‘Astoundingly rich’ Dinosaur Dig Reveals its Secrets

British scientists at the core of an international team of institutions excavating ‘whole package’ Jurassic site boasting trackways, giant dinosaur skeletons and plant life. Monday, March 25, 2019

By Simon Ingram
"An embarrassment of riches." A sauropod femur emerges from the rock at the Jurassic Mile dig site.jpg

When the Children’s Museum in Indianapolis approached the owner of a square mile of ranch land in Wyoming’s Big Horn Basin and asked to lease it, it's likely nobody blinked. Up here dusty-shoed scientists and badlands were often found in the same location, thanks to a huge sedimentary deposit known as the Morrison Formation lying exposed hereabouts. This rock sequence stretches down much of the western United States, from Wyoming down to New Mexico, breaking out of the surrounding ground in outcrops here and there, like a surfacing whale. And this particular Wyoming square mile was one of the spots where it came up for air. 

Sandy and dotted with knots of scrub, it's quite unremarkable to the casual traveller – the sort of sandy-beige backdrop you might see in a western. But to a palaeontologist, anywhere with an outcrop of the Morrison Formation is one of the most desirable bits of go-to geology in the world. The Morrison Formation is the place you go if you wanted to dig up a dinosaur. 

Recruiting their two scientists-in-residence from the University of Manchester, the Children's Museum’s objective was to find a site with the potential to assist an expansion of its dinosaur hall. But what they found has caused a buzz that has crossed the globe – and this week launched an international palaeontological partnership to undertake one of the biggest and dinosaur digs in recent years. 

“There were literally bones poking out of the ground. I’d call it an embarrassment of riches,” Says Professor Phil Manning, a palaeontologist from the University of Manchester. Manning, along with Manchester palaeobotanist colleague Dr Victoria Egerton and Dallas Evans from the Children’s Museum, were in the midst of a month-long reconnaissance when the site caught their attention.  

Professor Phil Manning of the University of Manchester with an excavated sauropod femur at the Wyoming 'Jurassic Mile' site.

“The three of us called it ‘Jurassic June,’” Manning told National Geographic UK over the telephone from Wyoming. “A month just wading our way through western North America, hunting down the best locality we could find. We heard on the grapevine that there was a site on a rancher’s land that was astoundingly rich. You hear this story every time, but occasionally you hit gold. When we arrived we just looked at each other and said: this’ll do.” 

Nearly three years in, the partially-excavated site – now nicknamed the ‘Jurassic Mile’ – has yielded over 600 bones, and a rare combination of circumstances: footprints (or trackways) intact bones and plant life. Or in other words, a complete cross-section of behaviour, environment and beast, all in one place. 

“The circumstances that lead to excellent bone preservation doesn’t usually correlate with good trackways,” says Manning, “and likewise plants, which often produce really acidic environments, which leads to poor bone preservation. Here we have one of those Rudyard Kipling ‘just so’ moments, where we have ideal preservation for all three.” The bones that have so far emerged are from a range of Jurassic-age dinosaurs, with some predatory therapods but most impressively, so far, sauropods – the long-necked, long-tailed giants of the dinosaur age. These would have been the most obvious occupants of the Morrison River Basin, an area of swampy floodplains and grasslands which would later sediment and lithify into the rock formation of today. 

The view from the Wyoming dig site. This region was, during the Jurassic Period, a fertile area of swampland and river basin.

“We’re already getting incredible specimens. The bones are phenomenally preserved, and critically, they are uncrushed,” continues Manning. “We’ve got at least two major diplodocidae skeletons coming out of the ground, we have a brachiosaur coming out of the ground. But also the remains of some predatory dinosaurs too, both large and small. I mean, the scapula of one of these dinosaurs is taller than me. It’s over 6ft 6 in length. And when I say small, I mean turkey-sized. It’s these guys who probably have some of the closest links to flight in birds. We’re very excited.”  

As the significance of the dig asserted itself, the excitement began to spread – as did the realisation that the volume of material was going to require help to excavate and analyse. “We all sat down at the Children’s Museum and said, this is a major opportunity to do some incredible science,” says Manning. “We could build a team from around the world to really unpick some big questions about this period of time.” It was announced today that the ‘Jurassic Mile’ dig now has the backing of London’s Natural History Museum and the Naturalis Biodiversity Centre in Leiden, the Netherlands.

(Would the dinosaurs have did without an asteroid strike? Get the facts.)

Excavator Kimberley Calkins with a sauropod femur.
University of Manchester palaeobotanist Dr. Victoria Egerton at the dig.

Rock of Ages

Made up mainly of mudstones, conglomerates and sandstones, The Morrison Formation was laid down over approximately 10 million years in the Upper Jurassic period– around 157-145 million years ago. Despite spreading over a huge area, the entire sequence takes its name from the Colorado town of the same name near which the first dinosaur fossils were excavated from the formation in 1877, notably an Apatosaurus legbone. 

“The Morrison is the right age, it’s well exposed, and it was deposited by rivers and on floodplains. Basically anywhere in the world where those things come together, we find fossils,” says Dr Susannah Maidment, Researcher in the Department of Earth Sciences at the Natural History Museum – which will be assisting in both the excavation and study of the material. “This suite of rocks is the one where all your favourite dinosaurs are from, the ones you could name when you were seven: Stegosaurus, Brachiosaurus, Allosaurus, Brontosaurus.” 

And these were not occasional creatures amongst a menagerie: dinosaurs dominated the terrestrial ecosystem completely. “During the Mesozoic, literally everything bigger than a metre that was on land was a dinosaur,” says Maidment. “Burrowing dinosaurs, flying dinosaurs, herding dinosaurs. But the late Jurassic was really the age of the really massive dinosaurs – the biggest terrestrial vertebrates ever to have lived. You would have seen these huge herds of these animals moving across the Morrison floodplain. 

Footprints show the presence of both sauropod and therapod dinosaurs at the site.

“This suite of rocks is the one where all your favourite dinosaurs are from – the ones you could name when you were seven. ”

Dr Susannah Maidment, Natural History Museum

These very large dinosaurs were relatively common – and due to their size, and when they died, sooner or later ended up being washed into rivers. Common to many of the remains found in the Morrison Formation is the tendency for skeletons to disarticulate and mingle, probably as a result of washing downstream and ending up buried in the same site of deposition – such as a sandbar or river bend. This has led to the discovery of many dinosaurs here, but few complete ones. And fewer still in good condition.   

“It’s incredibly rare to find a complete articulated skeleton – especially this far back in time," continues Dr Maidment. “Animals that were living 150 million years ago were already fossils by the time something like, say, T Rex or Triceratops was alive. T Rex is closer to us in time than it is to Stegosaurus and the other animals that were living in the Morrison Basin. So while it’s not super uncommon to find complete skeletons of Triceratops and T-Rex [age], when you go that much further back in time that becomes much less likely. What we have at the site at the moment is associated and articulated material – however we hope we will find some spectacular complete skeletons.” (See the dinosaurs that didn't die.)  

Phil Manning and Dallas Evans of the Children's Museum use a pneumatic and chisel to extract a bone using a plaster 'jacket.'

The mysterious north-south divide

Not only are the Morrison dinosaurs of the northern outcrops in Wyoming and Montana well-preserved – they aren’t necessarily the dinosaurs we know. “There’s an increasing body of evidence only just coming to light that the dinosaurs up there in Wyoming are just a little bit different,” says Maidment. “I was working on a stegosaur last year and it was something else. Not your bog standard, typical stegosaurus. They’re a different genera, closely related… but we don’t know whether it’s time difference between the rocks in the south or north, whether there were two distinct faunal provinces separated by a difference in the climate. We just don’t know yet.” 

Maidment hopes this site will give us the opportunity to address some of those questions. “I think we’re going to find some new species up there, but also find out why we’re getting different types of species in the north.” 

The underlying strata reveal marine organisms such as reptiles, fish and invertebrates.

A coalition of research

The addition of the Natural History Museum to the dig team is likely to bring a very modern dimension to these 150 million year-old items of interest. As well as cutting-edge technology being deployed at the dig, footage and discoveries will be broadcast on the Natural History Museum’s digital channels. The dig will even have a hashtag: #missionjurassic

Due to the promisingly rich variety of species already discovered, Professor Anne Schulp from the The Naturalis Biodiversity Centerin Leiden has visited the site. And in a press release, Dr Jeffrey H. Patchen, President and CEO of The Children’s Museum of Indianapolis, reflected on the “natural synergy between three world-renowned museums, their research scientists and highly-respected research universities, each providing unique elements to complete one of the most interesting chapters in the evolution of Earth.” 

Scientists from London's Natural History Museum will be helping excavate and study the Wyoming finds. It is hoped some of the excavated material will make it to the museum's displays.

So the chances look good that the Children’s Museum will be getting its new dinosaur gallery after all. But as Phil Manning notes, there is much we can learn for the future by what is coming out of the ground.    

“This was a period of major climate change,” he adds. “We’re hoping to map these massive changes and how it impacted big animals. And the information we can get from that is very relevant to the world today.”

Right now, however, it’s all about the dig. “You’re touching the past, and connecting with a lost world,” says Phil Manning. “I’ve been digging fossils since I was five years old, and it still puts the hairs up on my neck.” 

And there’s likely to be plenty more to come. Only a fraction of the Jurassic Mile has been excavated, and with the addition of more resource to help with the science and heavy lifting, hopes are good for more discovery. “Dinosaurs dominated terrestrial ecosystems for 170 million years. That’s a huge amount of time, a vastamount of time, to possibly understand,” says Susannah Maidment. “We’ve really only scratched the surface in terms of the number of dinosaurs that we know about.”

Keep up with the dig's progress here

Gallery: some of the world's most spectacular dinosaur fossils 

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