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YOUTUBE VIDEO:Diving with Cow Sharks

Short video of diving with the Sevengill Cow Sharks near Cape Town, South Africa.

Sevengill Cow Sharks off Miller's Point, near Cape Town South Africa. This image was taken by: Derek Keats.

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Cow Shark Details - Origins, Description, and Habits

Two Sevengill Cow Sharks off Miller's Point, near Cape Town South Africa. This image was taken by: Derek Keats.

Origins of Cow Sharks

Cow sharks first appear in the fossil record in the late Cretaceous as the Hexanchus genus, while the Notorynchus genus first appears in the late Paleocene. They have not changed much in the 60 or so millino years. Today, there are four extant cow sharks. The two most common are N. cepedianus (the Bluntnose sevengill), and H. griseus (the Broadnose sixgill).

Description of Cow Sharks

Cow sharks in general have a characteristic appearance in that they only have a single dorsal fin toward the back of the shark. They are missing the large central dorsal fin that is found on most sharks. They also have very round, blunt snouts.
The sixgill sharks have (you guessed it) six gill slits, while the sevengill sharks have (right again) seven gill slits. Sixgill sharks are also larger than sevengill sharks. The Broadnose sixgill sharks have been known to reach lengths up to 4.82 m (15.8 ft) (Castro, p. 27), while sevengill sharks have been known to reach lengths of up to 2.64 m (8.7 ft) (Castro, p. 39).
The sixgill shark has a dark gray to brown color, with a lighter underside, while the sevengill shark has numerous small dark spots on the dorsal surface.

Differences and Behavior between the Cow Sharks

Although they appear similar, these sharks occupy different ecological niches. The larger Broadnose sixgill shark is primarily a nocturnal deep water shark often reported from depths of 100 - 600 fathoms (1 fathom = 6 ft = 1.8 m) (Castro, p. 27). They have a worldwide distribution in temperate and tropical waters. They feed on crustaceans and a wide array of fishes. The Bluntnose sevengill cow sharks, on the other hand, are aggressive sharks that prefer shallow near shore waters. They are often reported from depths of 3 - 6 fathoms (Castro, p. 39). They are found throughout the Indian and Pacific oceans, and feed on a variety of prey, from fish, including other sharks, to marine mammals. Bluntnose sevengills have also been observed hunting in groups, or packs, to take on larger prey.

Cow Shark Tooth Morphology - Differences/Identification between the Cow Shark Teeth

Notorynchus cepedianus tooth identification

Lower lateral Notorynchus cepedianus fossil shark tooth identification diagram from Calvert Co., MD

Hexanchus griseus tooth identification

Lower lateral Hexanchus griseus fossil shark tooth identification diagram from Aurora, NC.

Symphiseal Teeth

This one was found by a nice website visitor, Jon, who found it at a quarry in Shark Tooth Hill

Cow Shark Tooth Positions

Due to their self-evident shape, fossil Cow shark teeth are nearly impossible to confuse with other shark genera. Lower laterals have a unique rectangular shape lined with cuspls, which become smaller toward the distal end. In front of the first cusp, or primary cusp, on the mesial edge, are serrations. The roots are generally thin and rectangular shaped. Uppers are generally more square-shaped than the lowers, have less cusps, and often lack serrations on the mesial edges. Upper parasymphyseal teeth (front teeth) consist of a single angled cusp and a narrow root. Cow sharks also have a unique lower symphyseal tooth (center tooth). These teeth are fan shaped. Refer to the following image for examples of upper and lower teeth.

This image shows Notorynchus cepedianus upper and lower fossil shark teeth from the Calvert Cliffs of MD. Notice the lower symphyseal tooth.

Hexanchus vs Notorynchus teeth - Differences

There are also some differences between male and female teeth. These differences, however, will not be discussed here.

Even though Cow shark teeth are easily differentiated from other shark genera, H. sp. and N. cepedianus can be very difficult to distinguish from each other. There are small differences between the teeth, most of which are beyond the scope of this webpage. However, here are a few general guidelines to follow. To start, H. sp. is a larger, more robust, version of N. cepedianus. The typical size of H. sp is around 32-38 mm (1.25 - 1.5 inches), while N. cepedianus is slightly smaller, around 25 mm (1 inch) (Cocke, p. 82-83). There are two key differences between the two sharks lower lateral teeth. N. cepidianus has less cusps that run behind the primary cusp. Typically there are around 5 or 6 cusps on N. cepedianus, while H. sp. has up to 13 cusps (Kent, p.18). The second difference lies in their mesial edges. H. sp. has very fine serrations on the mesial edge, while N. cepedianus has larger recurved serrations on the mesial edge. A comparison of the shoulders is shown in the image below.

This image shows a comparison between lower lateral Notorynchus and Hexanchus serrations on the mesial edge. Hexanchus has very fine serrations, while Notorynchus generally have larger, curved serrations.
This is one of the main identification differences between the two fossil shark teeth.

Recommended Shark Books

Sharks of the World: A Complete Guide

Sharks of the World: A Complete Guide (Wild Nature Press)
Authors: Dr. David A. Ebert, Marc Dando, Dr. Sarah Fowler: 2021

Fully revised and updated, Sharks of the World is the ultimate reference guide for shark enthusiasts. Covering 536 species, it boasts vibrant illustrations, photos, and informative diagrams. The comprehensive guide incorporates the latest taxonomic revisions and offers insights into shark biology, ecology, and conservation. A must-have for any shark enthusiast.

101 American Fossil Sites You've Gotta See

101 American Fossil Sites You've Gotta See
Albert B Dickas, 2018

This is a great updated fossil sites book with at least one fossil site in each state. Each site is broken into 2 pages. One has detailed information, such as directions, GPS coordinates, formation information, etc... The other is dedicated to images of the site and the fossils found there. It also gives information on fossil 'viewing' sites such as dinosaur trackways, museums, and active excavations.
Plus, my fossil photos are peppered throughout this book!

Dinosauria and Prehistoric creatures: Ancient Sharks

Dinosauria and Prehistoric creatures: Ancient Sharks

Shetan Noir's paperback compilation of interviews with leading prehistoric shark experts, including Dr. Shimada, Kent, and Godfrey, offers diverse insights on an array of prehistoric shark topics like Helicoprion jaw structure. Despite minor formatting issues, the large-print book, over 100 pages with vibrant photos, provides a quick, fascinating read. Highly recommended for any prehistoric shark enthusiast. Plus I have a chapter in it!

Fossil Examples of Cow Shark Teeth and Fossil Hunting Locations

Fossil Cow shark teeth are uncommon to find. However, they occur in many miocene and pliocene formations. Some of the more well known fossil bearing formations include:

Places to find them include the Chesapeake Bay Area (Calvert Cliffs Site), North Carolina (Aurora Site), and Florida (Venice Site).

Hexanchus cow shark tooth found at Aurora, NC.

Notorynchus cepedianus cow shark tooth found at Aurora, NC.

Fossil Examples:

Hexanchus cf. collisonae, Hexanchus griseus and Notorynchus cepedianus Cow Shark Examples (Cow Sharks)

Hexanchus cf. collisonae
Eocene sixgill cow shark

This is an Eocene species of Cow Shark. These Eocene cow shark teeth use to be called Hexanchus agassizi.

These fossil teeth are very fragile and hard to find. This is a lower lateral tooth.
Hexanchus collisonae is an Eocene cow shark.
Formation:Nanjemoy Formation, Potapaco Member, Bed B    Age:Lower Eocene (Ypresian), ~55 m.y.    Location:Fisher Lane Bone Bed, Fisher Branch of Muddy Creek, Staffod Co., VA    Size: ~5/8" long (15mm)   

Hexanchus griseus (Bonnaterre, 1788)
Broadnose sixgill cow shark

H. griseus is a living species today. The fossil teeth are probably from this extant species and first appeared in the miocene.

Hexanchus teeth can be easily differentiated from Notorynchus teeth. Notorynchus teeth have serrations on their mesial edge, whereas Hexanchus teeth have very fine serrations on the mesial edges. Also Hexanchus teeth tend to have more cones running down the length of the tooth.

This is an outstanding lower Hexanchus tooth.

Formation:Yorktown    Age:Pliocene: Roughly 2.5-5 m.y.    Location:PCS (Nutrien) Mine, Aurora, NC    Size:~ 1 5/8" (41mm)    Date:Feb. 2009 TRIP

The teeth of Broadnose sixgill sharks are fragile and are often found broken, like the one in this image. Sadly, the conules are missing on this specimen.

Formation:Yorktown    Age:Pliocene: Roughly 2.5-5 m.y.    Location:PCS Mine, Aurora, NC    Size:~ 1 5/8" (41mm)    Date:March 2008 TRIP

Notorhynchus cepedianus (Peron, 1807)
Bluntnose Sevengill Cow Shark

Purdy et al (2001) believe these teeth are identical to the extant N. cepedianus, and therefore N. primigenius is just synonymous to the living N. cepedianus.

This is my best Notorynchus tooth to date. It is nearly perfect, and was plucked straight from a clay block.
Formation:Choptank, Zone 17?    Age:Middle Miocene ~ 15 m.y.    Location:Calvert Cliffs of MD    Size:~ 1" (25mm)    Date:June 2006 TRIP

This image shows different tooth positions of fossil sevengill Notorynchus cow shark teeth

Formation:Calvert    Age:Middle Miocene: Roughly 18-15 m.y.    Location:Calvert Cliffs of Maryland   

Here is a beautiful complete Bluntnose sevengill cow shark tooth

Formation:Yorktown    Age:Pliocene: Roughly 2.5-5 m.y.    Location:PCS Mine, Aurora, NC    Size:~ 1" (25mm)    Date:Sept 2008 TRIP

Another complete Bluntnose sevengill fossil cow shark tooth

Formation:Pungo River    Age:Miocene: Roughly 18-22 m.y.    Location:PCS Mine, Aurora, NC    Size:~ 1" (25mm)    Date:Sept 2008 TRIP

Here is another complete cow shark tooth

Formation:Pungo River    Age:Miocene: Roughly 18-22 m.y.    Location:PCS Mine, Aurora, NC    Size:~ 1 1/8" (27mm)    Date:March 2006 TRIP

Another complete fossil cow shark tooth

Formation:Pungo River    Age:Miocene: Roughly 18-22 m.y.    Location:PCS Mine, Aurora, NC    Size:~ 1 1/8" (27mm)    Date:Feb 2009 TRIP