The I Know Dino podcast is going strong. We have multiple episodes up already, and are working on getting them all transcribed.

You can find our free podcast, with both episodes, on iTunes at:

https://itunes.apple.com/us/podcast/i-know-dino/id960976813?mt=2

In our second episode, our featured guest is Dr. Anthony J. Martin, a paleontologist who specializes in ichnology, which according to his website, is “the study of modern and ancient traces caused by animal behavior, such as tracks, trails, burrows, and nests.”

Dr. Martin is also the author of several books, including his most recent one, Dinosaurs Without Bones. You can also find him on Twitter, @Ichnologist. and I recommend reading his post that dissects the ichnology in the Jurassic Park movies.

In this episode, we discuss:

• The dinosaur of the day: Oryctodromeus. The name is Greek for “Burrowing Runner.”
• Oryctodromeus was the first known burrowing dinosaur, and Dr. Martin and his colleagues found an adult and two juveniles in a fossilized chamber, in 2007. They had died and decayed in the burrow, which looked similar to those made by hyenas and puffins.
• Having juveniles with the adults suggests Oryctodromeus provided parental care for an extended period of time.
• Oryctodromeus lived during the Middle Cretaceous, about 95 million years ago, in southwestern Montana and southwestern Idaho.
• Oryctodromeus was up to 6.8 long, and weighed 70 pounds (it was small, but quick)
• Oryctodromeus did not have long arms and legs, like modern burrowing animals. But it did have more specialized adaptations, such as a flexible tail it could curl up underground. This makes it similar to rabbits, aardvarks, and hyenas.
• Dr. Martin recommends visiting Dinosaur State Park in CT to see dinosaur tracks.
• Fun Fact: The largest dinosaur eggs were as big as basketballs. Bigger eggs had thicker shells, so if the eggs had been larger than basketballs, dinosaur babies probably would not have been able to hatch.

For those who may prefer reading, see below for the transcript of the episode, including our interview with Dr. Martin:

Garret: Hello and welcome to IknowDino, a podcast about dinosaur and all things dinosaur related. I’m Garret

Sabrina: And I’m Sabrina.

Garret: Today we will be interviewing Dr. Anthony J. Martin, who is an ichnologist, which means he studies all of non-bone related traces from dinosaurs which is also coprolite, also known as dinosaur fossilized poop, and dinosaur tracks and gastroliths, which are stones that they swallowed, and anything else that gets fossilized or preserved that isn’t the dinosaur itself. It gives a deeper understanding of the day-to-day lives of dinosaurs that you can’t get that from their bones or even their skins or feathers or anything. It’s really in some ways a lot more interesting than studying bones because you can see whether the dinosaurs raised their young or whether they left them at a young age, you can tell if they hunted in packs or if they migrated as a herd, you can tell how quickly they moved by how far apart their footprints are spaced, and you can tell how big they were when they were born because it includes things like their nests.

Sabrina: Joining us is Dr. Anthony Martin, a paleontologist and professor at Emery college at Atlanta Georgia. He specializes in ichnology, which studies things such as animal tracks, burrows, trails and feces and can ascertain dinosaur habits, diet, and migration patterns, among other things. He’s known for discovering the first burrowing dinosaur as well as discovering the best assemblage of polar dinosaur tracks in the Southern hemisphere and he’s also the author of several books, and the most recent one is called Dinosaurs Without Bones: Dinosaur Lives Revealed by Their Trace Fossils. So welcome and thank you again for this interview.

Dr. Anthony J. Martin: Well thank you for asking me Sabrina. This is a pleasure.

Sabrina: So how did you get into this field, specifically ichnology? What made you interested?

Dr. Anthony J. Martin: Ichnology interested me when I was in graduate school. I first started learning about these trace files, these are traces made by animals and plants and preserved in a fossil record what really drew me about trace file was realizing that these were the products […] these trace files will tell you facts, burrows, nests, feces these tell you what a particular animal was doing in on a particular day millions of years ago for me that imaginative draw of trace fossils I just haven’t gotten over it, it’s something that excites me every time […]

Sabrina: I read that you studied both modern and ancient traces, do you have a preference?

Dr. Anthony J. Martin: Yeah, depends on which day it is, where I am ,like right now I’m at Atlanta Georgia area, so necessarily I have to look at modern traces if I’m going out for a stroll so that’s going to be fantastic as I walk through a city park I can see there are burrows made by […] or there’s a head nest or there’s the drilled hole on a tree left by a woodpecker. There are those raccoon tracks going through the park in the middle of the night that people didn’t know, no raccoons live there, those sort of traces all draw me in for a modern perspective but if I’m out West let’s say just three weeks ago I was out at Montana watching […] traps and other traces those then are what are going to be my focus although I don’t ignore the modern traces I see around there too, okay, so yeah just depends on where I am, what I’m doing those days.

Sabrina: So I read in your recent book you said ichnology is about storytelling and coming up with a lot of what if scenarios. So how can you be sure of these scenarios and what’s the typical process of coming up with them?

Dr. Anthony J. Martin:  Some of the scenarios as I bring into that story, at the beginning of Dinosaurs Without Bones some of them are, I’m pretty sure about we are very sure for instance that there were dinosaurs of […] or made nests a certain way or made burrows so these sort of ideas have been backed up again and again from the evidence that we get from dinosaur trace fossils sometimes we just have the trace fossils, sometimes we have their bones associated with the trace fossils or we have other fossils that might be interacting like the dinosaur feces. For instance I wrote out there were dung beetles, great thundering herds of dung beetles as I would like to say, they were attracted to the dinosaur dung well we know about that because of the research that Dr. Karen Chin did on dinosaur feces has shown that there were traces left behind by dung beetles that match obviously modern dung beetles, we’re very sure about that, so some of the scenarios that I presented were a little more imaginative, but in those cases I admitted it and said also that in science we predict, sometimes we get trace fossils that show a certain kind of behavior. Well it might be something else but we also can predict that we should find these […] trace fossils and I have a little wish list that end of the book that kind of says here’s some future scenarios we might be fulfilling with scientific evidence.

Sabrina: What’s at the top of your list?

Dr. Anthony J. Martin: At the top of my wish list, I think it was track way made by a large predatory dinosaur, something like a tyrannosaurus, Spinosaurus, one of those other really large predators. What’s very cool is that that was towards the top of my wish list, I don’t remember exactly which number it was, but then it got fulfilled last month. There were 5 or 6 ichnologists who published a paper just last month about these huge dinosaur track ways in British Colombia that showed these few large predatory probably, tyrannosaurus […] were walking parallel to one another so that suggested the various behaviors of these large dinosaur may have been hunting together or just moving together. That was pretty cool.

Sabrina: So just going back to the kind of the story telling aspect…what are your thoughts on fiction about dinosaurs? I think I already mentioned paleontologists in general try to steer clear of writing fiction but then your opening scene in the book was—just I really enjoyed reading it.

Dr. Anthony J. Martin: Yeah that’s right. I would love to see more paleontologists write fiction purpose point and tell everybody, please this is fiction but use their knowledge, use their experience to be able to spin some more imaginative stories. Now sometimes it does seem like we’re spinning imaginative stories already but we scientists, we try to use our evidence based reasoning as part of that or if we are being speculative we say, “Oh here’s a speculation and it’s a prediction,” and then we try to just prove it like any good scientists would do. But I would love to see more people doing fiction with dinosaurs that is not necessarily backed up by evidence but inspired by evidence. What also needs to be realized if you are doing that type of fiction is you start looking at what has been shown by the fossil record, especially for dinosaurs, and sometimes they were way more crazy than we could make up and sometimes […] especially when we get new revelations about dinosaurs and how they behaved, support one another, support other animals, support plants or to their ecosystems in general.

Sabrina: Do any examples spring to mind?

Dr. Anthony J. Martin: Well we are finding out now an example of how, we are finding out now that the line we draw between what’s a dinosaur, what’s a bird, we now know that modern birds are dinosaurs. I got a chapter in the book that’s about birds as modern dinosaurs […] that you can track a dinosaur today by just going through a local park and watching birds and seeing the traces they make. That line is getting so blurred now that we are now realizing some of these small feathered dinosaurs probably were arboreal that they were going up in trees and that they were either gliding or flying from tree to tree. That sort of blurred line where what’s bird what’s a dinosaur it’s now become confusing even for those of us who study that it’s getting really confusing and somebody just ask themselves, well where do we draw the line? Well I’m not really sure and some of what we have seen now is what we know are […] they were behaving in a very bird-like manner and I think in the future one of the other chapters, I got a chapter that looks at nesting and nesting behaviors of dinosaur, I think we’re going to find more examples of that where these […] dinosaurs were nesting very much like birds these sort of behavior goes back may be farther and in more miniatures of dinosaur than we ever would have suspected.

Sabrina: Yeah, your book also mentions dinosaur swimming. I didn’t realize, and they may have done recreational activities?

Dr. Anthony J. Martin: Recreational activities?

Sabrina: Yeah is there any evidence of that?

Dr. Anthony J. Martin: Oh yeah, yeah that’s right I did ask that question–is there any? We’ve seen this in a lot of animals today, modern animals, that they sometimes did play and we see play behavior in a lot of mammals that’s used as a way of teaching. We also see now there’s a learning behavior and teaching behavior in some species of birds, so I will get into that. By recreational activities do you also mean dinosaur sex?

Sabrina: Yeah.

Dr. Anthony J. Martin: Yeah I will tell you a little bit about that too and of course that wasn’t necessarily recreational, that was made procreation, but who knows? Yeah I did speculate a little about that because we haven’t found any definite dinosaur trace fossils having sex. We know they had sex; we know they had and they did for 150 million years and then with modern birds of course they continue that proud behavior, but we don’t really have a direct trace fossil evidence of that either, so I would be interested in seeing is there any evidence. I guess I can put it into place and say the courtship behavior if there’s any evidence of play courtship behavior, actual coitus, post coitus, I even make in a little joke in there about that and perhaps the gender differences one might see with those. Those sorts of traces we haven’t really nailed those down yet so that’s something that I took a little more speculative view on those, but gave a little summary and guide post for our future paleontologists. I think I have said dirty minded paleontologists, which basically all of us is, about how we could find these fossils in the future.

Sabrina: So what if anything tells us more about dinosaurs? Do you think tracks or feces, tooth marks, nests, burrows, maybe something else, or some examples where we can learn from them?

Dr. Anthony J. Martin: Oh gosh how can I choose? So I guess I am more of a holistic ichnologist in that, well for example when I was just doing this field work in Montana I was in […] 75 million years old and minimum a dinosaur trace fossils I could see there just in a day of walking around included coprolite, dinosaur coprolites, tooth marks, dinosaur nests, tracks. That was a minimum I could see that just in a morning I could walk around that area and see evidence through those trace fossils, so it really depends on where you are, what blocks you are in, what sort of evidence got preserved, if I’m in a place that’s famous for dinosaur tracks then of course I will focus on those that tells us all sort of fantastic behavior about how they were moving. On the chapter I have on dinosaur tracks, it’s the longest in the book, it’s titled “These feet were made for walking, running, sitting, swimming, urging and hunting,” that’s really the preview in the title because tracks can tell us even more than those. But nests are also extremely valuable, especially for telling us about post mating behavior, bringing up dinosaur babies, what happened after, after the eggs hatched. Nurturing behavior in dinosaurs nests have that potential to tell us about dinosaurs, and dinosaur burrows tell us about adaptation against say predators or just getting out of the way of natural disasters […] Of course tooth marks tell us about what dinosaurs ate, who ate who, and how did they eat them, and what sort of damage was sometimes left on teeth by plants, what that dinosaurs were eating, and then of course I love coprolites. Coprolites tell you exactly what a dinosaur was eating on a given day. Yeah I also, so yeah don’t make me choose. I just love them all.

Sabrina: That makes sense. Are trace fossils in general kind of hard to find and identify?

Dr. Anthony J. Martin: It depends. Tracks I think are very easy for most people to find and I think even an untrained amateur, if you go out in a place that has some well-preserved dinosaur tracks and they got to qualify that, well preserved dinosaur tracks, they often will spot them so how about that more than half of the dinosaur tracks that have been discovered from a fossil record have been by untrained amateurs, people who were out hiking in a remote area they found some three-toed or four-toed tracks and there is something in our primate brains that we go, that we instantly recognize that pattern as being something from an animal at sometimes it’s kind of paradoxical sometimes you overlook them if they are too big though.

Sabrina: Oh that’s interesting.

Dr. Anthony J. Martin: You walk by them and you think that that’s a pothole. Oh how many potholes were there in Mississippi? Come on, think about it and again you see the potholes resolved themselves in a pattern field, that’s a diagonal walking pattern–ohh cool. So I think tracks for most people are easy to spot, other ones, other trace fossils not so easy. Coprolites take a lot of training I think because a lot of people get a false identification. They’ll pick up something lumpy that, it looks like dung, it smells like dung. The thing [ 00:15:56:00 inaudible] they are very excited they bring it to their local museum, they bring it to the paleontologists at the museum they show it to her and then she goes, “I’m sorry that’s not a coprolite.” And that kind of reminds you of the XFiles. I want to believe you know, well it’s not about belief it’s about what’s there, it has to have digestive material in it for one, it just can’t look like a coprolite; it has to have evidence that it went through the gut of an animal and then did it belong to a dinosaur that narrows it down too […] and then which dinosaur it might have belonged to. I may think the toughest trace fossil of all to identify from a dinosaur, what I haven’t mentioned yet, is gastroliths. These are the stomach stones that dinosaur swallow, not all dinosaurs just a few we are finding now, swallow these stones to help them with their digestion. These rocks are so difficult to distinguish from just an ordinary rock that did not reside in a dinosaur gut so I have a whole chapter on it. It’s titled “Why would a dinosaur eat a rock,” and explores about how difficult it is to distinguish what’s a gastrolith and what’s not a gastrolith from rocks that are in the same sediments that contain a dinosaur valve, tracks, or other types of dinosaur fossils. That’s a tough one and those would be the most challenging for […] for public to be able to identify.

Sabrina: Sure how would you as a paleontologist identify it?

Dr. Anthony J. Martin: Oh boy I would have a tough time. There’s only a few people who I think are really good at it. You look for a polished surface that’s one clue, you pick it up and it looks like it’s been polished […] do contain remains of dinosaur from the right environment like river flood plains […] You might see some little chatter marks on it from where it impacted with another rock. Chatter marks have to be in a way that they weren’t made in a surf like from a surf knocking the rocks back and forth they also often times are coarse so they did not dissolve. Think about a dinosaur swallowing a limestone that would have been the equivalent of swallowing a […] If they have just dissolved in their stomach with no evidence of gastroliths there so it has to be something that would be resistant to stomach acids too, so it might actually show some evidence of that as well that there might even be a little bit mass that’s actually preserved in it. But usually the people who are distinguished this they had to use microscopes or lasers or other types of special equipment to be able to determine for sure that this came from a gut of a dinosaur. Fortunately modern birds also swallow stones, we also have big birds that lived just recently called […] in New Zealand and they also swallowed stones so they had gastroliths. So we can actually look at […] gastroliths as recent examples of avian dinosaurs doing this, also look at modern birds that swallow stones and look at the characteristics of those and then we can do the comparison so we have these modern equivalents with our modern dinosaur that we can compare of what we would see in a fossil of dinosaurs.

Sabrina: You’ve mentioned […] Australia is a good place to, was a famous dinosaur tracks site–what are some other places with trace fossils that are kind of famous?

Dr. Anthony J. Martin: Yeah, […] was in the news again because the most recent study done on it, I mentioned a researcher in that chapter, and I’m glad I left the chapter at, ended it kind of open ended as a question of [ …] who knows, rather than taking a stand because we are now finding that […] looking at the evidence I have read the most recent newspaper it does look fairly convincing that this was a dinosaurs swim site rather than dinosaur track site and they got their tracks there but they were probably from a dinosaurs that were going across water […] They look very similar to the tracks then that we see in South-Western Utah, St. George, Utah which has thousands. And I have seen them; it’s incredible, thousands of dinosaur tracks that have been made by swimming. That they have the right pattern, they have the right form to them, and they just have all of these characteristics that show these were dinosaurs that were probably buoyed up by water and their […] were just touching their bottom as they were kind of I will say dog-paddling, dinosaur-paddling along.

Sabrina: I was also fascinated you mentioned sauropods may have made trails that transformed the land and waterways of the areas they lived in. Could you elaborate?

Dr. Anthony J. Martin: Yeah I had to say what was my favorite chapter to write in the book, it was the last chapter it was called “Dinosaurs and landscapes ,“ and evolutionary traces, and that was one of the points I brought up is that sauropods probably changed their landscapes and those changes then in an irrigative sort of way then affected landscapes that we have today. And I even speculated, I don’t think I reasonably speculated, that maybe some of these river valleys that we have today that take back to the time of sauropods may be those were affected, the course of those river valleys were affected by sauropods. Now the modern analogies I used, and they are really weak analogies I would connect because they are too small, would be elephants and hippos. Hippos, for instance, make these trails that go from their water bodies across land and connect water bodies, and because they are big animals and they wear down these trails, they end up connecting the water bodies and they get this really deep channel forms that actually can change the courses of the rivers or otherwise change the landscape. Elephants do the same sort of thing but they completely change landscapes, especially wetlands, that the elephant trails over time will connect all of these wetlands that normally would not be connected, on a smaller scale flamingo […] and some of her colleagues that they did in Eastern Africa where they were looking at a flamingo nesting ground where these millions of flamingos were making this mound nest. Over time millions of flamingoes making nests in that same area around these lake shores completely changed the flow regime of those lake shores. So these are small animals compared to dinosaurs, elephants, hippos, flamingos for sure are very small animals, but then there’s that strengthening numbers and then time of course […] how that had have changed the landscapes so that evidence from Western Australia of dinosaur trails that Tony […] proposed. I think he’s absolutely right that these were the trails that sauropods over time wore them down actually changed the landscapes there at that time clearly millions of years ago.

Sabrina: It’s just crazy to think about.

Dr. Anthony J. Martin: Yeah like I said that was my favorite chapter to write because it has, okay you thought stuff was mind boggling, wait till you read this and just kind of piece it all together how these traces are more than just a single footprint, a gastrolith, a coprolite. No, you look at your landscape that might have been affected by a dinosaur.

Sabrina: Yeah, I also noticed that you mentioned Jurassic Park a few times in the book, and it sounded like you didn’t care too much for the sequels. What’s your feeling on the first movie?

Dr. Anthony J. Martin: Yeah it’s funny I finally got myself to watch all of the Jurassic Park 2 recently, and it wasn’t actually that bad as I originally thought because I only saw, I never saw the whole thing, always caught snips of it on TV or saw some clips on YouTube, and then I heard from my colleague paleontologist friends they were like, “Ohh it is so bad compared to the original.” I mean, almost everybody loves the original; then I watched it and it actually wasn’t that bad. A cool thing that happened in it, that I wish I had known about before, was that a big game hunter character, I forgot his name in the movie, he’s actually tracking the tyrannosaurus one time and they showed this tyrannosaurus track and I was like, “Ohh that’s cool.” So now and then I make myself rewatch. I have seen all of Jurassic Park.

I am going to make myself rewatch it and then again think about what sort of traces were in the movie and then I, on my blog like the traces of the […] I did a blog on it last year about the re-release of Jurassic Park in 3D I went to see it in the theatre to see it in 3D but I took of what traces were shown on the movie, what was based on ichnology, what were some of the dinosaur behavior that would be based on ichnology and that was really fun to do. It was actually fairly extensive. It was a long post on the topic and I titled it the “Ichnology of Jurassic Park,” so I totally expect to do that with Jurassic World or so-called Jurassic Park 4, which is supposed to come out next summer. So we will see I may enjoy it just for the ichnology and hate the movie. Who knows we will see.

Sabrina: I will look out for your blog post.

Dr. Anthony J. Martin: Yeah that’s right.

Sabrina: So do you have a favorite dinosaur?

Dr. Anthony J. Martin: I’m pretty biased about that. It’s Oryctodromeus cubicularis. I have described it in detail in chapter 4 in the book which is titled, no chapter 5, I’m sorry. It’s dinosaur down underground Oryctodromeus cubicularis. I got the cool name it means you have seen […] roots, it means […] and it was an ornithopod dinosaur, small herbivorous ornithopod dinosaur that targets on burrows and it was found in it’s own burrow with two of its partially grown juveniles. So this was the first evidence of dinosaurs having any behavior. I describe this the burrow with my colleague and friend David […] and we got a colleague […] who discovered the dinosaur in the field in South Western Montana once the bones were extracted from what was originally the den they realized that this dinosaur has had adaptations for digging. Its shoulder girdle was perfectly adapted for digging, had an extra vertebrae and its hip to brace itself and its snout was also kind of shovel-like and probably repeated it also in digging. So these three traits of that dinosaur along with it being in a burrow along with the two juveniles being in burrow and both of those juveniles being of the same age this was all very persuasive evidence that Oryctodromeus was a burrowing dinosaur, and the first that we know of in the paleontology record. I think we will find more of it now I think we will find more it’s a prediction I make in the book and there will be someday that I think we will find some other small dinosaur probably […] too.

Sabrina: My last question is: what advice would you give for amateur dinosaur enthusiasts, like where should they go to learn about their favorite dinosaurs?

Dr. Anthony J. Martin: One of the best resources that they could use will be National and State parks, we have as a public resources is better, readily available for the public to use so I always urge the public to use these public resources because then you are the user and you will benefit from it and then future generations will too. And the sample of that might be I don’t know the exact name I haven’t been to it, in Connecticut I think it’s Dinosaur State Park, so that’s a dinosaur track site there in Connecticut that people can go to. It’s enclosed in a building and they can see hundreds of dinosaur tracks from the early Jurassic from about 200 million years ago there or you can go to Dinosaur Valley State Park where I did some research a couple of years ago. I’m currently writing an article on the trace files there, Dinosaur Valley State Park that’s in Texas, that has some of the best preserved sauropods tracks of anywhere in the world. Right there in the state park you can go see them and for dinosaur bones if you want to see those then, you know I’m okay with bones, I joke about that throughout the book like bones, ahh who cares, but actually one of the coolest places you could ever see a dinosaur bones is at Dinosaur National Monument in Utah.

Sabrina: Oh yeah I’ve been there.

Dr. Anthony J. Martin: I just heard […] possible to go there make a trip go see it. What’s also cool is just if you are self-prepared just go around some dinosaur track sites around Utah and then there’s a few other places where you can, in public resources like […] public lands. These are some of the best places to go and see say dinosaur tracks and feel what’s cool about that. Where you see those tracks, that’s where the dinosaur was, and you don’t always know that with them but those sorts of resources that are out there I say available out there I say avail yourself as much as possible, and museums, don’t ignore museums. Museums are fantastic resources too. Some of them are public, some of them are private, but if you can actually get to a park or any place that has these tracks or bones available for you, the public, that’s something I would do; it will fill you with awe.

Sabrina: Great well thank you so much.

Dr. Anthony J. Martin: Thank you Sabrina it was pleasure talking with you.

Garret: So as Dr. Martin mentioned dinosaur tracks play a big role in understanding dinosaurs. You can tell whether they were in a herd or whether they were solo. You can tell how quickly they were moving and all sorts of things of that nature. There’s a neat place in Connecticut called Dinosaur State Park and there’s a website dinosaurstatepark.org where you can learn more about it. It’s actually a preserved area of dinosaur tracks where you can see several different dinosaurs and they explain what the dinosaur were doing in that area at that time and if you want to see the exact address you can also go to our website IknowDino.com and we’ve got a map of lots of dinosaur museums and sites. Our dinosaur of the day is Oryctodromeus which is the dinosaur that Dr. Martin mentioned having co-discovered.

Sabrina: So Oryctodromeus is Greek for “burrowing runner” and as Dr. Martin said in his interview, is the first known burrowing dinosaur which he and his colleagues found an adult and two juveniles in a fossilized chamber in 2007. They had died and decayed in the burrow which looked similar to burrows made by hyenas and puffins. Having the juveniles with the adult suggests parental care and that at least one motivation for burrows was to take care of the juveniles and the size of the juveniles suggests an extended period of parental care.

Garret: Oryctodromeus lived during the middle of the Cretaceous, which is the end of the dinosaur era. They lived in South Western Montanna and South Western Idaho. They are up to 6.8 feet long and weigh about 70 pounds so they are one of the small quick dinosaurs that you imagine. They didn’t have long arms and legs like modern burrowing animals but they did have specialized adaptations like a snout and a tail that was more flexible than other ornithopods so it can curl up under ground when it was in it’s little burrows . Those adaptations made it resemble a hyena more than some of the other modern burrowing animals. So our fun fact of the day is that the largest dinosaur eggs were about the size of a basketball, the bigger the egg the thicker the shell had to be so if the eggs had been larger the dinosaur babies may not have been able to get out. Aside from being able to break out of the egg shell as a baby dinosaur you could also have limits in the permeability of oxygen through the shell because if you imagine the baby dinosaur living inside it has to get all of its oxygen through the shell and it can only diffuse so quickly and obviously when you are going through a solid shell there are limits to that.

Sabrina: And that’s it for this episode of I Know Dino. Join us next time when we talk to Dr. Phillip Currie, a famous paleontologists from Canada who is also the creator of the free online course Dino 101.

Garret: If you would like to learn more about dinosaurs or see dinosaur events, dinosaur museums or other dinosaur sites around America, United States of America, and a little bit in Canada, really one or two sites up there so for, you can go to IknowDino.com. We look forward to talking to you next week.