Geisenoceras is an extinct cephalopod, similar to a squid with a long, pointed shell that lived during the Devonian period around 400 million years ago.
The lighter areas were cavities in its shell that it used for bouyancy and propusion in the water. The dark portion is the surrounding rock that the fossil was embedded in.
For many years, scientists thought this and many similar specimens were all one species called Orthoceras regulare.
But it was eventually discovered that there were in fact over 2,500 unique, conical-shelled, nautiloid species in the fossil record, and sorting the taxonomic record became quite an intensive undertaking.
This is an example of scientific progress. Often when we hear about scientists being wrong, it’s being reported in the news as a failure. On the contrary, being proven wrong presents an opportunity to learn something new. Progress can only occur where we have room to grow, and finding faults in our thinking illuminates areas of potential advances, but only if we adapt to the new information.
Era: Devonian (400 million years ago)
This listing is for one geisenoceras fossil. We prioritize sending the biggest specimens of the chosen size first.
Small specimens come in an acrylic case, large specimens come in a canvas bag.
Specimens picture are representative of our currently inventory. You'll likely receive a different—but similar—specimen.
For many years, many similar conical-shelled nautiloid species like this were lumped into the species Orthoceras regulare, what is now known as a wastebasket taxon. We now know there are over 2,500 unique fossil nautiloid species, leaving a confusing mess in the taxonomy record. These fossils are still commonly misattributed to Orthoceras.