howdy so let's talk about sauropods and the Cretaceous but we're going to go back a little bit we're going to keep talking about the Jurassic for a bit so the group we're really going to be talking about because they are the really dominant sauropods of the Cretaceous are the macronary so uh what are the macronary so they're one branch of the neosauropoda right so the other Branch are the the plots that are amorpha so the Diplodocus and the Amargasaurus and Etc the macron area um they so one of the earliest macro neurons that you've probably heard of before is camerasaurus and um uh I would say camera Source it's all the way through camarosaurus um uh I always think of that as being kind of like the most boring sauropod you know it's it's small it's got a short neck kind of a stubby face and um uh actually uh maybe a little sort of a thick neck a big head and sort of a blocky kind of head and it's it's limbs are really close equal in proportion to each other all right what it makes the macronary interesting why is Camaro saurus a macronarian why is it put in with these other uh sauropods well camarosaurus and all other macronarians they have really big Nares what are Nares nostrils well not quite but nostrils so macronary equals big nares so what are big Nares what does that mean so um the Nares are the openings all right and now I haven't talked too much about this but um this is actually more of a of a user photo or neosauropoda thing they uh move their nostrils to the top of their head we don't know why that is um and it's not their nostrils I keep calling it the nostrils they're Nares to the top of the head so those are the respiratory openings okay they're above the eyes so that's all star pots they do that now you might say yourself oh then they had like their noses up here right because you'd think that the opening is in the skull where you breathe are also where your nostrils are going to be no that's actually the important thing so if we think about a general store pod stall and this would be really poorly drawn to plotisted I'm sorry oh no I'm eating it like thing like Teeth oh no I'm really bad at drawing dinosaurs guys I'm sorry but so if we think of a sort of deposited with sort of peg-like teeth here a big orbital and then the Nares are up here okay but we found evidence more recently that there were cartilaginous tubes running down the outside of the skull and then the nostrils were down here at the front of the of the snout just like we would expect they would be in any sort of mammal or anything like that our narras are you know none of the Nerds any of the mammals are at the top of their head except in elephants and that's because of course this is supporting a big old chunk and so you know there's actually a time in which people really were sort of thinking oh well maybe maybe sauropods had a truck like elephants do well we don't actually think that anymore we think that they actually well I think that generally the evidence of that is that there's not really a trunk that there was just this tube and then there were nostrils at the end of the snout okay but why why would you move your nostril why would you move the openings in your skull for the respiratory system to the top of your skull but still breathe from the end of your nose like why would you need to do that we're not really too sure like maybe it's that they were moving the respiratory system out of the way so they had more room for the the digestive system moving stuff down the the throat but then you still have to get air down your neck all the way to your your thorax to your chest and then you know it doesn't make any sense I don't know why they do it but they do it all right so sauropods generally had like sort of like a big nose basically like a big cartilaginous set of tubes running all the way down there snout so that's how you should imagine them for now on um now the thing is is that in the macron area these Nares get really big why we don't know sorry it's not like we can give like a little adaptational just so story for every single feature that we see but it's an interesting question like why though right it's paleontologists have we see lots of things like this we try to think about why that could be and often we're kind of just left scratching our heads and wondering why that is and we do that for a bunch of years until maybe we have an idea or realization that we see something like that in some living group or something okay what camera Source had one of these large Nares at the top of its what actually two of these mirrors at the top of its head okay right because there's two openings uh we have uh one opening for our on nose I guess but the store positive two openings for um for air to flow through the skull now what as we uh the macron area really can be kind of thought of as being um a progressive kind of tree you know like I I just want to stress that evolution is not a ladder it's a bush but in a lot of groups man sometimes Evolution looks very lighter like so um overall the thing we're kind of headed to is a group known as the titanosource and along the way as we move up we kind of move through um different groups that may or may not be so monophyletic so after the the cap from from something that was probably very similar to a camera store a group of rows which were their own group and that was the Brachiosaurus right and they were well known for having this um very large uh inflated opening on their skull with a very large naris again the function of we're not really too sure um you know I kind of always thought that the elephant trunk idea looks kind of weird but you know maybe that doesn't make much sense but there's a few things that are really distinctive about Brachiosaurus one is is that compared to camera Soros Brachiosaurus they take their um so that's sort of a this is a this is a vertebrae and as we now know if we CT scan we look on the inside of one of these vertebrae we would see that's full of air spaces now in camera stores and many other dinosaur groups we would see that those in many other sauropod groups we would see that those are filled with large air pockets not so actually with the Brachiosaurus they would have air spaces that are about one centimeter in size so really a much smaller almost sort of um uh honeycombed in a sense okay so much smaller air spaces than their sort of uh than their ancestors the Brachiosaurus also have a very distinctive kind of like terrible brackets there you go my terrible bracket story I you know what this whole point of this class I think might be just to you know make you guys feel better about your own drawings of dinosaurs one they're high shouldered their front legs are actually longer than their back legs this is a thing that we'll see develop in a lot of the macaron area macaron area is that they're they've got a high shoulder body um and they've got long necks that they hold vertically we can see that actually based upon how the um the vertebrae fit together with the skull so they actually held their heads up high like that's like a giraffe kind of they're these high shoulder things and that the thing is is that camera sore brachiosaur Diplodocus apatosaur they all lived in the same ecological communities together so that's I think we're clearly doing very different things so there was a lot of diversity in terms of what sauropods were doing but the high shoulderedness is not just emblematic of Brachiosaurus themselves in fact there's another species of sauropod that you should all become familiar with sore Poseidon sore Poseidon also would have looked a lot like a brachiosaur it was High shouldered um we've never actually found the head to store beside it um which isn't that unusual um uh in fact it's quite usual not to find the head sore pods um but why is sore Poseidon really cool surface items really big okay but sorbicide is not a brachiosaur sore Poseidon has vertebrae that look a lot like Brachiosaurus vertebrae but they are filled with a dense array of air cavities that are much smaller so sore percent so that's a brachiosaur so Brachiosaurus Brachiosaurus item less than one centimeter in fact this group now of sauropods that we move into um they're named actually for having spongy bones um if I remember what the name is I'll write that down again but um but it looks a lot like a Brachiosaurus um we don't know actually what's really going on there so so maybe that's just that high shoulderedness was just something that evolutionarily was um uh more of a paraphilitic thing it wasn't just a feature of the brachi stores it was also a feature of groups close to this Brachiosaurus that gave rise to sword Poseidon um maybe you know server-side was for a long time considered a Brachiosaurus what is Sarasota was also once known so we've got soroposeidon and sore Poseidon is really interesting because not from the lake Jurassic storm Poseidon is from the early Cretaceous and in Factor sign is well known from Texas where when it was first discovered um it was named polexy Source now sorbicide already been named at the time when flux thesaurus was found and um even though there was a lot of work done to try to make sure that these were the same species turned out later on more material was founded they turned out to be the same species so sore Poseidon one however alexisaurus in 2009 our state legislature designated that as the Texas state dinosaur so anyone asks what is the state dinosaur of Texas you can tell them it looked like a brachiosaur and it's a sauropod we've never found the head too um uh a resort Poseidon itself was originally found in Oklahoma but we've now found um uh sorbicide and Plexi store in Utah so Texas Oklahoma and I think also Colorado so a very American very uh United States American dinosaur there right um and they're represented this Evolution towards very large sauropods that we see which will become quite distinctive of the Titanosaurus and this very refined humanization of the bones um uh so at the surface I didn't play is a very important role in our little story here so the Brachiosaurus they kind of um brachiosaurus and brachiosaur like sauropods they kind of gave rise to things like Sora Poseidon and um sore Poseidon was one of the first of a group that would eventually give rise to Titanosaurus so that's sort of been a story and part of the issue here is that we don't actually the the next time when sauropods really get densely into the record is at the very end Cretaceous and you're probably thinking yourself well this sounds like you're gonna say this is what we thought 20 years ago that's right so at the end Cretaceous there's the sauropod that comes in that's called Alamosaurus and it's found all over the US it's not actually named after the Alamo I'm afraid it's named after the El Alamo formation of New Mexico where it was first found but it is found all over Texas and in fact we believe that there's quite a few trackways in Texas made by sorposeidon and from Alamosaurus um however so we've got the um uh so we've never really understood why there was this Gap going on basically it looks like sauropods went extinct in North America they were what we call extirpated that means when you go locally extinct in a place um however there was actually turns out a whole lot of stuff going on in Africa and South America and particularly the fossil record of Argentina has been really useful to understand more about what's been going on with zoropods in the Cretaceous we're now into this group um by the way the Brachiosaurus along with the titanosaurs they this whole group everything that's descended from that point they get called sometimes the titano sore it forms so we now know that there's actually a whole bunch of stuff going on with the titanosaurs and sort of um uh late titanos or titanosaura forms in southern in particularly South America um in those places that we generally think of as gondwana in the Mesozoic um so they became actually very diverse in some places in um the Argentina remains have revealed that there's a lot of stuff going on here so the titanosaurs We Now understand were actually very different in terms of being a silver pod group so um let me actually erase all this and the next chunk I'll talk more about the titanosaurs themselves and what made them so different from others