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Key to skulls of British Mammals |
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| Rodent Key | Carnivore Key | Insectivore
Key |
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This first part of the key is intended to enable you to discover which
major group of mammals your skull belongs to. One of the most important distinctions is between herbivorous animals and the rest, and it would be useful to make sure you understand the terms "diastema" and "typical rodent dentition". Several questions depend mainly on length measurements, so check whether your specimen is complete, and make allowances if it seems to be broken. | |||
| 1. | a) | Very large skull, overall length greater than 300mm. | 3 |
| b) | Overall length less than 300mm. | 2 | |
| x | |||
| 2. | a) | Very small skull, overall length less than 30mm. | 4 |
| b) | Medium skull, overall length greater than 30mm, less than 300mm. | 6 | |
| x | |||
| 3. | a) | Rostrum long and narrow, with nostrils and nasal bones seemingly "drawn back" onto the forehead. Eye sockets not obvious, teeth simple points or absent *. | WHALE |
| b) | Not as above - nostrils near front of skull, eye sockets formed from complete ring of bone. (Hoofed mammal) | 9 | |
| * Whale skulls found on the coast often have the rostrum broken off by wave action, leaving a roughly spherical object with only the occipital condyles to show that it is a mammal skull. | |||
| 4. | a) | Typical rodent dentition - large, opposed, chisel-like incisors and a wide diastema. | RODENT |
| b) | No large spaces between teeth, all teeth pointed. | 5 | |
| x | |||
| 5. | a) | Zygomatic arches present, incisors and premaxillas divided at front of skull by a distinct notch. | BAT |
| b) | No zygomatic arches, tapering skull with protruberent incisors. | SHREW | |
| x | |||
| 6. | a) | Large diastema. Canines small or absent, or developed into tusks. Cheek teeth similar in shape and size, in a closely spaced block. (Herbivore) | 10 |
| b) | Teeth all or mostly pointed, if not pointed then similar in shape and size, any spaces between teeth less than 10% total skull length. | 7 | |
| x | |||
| 7. | a) | Canines large and prominent, postorbital process usually present. If no postorbital process (seal), then overall length greater than 100mm. | CARNIVORE |
| b) | Canines not or only slightly larger than neighbouring teeth, no postorbital process or eye socket enclosed by bony ring. | 8 | |
| x | |||
| 8. | a) | Braincase smoothly rounded, much larger than the rest of the skull. Muzzle reduced to give an almost flat face. | HUMAN |
| b) | Canines similar to neighbouring teeth, no postorbital processes, gap between top front teeth, overall length 50-60mm. | HEDGEHOG | |
| x | |||
| 9. | a) | Incisors present in upper jaw, infraorbital foramen above 2cnd or 3rd cheek tooth. | HORSE |
| b) | No incisors in upper jaw, infraorbital foramen above 1st cheek tooth. | CLOVEN-HOOF MAMMAL | |
| x | |||
| 10. | a) | Typical rodent dentition - large, opposed chisel-like incisors and a wide diastema. Eye socket not enclosed. Overall length less than 120mm. | RODENT or LAGOMORPH |
| b) | No incisors in upper jaw, eye socket enclosed by a complete bony ring. Overall length greater than 120mm. | CLOVEN-HOOF MAMMAL | |