ammonite
C2Pronunciation
UK
- /ˈæmənˌaɪt/
US
- /ˈæməˌnaɪt/
Description
- extinct shelled cephalopod
- fossil
- ancient sea creature
Imagine a swirling galaxy captured inside a stone – that's often what an ammonite fossil looks like! These fascinating creatures were marine animals related to today's squid and octopus, but they lived much longer ago, going extinct around 66 million years ago with the dinosaurs. They had beautifully coiled shells, and their fossils are found all over the world, giving scientists clues about ancient oceans and climates. If you find a shiny, spiral-shaped rock on a beach, it might just be an ammonite!
Ammonites were a group of extinct marine mollusks that thrived in Earth's oceans for over 340 million years – from the Devonian period to the end of the Cretaceous. Think of them as ancient relatives of squids, octopuses, and nautiluses, but encased in a distinctive coiled shell. These shells weren't just simple spirals; they were divided into chambers that allowed the ammonite to control its buoyancy, rising and sinking in the water column like a submarine.
The name "ammonite" comes from the ancient Egyptian god Amun, who was often depicted with ram's horns – resembling the coiled shape of these fossils. Ammonites varied greatly in size, ranging from tiny specimens less than an inch across to massive shells over six feet in diameter!
Today, ammonite fossils are highly prized by paleontologists and fossil collectors alike. They're not just beautiful objects; they serve as index fossils – meaning their presence in a rock layer helps scientists date the rocks and understand the geological history of an area. You can find them on beaches, in cliffs, and even embedded in building stone. Finding an ammonite is like holding a piece of ancient ocean history in your hand—a reminder of a world long gone, yet preserved for us to discover.
Examples
- 1
Fossil in rock
The guide showed us an ammonite embedded in the rock.
Meaning
ammonite
a fossil sea animal with a spiral shell
- 2
Beach fossils
After the storm, people searched the beach for ammonites and other fossils.
- 3
Museum souvenirs
The museum shop sold polished ammonites as souvenirs.
Forms and spellings
1 form open this card.
Main spelling
- ammonitenoun