Anomoeodus phaseolus tooth from the Navesink formation

Anomoeodus phaseolus was a species of Pycnodontid fish (shell crushers which lived during the late Cretaceous. It is somewhat common within the sediments of the Navesink formation (Maastrichtian stage) and is easily found in the brooks and creeks of Monmouth County, NJ. The specimen below was found in the Ramanessin creek near Holmdel, NJ.

The top or grinding surface

Side view

Underside, note the hollow nature of the tooth.

Profile

Anomoeodus replaced their teeth much like sharks do with old, worn ones falling out and replacements growing in. This would explain their common nature and often worn look. They typically preyed on invertebrates like shrimp, crabs and oysters. They possibly nibbled at epifauna on the surface of oysters and other hard sea floor surfaces as well.
Check out more pics and info at Oceans of Kansas which has many other species of Pycnodontid fishes.

The website Fossils of NJ has a nice page of specimens found in Monmouth County, NJ

Hybodont shark spine from the Navesink formation

This fossil was an odd one for me when I found it. It's a spine from a Hybodont shark but at first I thought it was a tooth from some sort of shell crushing fish or shark. It's a U shaped piece of bone with some small bumps along the surface. This was found at Big Brook near Marlton, NJ and comes from the late Cretaceous (Maastrichtian stage) aged sediments of the Navesink formation.

The fossil was delicate after I first found it and I had to repair a couple of breaks like the one you can see below.....

and along the ridge between the two sides.

The spine was on the exterior of the Hybodont sharks dorsal fin and ran along the front edge. Apparently it was used for defensive purposes.

Here is a good page from NJfossils.net which talks about Hybodont sharks and the material that can be found at Big Brook in Monmouth county near Marlboro, NJ.

Ophiomorpha nodosa from the Navesink formation

A common find in the brooks of Monmouth county, NJ are these preserved burrows called Ophiomorpha nodosa. They are the former homes of a species of Ghost shrimp often attributed to the genus Protocallionassa. These are technically trace fossils and not true fossils but they are interesting none the less.

The Navesink was lain down in the latest Cretaceous (Masstrichtian stage) as a layer of sediment that was (at that time) moderately deep water.

Hoploparia gabbi from the Navesink formation

Hoploparia gabbi is a lobster that is found in the Navesink formation of New Jersey. I found it in the Ramanessin creek near Marlboro, NJ. This is only a partial fossil of the whole animal as it's missing the legs, claws and tail but it's still fairly rare to find even this much.

Ventral (top) surface

Left side (Anterior to left)

Right side (anterior to right)

The Navesink was lain down in the latest Cretaceous (Masstrichtian stage) as a layer of sediment that was (at that time) moderately deep water.

Exogyra costa from the Navesink Formation

Another common oyster in the Navesink formation is Exogyra costa. This can be distinguished from other oysters by the curled shape of the shell and presence of a wrinkled surface. Some of these shells can get very large, approaching six inches across.

 Left valve top

Left valve anterior

Left valve, left side profile

Left valve posterior

Left valve, right side profile

Left valve interior

The right valves are layered and slightly turned up at the edge so that they look a little like a topographic map when viewed.

Right valve top

Close up of the surface layering

Right valve interior

Right valve posterior

These specimens were found at Big Brook near Marlboro, New Jersey in the Navesink formation which is upper Cretaceous (Maastrichtian stage) in age.