How To Identify Your Finds (Part 2 of 10)
Warning, latin names approaching!
All names for the species I describe in this guide are in latin. As far as I know, there are no common names, so I've got no choice. To ease the pain a bit I will tell you how to pronounce the names as we come to them. By the way, all species names have 2 parts to them e.g. Homo sapiens. The first part always starts with a capital, the second part doesn't. Sorting Your Finds
As I'm still learning the process of identifying shark teeth, I have developed a useful system for sorting the day's finds - anything up to 200 items - into individual species. It's made up of the following simple steps: 1a) Identifying the Striatolamia striata teeth
[Note: I was mistakenly calling this Striatolamia macrota before. The 2 are easily confused but S. striata is the only Palaeocene Striatolamia. Most of the rocks at Beltinge are from Palaeocene times, being around 58 million years old] [Striatolamia striata (pronounced "stry-at-o-larm-eeya stry-a-tar") is an extinct Sand Tiger shark. It belongs to the order Lamniformes, family Otodontidae. Lamniformes are commonly known as mackerel sharks] It makes sense to start with the commonest and possibly the easiest to identify. At first sight they are indistinguishable from similar species. However, on close inspection, they have a very recognisable feature: Fine striations on the lingual side of the crown (not to be confused with the usual cracks in the surface). These can be very pronounced or quite subtle but they are always there (especially near the root). You can see them in figure 1 below - Here you see 2 images of the same tooth except the one on the right magnifies the detail contained in the white box on the left. The striations are the vertical grooves seen all across the face of the enamel. Update: However, before you go assigning all striated teeth to S. striata, there are two other, far less common species at Beltinge that can have striations too: Sylvestrilamia teretidens; and Paraorthachodus eocaenus. So be sure to check out sections 1b and 1c below. |
Other important details:
Anterior teeth are long, slender, sigmoidal and upright (See figure 3); laterals tend to be shorter, relatively wider at the base, and lean toward the back of the jaw (see figure 2).
Anterior teeth are long, slender, sigmoidal and upright (See figure 3); laterals tend to be shorter, relatively wider at the base, and lean toward the back of the jaw (see figure 2).
- The crown is smooth-edged, flat on labial side, rounded on lingual side.
- There's a single, tiny, pointed cusplet (when present) on either side of the crown. Laterals: the single (occasionally double) cusplets are broad, and triangular or squarish (See figure 1 above).
- The root is strongly bi-lobed. Anterior: well separated. Large lingual protuberance and nutrient groove at centre of root. Lateral: separated, broad & grooved.
More pictures of Striatolamia striata can be found here, here, and here.
An artificial tooth set can be found here
An artificial tooth set can be found here
1b) Identifying the Sylvestrilamia teretidens teeth
Another extinct Sand Tiger shark. It belongs to the order Lamniformes, family Otodontidae. Lamniformes are commonly known as mackerel sharks. Sylvestrilamia teretidens is the modern name but some still call it Carcharias teretidens.
The teeth from this species can easily be mistaken for Striatolamnia striata because of the striations they often have. In fact, until recently (Aug 2018), I've been lumping them in with S.striata myself (Oops!).
The reference material on the web for this species is often ambiguous, with pictures looking just like S. macrota teeth. So it's obviously a tricky one, even for the experts, but here is a comparison. I'll add to it as I learn more.
The teeth from this species can easily be mistaken for Striatolamnia striata because of the striations they often have. In fact, until recently (Aug 2018), I've been lumping them in with S.striata myself (Oops!).
The reference material on the web for this species is often ambiguous, with pictures looking just like S. macrota teeth. So it's obviously a tricky one, even for the experts, but here is a comparison. I'll add to it as I learn more.
S. striata
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S. teretidens
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This may not sound like much to go on but, once you combine it with what you see in the images below, you'll realise most S. teretidens teeth are pretty recognisable. The full cutting edges, the robust, V shaped cusplets, the size, and the generally slender look of the crown/cusp, are all good pointers.
1c) Identifying Paraorthachodus eocaenus
This one belongs to the order Synechodoniformes, an obscure group of sharks about which little is known.
The teeth from this species are pretty rare at Beltinge but are very distinctive. They are small (< 15mm width), have a long, narrow crown with up to 4 cusplets on each side, and the root it generally flat based with deep pores and flutes/grooves.The crown often has striations at the base of the labial side but can also have them on the lingual side.
The teeth from this species are pretty rare at Beltinge but are very distinctive. They are small (< 15mm width), have a long, narrow crown with up to 4 cusplets on each side, and the root it generally flat based with deep pores and flutes/grooves.The crown often has striations at the base of the labial side but can also have them on the lingual side.