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Duration:12:13
Uploaded:2019-06-12
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Dr. Brandon Peecook thought he had made a major paleontological discovery that was going to alter decades of prior research in the field. Then, right before he was about to present his findings, he got a phone call that changed everything.

This episode is funded in part by the National Science Foundation! Check out the other episodes in this series: https://www.youtube.com/playlist?list=PLL8_5VpX9TxrP35cKyS8M6GVykLkb9BrW

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Executive Producer, Creator, Host:
Emily Graslie

Producer, Director, Editor:
Sheheryar Ahsan

Production Assistant, Content Developer, Writer:
Raven Forrest

Interview With:
Dr. Brandon Peecook

'Junk yard' animation by:
Mark Olsen
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This episode is filmed on location at the Field Museum in Chicago, Illinois.
http://www.fieldmuseum.org

Additional support for the episode is provided by:
The National Science Foundation:
Grants NSF EAR-1524938 and EAR-1524523
(http://www.nsf.gov)

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E: What can scientists learn from a single bone?  In 2014, a Field Museum paleontologist found this single small backbone during field work in Zambia.  He thought the discovery would end up changing decades of prior research, and then, he got a phone call.

B: I'm Brandon Peecook, I'm a post-doc of the Field Museum, and I'm a paleontologist.

E: A couple of years ago, you made a pretty significant discovery that, what I was gonna say, sent ripples throughout the paleontology..

B: That's way too strong.

E: I know. *laughs* That's why I backtracked.

B: "You had a public flip flop" *laughs* In the paleontoglogy circle.

E: How would you say it, like?

B: It has surprising implications. Yeah, so it was a great story of how science kinda just happens.  Like you're doing your work as best you can and you think you have one thing on your hands, and it turns out you're wrong but for not, not awful reasons, and then it kinda changes the whole story of what you were trying to talk about.  So I'm part of a research group that has been going to Zambia and Tanzania for over a decade now, we're collecting fossils from before and after the biggest mass extinction in Earth's history, and so there's lots of cool stuff we find, lots of new species, lots of just awesome straight up specimens.  Some of the things in the Triassic, for instance, are like the first relatives of dinosaurs-choice.  Very good.  And this one thing we found was in the oldest rocks we have there, which are in the Permian period.  And it was this single vertebra, so like the bone from the neck.  Right away, we're so stocked because we thought it belonged to a reptile, like an early relative of things like dinosaurs and crocodiles way back in the Permian, which, if you don't know, is not when we know them from.  They're from much later in time.

E: So finding this and thinking it's a reptile, what does that mean?

B: The global record, all the rocks from this period all over the world that are preserving like, land living ecosystems, we don't find them.  It's a huge problem.  Like, everybody knows these animals have to exist, but we don't have a record of them.  So we have this idea that they would have existed in this period but we've never found them.  And sometimes those periods of time are really really long for certain groups of animals, and that can be due to a bunch of different things.  And that whole idea is encapsulated by this term called a "ghost lineage."

E(voiceover): Alright, hold up.  What is a ghost lineage?

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E: Well, let's say for example that you're trying to make a catalog of every car ever.  You can't just look at what's on the road today, you have to go to the junkyard to see the cars in the past.  Still, one junkyard won't have every car in history, but by identifying which cars are related-for example, made by the same manufacturer-you can make an educated guess that some cars came between the Model-T and the Mustang. These missing cars would be referred to as the Mustang's ghost lineage, and the gap shortens as additional fossilized cars are found and can be inserted into the timeline.

Ghost lineages exist throughout the fossil record. Take the coelacanth; coelacanths are ancient, unusual looking fish that go way back in the fossil record.  There are coelacanth fossils spanning a massive 300 million years from the Devonian all the way through the Cretaceous.  But then no more fossil coelacanths were found and it looked like they went extinct some 65 million years ago.

Then, in 1938 off the coast of South Africa, museum curator Marjorie Courtenay-Latimer saw something strange in a fisherman's catch. Lo and behold, tens of millions of years with no fossil evidence and then here it is.

The discovery was mind-boggling. J.B.L. Smith, the fish expert who conclusively identified the first modern coelacanth said: "Coelacanth, yes, God! Although I had come prepared, that first sight hit me like a white-hit blast. It made me feel shaky and queer, my body tingled. I stood as if stricken to stone. Yes, there was not a shadow of doubt: scale by scale, bone by bone, fine by fin, it was a true coelacanth.

The thing is, just because there are no fossil coelacanths doesn't mean they weren't around later than the Cretaceous, it juts means they weren't being fossilised. This 65 million year gap is teh ghost lineage of the ceolacanth.

Ok. Tell me about ghost lineages.

B: So, paleontologists always draw, like, things on geologic time,

E: Yeah

B: Where stuff at the bottom is old and stuff at the top is new,

E: Yeah

B: Like layers of rock. So if we had on this chalk board, time is like this

E: Yeah

B: So you and I are standing way up in the ceiling somewhere today.

E: Ok.

B: And so things that are related to mammals have this long, thick rectangle is going to be a stand-in for their records.

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