Ancient trilobites had eyes made of crystals


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If you want to know more about trilobites, here’s some more about trilobites!


I saw this awhile ago. It was neat how he showed how the calcite lenses would have worked, which explains why they were arranged like they were. I love trilobites!

Though, odds are the ones he got are probably casts… Morocco pumps out like 10x more fakes than the real ones, even though they have some of the best real ones in the world. I have a Phacops that I am fairly certain is at least partially real, and I can’t remember the other species, but its the very common kind that is usually a little rough in shape, that is real. I got a third one that I was like 60% sure was fake when I got it, but when I got home and did more research I now don’t know. It looks way more real than the obvious fakes and it even has oxide residue. But for the price I paid, I decided fake or not, it was worth it as a decorative object.


Isn’t this guy some kind of raging misogynist?


Maybe? But at least he cites his evidence.


I think that’s a bit hyperbole, but his science stuff has nothing to do with his SJW opinion pieces. And since Trump got elected and the shit show with the Alt-Right, he wisely looked around, and started distancing himself from the Edgelords and has said hes moving on to concentrate primarily on science and debunking videos.

The science stuff is usually pretty good and some interesting stuff.


…and it’s also vulnerable to grass, ice and fighting type moves.


That’s good to hear, at least.


So they solved the spherical distortion problem via evolution of doublet lenses. Hah, intelligent design can eat its heart out.


I’ve always thought trilobite eyes are absolutely fascinating - which was lucky as I spent many weeks looking at them during my undergraduate years. Rather than just one type of eye, there are three different types.

  • Holochroal (similar to modern insect eyes but evolved separately) where thousands of tiny crystals share a single cornea;
  • Schizochroal which generally has fewer lenses than holochroal eyes where each crystal has its own cornea. The lenses are highly sophisticated. Cncreased magnesium content in the lower part of each lens causes it to act as a doublet which helps bring light to a focus at a point and give improved depth of field over holochroal eyes. It has also been suggested that each crystal was associated with multiple photoreceptors to give very high definition, colour vision.
  • Abathochroal (only found in the Cambrian Eodiscina) where there are a few large lenses, each with their own cornea. Later eodiscina were largely eyeless, so it remains a question if trilobites evolved eyes more than once or if holochroal eyes evolved from these eyes (annoyingly, most early trilobite fossils have lost their outer surface which would tell us more).

From the fossil evidence, it appears that immature holochroal trilobites possessed eyes that were to all intents and purposes, schizochroal; so it seems likely the schizochroal trilobites evolved when whatever gene was responsible for holochroal eyes stopped working.

There are also some features known as maculae on some trilobites which are caused by a thinning of the outer shell. It has been suggested these may have acted as additional light receptors to detect day and night and assist in orienting the trilobite when swimming.

I’ve always thought trilobites were adorable and it is a shame they didn’t make it through the late Permian.


I’ve always had vision problems and I went to get laser eye surgery done. The doctor told me, “I don’t know how to explain it, but, but you have calcite eyes. Perhaps you’re really a trilobite and not human at all.” That explains a lot for me, so I’m going with it.


@AndreaJames, loved the echinoderm link, thanks!

@MikeR, did you look at Andrea’s brittle sea star link? I think you would find it very interesting. The source paper’s about how the magnesium distribution in calcite lenses adds tremendous strength, but the LA NHM’s take on it is both shorter and wider ranging.


I have the brittlestar link waiting for me to enjoy when I have a glass of good whisky to hand.


I’m a trilobite lover myself. I have, a few times, hunted Trilobite fossils in the field. Some of the specimens in my area are not as exciting as some I see for sale. The excitement of finding one in the field and prepping it is worth the hunt. I have bought fossils on on occasion but anymore it seems there are many fakes showing up. I agree for decoration, at the right price, a fake can fit the bill.


Sadly, they are really rare in Kansas…

But, someday maybe I can go to OK which has some amazing specimens in the Black Cat Mt area. With spikes and stuff.


laser eye surgery done…you have calcite eyes

That sounds like a dance party waiting to happen.


It’s closest living relative, the Horseshoe “Crab”, has a whole bunch of special purpose eyes.


he harassed anita sarkeesian during gamersfake to the point he got kicked off twitter.

why should he get a pass? he never gave her one.

unless maybe he apologized for his behavior and made it publicly know he not only messed up but is working to make amends for it. (ha!)


Harassment, or mass flagging triggering an automatic suspension?


The irony that eyes have been used by creationists since the 19th century as supposed evidence of their position - when they’re actually such excellent evidence of evolution.
I remember hearing some creationist talk about how an engineer who came up with a camera that worked like a human eye would be a lauded genius. All I could think was that obviously this guy knew nothing about the eye - if you designed a camera that way (which a bunch of stuff in front of the photoreceptors), you’d be fired for incompetence.