17 October 2009

update: out of 7A, back in to deposit 1

they escaped from the tar pits, but not from each other: these two dragonflies were
found flying around together, attached at the hip by asphalt. Michelle kindly helped
free them. From 7A and back into 1

Right. So we've been working steadily in deposit 7A, and are about 1/2 a meter down in all areas. There were three bones immediately visible on the surface (all sliced by the tractor that found them, and horribly dried out), but other than that we've yet to find any substantial vertebrate fossil deposit. We've found a few scattered pieces of turtle shell (not to mention some extremely odd fragments of mineralized bone -- very rare for Rancho la Brea!) but none of the big jumbly bone masses we've come to know and love. What we have found:

Shells shells shells! From 7A and back into 1
Gastropods! And lots of them.

excavator hand for scale, From 7A and back into 1

These freshwater snail shells are further contextualized by the immense amount of plant material we've been getting out of the deposit as well; the northeastern corner of the deposit is filled with what appear to be tree branches (but possibly roots). Additionally, there's some interesting stratigraphy going on in this deposit: layers of river sand and large rounded rocks.

But as of yet no big vertebrate fossils. Boo.

For that reason (and because we're acutely aware we're already one year into a five year project!), we've put deposit 7A on hold, and re-doubled our efforts in deposit 1 (the big box we first started in).

That's usin' your head, Russ. From 7A and back into 1

And we've made some really impressive progress! But more on that next post. Until then, I leave you with this month's "What is it?" Check out the photo below, and leave a comment with your guess of species and element! Correct guesses win a congratulatory shout out on the next post, and the knowledge that they have bettered their internet peers!

I'll give you a hint: it's a fossil. From What is it?
Happy guessing!

01 October 2009

what we did over our summer vacation:

The scarab beetle in our compost pile says hello
From End of 7B, Beginning of 7A

Well, not a vacation from digging -- just a vacation from blogging. Apologies to all, and regular updates will commence henceforth. SO:

Nola hammers the lid on the last matrix bucket from deposit 7B
From End of 7B, Beginning of 7A

We finished excavating deposit 7B in early August. Final tally of things found is still pending, but all in all, it was rather pleasantly fossiliferous. Some of the cooler finds include a number of potentially associated bison bones (the bison itself has been named James K. Polk), a mostly complete sabertoothed cat skull (named Bixby) (I will have to explain our naming conventions in a later post...), several unusually large sabertoothed cat limb bones that might belong to Bixby, several rattlesnake vertebrae, a gopher skull, the usual slew of dire wolf bones, and lots and lots of tree branches (tentatively ID'd as manzanita). And nicely enough, 7B continued to produce bones down to its final few layers:

Sabertoothed cat cervical vertebra
From End of 7B, Beginning of 7A

This sabertoothed cat vertebra was found at the very bottom of the deposit. As you can see, the right-hand side of the vert was sheared off in the process of putting a bottom on the box -- no good! Ah well -- such is paleo-salvage. Of the 327 buckets recovered from the LACMA site, a substantial number were labeled "Deposit 7." Someday (hopefully sooner rather than later), we will degrease the buckets and try to find this vertebra's missing half, but for now, we best be moving on...

Deposit 7A
From End of 7B, Beginning of 7A

...to deposit 7A! 7A's a bit bigger than 7B, so we built this nifty railing to keep us from plummeting to our deaths (or, more likely, tumbling to a sprained ankle, but whatever, SAFETY FIRST dang it), and we've got some strategically placed Little Giant ladders around to help us in and out. But check out that silver thing on the side:

it's like a slide for matrix! wheee!
From End of 7B, Beginning of 7A

Rather than breaking our backs hauling buckets in and out of the box, Michelle came up with the great idea of leaving the buckets on the ground, and using a make-shift funnel to pour the matrix in. GENIUS! And I can't believe we didn't think of it earlier. It's not about working harder -- it's about working smarter.

After finding deposit 7B fossiliferous to the very end, we had high hopes for 7A, but were (understandably, I think) a bit disappointed to find only this dehydrated mess greeting us on the deposit's surface:

that chalky stuff in the center is bone. ugh.
From End of 7B, Beginning of 7A

Blech. Nevertheless, we soldier on! We've been working on Deposit 7A for about 2 months now, and we have found a few specimens, here and there...

Laura finds a specimen here, a specimen there...
From End of 7B, Beginning of 7A

...but more on that next post, which I promise will be next week (I don't want to overwhelm you after my long absence). Cheers!