Jersey Fossils :: Featuring Big Brook
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Crustacean
Protocallianassa mortoni (Pilsbry, 1901)
At Big Brook, the claws of this callianassid crustacean Protocallianassa sp. are occasionally preserved within burrows of sands deposited in an inner shelf environment sufficiently cohesive to permit callianassids to excavate burrows without the need to line the burrow walls with fecal pellets, which would have produced Ophiomorpha traces. This is the thin basal interval (Facies A of the Navesink) consisting of fine quartz sand with abundant carbonaceous matter, mud & some glauconite.
1 1/4" long
 
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Molluscs
Molluscs are typically soft-bodied, unsegemented invertebrates that possess an anterior head and a dorsal visceral mass. They are at least, partly enclosed by a fleshy layer called the mantle. In most molluscs this organ secretes a hard shell, however in some molluscs the shell has been reduced; incorporated into the body, or both. Many molluscs have a muscular ventral foot, which is primarily used for movement, and a rasp-like radula (a horny, band or ribbon that bears minute teeth on its dorsal surface) to tear up food and draw it into the mouth.
There are six different classes of Molluscs, Bivalvia, Gastropoda, Cephalopoda, Polyplacophora, Scaphopoda & Aplacophora |
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Pelecypoda (Bivalvia)..
"Oysters from the shell beds of the Navesink"
Exogyra costata (Say, 1820)
Agerostera mesenterica (Morton, 1830)
Pycnodonte convexa (Say, 1820)
Of the
large oysters, almost 100% show evidence of biocorrosion. Notice the
drilled holes from Cliona celata. Refered to as the boring sponge
because it bores into soft limestone, using acid digestion to form
systems of interconnecting chambers within rock. As seen here it
can also bore into mollusc & barnacle shells.
Other present borings can be attributed to lithophagid bivalves,
acrothoracican barnacles & polychaete annelids.
Ark Shell (Cucullaea sp.)
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Brachiopoda
Choristothyris plicata (Say, 1820)
Brachiopods have a very long history first appearing over 550 million years ago, during the Neoproterozoic period. They are said to have evolved from the small phylum Phoronida. The phylum Brachiopoda is divided into two classes: Articulata & Inarticulata. Inarticulata brachiopods are held together entirely by musculature, and articulata brachiopods have hinges. When an Inarticulata brachiopod died, the muscles that opened the valves would contract closing them together. So its very common to find them articulated in situ. They are characterized by their peculiar feeding organ, the lophophore. It consists of two tentacle-bearing arms that create currents, drawing water-bearing food particles & oxygen into the shell. |
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Cephalopoda
Cephalopods have a well-developed head with complex eyes. They have a cluster of arms and/or tentacles that form a ring around mouth. They have a funnel that is derived from the foot, in fact, their name means "head-footed". The sexes of cephalopod species are separate.
Belemnitella americana (Morton, 1830)
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Gastropoda
Meaning "belly-footed"., the gastropods make up the largest class in the phylum. Most gastropods have gills, and generally have a well-developed head with eyes and tentacles. When present, their singular shell is coil or cone-shaped and often sealed by a "trapdoor" called an operculum. Gastropods can be marine, freshwater or terrestrial.
Navesink casts
Misc. Casts & Molds
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You may come across these unique casts of a belemnites phragmocone "plug", which is the thin chambered shell attached to the alveolus, the conical shaped socket at the anterior end of Belemnitella americana. Also the siphuncle or cornicle, which is a tubelike structure extending through each chamber, has been preserved as a cast from the alveolus.
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Coelenterata - Devonian Coral
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Porifera (sponges)
Cliona cretacica
Cliona cretacica have left tubes extending into the shells of their host by attaching themselves to, and replacing entire shells of Mollusca-Pelecypoda & cephlopoda.
Annelida (worms)
Longitubus lineatus (Weller, 1907)
annelid biocorrosion at phragmacone of Belemnite
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