The cetaceans (whales, dolphins and porpoises) are marine
descendants of land-living mammals..
I've accumulated a decent amount of dolphin material
including a nearly complete skull from the Calvert Cliffs
area in Maryland but this is the first dolphin vertebra from New Jersey.
It measures 2.5 inches at the
widest point and 1 inch thick and my best guess would be a caudal
vertebra from an adult dolphin. The brownish coloration I suspect is
staining from the brown marl of the Kirkwood Formation. This
formation is Miocene in age and fits nicely with the current thinking
that dolphins first appeared during the early to mid Miocene.
Monmouth County, NJ.
I don't see any indication that the processes have broken off
which leads me to believe this is a caudal (tail) vertebra.
In a juvenile the epiphysis or growth plate is not yet fused to the
and normally falls off before fossilization when the animal dies leaving
a smooth surface.
In adults when growth
has completed the epiphyses
becomes fused to the vertebra.
This picture is an example of a fossilize epiphysis that has become
detached. These are common
at the cliffs but
found or seen one from NJ.