ABOUT THIS EPISODE

Bhart-Anjan Bhullar, from Yale University, talks with us about how the discovery of a 95 million year old Ichthyornis fossil in 2014 revealed some unexpected insights into the minds, and mouths, of modern birds. Subscribe: iTunes | Google Podcast | Google Play | RSS
English
United States

TRANSCRIPT

00:00:01They would have been flying around diving down catching fish it probably would have been really rude and really loud just like goals and turns are and so it would've chattered at you and sappy would've smelled kind of gross smelled like fish this is parsing science the unf published
00:00:17stories behind the world's most compelling science has told by the researchers themselves um ryan walk in and i'm doug lay the ability to fly has evolved on three separate occasions among vertebrate animals most recent were bats who figured out how to do so at least fifty million years
00:00:34ago before that were the birds which following the most recent of the earth's five major mass extinction events began to proliferate about sixty six million years ago But first we're the pterosaurs which emerged some two hundred twenty eight million years ago and among the most recent of these
00:00:50was the cornice which lived about ninety five to eighty three million years ago today we're joined by yale paleontologist pardon john bowler who talks with us about how the two thousand fourteen discovery of a nick the artist fossil buried in kansas ninety five million years ago revealed some
00:01:06unexpected insights into the minds and mouths of modern birds Hi my name's engine bowler i'm assistant professor of geology and geophysics at yale university and assistant curator of vertebrate paleontology and vertebrate zoology at the yale peabody museum of natural history I guess i was one of those kids
00:01:27who grew up always interested in the natural world in animals and things around us i think part of that was actually so i'm a second generation immigrant my parents were born both born in india and when they eventually came tio the u s we settled in the midwest
00:01:47and so i grew up in ohio and in kansas and was kind of ah steven spielberg childhood e get home every day and i'd go and knock on all of my friends doors and this big gaggle of us mostly boys would go off and ride our bikes all
00:02:02around town and playing backyards and we'd end up at people's houses ah and whichever house we ended up at the parents would feed us all and so and so spent a lot of time outside and and got to know the sort of suburban wilds of those places and
00:02:20i think during this time just fostered an easy interest in in animals went to the library a lot i was always ah bookish kid and that interests just continued sort of through my childhood through my education it might come as something of a surprise that birds like egg
00:02:38laying but cold blooded lizards snakes and crocodiles are also considered reptiles in modern classifications of animal life Doug and i began our conversation by asking on john how it was that he first became interested in the early history of birds well the thing about birds is that their
00:02:58bodies and their heads are just hugely modified from those of their reptilian and decedent's which are of course dinosaurs and we all know the bird body ah is designed for flight and we know that in part because we we eat them all the time so you know we
00:03:12have the breast which is ah one of the big flight muscles and we all know also intuitively that bird heads are instantly recognizable and if you look closely at a bird head you see a few really distinctive features in the back of the head there's this really round
00:03:28ball biss noggin which contains a very enlarged brain compared to those of other red piles and need birds are like really kind of dumb but they're kind of smart compared to other reptiles and some birds really smart s o they got a big brain they've really really big
00:03:42eyes which is not that separate from having a big brain because the eyes actually developed as part of the brain and so those are two things they have but of course the most distinctive thing about the bird head is the beak it's the beak that has allowed birds
00:03:57to radiate into many many many desperate logical niches darwin was inspired teo consider his theory of evolution by natural selection because of the beaks of finches and so it's a very very important oregon and it's a unique or in in that it's ah total reorganization of thie bird
00:04:19face most of the beak is composed of a single giant bone that in other vertebrates is very small just occupies the tip of the snout and that's a bone called the pre max scylla so there are all these translations also birds can do this thing with their beaks
00:04:34they use it as a precision grasping organ and part of how they do that is that they use it they use the upper and lower jaws like a pair of tweezers which means that you have to move both the upper and the lower jaws to get a really
00:04:45precision grasp and they can move their upper jaws with the upper beak independently of the rest of the head which is a really weird thing so they've a hinge in the middle of their skull ah and so so birds of all these unique features in their skulls and
00:05:00before we investigated if uranus there were a lot of gaps in our understanding of how these features originated the order in which they originated and what there's their first forms looked like and that's partially because the fossil record is really rich in terms of species but many of
00:05:19the fossils that preserve the transition from a dinosaur like head to a birdlike head are very heavily damaged and flattened and although they preserve wonderful things like many of these chinese bosses they preserve feathers and soft tissues They don't preserve the detailed anatomy of the head and it
00:05:36turns out that the stage at which these features are becoming modern is captured by it's your anus this tax on that's been known from fossils since the middle of the eighteen hundreds while not a dinosaur itself it's the earnest live near the end of dinosaurs rain about ninety
00:05:57five to eighty three million years ago long before humans ancestors emerged sorry arc layers i ran and i wondered what life in the cretaceous period was probably like for the animal it's named means fish bird it's the cornice and it's fossils were found in deposits made by ah
00:06:16the western interior seaway which was a tongue of the ocean that extended on to the main land of what would become the united states during the end of the time of the dinosaurs secret a cious and during this time the earth was very very warm the icecaps had
00:06:32melted sea levels were very high and so all of the midwest of the us basically in texas were covered by this warm shallow seaway including kansas where i grew up and in fact most of the fossils of a curious r like me from kansas and so these were
00:06:51deposits that contain fish they contain terrifying marine reptiles that air now fortunately extinct a quick spoiler alert if you've not get seen the movie jurassic world you might want to skip the next fifteen seconds or so like the giant moses horrors jurassic world the end of jurassic world
00:07:10the ultimate winner of the big dinosaur fight is a is a lizard actually the moses or and so those are swimming around at the time and so we're pleas e stores these long neck marine reptiles and a bunch of other strange things it was a scary time to
00:07:23go swimming at the end of the cretaceous but go swimming things did and among the things that were paddling around flying around or it was ah if your anus it was basically a seabird if you looked it from far away you would think it looked like a goal
00:07:40or a turn today it was a good flier we have we have most of its body and we can see from its body that was pretty much done with becoming a bird that it could fly more or less like modern birds that had all of the distinctive features
00:07:56of the bodies of modern birds and it would have been flying around diving down catching fish It probably would have been really rude and really loud Just like goals and turns are and so it would have chattered at you and sappy would have smelled kind of gross smell
00:08:09like fish had a little bit of ah of ah primordial hearing hanging out of its mouth But if you look closely at its mouth you would have seen that this little primordial hearing was speared on a beautiful row of dinosaur teeth because if you are his head yet
00:08:26lost its teeth in a may two thousand eighteen interview about this study with rebecca hirscher on npr on john remarked that if your nose fills in an important gap but of course everything that fills in the gap makes two more gaps on either side since doug and i
00:08:42had both listen to the interview when it aired we were curious to learn what he meant by this in any text on like birds like humans that has so many unique features there's there's a long chain of transitional forms that show the gradual acquisition of these features and
00:09:03once in a while we find in the fossil record one of these forms but of course it's gonna have whatever half of the features of the modern group and what you want to know then is what happened after that what happened before that and so how do the
00:09:18remaining features become assembled and how did the ones that it has appear in what order they've here and what did they look like at first before they started looking kind of more recognizable in modern and so it was like that for instance when archy optics was discovered in
00:09:33archaeopteryx rex is the classic from probably the most famous fossil in the world and that that's often touted as the first bird but the thing is that our key objects is in many ways it had it had feathered wings it could certainly be in the air and do
00:09:50something like flying but in many ways it's just kind of a little dinosaur and we had a previous paper actually that showed that that birds are in many ways sort of juvenile ized versions of dinosaurs malarkey operates looks like for all the world old is kind of a
00:10:05little baby version of one of the larger more ancestral dinosaurs and so that left open the question of how the features that are key objects already has became assembled and so that's the gap on the one side and that's a story that is told by by others but
00:10:21it also left open the question of how the remaining features of birds came about anarchy operates in particular its head is very much a little dinosaur head looks a little bit like a baby dinosaur head and it's in that gap that was made by one of the two
00:10:38gaps that was made by our key objects by archaeopteryx is haven't been dropped in the middle um it's the gap between our key optics and modern birds that picks the organist in particular phil's on the right hand side of the gap filled by the harness our modern birds
00:10:52and as we all know birds today have no teeth A two thousand fourteen study found that this may be because modern birds possess a gene that deactivates the formation of teeth so we have some idea how birds came to evolve toothless beaks but ryan and i wondered why
00:11:07it was that they lost their teeth in the first place people will tell you all kinds of stories as to how as to how y on ly birds lost ortiz i mean i've heard things for things like oh it it lightened the head because you need to be
00:11:22light in order to fly it's like he's trying like they'd all wave that much for gods and and and things like just orcs with giant bills flyer on teo s oh i don't think i don't i honestly i don't place a lot of stock in any of the
00:11:37modern hypotheses as the why wiberg saucer teeth why is the hardest question to answer in the deep past and it's the question that that people who are serious about science find the most difficult to venture answers on but i can tell you this we know a few things
00:11:57about tooth loss the first thing that we know is that when the asteroid hit and everything died and the world burned there were at that time a few different groups of toothless birds that were the ancestors of the various groups of birds alive today but they had already
00:12:18started to diversify so there are a few different groups of them and there were a number of groups of birds that had teeth stem birds that had teeth and so it wasn't like there was just a single species or a single tax on of toothless bird that was
00:12:35the ancestor of all modern birds and it just happened to make it through by chance know it was that there was a selection of some kind and when the extinction occurred all of the various groups of stem birds that had teeth went extinct and all of the toothless
00:12:52birds survived so if you look a tte living birds and especially the primitive groups of living birds they all nest on the ground and so the trees burn but those birds that nest on the ground and had habits like quail for instance were sort of ground foul they
00:13:09may have survived is they weren't in the trees and they weren't nesting in the trees on dh they were used to living in a world where ah in a world of sort of dense underbrush and hiding using their camouflage a sort of hiding burrows and and they were
00:13:23eating probably detritus seeds and insects and things that would have survived the extinction and that's the other big thing i was going to say it may so it may have been that the ancestor of living birds were nesting on the ground and so they survive because the trees
00:13:39burned and the birds with teeth december's with teeth were perhaps more a boreal and were nesting in the trees and we're really to the trees in some way on john and his team study is unique not just because of what they found by analyzing the newly discovered in
00:13:53the or nus fossil but also because of what was discovered about earlier specimens that were overlooked by previous researchers here on tron summarizes the new insights that came from his team study one thing we learned was that if your anus captures the first beak it captures the transition
00:14:12point to the modern abyan beak it had ah long upper jaw filled with dinosaur like teeth the part of the job was filled with teeth was much longer than had previously been expected and we found that the first beak actually was just a little tiny pincer tip at
00:14:30the very end of the jaw not the along it grabbing and cutting organ that you see and in every modern bird on dh that that pincer tip probably was used as as ah to grab your pecker i mean manipulate things in the manner of a hand and we
00:14:47also found that in concert with this transitional beak there was a fully developed hinge in the middle of the jaw in the exact same way that modern birds do it if he orders could lift the upper jaw independently of the lower which again supports the idea that it
00:15:04was doing this precision grip and that's what the original beak was used for not for all the things that modern birds khun dio with organ but just for grabbing and that it was still the teeth which were very big and very dinosaurian that did the holding and the
00:15:19processing of the food and so we've got a transitional beak a modern what we call kinetic john movement system this is all new information about how the transition happened but also because we had a complete beautiful brain case now we could see that the brain was already basically
00:15:38a modern birdbrain a huge modern bird brain and so the back of the head and already transformed it was thinking like a bird and it was flying like a bird and it was doing things and leaving us life and perceiving the world like a bird with its giant
00:15:52eyes and it's a giant flight adapted brain and so those were all things that we didn't know we didn't know that the brain happened first the beak happened sort of in steps later we didn't know what the first b looked like now we knew from makes your anus
00:16:06but the biggest surprise was actually something else stick around after this short break to find out what that wass this episode is sponsored by we share science when researchers are curious about what is happening in science they go twee share science to explore video abstracts uploaded by other
00:16:22researchers you khun search their vast catalogue of video abstracts learn about the latest scientific findings or you can share your research with the world whether your research is in progress are already published that we share science you can share your science and grow your impact Explore the world's
00:16:40research that we share science dot or ge now back to parsing science here's on john bowler way had always assumed that there were a series of consequences from having a large brain one of those was having large eyes another thing is that birds as i said they have
00:16:58they have a beautifully developed joe apparatus that allows them toe do a precision grip with the tip of their beaks but their jaws actually aren't very strong i was just in texas and i was ah feeding grackles which are native bird tortilla ships from my from my my
00:17:18taco basket and i was playing tug of war with this with this particularly plucky crackle and it's just you know i kept pulling the chip out of its beak it could see in speak opening and it just couldn't hold its jaws shot because they've really weak really small
00:17:31cha muscles were his dinosaurs of course as we know from jurassic park had very very strong jaw muscles and i had always assumed and had written about in the past that it was that it was a brain that's so huge that crowded out the jaw muscles and and
00:17:45sort of forced them to be really small because there's a competition at the back of the skull for space between the job muscles and the brains well it turns out that i was looking at if you're honest with my with my postdoc dan and he was rotating the
00:17:58brain case around and said one the world is this thing sticking out is this some weird there's some other bone that's going to stuck to the side of it like what's going on and we were staring at the this river and eventually i said oh my god what
00:18:11we're looking at is this bony cage that surrounds the jaw muscles in dinosaurs but that birds have lost but if the organists unexpectedly and so unexpected that we were that we weren't ready to see it and so we didn't recognize it at first in athe or n'est ce
00:18:28there is a really really dinosaur like architecture to the part of the head where the jaw muscles attach and we that was totally surprising because we knew that our key objects had this but we assumed that birds have lost that stem birds have lost that very quickly after
00:18:47archaeopteryx ricks because every single other fossil along that line is damaged and they were broken off and now when i go back i can see where they were broken off but basically this thing's head it had giant bird brain but it's djaq closing system was like velociraptors and
00:19:11so it was really really dinosaur like in that way so it really was this mosaic of dinosaur like in birdlike features and the way in which they were combined in this animal's was was quite surprising another fascinating aspect of on john study is that the newly discovered it
00:19:26theo ernest fossil the first ever featuring a nearly complete skull didn't have the rocky matrix surrounding it removed it's dead the head of the ernest was digitally reconstructed in three dimensions using computed tomography or ct scanning as on john explains next it's micro ct scan which is very
00:19:47high resolution and in micro ct scan on you have to mount things very carefully so they don't move but what a ct scanner is is it's just an x ray machine with a really really really expensive turntable in the middle of it and a really really good x
00:20:02ray source and a really good detector and so you put the object on this platform and you take a whole bunch of x rays while the object is rotating three hundred sixty degrees on this really precise platform and you might take three thousand or four thousand of these
00:20:23individual images x ray images and then what gets spat out is like i said three thousand tiff files that are just you'd recognise him as an expert just like you get when you go to the doctor and it's then the computational part the computer tomography that builds these
00:20:38individual raw projections into a three d volumetric reconstruction and the special thing about ct scanning about x ray scanning is that that that's different from something a three d imaging process like laser surface scanning which is also very useful or photo gramma tree which is also very useful
00:20:59is that you don't just get the surface you don't get a hollow shell you had everything that's inside as well and so i recently he have acquired a ct scanner here a yell on and on and i have ct scan things that harvard myself as well to soy
00:21:13so i gained an appreciation for the art of this i still cannot do it as well as tim rose team at texas which is why we still take all of our most important stuff to the university texas but tim rowe and matt colbert and jesse my sana where
00:21:28the people down there who are true experts at this stuff and no you have to set it up you have to think about what you're trying to look at and orient the block such that what you're trying to look at a centered and it's it's high enough resolution
00:21:42you have to orient the blocks so that the x rays air passing through as a little stone as possible because you had a lot of attenuation and so that means that if you have something that's long you don't want to orient it so the long axis at some
00:21:55point he's going to face into the bean you want to orient vertically is on john discuss picked the earnest had a much larger brain than its predecessors brian and i were curious what evolutionary advantages might be experienced by animals with larger brains you know the parts that get
00:22:10really big are really really really the parts that seem to be involved in sensory motor coordination and in aa visual processing and all of these things speak very heavily to the idea that that this is something related to flight and toe into the various ah the various things
00:22:30that you need to do when you're flying and much of that is seeing things really well on really quickly and much of it is also understanding all the parts of your body and controlling all the parts of your body and so birds can detect really subtle variations in
00:22:44air flow they after control every little bit of their skeleton that's still mobile birds have stiffened up a lot of their skeleton too and they also of course like as we get sensations from every hair on our body they get sensations from every feather and every feather is
00:23:00individually controllable too so they have a lot coming in and they have a lot of instructions going out and it's these channels that that seemed to be really really hyper developed in birds but you know as a byproduct of that the thing is you get smart for one
00:23:17reason but the cool thing about brain evolution invertebrates is that when higher brain mass relative rayna's is selected for you get all this excess processing power as well right because flight is demanding but it's really most demanding on takeoff and on landing and in harsh weather and when
00:23:36you're on the ground in bridge on the ground a lot of the time and when you're doing other things or when you've you know zoned out you've got this incredible processor and all this ram you know that you're just not using in that that sort of excess toph
00:23:51let's you'd be smart to be lets you have inner life and a complex social ality and lets the smartest birds like parents crows and ravens b as smart as many primates in addition to their interest in bones paleontologists are also concerned with the soft tissue the connects supports
00:24:12or surround other parts inside the body while bones fossilized soft tissue doesn't leaving researchers tohave to infer its form and function so doug and i wanted to know what's so special about soft tissue to paleontologist anyhow i'm a big proponent actually of the idea that the skeleton instead
00:24:33of being sort of an entity unto itself is more like connective tissue and it's a connective tissue that forms at in the interstices among all of the primary tissues of the body and i say this because it's actually the so called soft tissues that form first in the
00:24:52embryo those are the things that are driving the shape of everything else So for instance in the head the very first thing to have form is the brain and in the early embryonic head there is nothing but a giant bubble of a brain and the primordial skin over
00:25:08it and into the little gap between this brain bubble and the skin surrounding it migrate all of these mobile amoeba like cells in those cells will eventually differentiate will eventually divided differentiate inform all of the rest of the structures of the head including the skeleton but they form
00:25:30around the brain and the eyes and the nose and the jaw muscles which are already there and when they form the form is membranes that sort of separate and contain these structures and it's in these membranes also that things that structures that that supply the's primary constituents run
00:25:53too so it's in these membranes these connective tissue memories that nerves and blood vessels for and if you ever if you've ever had medical education i've taken human gross anatomy and you dissect a body you find that there is an organization blood vessels and nerves and things don't
00:26:08just run willy nilly through the body they always run in these sheets of what we call fashion and that's that this it's the grisly you know member nous part of stuff that we have to turn away when we're preparing a kind of meat but that's actually really important
00:26:22stuff and bone all bone really is is that it's a hardened version of that stuff so some subset of that member n'est stretchy stuff becomes mineralized and that's what bone is and so it's it's really it's not so much that we have to take into account the soft
00:26:41tissues it's really that bone is just this late forming kind of intra gresser in aa in a context that's entirely formed of the of the software tissues and so you can't just build stories that airbase on fossils without really really having idea of the way the soft tissues
00:27:05organized and so in fact one of the things that we're doing is trying to reconstruct the jaw muscles on some of these ancient birds tto learn more about how their jaws operated and that's part of my student mike anson's dissertation given the cutting edge nature of the research
00:27:18that on john engages in ryan and i were interested in learning if there is an idea which is prevalent in science that he believes is ready for retirement when i entered hell the idea that's sort of put into young people's minds about studying biology is really that the
00:27:37whole world is cell in molecular biology and that's really where all of the lucrative careers are on and this is the product of kind of the molecular revolution in the middle of the twentieth century in which the proponents of ah reductionist sort of ah dna a based view
00:27:57of life really were hugely successful because of watson and crick's great discovery of the genetic code and sort of managed tto stage a revolution and take over a lot of biology department's at universities and a push out though what they saw his older sciences of kind of the
00:28:16in the naturalistic fields where people describe things and went outside and looked at how the world works from the top down and send it from the bottom up and so a and so long past time for retirement and still marching geriatric lee ahn is the idea that there's
00:28:34a separation between the level of genes and molecules and the level of anatomy and morphology and on the applied side surgery this whole thing is a continuum and genes themselves nucleic acids they are anatomy there's structures within an organism and some organisms like viruses our made up structurally
00:28:57in part of nuclear acids and so we have to stop looking at biology as though there's one camp that works on the oil molecules and there's another camp that works on the anatomy or the morphology or the function and we have to stop looking at this when we
00:29:15do research and we think about research because there are all of these connecting threads and connecting scales that division is is is artificial it's based on our eyes it's based on our perception there's one scale of things that we can see and touch and feel easily and there's
00:29:30another we need tools to see and touch and feel but there's every scale in between and all of those things evolve and all those things change and we're not gonna make advances in basic science and we're not going to make advances in medicine unless we begin to see
00:29:45the connections much more clearly and i think many of those connections are going to be made by people who are working at the forefront of imaging technologies so that we could see the whole picture in eighteen sixty six yale university appointed a daniel charles marsh is a professor
00:30:03of paleontology the first such professorship in the united states and only the second in the world at the time marsh also was the first to study and named that harnessed as john is also on falco idiot you also an assistant curator for the same museum and also interested
00:30:22in the organist we asked what it's like serving in such an auspicious capacity ever since marsh yale has been the place to come to study paleontology generation after generation after generation of paleontologists have been trained at yale and yale has historically produced from its graduate programs the curator's
00:30:45and the head professors at many if not most of the top paleontology programs in the world it's just it's just an extraordinary place to work and it's it's i mean humbling doesn't begin teo doesn't begin to describe it it's man i'm just a kid from the midwest and
00:31:03my grandfather my grandfather came from india and and worked in a lumber mill his whole life in order to bring the rest of the family over worked alone for many years and eventually died from cancer from from chemicals that that he encounter in that plant but he and
00:31:22in my oldest uncle and the family you know we were were immigrants were immigrants and look where we are now i mean this is it's it's the american story and it's like my whole life i've been so grateful for this country and for its institutions and um and
00:31:39now to be here to be here is just it's just it's just it's just incredible thing and and all i try to do is to work hard it's a be good you know and and and and to be a force for good and to pay it forward it's
00:31:56a hell of a thing it's a hell of a privilege to be to be a teacher at all and it had to be a teacher at a place like this this is really really something special no that was on john bowler discussing the article complete pick the earnest
00:32:13skull illuminates mosaic assembly of the a v yeah which he published with dan field in six other researchers on may third two thousand eighteen in the journal nature you'll find a link to their paper on parsing science dot org's along with bonus content and other material that he
00:32:28discussed during the episode will be releasing our next episode of parsing science from the podcast movement conference in philadelphia if you're attending sent us a message in the podcast movement app if you would like to meet up just search for parsing science and you'll find doug and me
00:32:45if you're not attending visit us on twitter at parsing science for updates on what's happening at the event next time in parsing science will continue our exploration of paleontology by talking with our medium and off sida from brown university She'll talk with us about her research suggesting the
00:33:02pterosaurs probably didn't take flight Like scientists have long thought that they did If what we thought to be the case was true If it seemed like ligaments really would be preventing this belt like hippos than that would be going against the prevailing opinion for about two centuries we
00:33:22hope that you'll join us again Yeah

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