Question 1

How do you say Phacops?

Accepted Answer

Phacops is pronounced FAY-kops, with the stress on the first syllable. The PH at the start makes an F sound, just like in words such as phone or photo. A good memory trick is to think of it as FAY like the name Faye, then just add KOPS at the end. Once you say it a couple of times it feels completely natural, and you will definitely impress your science teacher with it.

Question 2

What does Phacops mean?

Accepted Answer

The name Phacops comes from two Greek words: phakos, meaning lens or lentil-shaped object, and ops, meaning eye or face. Put together it basically means lens-eye, which is a perfect description of this trilobite's most famous feature. German naturalist Ernst Friedrich von Schlotheim gave it this name in 1823 after being struck by its enormous, bulging compound eyes. The name was a great choice because those calcite crystal lenses are still the most talked-about thing about Phacops today.

Question 3

Was Phacops actually an insect?

Accepted Answer

Phacops was not an insect at all. It was a trilobite, which is a completely extinct type of marine arthropod, more closely related to crabs, horseshoe crabs, and spiders than to any insect. Insects evolved to live on land, while Phacops spent its entire life crawling along the bottoms of ancient shallow seas. The trilobite group it belonged to, Phacopida, went completely extinct at the end of the Devonian Period around 354 million years ago, leaving no direct living relatives.

Question 4

How old are Phacops fossils?

Accepted Answer

Phacops fossils range from about 458 million years old to around 354 million years old, spanning from the Late Ordovician Period through the end of the Devonian Period. That means the genus survived for over 100 million years, which is an extraordinary run. The most commonly found specimens in North America come from Devonian rocks, particularly from formations in New York, Ohio, and Pennsylvania that are roughly 375 to 390 million years old.

Question 5

Why did Phacops roll into a ball?

Accepted Answer

Phacops rolled into a tight ball as a defense against predators, a behavior scientists call volvation. By curling up, it tucked its soft underside completely inside its hard mineralized exoskeleton, presenting attackers with nothing but a smooth armored sphere that was very difficult to crack open or eat. Fossils of Phacops are frequently found preserved in this rolled-up position, which tells us this was a real and common behavior. The same basic strategy is used today by pill bugs and armadillos, proving it is one of the most reliably effective survival tricks ever evolved.

Question 6

What did Phacops eyes look like?

Accepted Answer

Phacops had large compound eyes made up of individual lenses, each one a single perfect crystal of calcite. The eyes had a distinctly raised, dome-like appearance and contained rows of big, bubble-like lenses that you can actually see on a well-preserved fossil with just a hand lens or magnifying glass. The number of lenses varied by species but some Phacops had as few as 70, which is far fewer than most trilobites. However, each lens was so large and optically precise that scientists discovered in the 1970s these eyes corrected for spherical aberration, a problem that human lens designers did not solve until the 19th century.

Question 7

Where can you find Phacops fossils?

Accepted Answer

Phacops fossils have been found on nearly every major continent, including North America, Europe, Africa, Asia, South America, and Australia. In the United States, some of the best specimens come from Devonian shale in New York and the Silica Formation in Ohio. Pennsylvania named Phacops rana its official state fossil in 1988, partly because the fossils are so abundant in that region. Amateur fossil hunters still regularly collect excellent Phacops specimens from roadcuts and quarries in the eastern United States.

Question 8

Did Phacops help prove a famous theory about evolution?

Accepted Answer

Yes, and this is one of the coolest things about Phacops in the history of science. In the 1970s, paleontologist Niles Eldredge studied populations of Phacops rana across different rock layers in New York and noticed that its eye structure stayed the same for long periods and then changed relatively suddenly rather than shifting gradually. He and Stephen Jay Gould used this evidence to develop the theory of punctuated equilibrium, which proposed that evolution often happens in quick bursts separated by long stable periods. This theory became one of the biggest debates in all of evolutionary biology, and it started with a careful look at this small sea creature's eyes.

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