Key to the Common Genera of Neogene Fossil Shark Teeth
How to Use this Key:
- Start with the first question. Decide whether the statement in the first box (1a) or the the second box (1b) best describes the characteristics of the fossil tooth you are trying to identify. (See this page for pictures and a glossary of shark tooth terms if you need help.)
- Click on the link in the row that best matches your tooth. Your choice will lead you to the next appropriate pair of questions.
- Work through the questions, each time choosing the characteristic that best matches your tooth from the two choices. This will lead you to the final choice which identifies the species the tooth is likely from.
| 1a) teeth labio-lingually flattened | Go to question 2 |
| 1b) teeth short, not labio-lingually flattened | Go to question 48 |
| 2a) teeth single cusped (includes teeth with lateral denticle) | Go to question 3 |
| 2b) teeth multicusped | Go to question 26 |
| 3a) cutting edges of teeth notched (angular) on one or both edges | Go to question 4 |
| 3b) cutting edges of teeth not notched | Go to question 9 |
| 4a) cutting edges of teeth partially or completely serrated | Go to question 5 |
| 4b) cutting edges of teeth smooth | Go to question 12 |
| 5a) one cutting edge of tooth with angular notch | Go to question 6 |
| 5b) both cutting edges of tooth with angular notches | Go to question 29 |
| 6a) angular notch deep | Go to question 7 |
| 6b) angular notch shallow | Go to question 35 |
| 7a) shoulder with fine to coarse serrations | Go to question 8 |
| 7b) shoulder with weak to very fine serrations | Sphyrna (in part), Carcharhinus (in part), Rhizoprionodon (in part) |
| 8a) basal margin of root strongly arcuate, transverse groove not well developed or absent | Galeocerdo (in part) |
| 8b) basal margin of root straight to subangular with well developed transverse groove | Go to question 15 |
| 9a) cutting edges of teeth are serrated | Go to question 10 |
| 9b) cutting edges of teeth are smooth | Go to question 16 |
| 10a) root does not protrude lingually at midline of tooth; labial face of root without valley | Go to question 11 |
| 10b) root protrudes lingually (may be slight) at midline of tooth; labial face of root with valley | Go to question 45 |
| 11a) teeth greater than 1″ (2.54 cm.) in height; coarse serrations, thick root | Carcharodon |
| 11b) teeth 1″ or less in height; basal margin of enamel of lingual face is root not massive | Carcharhinus longimanus (upper teeth) |
| 12a) one cutting edge of tooth with angular notch | Go to question 13 |
| 12b) both cutting edges of tooth with angular notches | Go to question 20 |
| 13a) crown contorted | Galeocerdo (in part) |
| 13b) crown not contorted | Go to question 14 |
| 14a) enamel shoulder with faint to coarse serrations | Galeorhinus, Paragaleus (in part), Rhizoprionodon (in part), Carcharhinus (in part) |
| 14b) enamel shoulder smooth | Go to question 21 |
| 15a) teeth much higher than wide | Prionace (in part) |
| 15b) teeth nearly equilateral | Go to question 39 |
| 16a) teeth have lateral cusplets | Go to question 17 |
| 16b) teeth do not have lateral cusplets | Go to question 22 |
| 17a) number of lateral cusplets on each side of crown equal | Go to question 18 |
| 17b) number of lateral cusplets on each side of crown unequal | Go to question 24 |
| 18a) lateral cusplets adjacent to basal edge of crown; cutting edge of crown complete | Go to question 19 |
| 18b) lateral cusplets well above basal margin of crown; cutting edge of crown incomplete | Hemipristis serra (in part, lower anterior) |
| 19a) transverse groove absent; cutting edges usually straight and never parallel toward apex | Lamna |
| 19b) transverse groove present; cutting edges usually concave and in more anterior teeth nearly parallel toward apex | Go to question 33 |
| 20a) root protrudes on lingual side; central foramen in shallow groove | Negaprion brevirostris (in part) |
| 20b) root does not protrude on lingual side; central foramen in deep transverse groove | Carcharhinus (in part) |
| 21a) cutting edge extends to base of crown | Rhizoprionodon (in part), Sphyrna (in part) |
| 21b) cutting edge does not extend to base of crown | Prionace (lower teeth) |
| 22a) transverse groove present | Go to question 23 |
| 22b) transverse groove absent or incipient | Go to question 28 |
| 23a) asymmetrical teeth; transverse groove does not extend to basal margin of root | Alopias (in part) |
| 23b) nearly symmetrical teeth; transverse groove extends to basal margin of root to form a notch | Carcharhinus (lower teeth) |
| 24a) main portion of crown recumbent | Echinorhinus |
| 24b) main portion of crown not recumbent | Go to question 25 |
| 25a) root not lobate | Go to question 47 |
| 25b) root lobate | Go to question 46 |
| 26a) mesial edge of main cusp serrated, cusplets decline regularly in size distally | Go to question 27 |
| 26b) mesial edge of main cusp with one or more denticles, cusplet distal to main cusp shorter than more distal cusplets | Heptranchias |
| 27a) 3 to 4 cusplets, serrations recurved | Notorynchus (in part) |
| 27b) 7 to 10 cusplets, serrations not recurved | Hexanchus (in part) |
| 28a) central foramen present; lingual face of root smooth | Go to question 32 |
| 28b) central foramen absent; lingual face of root striated | Hexanchus (upper anterior teeth) |
| 29a) cutting edges of crown smooth; enamel shoulders weakly to finely serrated | Go to question 30 |
| 29b) cutting edges of crown partially or completely serrated | Go to question 31 |
| 30a) transverse groove shallow or absent | Negaprion brevirostris (in part) |
| 30b) transverse groove deep | Carcharhinus (in part) |
| 31a) lingual face of root convex | Carcharhinus (in part) |
| 31b) lingual face of root flattened | Sphyrna (in part) |
| 32a) root lobes round and extend beyond basal limit of crown | Alopias (in part) |
| 32b) root lobes not round (in teeth under 1.5″ in height) and don’t extend noticeably beyond basal limit of crown | Isurus |
| 33a) lateral cusplets prominent, not strongly curved | Go to question 34 |
| 33b) lateral cusplets not prominent, strongly curved | Carcharias taurus |
| 34a) two or more pairs of lateral cusplets, root lobes deeply arched and narrow | Odontaspis ferox |
| 34b) one pair of long lateral cusplets, root lobes moderately arched and broad | Odontaspis noronhai |
| 35a) relatively narrow cusps | Go to question 36 |
| 35b) broad cusps | Go to question 37 |
| 36a) mesial cutting edge concave with slightly coarser serrations on both shoulders | Carcharhinus limbatus |
| 36b) mesial and distal cutting edges of cusps essentially straight | Go to question 37 |
| 37a) cusps with slightly coarser serrations distally | Go to question 38 |
| 37b) cusps with uniform serrations | Carcharhinus altimus |
| 38a) mesial cutting edge marked by noticeable gap in serrations | Carcharhinus falciformis (upper anteriors) |
| 38b) mesial cutting edge not marked by noticeable gap in serrations | Carcharhinus falciformis (upper laterals) |
| 39a) cusps narrow | Go to question 40 |
| 39b) cusps moderately broad | Carcharhinus brachyurus |
| 40a) cusps uniformly serrated with fine serrations | Sphyrna (in part) & Carcharhinus (in part) |
| 40b) cusps not uniformly serrated | Go to question 41 |
| 41a) saw-toothed serrations on distal enamel shoulder | Go to question 42 |
| 41b) fine serrations on distal enamel shoulder | Carcharhinus acronotus |
| 42a) mesial serrations fine | Go to question 44 |
| 42b) mesial serrations coarse basally | Go to question 43 |
| 43a) contact between root and labial side of crown V-shaped | Carcharhinus leucas |
| 43b) contact between root and labial side of crown flat and wide | Carcharhinus obscurus |
| 44a) mesial cutting edge essentially straight | Carcharhinus porosus |
| 44b) mesial cutting edge noticeably concave basally | Carcharhinus perezi |
| 45a) transverse groove present in lingual root protrusion | Hemipristis serra (in part) |
| 45b) transverse groove absent in lingual root protrusion; teeth greater than 1″ (2.54 cm); basal margin of enamel of lingual face is gently arched to straight in small teeth and becoming strongly arched in larger specimens | Carcharocles |
| 46a) basal margin of root broadly arched | Alopias (in part) |
| 46b) basal margin of root not broadly arched | Hemipristis serra (in part) |
| 47a) mesial cutting edge forms shoulder with one or more cusplets | Notorynchus (in part) |
| 47b) mesial cutting edge without shoulder and cusplets | Hexanchus (in part) |
| 48a) single long sharp cusp | Squatina |
| 48b) small center cusp with 3-4 cusplets on either side | Ginglymostoma |