Description
Genuine Canadoceras yokoyamai Ammonite Fossil
This genuine fossil ammonite is a Canadoceras yokoyamai from the Haslam Formation, Lower Quarry, Brannan Lake, Nanaimo, British Columbia, Canada. Dating from the Santonian Stage of the Upper Cretaceous Period, this specimen represents a fascinating marine cephalopod from the ancient Pacific margin of western North America. It is a carefully chosen fossil, with the photo showing the actual specimen you will receive. Full sizing can be seen in the photo, and the fossil includes a Certificate of Authenticity lifetime guarantee generic card.
Canadoceras yokoyamai is an extinct ammonite species belonging to a group of marine molluscs related to modern squid, cuttlefish, octopus, and nautilus. Ammonites lived inside coiled, chambered shells, using internal gas-filled chambers for buoyancy while the animal occupied the final body chamber. Their distinctive spiral shells, complex sutures, and rapid evolutionary changes make ammonites some of the most important fossils for understanding and dating Mesozoic marine rocks.
Species: Canadoceras yokoyamai
Canadoceras yokoyamai was originally described as Pachydiscus yokoyamai by Jimbo in 1894 and later placed within the genus Canadoceras. The species name honours the Japanese palaeontologist Matajirō Yokoyama. The genus is especially associated with Upper Cretaceous marine deposits of the North Pacific region, including Canada, Japan, and related Pacific-margin faunas.
This ammonite belongs to the family Pachydiscidae, within the order Ammonitida. Pachydiscid ammonites are well known from the Late Cretaceous and are often recognised by their rounded, robust shells, broad whorls, and variable ribbing. Canadoceras typically displays a strong, sculptural shell form, making it a desirable genus for collectors of Cretaceous ammonites and marine fossils.
Geology: Haslam Formation, Nanaimo Group
This specimen comes from the Haslam Formation, part of the Nanaimo Group of British Columbia. The Nanaimo Group is a major Upper Cretaceous sedimentary sequence exposed on and around Vancouver Island, preserving evidence of ancient marine basins that developed along the western edge of North America.
The Haslam Formation is mainly composed of dark marine shale, mudstone, and related fine-grained sedimentary rocks. These sediments were deposited in a quiet marine environment where mud settled onto the seafloor and gradually buried the remains of ammonites, bivalves, fish, and other marine organisms. Over millions of years, compaction and mineralisation turned these sediments into rock and preserved fossil shells within them.
The Lower Quarry locality at Brannan Lake, near Nanaimo, is part of this important fossil-bearing region. Fossils from this area are valued for their connection to the Upper Cretaceous marine ecosystems of British Columbia and the wider Pacific margin.
Age: Santonian, Upper Cretaceous
This fossil dates from the Santonian Stage of the Upper Cretaceous Period, approximately 86 to 83 million years ago. During the Santonian, sea levels were high and warm marine environments were widespread across many parts of the world. Along the western margin of North America, marine basins supported diverse communities of ammonites, bivalves, gastropods, fish, marine reptiles, and other sea life.
A living Canadoceras yokoyamai would have moved through the water as a free-swimming cephalopod. Like other ammonites, it likely used jet propulsion to swim and controlled its buoyancy through its chambered shell. Its tentacles would have extended from the shell opening, allowing it to capture prey and interact with its surroundings in the Cretaceous sea.
Morphology and Fossil Features
Canadoceras yokoyamai is known for its coiled planispiral shell, meaning the shell coils in a single flat plane. The whorls are generally rounded and robust, giving the ammonite a solid, substantial appearance. Depending on preservation, specimens may show curved ribs, growth lines, whorl contours, shell texture, and traces of internal chambering.
The internal chamber walls, known as septa, met the outer shell wall along intricate suture lines. These sutures are one of the most important features used by palaeontologists to classify ammonites. In ammonitic forms such as Canadoceras, the suture pattern can be highly complex, reflecting the advanced shell structure of Late Cretaceous ammonites.
Depositional Environment
The Haslam Formation represents an ancient offshore marine setting. Fine sediment accumulated in relatively calm water, allowing shells and other organic remains to become buried after death. Ammonite shells may have settled onto the seabed, been transported slightly by currents, or become incorporated into muddy marine deposits with other fossils.
This fossil therefore records both the extinct animal and the environment in which it was preserved. It represents the Santonian seas of British Columbia, long before the modern coastline, forests, and mountains of the region took their present form.
Collector Appeal
This Canadoceras yokoyamai ammonite is an excellent addition to a fossil collection, especially for collectors interested in Canadian fossils, Upper Cretaceous ammonites, Nanaimo Group material, marine cephalopods, or fossils from classic Pacific-margin localities. Its named species, precise locality, and geological formation make it particularly appealing for a labelled study collection or display cabinet.
The specimen is suitable for natural history display, educational use, classroom collections, office décor, fossil cabinets, or museum-style arrangements. Its combination of genuine fossil authenticity, scientific interest, and classic ammonite form makes it a desirable piece for both new and experienced collectors.
Authenticity and Presentation
This is a genuine Canadoceras yokoyamai ammonite fossil from the Haslam Formation, Lower Quarry, Brannan Lake, Nanaimo, British Columbia, Canada. The photograph shows the actual carefully chosen specimen you will receive, allowing you to view the fossil’s natural colour, preservation, shape, and overall appearance before purchase. Full sizing is shown in the photo.
This fossil includes a Certificate of Authenticity lifetime guarantee generic card, giving confidence that it is a real prehistoric specimen. It is a collectable Santonian Upper Cretaceous ammonite from Canada, preserving the remains of an extinct marine cephalopod that lived in ancient seas millions of years ago.
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