Spotlight on Science: Fossils

I hope you didn’t expect me to be serious about this “spotlight on science” business? I’m not looking at a different field of science every week. I am going to write about things I like and if I call this one fossils, I can talk about dinosaurs at a later date.

(Because honestly, I really like dinosaurs. I used to know stats for 50 or 60 different species, and my favourite book as a child was a really dark one about a bunch of Iguanadon that got caught in a storm and then they all died. There were many pictures of Iguanadon looking terrified. It’s surprising I’m so well-balanced.)

Fossils are pretty rad. Not just the big ones (read: dinosaurs), they are definitely cool, but the little ones. Right about now (funk soul brother), I’m going to talk about foraminifera.

Electron Scanning Microscope of a foraminifera
Example of a foraminifera.

What are foraminifera, I hear you ask? They’re microscopic sea creatures that live within that shell you can see there, made out of calcium carbonate. The reason they’re important is because they’re really easy to find in the fossil records – basically any limestone will have forams in them – and because they have distinctly different types at different stages. This is most notable during mass extinctions, when the make-up of said foraminifera will change massively.

This was first noticed in the Cretaceous – Tertiary extinction (I think the nomenclature has changed, but I learned the names for geological periods from the Magic School Bus computer games) where the serious and “weirdly” sudden disappearance of most forms of forams made some geologists begin to investigate that extinction. Before the mid-1970s, catastrophes were not accepted as a valid geological theory for happenings in the fossil record, and it was thought that change could only take place really, really slowly. Investigation showed that the only logical explanation was what we accept as the truth today, that truth being a giant rock fell out of the sky and killed all the dinosaurs so mammals could RISE UP.

Anyway, after that was recognized, it began to be recognized that the amounts and types of forams changed before and after (most) extinction events, ranging back to the first recorded one that I can remember/find on Wikipedia, the End-Ediacaran extinction (542 million years ago) and that is just before the Cambrian explosion which is mad cool.

Artist's impression of Opabinia
Opabinia. Note the five eyes and pincer at the end of a snout.

Opabinia (left) is just one example of a large amount of crazy-shaped animals that evolved during the Cambrian explosion. (FIVE EYES. GIANT PINCER.) The reason we know so much about the Cambrian explosion as well is the large amount of soft-tissue fossils. I’m not going to make a habit of quoting Dawkins, but I believe he’s said words about the creationist theory of the fossil records being flawed because there are many soft-tissued organisms that SURELY appear like they were created last Tuesday because soft-tissued organisms, such as jellyfish, don’t fossilize too good.

As it happens, in the Cambrian explosion, they did. There’s a massive amount of this type of sedimentary deposit called lagerstätten, which are really good at preserving soft tissues. Unfortunately I don’t have my fossils with me, but I too have fossilized shrimp-like organisms at my family home (my mother is against flying rocks up and down the country) which I believe may have come from a lagerstätten.

Two fossil fish from lagerstatten in Colarado
Fish from Green River formation in Colarado

The reason for this is that my rocks LOOK JUST LIKE THAT ROCK RIGHT THERE. I wish I could take some terrible selfies with me and my fossils, but that may have to wait until I travel home again. Anyway, I got them when we went on a school trip when I was a child in Beirut. As sort of 6-7 year olds, we got taken on a bus to a mountain that had been pushed up from the sea bed and so was covered in fossils of shrimp and fish and other things – mine probably have forams if you look with a microscope. We got given little rock hammers and screwdrivers and safety goggles and were told to break open rocks to try and find some fossils. I found three, and although we were only meant to take two home, my mum snuck the third one out in her bag because they were all SO INCREDIBLY COOL.

Came back to New Zealand, spent eight years writing about the Treaty of Waitangi. One guess which education system I preferred.

References:

1. T. rex and the Crater of Doom, Walter Alvarez (1997)
2. The Greatest Show on Earth, Richard Dawkins (2010)
3. Horrible Science: Evolve or Die, Phil Gates (1999)

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