northeast inland/freshwater living fossils?

[Chip]

A large clam in a local vernal pool freaked me out a little recently. "Did this EVOLVE HERE? " Was it deposited, left behind when the ocean receded ? Then I realized it's probably no more strange than many common plants and animals. What are some notible northeast inland/freshwater living fossils? For whatever reason I don't have a problem with saltwater living fossils, like horseshoe crabs.

 

[DougPaul]

A large clam in a local vernal pool freaked me out a little recently. "Did this EVOLVE HERE? " Was it deposited, left behind when the ocean receded ?

Past high water could be a factor. Or maybe the clam could have traveled in egg or larval form attached to a bird's feet or feathers. A bird might also carry it in adult form.

Some desert aquatic species have tiny eggs that can blow around as dust in the wind (eg fairy shrimp). After a rainfall, they hatch in puddles along with tadpoles and hope to produce more eggs before the puddles dry up.

Doug

 

[nartreb]

Many freshwater molluscs have larvae that can hitch a ride on fish. This means they can spread upstream, and it doesn't take long. 10,000 years or so since the glaciers receded is plenty.

Hm, crossing from one drainage to another is still a problem unless they can tolerate seawater... you'd expect major, non-connected river systems to have distinct populations. I wonder if the fossil record would reveal any changes coincident with canal-building in the 19th century?

 

[DougPaul]

Many freshwater molluscs have larvae that can hitch a ride on fish. This means they can spread upstream, and it doesn't take long. 10,000 years or so since the glaciers receded is plenty.

One of the features of many vernal pools is that they don't support fish... This is a big help to certain organisms that would be eaten (and eliminated) by any fish.

Hm, crossing from one drainage to another is still a problem unless they can tolerate seawater... you'd expect major, non-connected river systems to have distinct populations. I wonder if the fossil record would reveal any changes coincident with canal-building in the 19th century?

Yet many species are found in more than one unconnected drainages. Remember that currently unconnected systems may have been connected at some point in the past, for instance, by (continential glacier) glacial lakes.

Doug

 

[Chip]

I'd like to believe these clams have survived in this location since the glaciers receded...much more likely though that they were delivered here more recently hitching a ride as larvae or tiny babies. Ah well. Fun anyway.

 

[dug]

About 30 years ago, I found a fossil of a seashell (i.e. like the Shell Oil symbol, about the size of a nickle) on the shores of Moosehead Lake in Maine. We were floating on rafts near the shore and looking for interesting rocks in the shallow water. My eye caught a granite rock, looked like the size and shape of a thumb, with a hole in it. I pulled it out and it was a clear depression of a shell in the rock.

 

[DougPaul]

About 30 years ago, I found a fossil of a seashell (i.e. like the Shell Oil symbol, about the size of a nickle) on the shores of Moosehead Lake in Maine. We were floating on rafts near the shore and looking for interesting rocks in the shallow water. My eye caught a granite rock, looked like the size and shape of a thumb, with a hole in it. I pulled it out and it was a clear depression of a shell in the rock.

It would have been a fossil or granite, but not both.

Granite is formed by the slow cooling of an underground plume of molten rock.

Fossils are found in sedimentary rocks (rocks formed by solidification of sediments).

Doug

 

[peakbagger]

Lots of fossils over near Monson in the slate deposits. I think Little Wilson stream may have some, The stream that runs along the tote road at BSP reportedly has a section where there are slate rocks with shell fossils in them. The rocks are grayish black and there is are very distinct indentations that look like small shells.

 

[dug]

Let me clarify...it was the imprint of a shell that the rock formed around. I believed the actual rock was granite (with a quartz tip). It was possibly a shale composition, as I now remember it. I actually gave it to my college professor so I no longer have it.

 

[Remix]

I assume you meant the clam was live.....

You might be interested to know that there are fresh water jellyfish.

But if you meant clam shell, it could just be from transported fill.

 

[Chip]

I assume you meant the clam was live.....
.

Me ? Yeah, big fat live freshwater quahog in the mud. I'm sure there are more if I look. This "pool" is slightly more permanent than true vernal.
It has filled in more in recent years and in the past had been a tiny pond in farm land probably 500' higher than the Housatonic River which feeds into LI Sound.

Sturgeon are freshwater living fossils as are snails.