Hogtown Creek Gainesville Finds

[fangirl0708]

Hello again!! These are some of the odd things WilliamRock found today in hogtown creek. We think some of them may be rocks, but they have weird marks and cracks on them that make them confusing. If any additional info or pics are needed, please let me know.

Top

Bottom

will add the rest of the pictures in the comments

[fangirl0708]

[fangirl0708]

[finderskeepers]

4th and 5th picture is the jaw of a porcupine fish

Edited May 24, 2015 by finderskeepers

[Diceros]

1. The lumpy looking one at the top looks more like eroded rock than bone to me. Why the one area has all the small pits in it, I've no idea.

2. As finderskeepers writes above, a bony fish toothplate. My guess would be burrfish (Chilomycterus), rather than prcupine fish (Diodon). Both marine fish can "inflate" themselves, and both have scales like projecting spines (those of burrfish are short, and are always erect; those of porcupine fish are long and slender, and only becone erect when the fish inflates itself). I believe the broader toothplates, like yours, are the upper ones.

3. This is clearly a fragment of bone from a large mammal jaw. The concave, fairly-smooth, surfaces appear to the parts of two adjoining tooth alveoli (the holes where the tooth roots fit into the jaw). The deeper holes in one of these surfaces appear to be borings of marine lithophagid clams (they also bore into rock, coral, and shell). In spite of the name (Lithophaga means "rock-eater"), they're boring to form homes for themseves (trace fossils called domnichia), not to eat what they bore through (not feeding traces).

4. The one on the bottom is both the easiest, and the most obscure - it's a "Tilly bone", long ago named for brain researcher Tilly Edinger. She became involved in them, because people were always mistaking them for small ossified brains (they just look a bit like small brains, they're actually bones from a variety of large bony fish, often the jack Caranx). The obscure part is the function of Tilly bones. They were originally though to be pathologic bone growths, but they're too regularly-shaped for that. They're often found attached to the pterygiophores (long, narrow, mid-line bones in bony fish extending down into the back from the base of the dorsal fin spines - you can see the impression of one on yours). Now, are they providing some sort of balast, serving as a reservoir of bone, providing the fish with extra heft? - I've never read a conclusive explanation based on experimental work with living fish. Because Tilly bones are often found by fossil collectors, often ones in Florida, who often don't recognize what they are, they come up over and over. Help me out FF members - Tilly bones must have been figured, and identified, and discussed many times on FF (I'm fairly new to it) - could you please direct fangirl0708 to the previous Tilly bone postings?

[fangirl0708]

Thank you both so much!!!! Do you think it will ever be possible to ID what kind of large mammal the jaw bone came from? Or it is to small of a portion to get a confirmed ID ?

[Diceros]

If you click the Advanced Search cogwheel-icon in the upper right, and type in "Tilly bone" (in quotes), you get a long list of times Tilly bones from various places have turned up on Fossil Forum. Also, here's a webpage with data and pics of many Tilly bones, which will demonstrate why they get confused with small bony brains so often: http://www.lakeneosho.org/Fossil/index.html .