Scolecodonts -- Fossil Polychaete Worm Jaws
Many post-Cambrian polychaetes
possessed hard jaws, which are sometimes mineralized
with iron oxide. Such polychaete jaws are fairly common in the fossil
record, and are known as scolecodonts. This illustration of two
scolecodonts is taken from the classic 19th-century paleontology
textbook of Karl Zittel.