Amazing Ammonites

This fossil is a broken off section of an extinct ammonite shell from the genus, Mortoniceras. It was found in Arkansas in a dried up riverbed. The shell is characterized by deep keels and ribbing. It lived mainly during the Cretaceous Period beginning 145.0 million years ago and ending 66 million years ago when the dinosaurs died out. The chambers inside the animal’s shell held special gases which helped it descend deep down ocean depths or float up to shallower depths.

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Mortoniceras Ammonite Fossil

fossils 126

Mortoniceras Ammonite Fossil


The ammonites were ocean predators crushing their victims with powerful extended tentacles. They could move with jet propulsion in spurts by siphoning the ocean water and thus pushing it out powerfully. They had large heads and were intelligent. Their tentacles contained special sensors which helped it navigate in the vastness of the ocean.


Scientific Name:Mortoniceras

Common Name:Ammonite

Kingdom: Animalia

Phylum: Mollusk (large diverse group of invertebrates possessing a shell, i.e. clams, snails,oysters, etc.)

Order: Ammonitida (characterized by thick, ribbed patterned shells)

Class: Cephalopod (means prominent head and tentacles, i.e. octopuses, squids, nautilus)


Genus: Mortoniceras (characterized by deep keels and ribbing)


Mortoniceras Ammonite Artist Rendering

Dufrenoy, justinae (Ammonite)

Dufrenoy, justinae lived in the ancient seas when dinosaurs were still around about 135 mya  (lower Cretaceous Period).  Their fossils have a world wide distribution indicating the theory of continental drift.  Ammonites were very intelligent like their  cousin cephalopops such as octopuses and close relative nautiloids.  They first appeared in the fossil record as early as 400 mya during the Silurian Period.

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Dufrenoy, justinae (Ammonite Fossil)



Scientific Name: Dufrenoy, justinae Common Name: Ammonite

Kingdom: Animalia

Phylum: Mollusk (soft body of invertebrate animal encased in shell)

Class: Cephalopod (means prominent head and tentacles, i.e. octopus, squid, cuttlefish, nautiloid)

Order: Ammonitida (characterized by thick ribbed and patterned shells)

Family: Parahoplitidae or Acanthoceras (a fast moving type)

Genus: Dufrenoy Species: justinae


Dufrenoy, justinae Ammonite Rendering