First appearing in the early Cambrian Period (some 542 million years ago), the now-extinct Trilobite is one of the earliest-known arthropods. The name, meaning ‘three lobes’, is aptly descriptive of the marine animal’s distinctive 3-lobed, 3-segmented body type.
Does a Living Trilobite Exist Today?
Science tells us that Trilobites made their last appearance around 251 million years ago. For reference, this period was well before the age of the dinosaurs.
However, among the general public, there remains some confusion about whether or not Trilobite’s are in fact still living and thriving in marine environments. And this confusion is not without merit. There are, in fact, several ‘imposters’ that look eerily similar to the Trilobite, leading some to think that they are still among us.
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For example, aquatic insects (such as water pennies), segmented mollusks (chitons), and a myriad of marine crustaceans (usually isopods), bear resemblance to creatures of times long past.
In this guide, we’ll explore what makes people look twice at these creatures, sometimes mistaking them for the extinct Trilobite.
1. The Water Penny
Of the Phylum Arthropoda (Class Insecta), water pennies are occasionally reported as the potential find of the century: an actual living descendant of the Trilobite.
However, upon closer inspection, these aquatic larvae of the Mataeopsephus (a type of beetle), quickly reveal it’s true nature. A simple flip of the creature on its back reveals several pairs of limbs typical of insects.
Why all the fuss over the water penny? It is postulated that there could be potential for the Trilobite to have survived and evolved over 100+ million years, finding their way into freshwater habitats. However, this is an assertion that currently has no scientific merit beyond conjecture.
Of the Phylum Mollusca (Class Amphinerura), Chitons represent a common inhabitant of intertidal zones around the world.
What makes these a sometimes-mistaken candidate as a Trilobite? Chitons are notable for their distinctive armored plate outer shell (initially resembling segments similar to those of an arthropod).
Similar to the Water Penny, an inspection of its underside reveals its true nature, displaying a broad, muscular foot (similar to a snail). This is in stark contrast to the multiple jointed walking legs of a Trilobite.
These hard-shelled, segmented, multi-legged creatures are a pretty convincing trilobite imposter. Under the Phylum Arthropoda (Class Crustacea), these marine dwellers are one of the closest resembling creatures to the Trilobite. This is especially true of the species Serolis Trilobitoides (the name even has ‘trilobit’ in it!).
4. Tadpole Shrimps
Of the Class Crustacea (Order Notostraca), this group of branchiopod crustaceans is sometimes referred to as “living fossils”, and with good reason. Featuring a cephalon-like head shield and multiple body segments, we can see how they are quite reminiscent of the trilobites of the past.
Exciting, but Not as Exciting as a Living Trilobite
Unfortunately, trilobites have gone the way of the dinosaurs, having become extinct some 251 million years ago. Despite the hope of some scientists, to date, there have been no confirmed discoveries of living trilobites during the time of man. But that doesn’t mean that we can’t still enjoy these ancient creatures in fossilized form, in books, and in museums.
So the next time you think you may have made the discovery of a lifetime, don’t count your chickens before they hatch.
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