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With this post I have now posted on TFF at least one jaw from a species from each of the 9 shark orders (Hexanchiformes, Echinorhiniformes, Squaliformes. Pristiophoriformes, Squatiniformes, Heterodontiformes, Lamniformes, Orectolobiformes, and Carcharhiniformes). To understand and id fossil shark teeth it really helps if you are familiar with extant shark teeth. This post contains pictures of an extant Echinorhinus brucus Bonnaterre, 1788 (Bramble Shark) jaw. Links to my previous TFF posts on extant shark jaws can be found at the below TFF link. My Extant Shark Jaw Collection There are only two species of Echinorhinus, Echinorhinus brucus (Bramble Shark) and Echinorhinus cookie (Prickly Shark). There is some dentition/tooth-design detail given for the genus Echinorhinus in the published literature but no features that might provide a means of distinguishing between the two extant species. The only sure way to id an Echinorhinus jaw to the species is to see the actual shark that the jaw came from. To illustrate the differences in the two species of Echinorhinus I’m providing some illustrations from Compagno 1984 VOL. 4 “SHARKS OF THE WORLD An Annotated and Illustrated Catalogue of Shark Species Known to Date Part 1 - Hexanchiformes to Lamniformes”. Echinorhinus brucus (Bramble Shark): Echinorhinus cookie (Prickly Shark): Note that Compagno calls the Echinorhinus scales dermal denticles because of their large size and features. These scales look much more like the dermal denticles from the mid-line of rays than the much smaller placoid scales from other sharks and from rays. Echinorhinus brucus (Bramble Shark) jaw, 7 inches by 7 inches, (This jaw is definitely an Echinorhinus jaw and I’m using the species id provided by the seller of this jaw who is a very reputable seller of shark jaws) that has been professionally cleaned, prepared & shaped: Echinorhinus jaws are extremely thin, almost paper thin. Here is a random picture of an Echinorhinus jaw from e-bay. This is what an Echinorhinus jaw would look like without being professionally cleaned, prepared & shaped. Below are teeth from the jaw. The teeth display monognathic heterodonty. The teeth are very similar in both the upper and lower jaws and don’t change a lot moving distally in the jaw. Adult teeth can have 1 or 2 mesial and distal cusplets which are absent in young sharks. Weak serrations can be present. The below teeth show evidence of weak serrations. Because a number of the active first row teeth in this jaw are damaged, I’m only taking pictures of the better teeth. Teeth from the right and left side of the upper jaw: UR1 (10 mm): UR2 (10 mm): UL 4 (10mm): UL 8 (8 mm): UL9 (5 mm): Teeth from the right and left side of the lower jaw: LR2 (12 mm): LL 5 (10 mm): LL 7 (10 mm): LL 9 (7 mm): LL 10 (4mm): You can see in the below pictures that there are 4 upper rows of teeth and 4 lower rows of teeth in this jaw. The upper jaw has 9 tooth files left and 10 tooth files right of the symphysis. There aren’t any symphyseal teeth. The lower jaw has 10 tooth files left and 10 tooth files right of the symphysis. There aren’t any symphyseal teeth. Marco Sr.