Phyllodont Fish Tooth Plate

Marine Fossil
Scientific Name: Platysomus

This particular fossil has a somewhat mysterious origin. It was found as a loose block that had tumbled down the side of a cliff. This makes it difficult to determine what this fossil’s original position among the many rock layers of the Grand Canyon was. A fossil’s location within a rock layer is used to determine how old it is, which is why it is important to leave any fossils you may find in place until it can be looked at by an expert. Our best guess for this fossil is that it is early Permian in age. It is also difficult to determine what animal this tooth plate belonged to, since the rest of the body is not preserved. It most likely belonged to a platysomid, an extinct group of fish that had deep bodies and large scales. Instead of individual structures arranged in neat rows, these fish had teeth that formed rough, bumpy plates. They probably hunted shelled animals, and used the tooth plates to crush the shells to get to the meat inside. As the teeth wore out, new ones would grow in from underneath to take their place.

3D Fish Tooth Plate—Platysomus
Grand Canyon National Park, Arizona

_{Fish tooth plate by National Park Service Geologic Resources Division on Sketchfab}

Alternative Text for the 3D Model

A 3D model. This model shows a rock cliff with a trail and boulders below. A tree is visible in the image near the trail and serves as scale for the image. The model can be rotated and tilted using a computer interface.

Species: Unknown platysomid tooth plate

This is mold of a Permian age fish plate. Fish plates are tooth-like structures found in early fish and are known from the Pennsylvanian to the Permian periods. They are somewhat common in the Kaibab limestone, and can be found in expouses in the Grand Canyon.

Information used to describe this fossil was sourced from: https://www.jstor.org/stable/1304267?refreqid=excelsior%3Aa2dba2d64ca0d7b0218fe21a1411aa5d&seq=1#metadata_info_tab_contents

This fossil is in the collections at Grand Canyon National Park, Arizona. Learn about paleontology in the National Park Service: https://www.nps.gov/subjects/fossils/index.htm
Learn more about Grand Canyon National Park’s Centennial: https://www.nps.gov/grca/getinvolved/centennial.htm

Related Links

• NPS—Grand Canyon National Park Centennial
• NPS—Grand Canyon National Park Fossils
• NPS—National Fossil Day
• NPS—Photogrammetry
• NPS—Fossils and Paleontology
• NPS—Geology