Comments on: Sloth anatomy challenge http://slothcentral.com/archives/44 A 12,000 year-old mystery in SW Iowa Tue, 20 Apr 2010 02:51:50 -0700 http://wordpress.org/?v=2.8.4 hourly 1 By: David http://slothcentral.com/archives/44/comment-page-1#comment-226 David Mon, 20 Oct 2008 16:30:45 +0000 http://slothcentral.com/?p=44#comment-226 Hi Amanda. good hearing from you. Hint huh? Any combination of enamel and dentine is going to produce a jagged edge because of the big difference in hardness. 100% dentine (the cementum has a very similar hardness) means an edge which can be self-ground smooth and sharp. Think about who would need sharp teeth but not necessarily hard and why. Hi Amanda. good hearing from you. Hint huh? Any combination of enamel and dentine is going to produce a jagged edge because of the big difference in hardness. 100% dentine (the cementum has a very similar hardness) means an edge which can be self-ground smooth and sharp. Think about who would need sharp teeth but not necessarily hard and why.

]]> By: Amanda http://slothcentral.com/archives/44/comment-page-1#comment-222 Amanda Fri, 17 Oct 2008 19:38:49 +0000 http://slothcentral.com/?p=44#comment-222 I would have had the same initial guess as Pete. You really didn't give much of a clue for novices like me. I saw you in the paper today (http://www.press-citizen.com/apps/pbcs.dll/article?AID=/20081017/NEWS01/810170340/1079). Shoot me an email when you get a chance. We need to catch up! I would have had the same initial guess as Pete. You really didn’t give much of a clue for novices like me.

I saw you in the paper today (http://www.press-citizen.com/apps/pbcs.dll/article?AID=/20081017/NEWS01/810170340/1079). Shoot me an email when you get a chance. We need to catch up!

]]> By: David http://slothcentral.com/archives/44/comment-page-1#comment-220 David Thu, 16 Oct 2008 20:48:12 +0000 http://slothcentral.com/?p=44#comment-220 Thanks Pete, I didn't know the non-orange part was 100% dentin. That makes sense with what I've read about the sloth's teeth. I understand the rodent arrangement creates a very sharp but ragged edge, with the dentin wearing down faster and leaving the enamel layer unsupported and easily chipped. If true, that may be a helpful clue to the puzzle. Thanks Pete, I didn’t know the non-orange part was 100% dentin. That makes sense with what I’ve read about the sloth’s teeth. I understand the rodent arrangement creates a very sharp but ragged edge, with the dentin wearing down faster and leaving the enamel layer unsupported and easily chipped. If true, that may be a helpful clue to the puzzle.

]]> By: Pete Eyheralde http://slothcentral.com/archives/44/comment-page-1#comment-219 Pete Eyheralde Wed, 15 Oct 2008 19:46:00 +0000 http://slothcentral.com/?p=44#comment-219 If you look at a rodent's four incisors, the orange enamal is mostly on the front surface of the teeth. There's a little overlap on the sides, but not by much. The enamel is much harder than the white dentin, which makes up rest of the tooth. When chewing down trees or through walnut shells, the softer dentin wears away faster than the enamel. This creates a chisel-like (and self sharpening) cutting surface to the teeth as they wear. If you look at a rodent’s four incisors, the orange enamal is mostly on the front surface of the teeth. There’s a little overlap on the sides, but not by much. The enamel is much harder than the white dentin, which makes up rest of the tooth. When chewing down trees or through walnut shells, the softer dentin wears away faster than the enamel. This creates a chisel-like (and self sharpening) cutting surface to the teeth as they wear.

]]> By: David http://slothcentral.com/archives/44/comment-page-1#comment-218 David Tue, 14 Oct 2008 16:31:49 +0000 http://slothcentral.com/?p=44#comment-218 hi Pete, right you are. . . it wouldn't be that easy! You're the real naturalist in this bunch--is that orange enamel on all sides of the teeth or just the out-side? A different kind of enamel? Different hardness? It's not merely a different color is it?--what would be the point? hi Pete, right you are. . . it wouldn’t be that easy! You’re the real naturalist in this bunch–is that orange enamel on all sides of the teeth or just the out-side? A different kind of enamel? Different hardness? It’s not merely a different color is it?–what would be the point?

]]> By: Pete Eyheralde http://slothcentral.com/archives/44/comment-page-1#comment-214 Pete Eyheralde Mon, 13 Oct 2008 21:59:15 +0000 http://slothcentral.com/?p=44#comment-214 Given the self sharpening, ever-growing clue, my first guess would be something in the Order Rodentia. Beavers, woodchucks, squirrels and the like. But I'm pretty sure that the orange outer layer of material on a rodent's incisors is enamel, not cementum. So I'll have to keep looking.... Given the self sharpening, ever-growing clue, my first guess would be something in the Order Rodentia. Beavers, woodchucks, squirrels and the like. But I’m pretty sure that the orange outer layer of material on a rodent’s incisors is enamel, not cementum. So I’ll have to keep looking….

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