Diplomoceras

## DiplomocerasDouble Horn

### Temporal Range

83.6 - 66 million years ago, Campanian - Maastrichtian Stage, Late Cretaceous Period

### Episodes

* Oceans (Segment 5)
* What Do We Really Know About Ammonites?

## Characteristics

### Length

* 1.5 - 1.8 meters (5 - 6 feet) (Shell, Coiled)
* 3 - 4 meters (10 - 13 feet) (Shell, Uncoiled)
* 2 meters (6 feet, 7 inches) (Body Chamber, Uncoiled)

### Diet

Carnivore

**Life Expectancy** of around 200 years

***“ This strange, six foot-long giant is Baculites, which feeds near the sea floor. And almost matching it in size, Diplomoceras, shaped like a giant paperclip. ”***

― **David Attenborough**, *Oceans*
***Diplomoceras*** (Double Horn) is a genus of diplomoceratid ammonite cephalopod that lived in various parts of the world (but is primarily known from the López de Bertodano Formation of Seymour Island, Antarctica), 83.6 - 66 million years ago, from the Campanian to the Maastrichtian stage of the Late Cretaceous Period. It is distinct among ammonites for its paperclip-shaped shell. The species featured on Prehistoric Planet isn't specified, though given its size, it is likely *Diplomoceras maximum*, the largest species.

## Description

### Size and Physique

*Diplomoceras* is a large ammonite with a recognizable, 1.5-meter (5-foot) shell that resembles a giant paperclip. If it were to be straightened, the shell would measure 3 - 4 meters (10 - 13 feet) long, and the body chamber (the part that actually contains the animal) would be 2 meters (6 feet, 7 inches) long.

### Growth and Lifespan

*Diplomoceras* was originally believed to live for up to ten years based on its sinusoids (curves), each of which indicates 1.5 years of quick shell growth, a lifespan matching the brief ones of other cephalopods like modern-day species of octopus, which live for under five years. However, a more recent study in 2020, based on the ribs of the animal's shell (with each rib representing a year of growth), indicates that *Diplomoceras* may have grown slowly over the course of 200 years.

## Habitat

*Main: López de Bertodano Formation, Tethys Ocean*

Main: López de Bertodano Formation, Tethys Ocean

***“ They are one of the most successful groups of animals to have ever lived, flourishing in the warm, temperate seas, and even the coldest waters at the poles... ”***

― **David Attenborough**, *Oceans*
*Diplomoceras maximum* lived 66 million years ago in the López de Bertodano Formation of Seymour Island, which showed that the waters surrounding Antarctica were warmer than they are in the modern day, though, at 4 - 12 degrees Celsius (39.2 - 54 degrees Fahrenheit), the area was still very much cold, hence, the seas of Antarctica would have still been plausibly covered in sheets of ice, just as depicted in the sixth segment of Oceans.

Prehistoric Planet instead depicts *Diplomoceras maximum* in the Tethys Ocean of Europe. This is not entirely implausible given the wide range of habitats that ammonites can live in, and *Diplomoceras* specimens have also been found in other places like Japan.

## Behavior

Not much is known about the behavior and preferences of *Diplomoceras*. However, it is likely that this large ammonite was a bottom feeder, for traces of cold methane, coupled with its vertically-oriented shell, indicate that it lived near the sea floor.

## Appearances

### What Do We Really Know About Ammonites?

  **What Do We Really Know About Ammonites?**
**Subject**
Various facts and knowledge about ammonites.

**Experts**
Dr. Darren Naish, Zoe Hughes
TBA

## References

1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Discovery of a remarkably complete specimen of the giant cephalopod *Diplomoceras maximum* from the Late Cretaceous of Seymour Island, Antarctica
2. ↑ 2.0 2.1 Late Campanian–early Maastrichtian heteromorph-dominated ammonoid assemblages of the Nakaminato Group, central Honshu, Japan: biostratigraphic and paleontological implications
3. ↑ 3.0 3.1 3.2 Giant Heteromorph Ammonite
4. ↑ As stated in Oceans
5. ↑ 5.0 5.1 Discovery of a remarkably complete specimen of the giant cephalopod *Diplomoceras maximum* from the Late Cretaceous of Seymour Island, Antarctica
6. ↑ 6.0 6.1 Large squid-like creature that looked like a giant paperclip lived for 200 years — 68 million years ago
7. ↑ Late Cretaceous winter sea ice in Antarctica?