Invertebrate Fossils OF NJ

Choristothyris sp. (Linnaeus)
Choristothyris plicata (Say)
Choristothyris vanuxemi  (Lyell and Forbes)
 

Choristothyris plicata is a small  brachiopod from the Late Cretaceous period  measuring about ½ inch across and is a very common find. The majority of these shells are found fully articulated. Brachiopods, or “lamp shells”, are actually made up of two different halves, or valves, the pedicle valve and the brachial valve. When viewed from the side the brachiopod is not symmetrical. A very similar but much rarer species is Choristothyris vanuxemi, the main difference between the two species is the number of plications. C. plicata has between 8 to 12 while the number of plications on C. vanuxemi numbers between 15 to 23. C. vanuxemi is the smaller of the two species with a much more convex pedicle valve.         

Choristothyris plicata

Monmouth County, NJ

 

Top left to right - pedicle valve, brachial valve
Bottom—side view

 

The rarer Choristothyris vanuxemi, I've only found
these in one location and only as internal molds.
Monmouth County, NJ
 

Left - C. plicata      Right - C. vanuxemi
 

Typical finds of C. plicata