Fossil Art Contest: Scientific Descriptions
Compose your own title for each specimen. Label your names with the corresponding number of each image. Send in your suggestions by e-mail to scinews@sciserv.org, with the words "Fossil Art" in the subject field. Please submit only one title per image.
A pattern of curving folds suggesting fingerprints adorns the surface of a 140-million-year-old limestone slab from Germany, shown here in a cast of the original. Credit: William K. Sacco.
This complicated pattern, found in the Fish River Canyon of Namibia, formed almost 600 million years ago in the late Precambrian era. A muddy layer of sediments got trapped between two sheets of sand. As more sediments piled on, the mud compacted and broke into characteristic hexagonal plates. The sand layers compacted less and filled in the spaces between the pieces of mud, which eventually turned into shale. Millions of years later, the upper sandstone layer and the shale eroded away, leaving behind the sandy dividers on top of the underlying sandstone. The pattern is doubled, as in a poorly printed newspaper, because the two sandstone layers slipped out of register when the Namibian rocks were pushed up into mountains. Credit: William K. Sacco.
A half-billion years ago, just after the Cambrian evolutionary explosion, an animal left behind this looping trace, called Psammichnites gigas, in Spanish sandstone. Though researchers do not know what creature left these marks as it crawled beneath the seafloor, the details of the trackway provide "a phantom image of the animal," says Adolf Seilacher. "It moved through the sediment like a submarine, being connected with the sediment surface only by a narrow snorkel. During locomotion, this snorkel swayed to and fro, leaving behind a sinusoidal trace like a pendulum would if it were mounted in the back of a toboggan." The zigzag pattern runs down the middle of the track. Credit: Jens Rydell.
A tapestry from the Triassic period, this cast of a limestone bedding plane from central Italy shows the burrows created by mole shrimp more than 200 million years ago. Modern species of mole shrimp create similar tunnels by using their strong legs to dig several meters below the seafloor. Where three tunnels meet, the shrimp excavate an expanded junction where they can somersault to change direction. Wider sections may be used for storing or processing food, says Seilacher. Credit: William K. Sacco.
Paleontologists originally thought this fossil to be petrified sea weed and gave it the Latin name of Arthrophycus, or segmented alga. But the impressions are actually the remains of tunnels excavated by some unknown wormlike mud-eater during the Silurian period, roughly 420 million years ago. The creature first burrowed a U-shaped shaft down into the muddy sediment and then back out. To gather more food, it gradually filled in the bottom of the hole with sand, while scraping away the roof of the shaft. Eventually, this action produced a vertical wall of sand, says Seilacher. After the burrower had completed one wall, it made another tunnel at a slightly different angle to the first. This created the brushlike pattern, with tunnels seeming to branch out from a central point. Credit: William K. Sacco.
These loops in a half-billion-year-old rock represent the tracks of trilobites, one of the most successful groups of marine invertebrates. These ancient relatives of crustaceans appeared in the Cambrian period and survived until the end of the Permian, a span of nearly 300 million years. The name refers to their outer shell, which is divided into three lobes running front-to-back. The trackway, called Cruziana semiplicata, was made as the trilobites plowed through the sediments, with the outer margin of their shell submerged in the mud. The motion of their legs left fine grooves in the trackways, providing information on how they moved. Credit: Jens Rydell.
7. Ornaments on a Deep Sea Bottom
Photographs from the deepest reaches of the modern ocean often show seafloor scribblings called graphoglyptids, made by unknown animals. This fossilized version of graphoglyptids comes from sediments on the north coast of Spain that are dated to the Tertiary period, not long after the mass extinction that wiped out the dinosaurs 65 million years ago. Seilacher notes that the tunnels are not close together, but rather keep a distance from each other, much like the design of a drainage system. For that reason, he concludes that the creators were probably drawing their food from fluids in the sediment, rather than from solid material. Perhaps, the animals cultivated crops of bacteria, which grew on the wall of the tunnels and broke down organic matter in the seafloor fluids. Then the burrowing animals could periodically harvest the bacteria from the tunnels. Credit: Jens Rydell.
The startlingly handlike prints on this slab from Germany were originally though to be impressions left by ancient man. But geologists now know that the trackway hails from the Triassic period more than 200 million years ago, a time long before humans evolved. By studying the prints, scientists can create a portrait of the kind of animal that left them. Small forelimb impressions appear in the front of each larger hindlimb print and the "thumbs" of the large prints point away from the track's midline—just the opposite of the pattern that we would make if we walked on all fours. The prints appear to come from a large reptile that is known from similarly aged sediments elsewhere. The slab also has polygonally shaped mudcracks that formed when the moist ground surface dried out. The cracks must have developed before this animal made the prints, says Seilacher, because the tracks blot out the cracks in places. Credit: Jens Rydell.
A Billion Years of Beauty
Exhibit of fossils strains the definition of art A collection of geological designs straddles the divide separating art from science.
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