28 September 2008


Long time, no update, but with good reason: we finally officially "opened" our first fossiliferous grid in our first fossil box from Project 23, and we've been too busy digging to blog. Hopefully, some pictures will make up for the thousand or so words we have not written.

Below, a view of B-1 circa a few weeks ago:

roll-over for highlight

The three highlighted bones above are all tibias, and are all from the right leg. However, they're from three separate animals:

From left to right, you're looking at lower right hind leg bones of a coyote, a dire wolf, and a young saber-toothed cat.

We finally got the saber-toothed cat pelvis off the top of the grid:
Note the pelvis-shaped impression in the ground to the left.

Volunteer-of-the-Century Harry made us a brand new tool box:

which now holds our brand new phone, our brand new field notebooks, our brand new meter sticks, our really-old-but-still-totally-useful comparative collection of dire wolf and saber-toothed cat carpals and tarsals (wrist and ankle bones), and, apparently, my three-hour-old cup of coffee.

And speaking of volunteers, we've started bringing them up to help us dig! Tara-the-ever-persistent, of course, was our first:

And finally, we put together a small exhibit for the museum explaining how Project 23 came to be:

The two ribs on the left of the case are from our semi-articulated mammoth; the rib on top is normal, but the rib on the bottom has a large bump in the middle from a break that healed during the mammoth's lifetime. Zed (as the mammoth has been dubbed by lab supervisor Shelley Cox) has several broken-and-re-healed ribs on his right side; he must have sustained a massive injury which he subsequently recovered rather nicely from. And the fossil block on the right is the same block of skulls that came from the "blob" we wrote about last month. The brown vertebra in the middle is from Zed; the white vertebra above it is from Jenny:

Shelley borrowed an Asian elephant skeleton from the Natural History Museum and has been using it to help identify Zed's (much larger, but still comparable) elements. In the photo above, Shelley is comparing Zed's ribs to Jenny's (Zed's are La Brea brown; Jenny's are white).

More soon!

16 September 2008


One of the most frequently asked questions we get here at the La Brea Tar Pits is one so deceptively simple sounding that it regularly stumps us out of sheer, monosyllabic force. It's not that we don't have an answer -- it's just that the answer is exponentially longer and more complicated than the question.

That question, of course, is "Why?" Why, with a collection of more than 3.5 million fossils, do we keep digging? Don't we have enough fossils? Do we really expect to find anything new?

Some of the answers to these questions, in reverse order, are:

1) We find something new every week, if not every day. Not a new species necessarily, but things like a new and uniquely laid out deposit of fossils (such as our two associated sloth scapulae), or new information on the geology of the deposit. Mini-discoveries like these help color our continually evolving picture of the Pleistocene in Los Angeles. Now, new species are difficult to come by, but with this new project, we have sheer volume on our side. With the amount of fossiliferous dirt we have to dig through, we'd be surprised if we didn't discover a new type of animal.

2) You can never have enough fossils.

3) Now, the big question -- the big "WHY?" There are far more answers to this question than we could possibly cover in one meager blog entry, and many of which we hope to touch on in coming months. As for now, you'll have to settle for this lovely and informative graphic put together by one of our most dedicated volunteers, Tara Thara:

Click on the diagram above to be taken to Many Eyes website, where you can play with the image a bit more extensively. Currently, we're looking at the age of individual vertebrae organized by taxon; if you click through to Many Eyes, you can change that to compare, say, age by depth, or taxon by grid, etc etc.

Man, computers are great. One of the many many reasons we have to keep digging is because with statistical comparisons like the bubble diagram above (created from our Pit 91 Vertebrae Database), the more data, the better. In this chart, we're using the ontogenetic age (the developmental age of the bone) of different vertebrae to generate an estimate of how many very juvenile, juvenile, sub-adult, and fully adult animals we have in Pit 91. And from that information, we can make inferences about the animals' behavior in life. For instance, the large number of sub-adult saber-toothed cats found at Rancho La Brea has led some (such as my boss, Chris Shaw) to believe that Smilodon was a social animal -- the young cats would have gone after a trapped herbivore in the tar pits with their fully grown relatives, and all gotten stuck at the same time.

Now, the caveat to this -- the idea that more data creates more reliable statistics -- is that the dataset must be somewhat complete. Pit 91 hasn't been totally excavated yet -- we've got another 3-8 feet of asphalt to dig through, which equals tens of thousands of more fossils to find -- and we won't be able to make any final conclusions until we're done. On top of this, the database itself isn't complete; again, we have thousands of fossils that have been excavated and identified, but still need their data entered into the computer. However, with Project 23, we're hoping to enter the information into a computerized database as we dig. And since we'll be digging year-round with a much larger staff (as opposed to 12 weeks in the summer with a staff of two) we'll be able keep on top of data entry, and we'll be able to finish excavating each deposit in a much timelier fashion (i.e. under than 30 years).

So that, readers, is one of many reasons why we must keep digging. Population studies demand more data! Databases demand more data entry! And basic human curiosity demands that we slowly, steadily, someday reach the bottom of our inverted Everest.