Catalog Number: CG-0034

My first Petalodus ohioensis Shark Tooth of 2020 is my fifth overall. This specimen is the first with a three dimensional root.

I keep a ready supply of limestone boulders near the lab in which I can search through the matrix. This boulder perhaps came from the same general area as the first four teeth, although there is no way to know for certain. However, I can about 95% sure this did come from that batch of limestone.

The entire rock contains many other interesting specimens including a Sea Pen in the back, a complete Brachiopod, and a few other specimens. The negative includes an example of Fenestella visible on its surface.

Matrix Preparation

Many of the specimens I have found over the past month have received a polish if it was possible. When I found the tooth, it was attached to a piece of the boulder that was very heavy. So I cut the matrix using a 7-inch diamond blade down to the size you see below.

I then used a 4″ diamond blade to smooth down the cuts to ready it for polishing. I polished the front and left sides as the specimen is seen below to 6000 grit.

Negative Specimen Piece

I also kept the negative side of the rock as it includes very important details. Finding Petalodus shark teeth in limestone is difficult because the tooth doesn’t just fall out. It adheres tightly to the matrix and you can’t much control how it’s going to split. With this specimen, the right side of the crown stuck to the negative portion of the matrix that was sheered off.

Petalodus Shark Tooth in Limestone
Entire specimen with Petalodus tooth in top center. The polished front is below showing details of the fossil creatures embedded within the rock.

  • Wet specimen when first found. Increased contrast shows crown against the limestone matrix.
  • Wet view wider. This was before the bottom front of the rock was smoothed and polished.
  • Crown and cusp detail.
  • Root detail
  • Entire specimen after front and left side polishing.
  • Measurement of the serrated edge of the crown from the cusp.
CG-0034, Petalodus ohioensis
CG-0034, Petalodus ohioensis

Negative Side Views

The negative was nearly as interesting as the main specimen. Half of the crown is buried in the matrix and the serrations along the crown edge are shown in the rock. Meanwhile, the distal crown tongue is buried on this half of the specimen.

  • Negative view. Exists on separate rock specimen.
  • Negative side showing root impression. Top right contains missing crown from positive side. The ridges between the root and the crown are also here, face down.

Petalodus Tooth Anatomy

Lingual, Lateral and Labial views of a Petalodus Tooth. Redrawn from an illustration found in Albert J. Robb III “Notes on the occurrence of some petalodont shark fossils from the Upper Pennsylvanian rocks of northeastern Kansas”

The taxonomy of Petalodus

There are 16 different species of Petalodus described in literature. I am assuming most or all of these are only based on the findings of teeth. I have found no evidence online of anyone ever finding remains of Petalodus fossil bones or jaws.

More Online about Petalodus