Squailcorax kaupi (Agassiz)
Squailcorax pristodontus (Morton)
|Description: Two species of crow shark can be distinguished from this locality, Squailcorax kaupi and S. pristodontus.
At first appearance, both species look similar, except that S. pristodontus is generally the larger of the two. S. kaupi teeth are usually between 1 and 1.5 cm (about .5 in) long while the teeth of S. pristodontus are between 1.5 to 2 cm (about .75in) long. Both species have compressed and broad teeth, but S. pristodontus has a somewhat broader tooth. Both have distinctive serrations on the blade but the serrations on S. kaupi teeth are smaller. The main difference is in the development of the notch on the other side from the curved portion of the blade. The angle of the notch in S. kaupi is smaller and more deeply recessed into the tooth, while the angle for S. pristodontus is larger and not as recessed. The posterior teeth of both resemble the anterior and lateral teeth of each species, but they are smaller in size and have a greater curvature towards the notched side.
Some sources label S. kaupi as S. falcatus (Agassiz) which is the species that is found earlier in the fossil record, but the two may be synonymous nevertheless.
Commonality: Squailcorax is a very common genus at Big Brook.
Similar fossils: Crow shark teeth are fairly distinctive and the only difficulty is in separating between the two species.
Size: Judging from the size of the teeth, S. pristodontus probably reached up to 3 meters (about 10 ft) in length, while S. kaupi was about half as large.
Notes: At Big Brook, the Mt. Laurel in the cross over for the two species where they both exists. Below the Mt. Laurel only S. kaupi occurs, above the Mt Laurel, S. pristodontus occurs.
Crow sharks are listed by some sources as being in the lamnoid family, along with the porbeagle, mako, and the great white sharks. On the other hand, their teeth are similar to the modern day tiger shark, which belongs to the scliorhynoid family, along with the hammerhead and lemon sharks. If this is true, then it answers a mystery about the scliorhynoid type vertebrae found at Big Brook. Since no other shark described from Big Brook belongs to the scliorhynoid group, These vertebrae that are recovered from the stream could be loosely attributable to the crow shark. For more information on the shark vertebrae see the Other Shark Remains section. Since the crow shark has been extinct since the Cretaceous, paleontologists do not have a living specimen to study. The attribution of the vertebrae to the crow shark is only tentative and is only based on fragmentary information and research is continuing. This genus of shark was widespread worldwide during the Cretaceous but became extinct at the end of the Cretaceous.
a. Lingual b. Labial
|Squailcorax kaupi (Agassiz)|
|Squailcorax pristodontus (Morton)|
a. Anterior tooth b. Laterial tooth
a. Anterior tooth b. Posterior tooth