Every year during the Tucson Gem and Mineral Show, we make a stop at one of our favorite places: GeoWorld Gallery.
Filled with remarkable fossils from around the world, GeoWorld offers the opportunity to come face to face with animals that lived millions, and sometimes hundreds of millions, of years ago.
We were given special permission to take a behind-the-scenes look at this incredible collection. Join us as we travel back through time and explore some of the fascinating fossils we encountered along the way.
Giants of the Ice Age
Our journey begins in the Cenozoic Era with some of the most recognizable animals of the Ice Age.
Among the specimens at GeoWorld are fossils from cave bears, woolly rhinos, and mammoths.
One particularly interesting feature of mammoths was their teeth. Like modern elephants, mammoths had large grinding teeth designed to process tough vegetation. The ridged surface of a mammoth molar worked almost like the tread on a shoe, helping break down grasses and other fibrous plants.
Another unusual Ice Age fossil comes from a glyptodont, a massive armored relative of modern armadillos. Some glyptodonts grew to roughly the size of a small car, and their protective armor made them unlike almost any mammal alive today.
Fossil Fish from the Green River Formation
Next, we encounter fossils that are especially meaningful to us at Tyrannostorus: fish from the Green River Formation.
These beautifully preserved fossils provide a glimpse into freshwater ecosystems that existed approximately 50 million years ago.
Among the specimens at GeoWorld are several different kinds of fish, including Knightia, Phareodus, Diplomystus, and fossil gars.
Some fossils even preserve evidence of behavior. One remarkable Diplomystus specimen was preserved while attempting to swallow another fish. Fossils like this capture far more than anatomy. They preserve brief moments from an ecosystem that disappeared millions of years ago.
The gallery also contains Heliobatis, a freshwater stingray from the Green River Formation.
Extraordinary Preservation
Another beautifully preserved stingray takes us across the Atlantic to Italy.
Stingrays, like sharks, have skeletons composed primarily of cartilage rather than bone. Because cartilage usually decomposes before it can fossilize, exceptionally preserved fossil stingrays offer a rare look at animals that can be difficult to preserve in the fossil record.
Sites capable of preserving delicate organisms and unusual anatomical details are particularly valuable to paleontologists because they can reveal information that would normally be lost.
Enter the Age of Dinosaurs
Traveling farther back through time brings us into the Mesozoic Era, where GeoWorld's collection includes an impressive assortment of dinosaur fossils.
One fascinating specimen is the foot of Struthiomimus, an ornithomimid or “bird mimic” dinosaur. With long legs and a body built for movement, Struthiomimus would have looked somewhat like a large ostrich with a long tail.
Unlike humans, who walk with the soles of our feet on the ground, dinosaurs walked primarily on their toes.
Struthiomimus also had an arctometatarsalian foot, in which the middle metatarsal becomes pinched between the surrounding bones. Variations of this foot structure are found in several groups of theropod dinosaurs.
Meet Russ the Triceratops
One of the highlights of the gallery is Russ, an almost complete Triceratops skull discovered in the Hell Creek Formation of Montana.
Triceratops lived near the very end of the Cretaceous Period and had one of the most recognizable skulls in the dinosaur world.
Unlike many other ceratopsians, the frill of Triceratops was solid rather than possessing the large openings, called fenestrae, seen in many of its relatives.
Although we often see large herbivorous dinosaurs depicted in shades of brown and gray, we don't know exactly what colors Triceratops displayed in life. Dinosaurs may have been far more visually diverse than traditional reconstructions suggest.
A Thick-Skulled Dinosaur
Another impressive fossil belongs to Pachycephalosaurus, famous for the thick dome of bone on top of its skull.
These unusual dinosaurs are instantly recognizable because of their dramatic cranial anatomy. Their thickened skull domes have inspired extensive research and debate about how they may have been used during life.
Regardless of their exact function, seeing one up close gives you an entirely different appreciation for just how substantial these structures were.
A Dinosaur That Survived an Attack
Sometimes a fossil records an event in an animal's life.
A series of Edmontosaurus tail vertebrae from the Hell Creek Formation of South Dakota includes a bone that is visibly warped and remodeled.
The healing shows that this dinosaur survived the injury long enough for its body to repair the damaged bone. The specimen provides a fascinating glimpse into the dangers dinosaurs encountered during life.
Edmontosaurus also possessed one of the most sophisticated feeding systems among dinosaurs. Like other hadrosaurs, it had dental batteries containing rows of replacement teeth that allowed it to continually process vegetation.
Not Every Mesozoic Reptile Was a Dinosaur
GeoWorld also has a beautifully preserved ichthyosaur skeleton from Germany.
Although ichthyosaurs lived alongside dinosaurs, they were marine reptiles, not dinosaurs. Their streamlined bodies were remarkably well adapted for life in the ocean.
Some fossil deposits in Germany have produced extraordinary ichthyosaur specimens, including individuals preserved with embryos, giving paleontologists remarkable evidence about their reproduction.
Footprints from Ancient Arizona
Fossils don't always consist of bones or shells.
A sandstone slab at GeoWorld preserves an ancient trackway from Arizona, recording an animal walking across the landscape hundreds of millions of years ago.
Fossil footprints are known as trace fossils because they preserve evidence of an organism's activity rather than the organism's body itself. Paleontologists can study tracks to learn about movement and behavior even when the exact animal responsible remains uncertain.
Trackways can preserve fleeting moments that would otherwise have disappeared forever.
Ammonites and Ancient Seas
Moving deeper into the Paleozoic brings us to ammonoids, extinct shelled relatives of modern cephalopods such as octopuses and squid.
Their distinctive coiled shells contained chambers that helped control buoyancy in the water.
Long before people understood what these fossils really were, some cultures interpreted them as snakes that had somehow been turned to stone, giving them the nickname “snake stones.”
Today, ammonoid fossils help paleontologists understand ancient marine ecosystems and the changing environments of prehistoric Earth.
Before the Dinosaurs: Trilobites
Travel back more than 500 million years and we arrive in a world long before dinosaurs, mammals, or even plants had established themselves on land.
This was the world of the trilobites.
Trilobites were marine arthropods related to the enormous group that today includes insects, spiders, and crustaceans. Their bodies consisted of three primary regions: the cephalon, or head; thorax; and pygidium, or rear section.
They survived for hundreds of millions of years before finally disappearing during the mass extinction at the end of the Permian Period.
By the time the first dinosaurs appeared, every trilobite was already a fossil.
Meet Dunkleosteus
Our journey through GeoWorld eventually brings us face to face with one of the most formidable fish of the Devonian Period: Dunkleosteus.
Dunkleosteus was a giant placoderm, a group of armored jawed fish that flourished hundreds of millions of years before dinosaurs appeared.
What look like enormous teeth in its jaws weren't conventional teeth at all. Instead, portions of its bony jaw plates formed sharp cutting surfaces that created an incredibly effective feeding apparatus.
This was an animal built to tackle other inhabitants of the Devonian seas.
More Than Fossils
Fossils are only part of what can be found at GeoWorld Gallery. Its collection also includes meteorites, minerals, and gemstones from around the world, giving us plenty more to explore in the future.
From Ice Age mammals to dinosaurs, ancient fish, trilobites, and creatures that lived long before the first dinosaur ever appeared, walking through the gallery is like traveling through hundreds of millions of years of Earth's history.
And that's one of our favorite things about fossils: every specimen has a story to tell.
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