Michelle Ackerley:
In the live lesson we found out how the process of evolution filled the planet with such a wide variety of animals, Albert included.
Greg Foot:
Yeah, but Ben, you know, how are we so sure of this amazing array of life?
Ben:
Well, we look at a combination of things in evolutionary biology. We look at things that are alive today like Albert, we look at things that are fossilised like fossil snakes of Albert. And we piece them all together and we have a better understanding.
Greg Foot:
Mm.
Michelle Ackerley:
So how to fossils actually help with this?
Ben:
It's best to think of all of life on Earth like one big jigsaw. And if you're meant to have, say, 100 pieces to this jigsaw and you've only got ten pieces, you don't really understand the whole picture. Fossils help by acting like extra pieces and the more pieces you have, the better understanding you have of the total picture. So we can use these to fill in the gaps where we don't understand things yet.
Greg Foot:
And, you know, the word fossils is probably something that you've heard of before, but we scientists like to actually classify things a bit more than that. We get different types of fossils, right?
Ben:
Yes, and actually you can see them there with your ammonites, the first one is true fossil.
Greg Foot:
Okay, so that's this one.
Ben:
That one there. So that thing was swimming around in the seas probably around the UK millions of years ago and all the actual body parts have been replaced by rock and it's a complicated process. But that's a true fossil. The one next to it is a trace fossil. Now this is an imprint left in the mud, so the actual fossil itself was resting in the mud and the mud has been fossilised.
Greg Foot:
Like this.
Ben:
Just like that.
Greg Foot:
So it's actually pushed on top of it like that. Oh I see.
Ben:
So two types of fossil can really help us understand a lot of things.
Greg Foot:
That's amazing. And I tell you what, we are dying to know what this fossil is, uh, that Michelle presented us with earlier. I'm really hoping that it isn't dinosaur poo.
Ben:
Well, what do you think?
Greg Foot:
Well, Michelle, are you out there?
Michelle Ackerley:
Yeah, I'm gonna get a few guesses from the audience. So we saw that fossil earlier, what's your name and what's your guess? What do you think it is?
Maisie:
Maisie and I think it might be a plant or a leaf.
Michelle Ackerley:
Okay, a plant or a leaf. Interesting. And what's your name, what do you think it is?
Cowan:
[Cowan] and I think it's a fish.
Michelle Ackerley:
A fish, see I was thinking about a fish as well actually 'cause it almost looks like ribs. And finally, what's your name and what do you think it is?
Jude:
I think it might be a fish as well, and my name's Jude, because on the rock it looks like ribs as well.
Michelle Ackerley:
Yeah, looks a bit fishy, doesn't it? Ben, are we along the right lines?
Ben:
Well, there are some good guesses there and I guess if you look along here you can see the vertebrae, you can see the backbones, you can see the ribs of this fern. This is actually a plant and it looks like a fish, it's over 140 million years old, was found in the UK and you're right, it does look like a big flat fish. And this is part of the problem with fossils, we're never quite sure all the time. So this is a really good example why you've gotta be really good at what you know.
Greg Foot:
Oh you've gotta be a good detective, I tell you.
Michelle Ackerley:
[LAUGHS] Ben, I know you've got a few more examples of fossils to show us, so whilst you get set this is a good chance actually for everyone else to grab activity sheet number one, because we're about to do some fossil detective work of our own.
Greg Foot:
Ben, this is amazing, right, it's pretty terrifying. Who, or indeed what, did it belong to?
Ben:
Well, this thing was walking around about 100 million years ago and was a terrifying animal indeed. What do you think?
Greg Foot:
Hm.
Michelle Ackerley:
Hm.
Greg Foot:
I don't know. We're gonna need to do some detective work and work this one out.
Michelle Ackerley:
I think so. So guys, get your worksheets out, this is your chance to play prehistoric detective. You've got 30 seconds to jot down a few things you think this fossilised foot told scientists about its owner. Okay, you ready? Off you go.
Greg Foot:
Right, so let's find out. What do you guys think that foot can tell us about its owner. Hello, what's your name?
Sophie:
Sophie.
Greg Foot:
What did you write down then? What size is this animal?
Sophie:
It's very huge and it has sharp nails.
Greg Foot:
Oh so what do we think it might have eaten if it's got very very sharp nails?
Sophie:
Some rocks.
Greg Foot:
Some rocks. Something big, possibly. What about you? What do you reckon?
Boy, brown hair, white shirt:
I think it like eats something sharp 'cause it's got sharp nails.
Greg Foot:
Ooh and how many legs do you think this animal would have had?
Boy, brown hair, white shirt:
Four.
Greg Foot:
Four legs. All right then, we've been playing detective. What's the answer?
Ben:
There are some good detectives out there looking at these things. Now, when we piece this together we don't always have the full fossil at the same time, so we've gotta look at what we've got and guess and estimate really of what we've got here. So this thing would have come from the foot of an animal about as tall as this studio. So a very big animal first of all. And we know that by having feet like this you never have more than two legs. So we know this thing was a two-legged animal about the size of this studio. And you said it had big claws and big teeth, it did. This was an ultimate predator.
Greg Foot:
What is it? Come on, tell us.
Ben:
This is the foot of a Tyrannosaurus Rex.
Greg Foot:
No!
Michelle Ackerley:
No way.
Greg Foot:
Wow.
Michelle Ackerley:
That is amazing and all that just from a foot?
Ben:
Yep. We can tell so much just by looking at one little bit of an animal to understand the rest of it.
Michelle Ackerley:
That is so impressive. I mean I wonder how old T-Rex would have done in our terrific scientific flexible foot investigation.
Greg Foot:
Well, not very well because this is a T-Rex right? It wouldn't actually be able to reach the piece of paper to write down the answers.
Michelle Ackerley:
[LAUGHS]
Greg Foot:
All right, Ben, what else have we got on this table of fantastic fossils?
Ben:
We've got some great discoveries here. The tooth you can see over there is from, well it's a very special animal.
Michelle Ackerley:
That is massive.
Ben:
Big cheesy grin there. Now this is the tooth of a shark. It's from a fossilised shark and it's one of the biggest sharks that we ever had. This is from Megalodon.
Greg Foot:
Wow.
Michelle Ackerley:
Wow.
Ben:
Megalodon was so big, it was swimming around the oceans about 30 million years ago and it ate whales.
Greg Foot:
Wow.
Ben:
Not the country, the animals.
Greg Foot:
Must have been humongous.
Ben:
It was. It was absolutely massive. So these teeth can get even bigger. They can get twice as big as that, so that wasn't fully grown.
Greg Foot:
Gosh.
Michelle Ackerley:
That is seriously amazing.
Greg Foot:
Wow, wow, wow.
Michelle Ackerley:
And what else have we got?
Ben:
We've got this discovery here. Now, this is one of the most important fossils that we know of ever. If you look really closely you can see these tiny trace fossil imprints next to the real fossil.
Michelle Ackerley:
Oh yeah.
Greg Foot:
Yeah.
Ben:
And you've got the trace marks of feathers.
Greg Foot:
Gosh!
Ben:
This is a dinosaur that could fly and it looks half bird, half dinosaur. It lived about 150 million years ago and is called Archaeopteryx.
Greg Foot:
Oh wow.
Michelle Ackerley:
Great name.
Greg Foot:
So we've seen loads of different types of examples of fossils. I think we should have a look at how they are actually formed, all right. Now it's my turn to do a very complicated demo. It's not, it's fantastic, you can try this one.
Michelle Ackerley:
I'll be your assistant.
Greg Foot:
Yeah, please do. All right, so talk us through this one, Ben.
Ben:
You've got your little fish, beautifully made here, swimming around about 100 million years ago. Sad news, your little fish dies.
Greg Foot:
Ah!
Michelle Ackerley:
Oh.
Greg Foot:
Sinks to the bottom of the ocean.
Ben:
Sinks to the bottom and lays on the seabed.
Greg Foot:
Yes.
Ben:
Now, waves come in and other sand gets washed over him and it builds up.
Greg Foot:
So layers of sand start pressing down on top of it.
Ben:
Over hundreds of years, then thousands of years and millions and millions and millions of years. And you're squashing down there and that's right, because there's lots of pressure squashing down onto these body parts and it squashes so much that all the body parts disappear and tiny bits of rock seep in instead and only a rock fossil, like these ones, are left. Now, what happens millions and millions of years later erosion. So either the seas disappear or the wind comes in or people dig deep down, and all these extra layers get removed.
Michelle Ackerley:
Digging.
Greg Foot:
Digging.
Michelle Ackerley:
That's it.
Ben:
Here we go.
Greg Foot:
Digging down.
Ben:
Greg's the erosion here. And eventually somewhere deep underneath all this extra stuff you might find a fossil and this is how they're made.
Greg Foot:
It's hard being a fossil hunter, I tell you. Hang on a minute, digging down my next layer.
Michelle Ackerley:
So fossils are basically an animal or a plant that has been turned into rock.
Ben:
Into rock, yeah.
Greg Foot:
I think I've got it. I've got it. Would you be able to tell what that was?
Ben:
You could sort of tell it's a fish. Now this I the problem.
Michelle Ackerley:
Yeah, yeah you can.
Ben:
Identifying fossils and getting them out the ground can be really hard, as you've seen.
Greg Foot:
Wow, okay, well I think that worked perfect. What else have you got here? What's that one there?
Ben:
I've got one more very important discovery. Now this is one of the best things I own. This is a footprint. This is a laser scanned footprint, a cast of a fossil, and it was taken from Norfolk in the UK from a footprint left by a person nearly a million years ago.
Greg Foot:
Wow.
Ben:
This is one of the first people that ever walked or lived in the UK. Now this is before our species, homo sapiens, it's before the Neanderthals, this is four species of humans ago. And this is still left in the UK.
Greg Foot:
So we're looking at the actual print that their foot made and you've scanned it with a laser and then reproduced it?
Ben:
Yep.
Greg Foot:
That's incredible.
Michelle Ackerley:
That is incredible.
Ben:
We even know it's a size nine.
Greg Foot:
[LAUGHS]
Michelle Ackerley:
[LAUGHS]
Ben:
That's how cool this is.
Michelle Ackerley:
Well there are lots of footprints left in the sand here today from our earlier Live Lesson. So footprints are usually in soft earth aren't they, so how can they leave a fossil?
Ben:
In exactly the same way. You don't always need just an animal to be dead or a plant to be dead. You can leave a footprint. And we've even found burrows or worms that have been fossilised over millions of years. So if we leave a footprint or our camel leaves a footprint here, then millions of years later as more mud, as more sediment is pushed on top of it, then that eventually can become fossilised as well.
Michelle Ackerley:
That is absolutely incredible. And we've got a lot of footprints left in the sand here from our earlier Live Lesson with Abdul the camel, so when footprints are made in soft earth or sand, how can they leave a fossil?
Ben:
Well I could explain, but I'm gonna show you. So unfortunately Greg, your shoes need to come off.
Greg Foot:
All right sure, all right.
Michelle Ackerley:
I mean this is kinda good for you Greg, isn't it. I mean your surname is Foot so it's only right.
Greg Foot:
My surname is Foot. Greg Foot: . Right, so I'm gonna be one of these old humans, right walking through the-- grr, how do they鈥? Ug, Ug.
Ben:
Nothing like that, but good impression.
Greg Foot:
Argh, urgh.
Ben:
Now what you can see here is Greg, our early human, is walking around a beach or an estuary and he's leaving loads of little footprints. And we're gonna pick this one here, this is a nice one. Now what would happen is he's walking around and a load of mud washes in or something happens to preserve this footprint. Now these get preserved for millions and millions of years, covered in loads of mud and fossilised. And then millions of years later someone like me, a fossil hunter, comes along and we need to preserve it. And we can use lasers and all this amazing technology now.
Greg Foot:
Like we saw for this one.
Ben:
Like we saw for that one.
Greg Foot:
Yeah, yea.
Ben:
But probably one of the best ways and one of the oldest ways to do it is to use this stuff. Now this is Plaster of Paris and it's a liquid that turns solid. Now what we're gonna do is pour, it's really thick and gooey, gonna pour that into your footprint here.
Michelle Ackerley:
Oh that's so cool.
Ben:
It's great, isn't it?
Greg Foot:
It's filling up all the gaps.
Ben:
Filling all the gaps and eventually, within about ten minutes this will become absolutely solid.
Michelle Ackerley:
Well, Ben it's just as well we have one that we made earlier.
Greg Foot:
Look at this. Look at that, it's my foot!
Ben:
[LAUGHS]
Greg Foot:
That's my foot! [LAUGHS]
Ben:
Now we can see your foot here is beautifully pre-- I say beautifully, It's preserved, it's not beautiful. You've got your heal here, you can see the side of your foot and we can even count the number of toes. Now this would be great if we were trying to understand what you were like half a million years ago.
Greg Foot:
Yeah, I love that so much. It's wicked. And you can try this yourself at school. Just get a shoebox, fill it full of sand, get some Plaster of Paris, give it a go.
Michelle Ackerley:
That is a great activity to try and who knows what footprints future scientists will be digging up millions of years on from now?
Greg Foot:
You know what, they could be yours.
Michelle Ackerley:
[LAUGHS]