Spotted Hyena (Crocuta crocuta) dentition : 無料・フリー素材/写真
Spotted Hyena (Crocuta crocuta) dentition / Dallas Krentzel
| ライセンス | クリエイティブ・コモンズ 表示 2.1 |
|---|---|
| 説明 | Here we have the massive bone-crushing teeth of the spotted hyena (Crocuta crocuta). The other hyena species, excluding the aardwolf, are overall pretty similar. The most massive tooth is the carnassial (premolar four or P4), which is plesiomorphic (or primitive) for all carnivoran mammals (some groups, such as pinnipeds, bears, raccoons, etc, have reduced the carnassial) that is adapted for cutting and serrating flesh. Here in the hyena, it is much larger and blunter, but so are the other premolars, which makes the hyena exceptional among mammamlian bone-crushers (for example, the wolverine only has a highly modified P4, while the other premolars are not as exaggerated in size. See the link below). The only true molar is highly reduced, and sometimes absent. You can see it right behind the carnassial (P4) tooth, and it looks sideways. That's just because it's antero-posteriorly compressed, not rotated, and it still retails the same cusp arrangement you would find in other carnivores (felids [cats], close relatives of the hyenas, have completely lost their upper true molars). Anterior to the molar and lateral to the carnassial you can see a smooth depression, which serves as an insertion point for the corresponding lower carnassial tooth. The rest of the skull is very robust and impressive, like the teeth. I should have included a photo of the sagittal crest, as there's a whole other interesting story to tell there...For the wolverine, see: www.flickr.com/photos/31867959@N04/3243598040/Compare with another hyaenid carnivore, the aardwolf: www.flickr.com/photos/31867959@N04/4121244926/ |
| 撮影日 | 2012-01-05 03:57:15 |
| 撮影者 | Dallas Krentzel |
| タグ | |
| 撮影地 | |
| カメラ | DSLR-A300 , SONY |
| 露出 | 0.04 sec (1/25) |
| 開放F値 | f/5.6 |
| 焦点距離 | 80 mm |