Quiz - Mammal Tooth

[Harry Pristis]

Okay, here's a quiz to see who's been paying attention lately.

Here are three views of a little tooth from a mammal many of you vert collectors may recognize. The animal lived in the Pleistocene of Florida. Name the animal (genus name) and give us your reasoning.

Best, most complete, answer wins a Golden Kudo!

Hint: this is NOT a deciduous tooth.

[Cris]

Well, it certainly appears to be a Xenarthran tooth. My first instinct said Paramylodon (glossothertium) tooth, but I think I've decided to go with Megaloynx for this guess..although it does appear a bit small..

[MOROPUS]

I would say some sort of peccari incisive....

[Harry Pristis]

Not much interest in sloths, it seems. Cris has provided the best answer, though he backed away from it. He did appropriately note that the tooth was small for a giant ground sloth. For Cris, a rare Silver Kudo!

This tooth is a juvenile tooth, one of a set, from a very young Paramylodon (Glossotherium) harlani. Remember giant ground sloths have no deciduous ("milk") teeth; they have no canines; they have no incisors; they have no enamel; and, they have no tooth roots (ever-growing or hypselodont).

"The dentition in xenarthrans is typically reduced in tooth types and numbers and all lack enamel. There is no milk dentition, and the teeth are ever-growing. No xenarthran has identifiable incisors.

"Sloths are the only xenarthrans with canine-shaped teeth, and in these animals they occlude upper in front of lower, opposite from the pattern in other mammals, making their relationships to true canine teeth uncertain. Therefore, in sloths those teeth are called 'caniniform.'

"Likewise, neither premolars nor molars can be distinguished in sloths, armadillos or glyptodonts, and the cheek teeth are all similar in appearance and all called "molariform." The anteaters are the only edentulous xenarthrans, although the group was previously known as the Edentata.

"The teeth in sloths erupt as simple cones, and acquire the cusp pattern characteristic of each species through wear caused by movements of the masticatory muscles. The generation of tooth wear patterns in other xenarthrans has not been studied." [from novelguide.com]

[Cris]

Good info, Harry. I didn't realize there was so much variation in the size and shape of an individual sloth's teeth. Are there any easy ways to distinguish between Paramylodon and Megaloynx teeth?

[Harry Pristis]

Good info, Harry. I didn't realize there was so much variation in the size and shape of an individual sloth's teeth. Are there any easy ways to distinguish between Paramylodon and Megaloynx teeth?

The Paramylodon mandibular teeth tend to have a more complicated cross-section than do Megalonyx teeth. I have to rely on illustrations like most of us.