the gap in evolution? Punctuate equilibrium does not necessary produce, let me see. Okay, it does predict gaps in evolution, but it doesn't mean that we have to look at the fossil record to understand the gaps. So punctuate equilibrium, just say, sometimes you have rapid evolution, followed by slow evolution. So that, yes, it can produce gaps. Okay, I'm gonna use a few examples to illustrate the challenges in interpreting and understanding some of the Idiacran STEM group animals. And this is one of example that was published in 1998. So more than 20 years ago. This or a group of fossils, you have a scale bar here. Each of this little thing is about half a millimeter in diameter, okay? And they're made of cells. And the cells can divide. So wine cell divide into two, four into eight, 16. So the cell number doubles whilst the cell size decreased exponentially. The entire organism maintained a similar size. Okay, so yeah, this have been interpreted as animal embryos. So they have the kind of development of cell division that reminds us of animal embryonic development. And they don't feed, of course, they don't grow, just like modern animals. They actually encased in this ornamented envelope. So this has been interpreted as STEM group animal embryos. It is still controversial. Not everyone agrees with this interpretation. But I'd like to say that, for example, the T-shaped cell junction here requires the cell membrane of flexible. They don't have cell walls. So they're not plants, they're not algae. And also as the cell divides, the deformation of the cell since they indicate that they probably had cell adhesion proteins to keep the cells together. And this altogether suggests, I think, more likely to be related to you or more closely related to animals than to anything else. Here, the next slide is animation to show you the configuration of the full cell stage. So I think we need to move to the next slide. I forgot to tell you that. Yeah, move to the next slide. Yeah, this one. So if you skip the previous slide and you look at this slide, if you can look at the animation, this shows the separation of the four cells. They're amazing preservation. The cells are preserved three-dimensionally, no deflation. So it's almost like the cells are frozen into the rock. So yes, this is amazing preservation. So if our interpretation is correct, then I would place this animal embryo fossils somewhere between the kind of flagellates and animals. And considering that they probably had no cell wall, they probably had cell adhesion protein, and some recent evidence suggests that they even had programmed cell death. So I think more likely they are on the animal side. In other words, they are probably stem group animals. So if you have stem group animals, what about stem group eumetazoans, which are the Nidarians plus the bilaterians? And the stem group bilaterians, do you have fossils? This kind of fossils in the Idiacran period. And the short answer is yes. So if we move to the next slide, so this is where we put that phylogenetically or in the family tree of animals, where we put that embryo in the next slide. I have a few examples of stem group eumetazoans, which include Nidarians and the bilaterians, and the stem group bilaterians. So I'm gonna show evidence of this. So go to the next slide. Earlier we talked about some of this sponge biomarkers. And there's a possibility that this represent stem group sponge. Like I said earlier, this is not universally accepted. It's still a controversial evidence. Next slide. But we do have in the Idiacran time period, something that we think are very convincing evidence, fossil evidence for stem group, perhaps stem group tinnophores. The tinnophore is a group of animal that is related to the Nidarians. And they're colloquially known as a comb jelly. Typically, they're eight-fold symmetrical. They have 18 rows or comb rows. So eight-fold symmetry is not very common among living organisms. And a tinnophores or comb jelly is a one group of these eight-fold symmetry. Then we have a group of fossil that are called eoandromeda. So this fossil is, yes, someone asked whether Nidaria includes corals and a jellyfish. Yes, Nidaria includes jellyfish and corals. I'm talking about here a group of animal that is related to Nidarium that is technically known as tinnophores or colloquially known as comb jelly. But it's not jellyfish. So it's characterized by this eight-fold symmetry. And this is very likely related to comb jelly. And this is found not only as this compression. So there's squash on the bedding surface. You can see the eight arms. There's spiral arm. When you look from the top, it's all with clockwise spiral. You look from the bottom, it's counterclockwise. And then go to the next slide. You also find the same thing in Al Shadia, in sandstone. This is sort of a different kind of preservation. But it's the same thing as the previous one from South China that is squashed on the bedding surface. It has some features that are similar to living comb jelly, but is critically different from modern comb jelly. Again, suggesting this damn group concept, extinct transitional form that have some, but not all the features of the living relative. And sometimes they have their own features. And the one thing they don't have is the tentacles that are all most living comb jellies have. Next one. So this is a reconstruction of what it looked like. E.O. Andromeda looked like in life. It's a little spirally arm that ate of it. It's probably either benthic or pelagic. So this is certainly something related to comb jelly here. Next one. This is another thing from Younger Rocks from the early Cambian, about 525 many years old, or 520 many years old. This is another damn group, a tenor form. Again, has these eight flaps, almost like the revolving doors. And revolving doors typically have four panels, but imagine a revolving door that eight panels. With the central axis and the bottom has a little skirt that also have eight pleats. And it has many tenor form structures. But it's got the spokes, make it a very rich structure. So that's something that living tenor forms don't have. So again, we think it is another example of comb jellies in the Cambian. The next one. So if we have spawns, they have stem group animals, stem group spawns and stem group comb jelly, what are stem group bilaterians? I have a couple of things here that I think are related to bilaterians and then maybe stem group bilaterians. I showed you Sprigina earlier, but this is something known as a yoghia. Again, it has a left and right side, head and tail and it's also an eventual. And this guy actually it has, you know, fossils on the left panel is on the top right. On the right panel is at the bottom. But if you look at the left panel, there's a series of this ovoidal or circular structure that is actually the footprint of the same organism that is preserved on the upper right, meaning that it's probably moved to make this footprint. Same thing on the right panel. So you have this animal that is at the bottom, but above it, you can see at least two footprints. So there's some sort of bilaterium, but also can move. If you go to the next one, that's the animation. I can't show the animation here. You guys can take a look at the animation. I think Bill has the link. And if you go to the next one, you can see here is another. So I give you a minute or maybe a few seconds to look at the animations perhaps, or you can look at later. This is another thing called Kimberal. Again, it has a left and right side, a head and a tail and a top and bottom, or Dawson eventual. This guy, it also moved, but unlike the footprint in the previous in the yogi, this one actually pushed its way against the sediment. So on the left, you see the animal preserved on the top batting surface, in the middle, you see this animal actually moved backwards. So the top part of the animal, the front side end of the animal, actually have a little pro-bosses. It's extended beyond the animal and it has mouths and perhaps teeth, it is mouth, and it actually scraped the sediment to collect food particle from the scum seen in the sediment. So it feeds, it worked backwards and the feed from the sediment, same thing on the right panel, you see that the front part of the animal actually is deformed, so not just movement, but this guy had muscle and probably the kind of locomotion or movement is self-powered. Then again, to the next slide, we have a little animation showing how it moved and how it might have moved and then go to the next one. And there's actually a number of choice fossils, for example, burrows, tunnels within the sediment that are made by, certainly by animals and nothing but bilaterian animals could have made this kind of tunnels. In this slide, we are looking at we are looking at the tunnels from the top side, so the sediment actually pushed up. So this is clear evidence for bilaterian animals. Move to the next one. And sometimes they have very high density, this is several tens of these burrows or tunnels within sediment and this is actually a close up if you move to the next slide, you see the density in the big slide, so the previous slide is just part of this big slab that have thousands of burrows on it. So the sediment, a turn up and a turn upside down that have a significant biogeochemical impact on a global scale. They are actually tracks. If you move to the next slide, you'll see that this is actually an animal that probably moved to make the tunnels and then move out of the sediment and then make a row of two rows of tracks. So this animal probably had legs. So that would be something important because the legs make it possible to walk and do a number of things to some animals. You just like to run from the predators to mate, to fight, and do a number of things. So it's a very important innovation. Move to the next, we have a little animation here. Yeah, apologize, we cannot run the animation but I think Bill has the animation and you can go to YouTube and take a look at this. It actually has the animation and also the fossil. So you can link the animation and the fossils in the same movie. If we move to the next slide, this is a phylogenetic tree or the family tree of animals. Again, I have the three groups of bilateral animals that are known as ectozoans in green. They are low-forker cozoans in red and the deuterostomes in purple. So these three groups of animals, some of them have legs if you move to the next slide. So the second branch have legs, so human and tetrapods and also other parts have legs. So some people think that perhaps the last common ancestor of volunteering had legs or at least had the genetic possibility to make legs whether they actually had legs or not is a question that we need to test by looking at the fossil record. So that's why this kind of fossil from Pre-Kambia, the trace fossils that tracks are very important. Move to the next slide. So I mentioned very earlier that toward the very end of the Ediacaran period we have a few animals that learn how to make skeletons. This is one of them. They're a handful of this species in the Pre-Kambian that learned how to make mineralized skeletons. So making mineralized skeletons is very expensive metabolically. So why animals bother to make skeletons? One of the possibility is that animals make skeletons to protect themselves against predators. And this is a, I think a smoking gun evidence for the predation protection. So on the right you see a, this is a blow up picture of the side of one of those two blow fossil called caldina that have skeletons. And you see a little circular hole that is made by a predator. So this clearly suggests that, you know, both predators back then, maybe they are not very big, but they did pose a threat. And a big way to fend them off is to armor yourself or to become big or to become a predator yourself or to make a skeleton and make it more difficult for the predators. So that leads to the arms races and that perhaps the ecological driver that calls the explosive evolution during the cambia. So actually, you know, they lead to what they, or the fuse to what the cambia explosion is in the aachron period. So let's go to the next slide. So to summarize, you know, we do have stem group animals, certainly stem group bilaterians in the Edeafren period. And perhaps before the Edeafren period, considering that the fossil record is never complete. And it's possible that stem group animals and the stem group, you know, you metazones and stem response evolved in cryogenin and perhaps in the tonic. And keep in mind that, you know, A, the fossil record is incomplete and a B, the interpretation of some of these stem group animals can be challenging. And a C, we have continued discovering new fossils in the Edeafren and the older rocks. Let's go to the next slide. So this is just putting all the fossils that I've talked about on the family tree of animals and the relatives. So I talked about the athazone embryo animals. I've talked about some molecular fossils that perhaps bonds bilaterians. I talked about some penifors. So there are a bunch of fossils in the Edeafren period. Move to the next slide. So, and then the next, I think this two slides, you know, I talked about this same slide earlier. This is just to show you, again, to recapitulate the time scale and the molecular clock data and the fossil data putting all together on the same page. Abtonium, Phrygenian, Edeacron, Cambian and Audivision, that's the next stage, next period. I have the molecular clock, just in diverged in the tonium period. We don't have any conclusive fossil from the tonium, but studying in the cryogenia, we got some haint of animals, sponge animals. In the Edeacron, we have a bunch of animal fossils, including bilateria animals, including animal bimealization, animal embryos, et cetera. So move to the next. So if Darwin were alive today, what he would say, he'd be satisfied. I think he would certainly be happy to see, you know, there's a large number of animal fossils seen in the Edeacron and perhaps the older rocks. But he, I think he would be disappointed that we didn't find the animal as old as a billion years old, because that's what he predicted. He envisioned that the missing part of the animal evolution history was as long as the recorded part, record. But I think we are taking a sort of a compromise here. It's not as Darwin, not as ancient as Darwin suggested, but it's certainly before the Cambian. And then one other thing, I think Darwin would be disappointed is that the Edeacron Cambian boundary remains an important geological and evolutionary divide. Something ecologically evolutionally happened at the boundary and make it the Cambian evolution very different from the Edeacron. But how did that, what is it? The next slide. What I think it's important is that the arms race or things like this or ecological feedback, positive feedback. So this slide here shows, you know, to make animals, you need to have few things. You need to have the capability to make an animal, the genetic possibility you make an animal. Yeah, someone asked whether the pre-Cambian Cambian boundary is 543, roughly, yes, the 540, about 540 many years before, defined by a barrel, yes. So to make an animal, you must have the genetic possibility to make an animal. You must have the kind of environment in which animal, right? But making animal is not the Cambian explosion. The Cambian explosion is not the origin of animals, it's the explosive evolution of animals. It's the acceleration of evolution of right, of animal evolution. So what I think happened during the Cambian is the positive ecological feedback. And that is, we kind of saw a hint of this in the light Edeacron when you see the skeletonized animals and the jewelry holes. You sort of have a taste of this arms raises in the light pre-Cambian, light Edeacron. So that accelerated in the Cambian and it become the explosives of the Cambian explosion. So I think, yeah, the next slide sort of captured this in a autonomistic way. You know, the positive ecological feedback, it's a driver to drive evolutionary innovation. So the next one, oh yeah, so let's skip this one. I just, another quote from Darwin, I want to just wrap up my talk by thanking many of my colleagues, my students and the funding agencies, NASA, NSF, American Chemical Society and my university at Virginia Tech. So thank you very much, of course I'd be happy to take any questions if you guys have any. So how are we gonna do this, are we gonna, so people are talking questions, they're coming so rapidly and so many of them picks. So here's one question, do molecular clock models include adjustment for low CO2 levels and metabolism, which would lower the mutation rate? Yes, the modern type of molecular clock can't take this into consideration. So they do a lot of statistical tests to account for the variable rates. So that's a short answer to your question. And if I missed any questions during my talk, I was looking at my presentation and then looking at the screen, the second live screen, because my, the picture doesn't show up very well on my second live, but I had to use PowerPoint. But I might have missed a few questions during the presentation. Okay, here's for someone new to second live. Okay, yeah, this is my first time. This is my first time in second life. Is there any way to know what is possible in multiple space? What gap to expect? Yes, so there are two ways to do this, right? So one way is theoretical multiple space. So there are certain part of the multiple space is not possible theoretically. So you can exclude those. The second way to look at this is empirical. So evolution, presumably if evolution happened long enough, it can explore much of the feasible multiple space. And you can look at the empirical data and to see whether which part of the multiple space is crowded, which part is empty. And I'll try to answer the question, why is empty? Most likely it has some functional constraint. It has some evolutionary constraint. For example, if my ancestor had four legs, then my descendants are gonna have four legs. We can have six legs or eight legs. So that's evolution constraint. Sometimes with developmental constraints. So for example, if I put a limb here, I can't put the structure in the same place in same time. And sometimes it's just theoretically impossible. For example, trying to give us, you can't be a, you can't live in a, completely in a deep ocean and in a sediment and there's still be a photosynthetic organ. Because there's just no sunlight there. So that's theoretically impossible. Yeah. But other than that, they are some functional, some evolution constraints and a theoretical constraint. Most of the multiple space is explored. Okay, I guess that's the question I have so far. So it's the recording is okay. The sound and thank you and thank you, gentle. Thank you very much. Thank all of you for attending. I'm sorry, it went a little longer than an hour. Part of that is because I had a lot of animations. So I had to break up some one slide into several. Is there part three of the topic? Yeah, I didn't know it's Bill. I don't know whether you have something else lined up for the same, for the camera explosion. Yeah, the animations Bill can send you guys the link. So they're on YouTube. Okay, great. Thank you very much. They're followed by Paul.