|Other Shark, Ray, and Skate
Coprolites & vertebrae
Description: Besides teeth, there are other shark, ray, and skate remains found at Big Brook.
The most common are coprolites or fecal pellets. These are round to ovate or sometimes flattened in cross section. Some
coprolites are probably flattened due to the fossilization process. The general shape of the coprolites is not unlike the stream
worn gravel except that the top is rounded and the bottom is somewhat pointed. Most coprolites do not exceed 4 cm (about
1.5 in) in length and 1.5 to 2 cm (about .5 to .75 in) in diameter. The best way to identify them is to look for the spiral patterning
on the surface. This is caused by the sharks spiral shaped intestinal tract. They also possess parallel vertical grooves on each
spiral. In well preserved specimens, scales, vertebrae, and/or bones from fish that were the undigested remains of their meal can
be observed. Paleontologists make an important study of coprolites to find out what the sharks of the time were eating and
compare it to the prey of modern sharks. The exact species of shark, ray, or skate that made the coprolites is not known.
There are two types of shark vertebrae that are recovered, the scliorhynoid type and the lamnoid type. The centrum is the only
part of the vertebrae that is preserved. Both types of centra have a cylindrical shape with conical shaped depressions at both the
anterior and posterior ends (amphacoelous). There are concentric circular markings on the surface of the openings, which, like
trees, are growth rings. The difference between the two would seem to be in the side structure. The sides of the scliorhynoid
type vertebrae are mostly solid with two openings on the top and two on the bottom. It is in these slots where elongated
cartilaginous processes extended outward for various muscle attachments. They are generally smaller than the lamnoid vertebrae
with an average of about 2 cm (about .75 in) in diameter and about 1 cm (about .3 in) high, but they can be smaller. The second
type is the lamnoid vertebra. Their vertebrae have many thin struts and additional openings in the sides along with the four main
holes. In life cartilage filled these minor holes but did not extend past the centrum. They are also generally larger than the
scliorhynoid vertebrae with an average of about 3 cm (about 1 in) in diameter and about 1.5 cm (about .5 in) high, but they can
also be smaller or larger. The scliorhynoid type vertebrae would seem to be more abundant than the lamnoid type but this might
be partly due to their construction. The scliorhynoid vertebrae are more solid and smaller making them less likely to be worn and
broken. The lamnoid vertebrae are larger and not as solid, so more often than not, their vertebrae are broken. Finding a
complete lamnoid vertebrae is uncommon.
Commonality: The shark coprolites are common. The scliorhynoid type vertebrae are more common than the lamnoid type
vertebrae. Both are less common than coprolites.
Similar fossils: The coprolites superficially resemble the gravel hut the patterning on the outside of the coprolite should
differentiate it. Shark vertebrae have a more circular outline than the crescent shape of batoid vertebrae.
Size: Since the exact animal that these fossils came from is uncertain, the size of the animal is unknown.
Notes: In general, other than teeth, fossilized material from sharks, rays, and skates is somewhat uncommon. The teeth are the
only "bone" in their skeleton. The rest of their skeleton is made of a material called cartilage. Except under favorable conditions,
cartilage does not fossilize. The cartilage of the vertebrae is calcified (have a coating of calcium) and is more likely to become
fossilized. Coprolites also had to be deposited under favorable conditions to become fossilized. They had to be buried quickly
by mud and other sediment so bacteria or worms did not decompose them.
Some paleontologists believe that much like a tree, one can count the number of concentric rings in the conic openings on the
vertebrae to determine the age of the shark when it died.
(Lamnoid - Scroll Type)
a. End view b. Side
a. Side view b. End
a. End view b. Side
a. Dorsal vertebra b. Tail vertebra