Comments on: A clam-tastic find!

By: David

David — Tue, 03 Mar 2009 21:00:25 +0000

Hi Pete, we’ve tested several samples–used seives and floated at least 50# of clay, but as Holmes mentioned, findings were surprisingly meager. This small area by the juveniles seems to have enjoyed better conditions for preserving shells like this. No snails yet. Your work with insect larvae is the kind of thing we hope to accomplish using the clams or microfossils in the clay–diatoms may hold out some promise. We’ll be back digging in this vicinity next month and hope to collect a lot more samples. We may have your crayfish burrow. We’re taking a mysterious cavity full of rocks that we collected to the hospital Friday to be CT scanned. Watch for a report on that soon.

By: Pete Eyheralde

Pete Eyheralde — Tue, 03 Mar 2009 04:36:58 +0000

Very cool! Are you wet screening the clay samples to find small bones, shells, etc ? Any evidence of crayfish burrows? Snail shells? These days we often use benthic macroinvertebrates to help determine water quality. Can we do the same with paleocritters?

By: Holmes Semken

Holmes Semken — Sat, 28 Feb 2009 21:06:40 +0000

There is another intriguing aspect to the clam concentration. I suspect that clams were widespread in the sloth-bearing clays when they were alive but now are only preserved in this relatively small area. For some reason, this portion of the site was not subjected to as much weathering (leaching) as the remainder of the deposit. We have collected both pollen and seeds elsewhere at the site but both are degraded and clearly were subjected to the vicissitudes of nature; specimens of both are sparse. Since the clams are preserved in this area, this matrix sample also probably contains better preserved pollen grains and seeds. A thimble-sized pollen sample can be removed without material damage to any preserved clams. A much larger amount of the clam-bearing matrix will be required to recover any enclosed seeds. Seeds are exceptional paleoenvironmental indicators and also provide our only hope for a radiocarbon date on the deposit. Seed extraction techniques will damage any embedded clams. The quandary: While we will recover more of each, should we emphasize clam or seed recovery?