thank you very much good morning everybody can you hear me yes okay I must say I'm very grateful to France paws and the museum for inviting me to be here today because for many years I've wanted to come to the Royal Tyrrell Museum in fact I first knew of it when Phil curry asked me in the early 1980s if he could have a cast of a saber-tooth cat skeleton to put on display at the Tyrell Museum I thought well Thoreau Museum dinosaurs and saber-toothed cats it's a place that you have to go but unfortunately circumstances have conspired against me and this is the first time I've actually been able to visit the museum so I'm greatly looking forward to seeing more of the museum after the talk but in order to sing for my supper as it were I'm going to talk this morning about another fascinating fossil locality of the ranch ellebra or the La Brea Tar Pits just to put you in perspective the bread Tar Pits is about 2,000 kilometers south of here it's a three-hour flight or a 24-hour drive the name Rancho La Brea comes from the old Mexican land-grant of Rancho La Brea which was one square Leegin extent and was located one league that is several miles west of the Pueblo of Los Angeles branch ellebra means tar ranch and it got its name from the asphalt seeps that were seeping out in its southern border and these were first documented by the portuguese deport or Portola expedition in 1769 now raunchy la Praire includes much of Hollywood and Hancock Park and Beverly Hills and is totally built over except for 23 acres along the southern border which are where the remains of the astronaut seeps the La Brea tar it's are located rocha lab rare is the type locality of the raunchy Lybrand land mammal age that means it's the the type locality for in North America for the last two hundred thousand years of the Ice Age ever since bison migrated into North America and from the asphalt seeps of Rancho La Brea we have recovered more than three and a half million fossils which represent more than 600 species of animals and plants the seeps come up from oil reservoirs which occur in late miocene sedimentary rocks somewhere between 1,000 and 10,000 feet below the surface and as the asphalt migrates upwards from the oil field and seeps onto the surface it traps unwary animals in the surface seeps and here's an example of some animals trapped fairly recently dragonfly spiders rabbits wax wings birds squirrels and a goat the thing is that the asphalt seeps can be very sticky particularly when the temperature is above 65 degrees Fahrenheit and it only takes an inch and a half to two inches to totally mobilize an animal the size of a horse or a cow and so unwary animals stepping into the oil asphalt seeps get trapped like flies on flight paper and they're immobilized and if they're lucky in a week or 10 days they'll die of hunger or thirst if they're not so lucky they'll be torn apart by other animals that come in to feed from them and this is the scenario that you had during the Late Pleistocene at Rancho La Brea so the animals were trapped in the asphalt seeps and were torn apart by animals that came in to feed on them and over time these built up great or apparently built up great conical masses of bones that that are now called the La Brea Tar Pits asphalt from the Tirpitz was used by Native Americans and early settlers from many domestic purposes the the Native Americans used it for lining baskets caulking plank canoes and as an adhesive for necklaces or office dishy sticking fishing hooks on fishing lines and the early European settlers used it for fuel and for putting on the roof of their houses and then in the late 18-hundreds it started to be mine to be used for cementing cobblestones onto roads and impregnating wood railroad sleepers and so on and so forth and the the big asphalt mind was on the edge of Rancho la Praire owned by the Hancock family and the first fossils were discovered in that wine what had happened is over the years they as they were digging out ash felt they come across bones and they thought these were the remains of domestic animals cattle and sheep that had inadvertently fallen and got trapped by the the asphalt but then William Denton a professor from Wellesley College had heard about the Tar Pits and he went down to see for himself and the landowner presented him with the canine of a saber-toothed cat whereupon they realized these weren't just domestic animals in the asphalt seeps these were fossils and unfortunately although William Denton published on this this the these findings nobody took any notice of him largely I think because he and his wife said that the bones talked to them and he was rather dismissed as a bit of a a weird English eccentric and sadly he then travelled to crap to Indonesia and he perished in the Krakatoa explosions but bones were Riku was started to be found again and were recovered in the early nineteen hundreds as people started prospecting for oil and came across the bones in the ash felt seeps the first excavations were by UC Berkeley in 1906 and they later excavated in 1912 1913 and then the Southern California can reassess started excavations there for two years and the bones that they recovered were one of the reasons for the founding for the LA County Museum and then when the LA County Museum had been built in 1913 the landowner gave permission to the LA County Museum to excavate at the Tar Pits for two years and during those two years they dug a hundred excavations and recovered well over a million bones this is a map of Hancock Park today the page museum is here this is the Art Museum and you still see the remains of some of of the old pits this is the old asphalt quarry that was mined and here some of the other pits that are still in existence and it can still be seen today this is what they looked like this is the remains of the old asphalt quarry pit nine and thirteen were excavated in 1913 and pit 91 was found in 1915 and started to be excavated in the 1960s so there were free three main phases of collecting from the tar pits by the LA County Museum the 1913 to 1915 excavations and then the pit 91 excavation in 1969 through 2006 and then the project 23 excavations 2008 to the present day this is what little Brea Tar Pits looked like in 1914 this is pit 67 which has been flooded and you can see in the background the Derrick's from the oil field which is the source of the asphalt from these for these fossil localities this is bit 67 before it got flooded and the excavators divided the area into three-foot square grids and they excavated 6 inches at a time and they kept records of that so you have a fairly good record of where the individual fossils came from as you can see they sometimes they went down to great depth I guess the deepest was about 30 feet and they didn't shore up the sides so that periodically there were collapses particularly when it rained and that that tends to mix up burns from different levels this is some of the activities that bones were taken out of the pits they were cleaned on the spot by boiling them in kerosene and then they were transported to the LA County Museum and this is a photograph of the basement of the LA County Museum with the remains of the Smilodon collection there as you can see that there we've got lots of bangs but unfortunately these are nearly all isolated bones there are very few associated skeletons and so although we have well over a million million bones recovered from the tar pits the number of actual skeletons you can count on the fingers of two hands during the 1913 15 excavations they recovered about 300 different species of animals and plants 29 species of plants 63 insects 133 birds and 43 mammals but most of the attention subsequently was paid to the mammals the rubra herbivores included the elephant relatives the Columbian mammoth and the slightly smaller American Mastodon two species of camel the Western camel and the long headed llama at least two species of ground sloth the browsing sheffster ground sloth and the grazing harland's ground sloth two species of bison the long horned bison Latta Cronus and the war short-horned bison antiquus the flat-headed peccary a couple of species of pronghorn a couple of species of horse and as a rare in occurrence the California tape here but these were far outnumbered by bones of the carnivores that fed on them they included the short-faced bear which was about the size of a Kodiak bear but very long-limbed and then was the largest carnivore from Rancho La Brea the communist carnivore was the the DA Wharf which brought much like a timber wolf except it was much more massive it's like a timber wolf on steroids then more fearsome you had the saber-tooth cat smart on fatalis which is about the size of an African lion but weighed as much as a Siberian tiger and you have fans there are eight trucks which is usually called the American lion which is about 2/3 were a third again larger than an African lion and it's probably actually more closely related to a Jaguar than its Alliance and of course you have the the species that still persists today and the Coyotes and the Bobcats and so on the ranch ellebra fossils are dominant but the birds and mammals are dominated by carnivores of the mammals well over 80% are carnivores of the birds well over 60% of birds of prey and the only way we can explain this is that the asphalt seeps acted like a carnivore trap and herbivores got stuck on the surface like flies on five paper and these attracted carnivores and scavengers which in turn became trapped this little scene from a mural by mark Hallett gives the the representation that we have in the collection that is for every herbivore you've got a coyote two saber-toothed cats and three to four dar wolves so to give you some indication we have well over 4,000 individuals of dire wolves well over 2,000 individuals of saber-tooth cats and more than a thousand coyotes because you've got such large samples this is very good for interpreting how the animals grew and matured for example in the top here you've got the palates of a saber-tooth cat kitten with the milk canine sticking out and then you go through progressively more mature specimens the permanent canine is just coming through the permanent canine is now bigger than the milk canine and the permanent canine is two entirely replaced permanent care the more canine and then you're so you've got a contrast between the first tooth in the Columbian mammoth jaw and the last tooth large samples also help you to document sexual dimorphism for example in bison males have much longer a much starter horns than females or in the turkeys the male's have spines on their legs whereas females don't and large samples also help you document pathologies of the past here we got saber-tooth cat skull where the canines were broken off and then worn down as the animal continued to live you have fused neck vertebrae fused number vertebrae fused toe bones where the animal got stepped on healed ribs and so on all together their world more than ten thirteen thousand pathologic specimens in the collection and at one time it was thought that perhaps the Tirpitz were a site where injured animals came to injured carnivores came to feed because they couldn't catch others but the actual number of pathologic specimens is only about 1% of the bio test which is kind of what you'd expect in a normal population because we got so many bison jaws we can actually indicate actually document that the fact there was migration going on because if you look at the Bison jaws they're either for 2 to 4 months old or they're 14 to 16 months old or they're 26 to 28 months old or they're fully adult which means that the Bison were in fact only presence in this locality for a short period of time each year whereas if you look at the the horse remains the the the animals are represented by all stages of life and not just periodic intervals the 1913 to 1915 excavations focused on the larger specimens such as this groups such as this Hollins ground sloths specimen found here but we now know of course there is not the largest species that provide the most useful environmental situation but the smallest large species like saber-toothed cats mammoth dire wolves horses camels were wonderful miles during the course of their life and just happened to die at the La Brea Tar Pits whereas the smaller species the insects their snakes the lizards the mice actually lived in the neighborhood of the Tar Pits or their life and so in nineteen this is repet 91 comes in pit 91 was actually discovered in 1915 and it was worked for three three weeks and then it was decided that we'd leave it for a site museum showing the public how fossils occurred in the ground well like many museum projects this one actually never got funded and so when they did build a site museum they you a different place entirely so in the 1960s when we were looking for another site to excavate just to collect all the fossils and not just the big ones print 91 was already there and so we made use of that syringe on June 30th 1969 which is seeing graved in LePage Museum lures ashphalt Friday the we started their the re excavation of pit 91 with the intention of taking out all the fossils and not just the larger ones and to date we've reached 15 feet below the surface and people excavate by by from planks that are extended across the surface of the ash fort deposit because that's to avoid actually treading on the bones that you're you're collecting and the bones are exposed plotted and then removed for cleaning and the surrounding matrix is collected for processing micro fossils and during the course of the last 40 years we've added well over 300 species to the LaBrea biota we've added 18 more mammals mainly smaller ones like rodents but we've also added 131 species of plants 88 species of insects and 63 species of mollusks so pit 91 provides us a very good indication of what the life was like in Los Angeles 27,000 years ago and it provides information about the local habitats the way the fossils were preserved and who ate who what or whom the dominant Pleistocene habitats twenty seven thousand years ago was sagebrush scrub this included sagebrush sage and salt Bush with Valley Oaks Monterey pines Cypress and juniper and was inhabited by grazing animals the Bison by some horses camels and the grazing ground sloth and the animals that fed off them the saber-toothed cats the divorced the Coyotes and the American lions riparian woodland was present near the major rivers and this was composed of Sycamore arroyo willow elderberry and so on and in those riparian habitats you'd have the peccaries the browsing ground sloths and the mastodons and up on the hills behind LaBrea you have you had chaparral vegetation including chemise wild lilac scrubber manzanita a walnut and some of these remains of some of these plants like manzanita berries were washed down from the hills and in streams and ended up in on top of the asphalt seams bone damage from pit 91 is very rare suggesting that the bones were covered quickly by asphalt you don't have many signs of weathering or tooth marks or water wear what you do find on many bones from all of the ricotta's are grooves and furrows that are known as pit wear and this is because the bones are so tightly packed that when earthquakes happen the bones rub against each other and they wear grooves and furrows in each other so the the pit where is paleontological evidence of earthquakes I said that there were very few nor marks or or tooth marks and that it seems to be counterintuitive if the astronaut seats were actually an osmotic trap but there is some talk of some support for that from the facts of that we have an a skeletal representation anomaly that is for each skull that we find in pit 91 we have only one heared where we have one head obviously but we only have one for limb and one hindlimb which suggests that the free limbs were removed by scavengers or predators but the Milan wetlands were left behind the the bones from from Rancho La Brea are very well preserved which renders them very good for radiometric dating and for isotopic studies and the isotopic studies help determine the food chain we analyzed a number of different species for from nitrogen 15 and there was a clear difference between the non ruminants such as mastodons and and horses and the ruminants such as camels and bison and the carnivores now normally there's a jump in the in the nitrogen composition as you go up the steps in the food chain and this is about four parts per mil and if you will go four parts from mil down from the carnivores to the next people in the food chain you find that they hit the ruminants but they don't hit the long runs so this wonderful representation by mark Hallett's of Smilodon feeding on horses is probably wrong and fights my lungs were not feeding on horses or mastodons but they were feeding on bison and camels we've got so much information out of pit 91 that I'd offer often thought that would be wonderful to be able to go back and reactivate at some of these earlier sites and take out all the fossils and not just the big ones but of course that's not no longer possible but coming to our rescue was a what we think of the evil empire across the park the LA County Museum of Art this is the page museum this is the LA County Museum of Art initially the Hancock Park was administered by the Natural History Museum and the art museum said we could have just one time corner we would promise not to expand and so but in the course of their expansion their recent expansion the art museum bought the may company next door to to itself and also in the may company parking structure and decided it will be environmentally more friendly if it replaced the parking structure with an underground parking structure and that involve digging a big hole for the underground parking structure and if you big dig a big hole next door to the world's richest Ice Age fossil site you're likely to find the odd bone or two and that was in fact the case here you can see the Art Museum this is Curzon Avenue that's the parking structure it's the Art Museum the road where the parking structure was and they recovered or they documented at least 16 new fossil deposits there in 2006 well they didn't allow us to excavate those fossil deposits on the site because that would have slowed the progress of the construction so instead or let me just just indicate that this is a section through the ground to show the depth of the individual fossil deposits and you'll note that they're all between 10 and 25 feet below the ground so they wouldn't have got this is why they weren't discovered by the the early prospectus and they wouldn't in fact have been found unless the art museum dug this hole so when we found a fossil deposit the edges were were clearly demarcated and then we started to clear away the dirt from the edges of the deposits starting off with hand tools and ending up with with large constructions and so here's a fossil if to fossil the first deposit isolated and then those fossil deposits were wrapped with with plastic and boxes and crates built around them and this is the largest crate its measures 20 feet by 12 feet by 10 feet tall and weighed 125,000 pounds and then then they were winched out of the the construction zone and eventually they ended up right outside pit 91 where we have started to excavate them and the excavation of the first box box one began in august 2008 coming out of these boxes are the usual cast of characters saber-tooth cats diverse horses camels growl slopes but they do have you did some some interesting fossils that weren't found previously for example they're a whole whole millipedes preserved fragile bird skulls insect heads rafts of oak leaves insects with their original coloration on their wing cases and by looking at these deposits we find in fact there are four different kinds of deposits there are horizontal ash Carter commissions vertical fossil accumulations some fossils that were secondarily impregnated with asphalt and some fossils that really have nothing to do with the ash part at all box 5b is an example of a horizontal deposit you got a thin layer of asphalt packed with burns and the bone zinc and this is about 43,000 years old and the bones include those of a camel Pacific rattlesnake a long term weasel and as well as the usual cast of other cast of characters Safety's cats and direwolf's and so on but the interesting thing about this deposit is that although carnivores again were the most common there were at least 25% of the bones coming out of here were rabbits and rodents which wasn't the case from the earlier issues this this these were this horizontal deposit is how we envisage most of the aesthetic fossil accumulation started you had astronauts spreading out over the surface and trapping fossils but this different kind of fossil deposit was found in inbox one there you had a vertical pipe of bone you've got to just in one corner this is about a meter across and that's what it looked like when we first started excavating it the bones are sort of white because they've been exposed to the earth and weather for two years before we started excavating that's what it looks like after we excavated a meter and you see the column of densely packed bones in asphalt surrounded by non asphaltic sediments and that looks what it looked like after we'd taken off the first meter and that's going down into the ground and you can see again densely packed bones but only about a metre across and this this deposit was very interesting to us because it provided the first path there about there eight trucks or American lion skeleton and this is a representation we had the scape here at the top underneath that was the skull and there were very slim burns and this was the first meter and the second meter there were more bones and there was a small Panthera a rock foot foot bone right at the bottom of the 2 meter deposit well this is a bit of a conundrum because you've got a cylindrical pipe that's a meter across and two meters deep and packed into that cylinder cylinder that you're Panthera a trot skeleton plus five adults male Don's eight juveniles milodon so mountain-lion six adult Davos five juvenile Wolf's a gray wolf a bobcat and a juvenile Bobcat and remains of parts of Harmons ground sloths Shasta ground sloths juvenile bison Western horses and two dwarf pronghorns now this is only a meter across these animals are much larger than that so it's unlikely that they stood on top of one another to sink down into the asphalt so we this finding deposits like these has meant that we need to totally reevaluate how these fossil deposits are found but an interesting thing is again carnivores were the most common elements found of the 12th at twelve to fourteen thousand bones that came out of this car but 40% of those 14,000 bones were actually rodents and rabbit remains - and we have here box 14 which is a similar situation instead of being a cylindrical pipe it's a vertical fissure it's only about a foot and a half wide it's three or four feet long and you see bones again are densely packed inside and this deposit has you did a juvenile Mastodon a bison several saber-toothed cats several direwolf's some horse remains and again it's only one one half feet wide how the fossils got into of that or how they ended up in that configuration is still to be worked out but again although carnivores are the large the the colonists large mammals in this particular deposit the carnivores are outnumbered by rodents and lack moss rodents of nagging off sir rabbits are more than 50% of the deposit then there were non estatic deposits and this was very exciting for us because in these non aesthetic deposits we found our first skeleton of a mammoth from Roger Bobb rare we had remains of some 35 other individuals but just isolated burns and jaws and here we have for the first time a skeleton and here here is his tusks and these are various parts of the body wrapped up in plaster for transportation to the museum this is a map of the site the bones in red are left bones those in writer and green are rights and those in blue are center so you have the left and right tusks the lower jaw the front legs here the ribcage and ribs the pelvis and one of the hind legs the only bone that's way out of place is the skull and you record there elephants like and mammoths have lots of air spaces in their skull so that they tend to float if there are rivers and then they would have floated out of position well the interesting thing was that this was found in an honest Arctic matrix this is the kind of grey Green River clay and sand that there is a small gopher skull this is the skull and this is the matrix around the skull there's no asphalt in the matrix and yet most of the bones have got as far impregnated with asphalt so this is a question how did these bones get impregnated with us felt there I guess basically two solutions either the the mammoths got trapped in a tar seep and then was washed out of it wore and probably more likely yeah the mammoths actually died in a river channel and water in the flowed part in the river I'm floating on the river was oil and the oil which itself into the bones well that sounds story okay and then just as a last as non aesthetic we have ciseaux ciated with the project 23 area the in the in the art museum excavation some fossil trees now these fossil trees look as though they died yesterday but they are in fact between 25 and 55 thousand years old and they have well preserved rings and this is interesting because the you can analyze the Rings to provide all sorts of information and in modern juniper trees you notice that's the carbon content of the Rings varies greatly because of changes periodic changes in the soil water and these changes answers well demonstrated in junipers from higher elevations where you've got wetter and cooler conditions and this this is ok this is a high elevation model wooden junipers from wet and cooler conditions and here are rings from some of those LaBrea trees and you can see these are almost flat light in contrast to these it's not until fourteen and a half thousand years ago that you start getting the the kind of variation that you get even in modern high elevation so this means that for much of the the interval between 50,000 and 60,000 years ago the area of the prayer was was cool and dry and cool and wet sorry the isotopic compositions of the plants also indicates that the plants were under severe climatic stress because of low atmospheric carbon we have to realize that during the peak of the last ice age about 20,000 years ago the amount of carbon dioxide in the atmosphere was lower than it had ever been in the in the previous two hundred thousand two hundred million years and if you put modern plan C into carbon dioxide like that you'll find that they they don't grow very well and they often fail to reproduce and so if these atmospheric conditions were their presence back back twenty thousand years ago when the rare fossils were being to perform being formed this means that there was low plant productivity which meant less food for the herbivores which we would tend to stress the entire population and this may perhaps be contributing to the end Pleistocene extinction which happened about eleven thousand years ago eleven thousand years ago most of the large mammals of North America the mammoths mastodons the horses the camels and the carnivores that fed of them became extinct coyote and smaller sized mammals persisted but that the larger the megafauna became extinct and there are various theories that have been put forward to explain this and they center around I guess four main ideas one climate change and we do know that's at the end of the last ice age the climate warmed up very rapidly and this would have stressed the the the plant populations and and so on but you have to remember also that during the last two million years there were at least ten episodes where the earth became very cool and then very warm again then warmed up afterwards and it's only during the last of these episodes that the tenth warming episode that the large mammals became extinct so environmental changes by themselves are probably not the answer so what was different between the last warming episode and the preceding ones and there are a three possible differences one of course is the arrival of humans one is the arrival of bison into North America and there's a there has been a theory that a large comet exploded over the Great Lakes region and resulted in wildfires throughout North America unfortunately it's at least some of the traces that was supposed to be carbon from wildfires from this asteroid ended up as B interpreted as algae so probably this this theory doesn't control have much to contribute but the arrival of humans and the arrival of bison does but by themselves probably not enough to cause the extinction of everything but in combination with a period of time when the plants were in very low growth and you've suddenly had the arrival of a large herbivore which would tend to convert grass first into grasslands and the arrival of humans which would added another carnivore to to the carnivore guilt of the Late Pleistocene probably a combination of all those factors contributed to the end Pleistocene extinction I arrived at the page museum some 30 odd years ago at least I arrived at the Natural History Museum and they said don't bother with ranch and lab rare because it's all been done and the last 30 years I've indicated to me that nothing could be further from the truth and we still have lots to go we've have to find out for example how these got fossils got preserved in the first place and we still have a lot of information to be gained from studying the remains and to try and figure out how how and when climate changes affected the Late Pleistocene biota I end up by by just saying a few words about mr. George Page who after whom the page museum was was named George Page was was raised in Nebraska and at age 16 he ran away from home to California because he'd seen oranges and thought of placement oranges couldn't be all that bad and he he became a millionaire by investing in real estate and mission pack and and so on and he went to in 1975 he went to the county of LA Angeles and said I will build you a museum for the tuffets and they said no thank you very much and then he built the museum he handed over to the Natural History Museum and they said well I'm sorry but we don't have the money to pay for any exhibits so he raised the money for the exhibits too and we're very fortunate that that he thought of us and so that's the George C page museum today we see it's sunny there our temperatures are warm it was 80 degrees when I left yesterday and I know at least some of you will be coming down to SVP in Los Angeles but those of you who aren't coming to SVP in Los Angeles I do invite you to come down and see the fascia resume because you can see for yourself this vast array of fossils that we have from the last 50,000 years okay thank you very much [Applause]
