Zygosphene

Part of speech: noun

Definitions

1. A wedge-shaped projection on the front of a vertebra in snakes that fits into a matching notch to strengthen the spine
2. An accessory bony process on the anterior edge of certain reptile vertebrae that interlocks with a cavity on the preceding bone
3. A small articulating protrusion found on the front of snake backbones, helping to brace the vertebrae against one another

Etymology: Zygosphene is a technical term from anatomy, coined in the late 19th century for a small process on the front of certain vertebrae in snakes and some lizards, a wedge-shaped projection that fits into a matching notch (the zygantrum) on the back of the preceding vertebra. It was formed from Greek roots: "zygon," meaning yoke, and "sphen," meaning wedge. The name thus describes the function directly, a wedge that locks the vertebrae together like a yoke. The term was introduced by the English-born paleontologist and anatomist Richard Owen's circle of comparative anatomists in the 19th century, which is why it appears in Victorian studies of reptile skeletons rather than in any ancient text. The Greek elements themselves are old, but the compound is a modern scientific coinage, built the way many anatomical terms were in that period.