See the interesting answers to all your interesting questions about trilobites and trilobite fossils below. What's the story with these fascinating little creatures? How about their zillions of fossils that are still unearthed every day somewhere in the world? Here's where you find out all you need to know about the facts about trilobites!
Short answer: in oceans, all over the world.
Trilobites were common worldwide. Trilobites were survivors above all. Sticking to the shallows, these marvelous creatures survived by scavenging edible debris from the seafloor. On account of their great genetic diversity, they found considerable success in a variety of different environments. They were, however, most commonly found near the equator and the South Pole.
Today, Trilobite fossils can be found nearly everywhere. There are well-known deposits scattered throughout North America and the Mediterranean. Many of the Mediterranean fossils are notable for their unusual size. Some of these giant arthropods could grow up to three feet in size, dwarfing their relatives from other locales.
In depth: Where did trilobites live?
Short answer: 520 to 250 million years ago.
Like the vast majority of animals at the time, they went extinct during the Permian Extinction, or “Great Dying.” While all trilobites lived during the Paleozoic Era, which preceded the much better-known Mesozoic Era or “Age of Reptiles,” different genera of trilobites lived during different periods. Over 20,000 species of trilobites have been identified, and they have been placed in the following ten orders: Agnostida, Asaphida, Corynexochida, Harpetida, Lichida, Odontopleurida, Phacopida, Proetida, Ptychopariida, and Redlichiida.
In depth: When did trilobites live?
Short answer: no.
Generally speaking, trilobite fossils are not rare. Trilobites were among the most diverse and abundant animals during the late Cambrian Period. They left behind plenty of fossils. They also had enormous amounts of time to diversify into different species and there are tens of thousands of identified species today, divided into ten different orders.
Naturally, the fossils of some species of trilobites are much more rare than others. Collectors often look for a range of common and rare trilobite fossils. Some are known by only one specimen, and new rare trilobites are being unearthed all the time.
In depth: Are trilobite fossils rare?
Short answer: their cells turned into rock, one by one, over millions of years.
The skeleton of a dead trilobite went through several stages over a very long time. After the body came to rest on a rock, its outer shell would have spent millennia dissolving. The exoskeleton is replaced with molecules of calcite or other minerals through a slow transformation.
It can take a period of many millions of years, but the entire shell eventually dissolves. The trilobite skeleton blends into the rock, leaving a perfect impression of the creature that used to be.
In depth: How are trilobites formed?
Short answer: not enough oxygen.
Climate change has been an ongoing phenomenon with Earth and is suspected to have played a primary role in the extinction of many species. What does this have to do with trilobites, who appeared so adaptable during their hundreds of millions of years of success? A likely scenario is this: Towards the end of the Permian Age, a perfect combination of phenomena led to a disruption of the carbon cycle, anoxia in the oceans, and eventually the extinction of trilobites. Massive volcanoes emitted carbon dioxide and other poisonous gases that caused global temperature increases. Magma chemical explosions released large amounts of nickel into the soil and atmosphere that would eventually feed oxygen-greedy bacteria living in the ocean.
As a result of all this, methane gasses and increased carbon dioxide levels poisoned the seas. Experiencing greater oxygen demands from higher water temperatures, trilobites suffocated. They had survived a lot of calamities but the Permian catastrophe proved too great for trilobites, as well as 90% of all life on Earth.
In depth: Why did trilobites go extinct?
Short answer: on average, from a few ounces to a few pounds.
Weights of trilobite remains differ quite a bit, and depend largely upon whether or not the fossil is still embedded in rock. The weight variations of these pieces can be extreme. Most trilobite fossils themselves (without the rock) are less than 6 inches in length and weigh less than 2 pounds. The largest known trilobite fossils grew to more than 18 inches and weighed an average of 10 pounds. When buying trilobites online, be prepared for the associated shipping costs.
In depth: What did trilobites weigh?