Ancient Trilobite Fossils on Display
by AMNH on
A new display in the Grand Gallery on the Museum’s first floor includes some of the oldest fossils on exhibit.*
Called trilobites, some of these extinct marine arthropods are more than 500 million years old. (Just as one comparison, the famed Tyrannosaurus rex dinosaurs lived from about 85 to 65 million years ago.)
Trilobites first evolved about 520 million years ago, during the Cambrian Period, when the planet was mostly covered by water. “The world looked very different then,” notes Neil Landman, curator in the Division of Paleontology, “and there were stretches of ocean that no longer exist.”
Cambrian trilobites shared the shallow seas with jellyfish and primitive mollusks such as snails and clams, along with annelid worms and sponges. “There were no vertebrates, of course,” says Landman, “nor, at that time, was there life on land.”
Over time, plate tectonics have completely shifted the planet’s topography. Trilobite fossils have been uncovered in locations ranging from the top of the Himalayan Mountains to the areas surrounding California’s Death Valley, with more than 20,000 trilobite species identified so far.
The new exhibit includes 15 fossils of trilobite species from the Museum’s collections. The fossils on display are so exquisitely preserved that the animals seem almost alive, crawling along the seafloor, not unlike the way horseshoe crabs do today.
Trilobites’ shells were made of the mineral calcite, like clam- or crabshells. They were also the earliest known life forms with compound eyes—eyes with multiple lenses. Some trilobites had eyes on stalks, perhaps for peering above the sediment in the waters where they lived.
Trilobites became extinct 225 million years ago. In all, trilobite species inhabited Earth for about 300 million years.
This exhibition is made possible thanks to Martin Shugar, M.D., and Andy Secher.
There is lots more about trilobites here.
* The oldest fossil on display at the Museum is a stromatolite from the Warrawoona Group of Western Australia that is 3.45 billion years old, on display in the Heilbrunn Cosmic Pathway, which is in the Rose Center for Earth and Space. Stromatolites are structures built by single-celled bacteria.