Diplomoceras

DiplomocerasDouble Horn
Classification
Domain	Eukaryota
Kingdom	Animalia
Phylum	Mollusca
Class	Cephalopoda
Order	Ammonitida
Suborder	Ancyloceratina
Superfamily	Turrilitoidea
Family	Diplomoceratidae
Species	Diplomoceras maximum
Presence
Location	Kawaruppu Formation, Nemuro Group, southeast Hokkaido, Japan López de Bertodano Formation, Seymour Island, Antarctica Nakaminato Group, central Honshu, Japan Tethys Ocean, Europe
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	Carnivorous (Benthivorous)
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 known species.

Paleobiology

Size and Physique

Diplomoceras is a large ammonite with a shell around 1.5 - 1.8 meters (5 - 6 feet) long, recognizable for its resemblance to a 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. Prehistoric Planet itself depicts this in the fifth segment of Coasts, with the short lives of scaphitids coming to an end soon after mating and reproduction. However, a more recent study in 2020, based on the ribs of the animal's shell (with each rib representing a year of growth), suggests that Diplomoceras may have grown slowly over the course of approximately 200 years.

Paleoecology

Paleoenvironment

Main: López de Bertodano Formation, Tethys Ocean

Main: López de Bertodano Formation, Tethys Ocean

The sun melting the ice sheet covering the seas of the López de Bertodano Formation

“ 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.

Diplomoceras was rendered extinct by the Cretaceous-Paleogene Extinction Event 66.043 million years ago, a catastrophe that wiped out three-quarters of all life on Earth, including all non-avian dinosaurs, pterosaurs, plesiosaurs, and mosasaurs. However, while many ammonites like Diplomoceras perished by the end of the Cretaceous, a few of them, like certain species of Baculites and Pachydiscus survived into the Danian stage of the Early Paleocene Period, approximately 61.6 million years ago.

Feeding Preferences

Not much is known about the behavior and preferences of Diplomoceras. However, cold methane vents closely associated with the fossil, coupled with the cephalopod's vertically-oriented shell, indicate that Diplomoceras lived close to the bottom of the ocean, and was thus likely a benthivore, a bottom-feeding animal that filtered food on or near the sea floor. One of the tiny creatures that Diplomoceras may have plucked from the bottom of the ocean is Rotularia, a serpulid polychaete worm approximately 13 centimeters (5 inches) in length.

Appearances

Oceans

TBA

Uncovered: 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

What Do We Really Know About Ammonites?

Subject
Various facts and knowledge about ammonites.

Experts
Dr. Darren Naish, Zoe Hughes

TBA