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How is it that a Museum can have 1,200+ fossils of a particular species in its collection since the 1960's... and not even know what it is? For decades, it was thought the 'Tully monster' -- a bizarre animal that lived 307 million years ago -- was an invertebrate, like a kind of worm. But in March, Field Museum scientists helped finally crack the mystery of the monster, to reveal it's actually related to lamprey fish. BOOM.
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"The 'Tully monster' is a vertebrate," Nature, 16 March 2016. See the abstract here:

For even more detailed information on the history of the Tully monster and other Mazon Creek fossils, watch 'Tully: Monster vs Method'

Want to know more about the Tully monster, and other specimens from this collection? Check them out on our website:
Fossil Invertebrates:


Big thanks to Scott Lidgard and Paul Mayer for entertaining one more interview about the Tully monster!
Come hang out in our Subreddit:
Twitters: @ehmee

Producer, Writer, Creator, Host:
Emily Graslie

Director, Editor, Graphics, Sound:
Brandon Brungard

Editor, Camera:
Sheheryar Ahsan

This episode is supported by and filmed on location at:
The Field Museum in Chicago, IL

This episode of The Brain Scoop was made possible by The Harris Family Foundation, with additional support from the Lauer Foundation for Paleontology, Science and Education NFP.
Hey, we're here with Paul We're gonna bust some nodules.

We are back with Scott in the...invertebrate paleontology collections here at The Field Museum. Hi I'm Scott Lidgard I'm a Associate Curator of Fossil invertebrates here.

So Scott, you're one of co-author on this paper that was published in Nature about a months ago, Right! Saying that... The Tully monster-- our state fossil known and loved by many... is actually a vertebrate.

How come it took people so long to figured it out what exactly it is? Well... looking at it, looking at your model, it's a really bizarre looking creature. and... It that had perplexed scientists because it has different kinds of characteristics that are shared by some other groups of animals, but not by others. and the combinations of those characteristics has meant that scientists have gone back and forth as to what major group of animals that might belong to.

There is something like 2000 on our collections plus an un-processed group of specimens just recently just got in. So out of this 2400 specimens, there's was no consistency through out them? There's consistency but some of them are... are preserved as fragments.

So they're not the complete... whole body. And some of them are preserved in different ways So you look at one and it might be... looking at the back of the specimen. Another might be looking at a twisted specimen or just a fragment of the front part of that the organism Because it was compressed after its death, this animal and the layer of sediment around it and were hardened into these nodules, what you get when you open up one of these nodules and look at the organism is a part and a counter part of a of a flattened non hard part...

Blob. One of the things that we saw, were these segments where you can see the dark and the light and the dark and the light and the dark and the light alternating some way. on... vertebrate fossils -- think of a nice piece of salmon on your you dinner table. uh-huh and after you've cooked it, the salmon flakes in this planes, and those muscle bands, as a body is decomposing after its death, tend to separate one from another. and these are separating in a very similar way and if you looked a lot of fossils, you can see that the separation goes all the way to the margin of the outside fossil. so that gave us a clue that this might not be the kind of segmentation that an annelid worm had. There's also a light strip on this one, that had been interpreted as a gut trace that is where your digestive track would go through or where and organism's digestive track would go through.

But what really became apparent is that the light band along the back of the body was different from a dark band and that dark band went all the way out to the end of the proboscis, and the light band went all the way down the body to the end of the tail. So we re-interpreted that light band which we see most of the fossil as the notochord, and you can think about the notochord in a primitive fish as being a kind of precursor to the back bone that's in us. You didn't just look at handful of these fossils

Emily: I mean we look into... - We looked at thousand of fossils and we were also betting and thinking and there's more and more data came in, It became very very clear that the vertebrate folks were.. were gonna be the winners. [Yay!] So when this was published in Nature, I mean it's not very frequently that a nature paper gets... circulated- or as much attentions as the... [laugh] the tully monster does. And for it being a state fossil, it surprises me that people all over the world were talking about it. So would you..why you think that it is? -- There's kind of a mystery, -- uh-huh to what past worlds looked like. and a lot of people share that... that...feeling you know, what was a world like in my grandfather's day, what was in my great great great grandfather's day, what was it a millions years ago? And this was three hundred million years ago.

A lot of people I believe have a... an imagination that allows them to venture into those past worlds when they go to a museum look at a dinosaur or...they see a tully monster. I think for me the biggest thing is that... tully monster had been living in the drawers down here staring at me and and whispering to me, "You don't know what I am" [laugh] and now I feel very relieved and proud to have a... finally -- with some help-- figured out more or less what tully monster is. So...

Paul the... fossil invertebrate collection manager has some unopened nodules that may contain tully monsters in them. Let's go find Paul. Alright Paul, so we have our nodules here when was the last time that... whatever organism is inside saw the light today?

About three hundreds and seven millions years ago in Pennsylvanian period. We're gonna shed some light on... on whatever in here. We have no idea!

We have no idea what's in here. Could be anything. Alright!

Paul: try... - So...what's that...what's the technique here? it is just a... I wont try too hard. Try for a big surface. Alright.

Give me a Tully monster. The nodules are pretty hardened brttle, and shatter in all kind of pieces so... Yeah, it seems to be breaking in every direction except for the plane that we want it to split on. [Banging] woo... is there anything in it? and...

Both: No! [chuckles] How frequently did you find this things in these nodules? About half of them have something in it. [Banging] Might be a little bit of a fern in this one. Oh nice! Just a... a small fragment.

So far we've got nothing - and a little bit of a fern. But you mentioned there was a...another way, a better way-- There's a better way. So when I did with these, is I froze them, Several times in my freezer at home, you let em soaked in water for a while, the water gets in, and then when they freeze and though the ice forms, expands, and splits them right open right along-- theoretically -- right along where the fossil is.

So you want to smash that open. See if we found anything in here. Yeah!

That's a whole lot a... whole lot a just... Yeah! most of em...aren't... you know, beautiful spectacular fossils that you see on display, you get a lot of small fragments and stuff. [Banging] oh!

Emily: What?! - it's alright.

Emily: Oh! you've been... - So there's a nice fern, [chuckles] oh... way to go! So..what make it a nice fern? You can see there's the the whole fern is exposed along here, I see... Oh hey...

Emily: There you go. - There you go. It's some kind of leaf. That doesn't look terrible. [chuckles] That's a ringing endorsement right there. [laugh] nothing. Well... no tully monsters this time.

But a... that's a good effort. Yeah. But tully monster are very rare, so here... you know lot less than one percent of the fauna is gonna be tully monsters.

Less than a tenth of a percent really. Oh, that's make me feel better. I'll take my leaf.

It's like winning the lottery.