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Fossils from Monmouth County, New Jersey

Plesiosaur (Cimoliasaurus magnus)

Age – Late Cretaceous; Commonality – scarce; Size – teeth: ½ to 2 inches, vertebrae: ~1 ½ to 5 inches, most are around 2 inches

The teeth of this plesiosaur have a circular base and a slender crown. The crown may or may not have striations on it; depending on the size of the tooth (most small teeth don’t have distinct striations and large teeth usually have striations). Their cutting edges can also vary. Some teeth have two rather distinct carinae, and others may seem to have no cutting edges at all. Usually teeth with diminished carinae appear to have more striations present, and teeth that have pronounced carinae have small striations. The teeth curve backwards toward the lingual side. The curvature in plesiosaur teeth is different from the curvature in crocodile teeth in that the tooth does not curve back much in the bottom section of the tooth, and then at a certain point on the tooth it starts to curve back significantly. The vertebrae are massive and distinct. The dorsal side has a hole and the ventral side has two holes. The two faces are slightly concave. The thoracic vertebrae are longer than the neck and tail vertebrae. Other bones are rare.

Teeth

Labial View

Lingual View

Lateral View

Lateral View

Basal View

Classical Plesiosaur tooth: strong striations, no carinae, and a lot of the enamel missing. Most NJ Plesiosaur teeth are about an inch long. The slender and pointed shape of the teeth helped the plesiosaurs catch fish.

Labial View

Lingual View

Lateral View

Lateral View

Basal View

This tooth has carinae. It does not resemble Croc teeth. It is just under 3/4 of an inch (which is too large for most NJ Croc teeth), it is not robust enough for the length, and the base looks different.

Labial View

Lingual View

Lateral View

Lateral View

Basal View

This Plesiosaur tooth with a “classical” shape actually has faint carinae. The tip damage is either in vivo wear or some kind of post-mortem wear.

Lingual View

Basal View

This tooth shows the basal structure well. This would have been a nice size tooth at about 5/4 inches if whole.

Vertebrae

Dorsal View

Ventral View

Rostral/Caudal View

Rostral/Caudal View

Oblique View

Oblique View

This is a nice large Plesiosaur thoracic vertebra. It is 2 ½ inches long, 3 inches wide, and 1 ¾ inches in height. When complete, Plesiosaur vertebrae are very distinct and hard to mistake for something else.

Fragment 1 - Oblique View

Fragment 2 - Oblique View

These two fragments show the bone structure/texture well. The vertebral surfaces are much denser, while the inside is more porous and has a unique pattern.

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