Turtle Dermal Denticle?

[Ludwigia]

I obtained this recently on a trade with Seaforth. I've been told that it might be a turtle dermal denticle from the Miocene/ Pleistocene, but I'd sure appreciate it if someone could give me some more details about it, like at least order, class or even genus. It's 2cm. long. Thanks.

Edited March 31, 2015 by Ludwigia

[RichW9090]

Where was it collected, Ludwigia?

[PFOOLEY]

Tortoise (?Hesperotestudo sp.) spur.

Edited March 31, 2015 by PFOOLEY

[Ludwigia]

Where was it collected, Ludwigia?

I believe somewhere in Florida, but I unfortunately can't get any more precise information.

[Ludwigia]

Tortoise (?Hesperotestudo sp.) spur.

Thanks Mike. I'll check that out.

[Shellseeker]

The size, shape and coloration are exactly the same as many that I have collected and seen collected in the Peace River Formation, Southwest Florida.

[Ludwigia]

The size, shape and coloration are exactly the same as many that I have collected and seen collected in the Peace River Formation, Southwest Florida.

Thanks for the info.

[Carl]

Osteoderm would be a better word than denticle here. Denticle should only refer to the tiny elements in the skin of sharks and their relatives.

[jcbshark]

Tortoise (?Hesperotestudo sp.) spur this is who I was told they belong to Roger. It was found in Desoto county Fl. Thanks for the info Mike : )

[Ludwigia]

Many thanks Carl & jcb. That's rounded it off for me now.

[Diceros]

In recent years, the Pleistocene American giant tortoise has been called Hesperotestudo (Caudochelys) crassiscutata (Leidy, 1889). It used to be called Testudo crass., but in a review of the tortoises of the world, Testudo got restricted to the Old World. "Hesperotestudo" means Western tortoise, "Caudochelys" refers to the odd broad armored tail (which covers its rear, so to speak). "crassiscutata" refers to the huge thickness of the shell's bony scutes.

The conical element you have is leg armor, which helped cover the front and back openings of the shell (the legs are pulled in, and the armor studs stick out - most are oval and flatter). I believe it would be called a bony scute (there are also thin keratinous scutes, enlarged scales, really, over the bony plates). It seems odd for such a large animal to need so much protection, but it has to be out in the open grazing all day, where predators can get at them. It can't exactly run away.

[Ludwigia]

Thanks very much for the informative facts!

[Carl]

In recent years, the Pleistocene American giant tortoise has been called Hesperotestudo (Caudochelys) crassiscutata (Leidy, 1889). It used to be called Testudo crass., but in a review of the tortoises of the world, Testudo got restricted to the Old World. "Hesperotestudo" means Western tortoise, "Caudochelys" refers to the odd broad armored tail (which covers its rear, so to speak). "crassiscutata" refers to the huge thickness of the shell's bony scutes.

The conical element you have is leg armor, which helped cover the front and back openings of the shell (the legs are pulled in, and the armor studs stick out - most are oval and flatter). I believe it would be called a bony scute (there are also thin keratinous scutes, enlarged scales, really, over the bony plates). It seems odd for such a large animal to need so much protection, but it has to be out in the open grazing all day, where predators can get at them. It can't exactly run away.

I was told long ago by fossil turtle man Dr. Gene Gaffney that no turtle bony elements (and by extension no bony elements from anything) should ever be referred to as "scutes." Osteoderm is what most people mean. Scute should only refer to large keratinous external scales, like those covering a turtle's shell. I know everyone calls croc and glyptodont osteoderms scutes but it's really a misnomer.

[Al Dente]

Here's an interesting photo from an old publication that shows some that are nicely preserved.

[Ludwigia]

Here's an interesting photo from an old publication that shows some that are nicely preserved.

TortoiseSpurs.JPG

Thanks. It's great to have an illustration to help the imagination.

[Carl]

GORGEOUS!!!

[Diceros]

Carl - Gene (who had a clear preference for whole turtle skulls over any part of their shells) also used to say that identifying turtles by their shell fragments was like identifying mammals by their rib fragments. Like many professionals, Gene was a bit of a fossil snob, and likely wouldn't have bothered with an osteoderm like this one. It's because of people like Gene that the Fossil Forum is needed.

Eric - Nice photo!

Earl

[RichW9090]

Earl, the mammal equivalent, of course, was spoofed by Henry Galiano with his drawing for Malcolm of Pediodonta bullae. I can't find my copy of that illustration - do you have one?

Rich

Edited April 22, 2015 by RichW9090

[Carl]

Carl - Gene (who had a clear preference for whole turtle skulls over any part of their shells) also used to say that identifying turtles by their shell fragments was like identifying mammals by their rib fragments. Like many professionals, Gene was a bit of a fossil snob, and likely wouldn't have bothered with an osteoderm like this one. It's because of people like Gene that the Fossil Forum is needed.

Eric - Nice photo!

Earl

Regardless of how you feel about Gaffney, he has a good point to make: in science, always shun the ambiguous word for the precise one. I think the scute/osteoderm distinction is very useful. That shouldn't make someone a snob.

[Diceros]

Rich - Sorry, I don't have a copy of Henry's funny sketch, of a fossil mammal made up only of the parts most studied - the foot bones and ear regions. You'd have to get it from Henry.

Carl - I've always thought highly of Gene, and will always be grateful for his teaching us cladistics. Still, when a visitor brought in a fossil to the AMNH for identification in the 70's, it was I who helped them, not Gene, who was more likely to mock poor material. To honor his teaching, we gave him the Turtle Pot award, including a pot made from fossil turtle shell shards. He was also rather proud of a duck-billed dnosaur skull in his office, which he'd labelled "Chinese Plow".

[Ludwigia]

Looks like Gene has hijacked this thread, whoever he was...