Ice cream cone of the ancient seas
An orthoceras is an extinct marine invertebrate that lived 400 million year ago during the Paleozoic era. It looks a little like a squid in an ice cream cone. In fact, it is a distant ancestor of the squid, belonging to a group of animals called cephalopods. Specifically, it belonged to a group of animals called Nautiloids, of which only one type has survived to modern times – the modern nautilus.
The orthoceras has a long cone like shell divided into segments or chambers. The body of the orthoceras is housed in the larges chamber on the very end. As the animal grew, it would develop a larger chamber and move into that one – this is what made the cone shape of its shell. The shell has a long tube that joins all the chambers called a siphuncle. This tube was used to bring water into the shell – adjusting the buoyancy of the orthoceras. Water could also be ejected from the shell rapidly through this same tube allowing the animal to propel through the water like rocket.
The orthoceras has a long cone like shell divided into segments or chambers. The body of the orthoceras is housed in the larges chamber on the very end. As the animal grew, it would develop a larger chamber and move into that one – this is what made the cone shape of its shell. The shell has a long tube that joins all the chambers called a siphuncle. This tube was used to bring water into the shell – adjusting the buoyancy of the orthoceras. Water could also be ejected from the shell rapidly through this same tube allowing the animal to propel through the water like rocket.
The Fossils
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Orthoceras fossils are abundant. The fossil is shaped like a finger and will have several bands separating the chambers of the shell. Most Orthoceras fossils are molds of the inside of the shell. This means that after the animal died, its hollow shell was filled will minerals that took the form of the inside of the Orthoceras shell. The shell later broke down leaving only the rocky mold.
The unfinished fossil provided in a sorting kit will often be a dull brown or grey but when cleaned up usually reveals an attractive marble/granite appearance. Orthoceras fossils are so abundant and clean up so beautifully that you will often find them polished and sold in stores as decorative trinkets and charms. |
An orthoceras fossil before it has been cleaned.
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Activities
Coloring Pages - color an orthoceras swimming in the sea or use an outline of a fossil as a base for the children making their own orthoceras drawing.
Dinosaur Dig - include orthoceras fossils in our own dinosaur dig. You can include then in both a basic dig or a faux excavation.
Complete a partial fossil - Many of the fossils you get on sorting kits or bulk collections are partial fossils - this is especially true with the orthoceras - great for learning how to repair or complete a fossil using modeling materials.
Dinosaur Dig - include orthoceras fossils in our own dinosaur dig. You can include then in both a basic dig or a faux excavation.
Complete a partial fossil - Many of the fossils you get on sorting kits or bulk collections are partial fossils - this is especially true with the orthoceras - great for learning how to repair or complete a fossil using modeling materials.
