From The First Scientist by Brian Clegg
From The First Scientist by Brian Clegg |
Before the first dinosaur ever walked on land, millions of marine crustaceans scuttled across the ocean floor. When threatened, these weird water bugs could roll up like pill bugs. Some grew long spines, to discourage predators, or perhaps to keep themselves from sinking into the soft mud of the sea floor. Others deliberately burrowed beneath the mud, their eyes protruding up to the surface on the ends of stalks. These creatures first appeared in the fossil record in the Cambrian Period, over 500 million years ago. They were among the first animals to evolve mouths, legs, heads, and eyes (made of calcite crystal). They went completely extinct at the end of the Paleozoic, so by the time the first dinosaurs evolved, these water bugs existed only as fossils.
When first discovered in the 17th century, these animals were called "flatfish." Today, they are known as trilobites for the three lengthwise lobes that divide their bodies. The man who named them was Bohemian paleontologist Joachim Barrande.
Barrande happened upon his calling when he found trilobite parts on a Sunday stroll. Employing talented artists, he produced beautifully detailed illustrations of trilobites throughout the 19th century. (He also studied mollusks and corals, but trilobites were apparently his favorite.) Through meticulous study, Barrande uncovered how trilobites grew. Baby trilobites did not look like miniature adults. Instead, they moulted thoughout their lives, and added body segments in their early moults. Considering newly hatched trilobites were often as small as the head of a pin, Barrande's research could not have been easy.
Naming trilobites wasn't Barrande's only contribution to geology. Tutor to the grandson of Charles X, the king of France, he settled with the family in Prague while they were in exile in the early 1830s, and took up geological investigations. He noticed a similarity between the rock layers of Bohemia and those of England, and published Silurian System of Central Bohemia recognizing the Silurian system originally named by Roderick Impey Murchison. Barrande's book described more than 4,000 fossil species, and it continues to be used as a reference book today.
For more information:
Trilobite! Eyewitness to Evolution by Richard Fortey
Life on the Earth by John Phillips
Joachim Barrande (http://www.britannica.com/eb/article-9013459/Joachin_Barrande)
Narrative text and graphic design © by Michon Scott - Updated January 16, 2008