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Fossils from Monmouth County, New Jersey

Pycnodont (Anomoeodus phaseolus)

Age – Late Cretaceous; Commonality – common; Size – teeth: 1/8 – 5/4 inches, mouth plates: ~ ¾ – 3 inches (vary based on completeness/age of animal), possible vertebrae: ¼ – ½ inch, scales: ~ 1 inch (when complete)

Anonoeodus belongs to a group of fishes known as the pycnodonts. These fishes had crushing teeth (which were shed and replaced) which they used to eat invertebrate prey such as lobsters, ghost shrimp, and gastropods and bivalves. They are commonly and erroneously called drum fish, but this is not an appropriate name (the drum fish came later during the Paleocene, and are not related to the pycnodonts). Their teeth look like hollowed out beans and can easily be mistaken for rocks. Sometimes jaw sections can be found, but these are rare. Pycnodont/Hadrodont (most are likely pycnodont) vertebrae are slightly concave and have their neural processes fused to the centrum. The scales of the pycnodonts are thin and have a pattern on them. These will be discussed below. These scales are sometimes incorrectly referred to as gar scales (which can also be found here).

Lateral/Vomerine Teeth

Occlusal View

Basal View

This image likely contains both lateral (which are more common) and vomerine teeth. The lateral teeth are located on the front and back (on the sides of the medial teeth) of the prearticular mouth plates. The vomerine teeth are located only on the vomerine mouth plate. These two types of teeth cannot be distinguished from each other (unless comparing mouth plates with teeth) due to similarity and variation.

Occlusal View

Side View

Lateral/Vomerine tooth on a section of mouth plate. These teeth can sometimes be confused with Hadrodus priscus oral teeth.

Medial Teeth

Occlusal View

Oblique View

Basal View

Medial teeth are very distinctive and were part of the prearticular mouth plates. This is a medial tooth (with some visible in vivo wear) on a mouth plate section. There is also part of a lateral tooth next to the medial tooth (seen on the lower right of the occlusal view).

Occlusal View

Basal View

Here is a good perspective of their color range. Most teeth found here are a black color.

Occlusal View

Basal View

Here is an adult tooth compared to a much smaller juvenile tooth.

Occlusal View

Basal View

This seems like a pathological medial tooth.

Mouth Plates

Occlusal View

Side View

This is a nearly complete left prearticular mouth plate. It is super rare to find them in such nice condition.

Occlusal View

Oblique View

Basal View

This is a small mouth plate section. These are the typical mouth plate sections that are sometimes found.

Vertebrae

Rostral/Caudal View

Dorsal View

Ventral View

Oblique View

These vertebrae are probably from a deep-bodied fish. The fossil record is far from complete, but since the pycnodont is the most common deep-bodied fish found here, these vertebrae are likely from it. The vertebrae are laterally compressed, have the neural processes fused to the centrum (seen in dorsal and ventral views), the anterior/posterior faces are slightly concave, and when viewed from the anterior/posterior face, the vertical (dorsal-ventral) measurement is larger than the horizontal (lateral-lateral) measurement (this can vary based on position in the spine). The vertebrae usually have about the same length and width, which is usually between 1/4 and 1/2 an inch.

Rostral/Caudal View

Oblique View

Here is another similarly-sized vertebra. Its anterior/posterior face height and width are about the same.

Rostral/Caudal View

Dorsal View

Ventral View

Oblique View

This vertebra is smaller than the two above. It also has a smaller anterior/posterior face height than width, which means that it is either from a different part of the spine or possibly from a smaller individual.

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