update: more sabertoothed cats and kittens

Solar flares over our pulley. From Back in Dep 1

As I reported last post, we've moved back into the big box: Deposit 1!! And look how excited everyone is:

Volunteers Christina Lutz and Tara Thara. From Back in Dep 1

Those are the smiles of happy fossil finders. Why? Because they're actually finding fossils again! Between mostly planty deposit 7A, and really hard and sterile parts of deposit 1, we're been spending entirely too much time digging up dirt rather than fossils. Dirt = not fun. Fossils = awesome. It's very simple.

I've posted many, many pictures of this bone bed before (it's where we found our North American Lion skull and assorted long bones). And it's once again producing some really great feline finds:

Sabertoothed cat skull! From Back in Dep 1

The big dusty skull-looking thing on the bottom is a... big, dusty sabertoothed cat skull, with a complete sabertoothed cat pelvis immediately above it. And look a little above the skull and to the right:

Smilodon saber in situ. From Back in Dep 1

It's a complete sabertoothed cat saber!

Smilodon saber in one piece! From Back in Dep 1

And in the grid directly across from this one, we found 2 more sabertoothed cat kitten sabers:

Volunteer Steven Wintergerst holding a Smilodon kitten saber From Back in Dep 1

This may bring our (estimated) minimum number of sabertoothed cats in this deposit to around 7: 3-4 juveniles, 1 sub-adult (teenager) and at least 2 adults (I will have to double check these number with the lab). It's actually possible to match sabers to skulls, by taking casts of the alveolus (tooth socket) and comparing the cast to the tooth! This is something we might want to do in the distant future; because this deposit is so small we may be better able to discern which bones belong to which individual cat -- especially for these 4 "kittens" we've found. Yes, they're all young, but they're not of the exact same age (which makes me think this isn't a singular litter that got stuck). So by determining the age of each young sabertoothed cat bone we find, we can figure out whose limbs are whose, and then perhaps extrapolate from that how much the asphalt has moved/disturbed the skeletons since they first got stuck 10-40 thousand years ago.

In non-mammalian news:

Turtle shell! From Back in Dep 1

2 partial turtle shells have come out of the formerly sterile areas west of the main bone deposit. Turtle shells are made out of a number of interlocking plates, and while the individual plates are extremely common, articulated/associated ones are not -- in fact, these may be the only even semi-complete shells we've ever found at Rancho La Brea. Trevor's been working on them in the lab, and has one of them somewhat reconstructed (which he will hopefully tell you all about at some later date if he ever gets around to making a blog post, hint hint).

FINALLY two other items of business:

1) This is Carrie!

New excavator Carrie Howard! From Back in Dep 1

She works here now! She likes rocks and photography and is generally great.

2) I don't often share links on here, but for those who are interested in science education in America and the general fight to keep evolutionary biology from being grievously misunderstood may find http://www.dontdissdarwin.com/ helpful.

Next post: so, what's in that barn-looking building next to the trailer?

Greg A. hunts for lunch by Pit 10 From Back in Dep 1

No, it is not dinosaur! It is a degreaser, which is far more useful and hopefully far less dangerous! More later.

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!

a small but big discovery

Hello! We found a very neat thing a few weeks ago:

It's a bird! It's a plane! It's-- wait, nope, it's a bird. The many small bones in the upper left-hand corner (with the big arrow pointing at them labeled "bird") are all from a small passerine, (or "perching bird"). These bones likely represent an associated individual; they were found in a slightly separate layer of asphaltic sand than the rest of the deposit, and some bones even appear to be somewhat articulated. In other words: this is the almost complete skeleton of a small bird; this is extremely rare; I have named him Kevin.

Though most birds are passerines, they are nevertheless rare at Rancho La Brea; our collections are dominated by bigger birds of prey like teratorns and condors. It's hard to say what species Kevin is, exactly -- especially without cleaning and preparing the bones first -- but Lab Supervisor Shelley says he's about the size of a scrubjay.

The bones in the numbered in this photo are as follows:

1. carpometacarpus
2. scapula
3. 2 limb bones -- not sure which exactly
4. sternum
5. tibiotarsus? I think?
6. tarsometatarsus
7. femur?

The photo above was taken after removing a number of other bones separately, such as ...

the furculum...

another scapula...

...and a humerus (as well as an articulated synsacrum and femur, several vertebrae, and several phalanges that I don't currently have photos for). After removing these uppermost bones and discovering there were even more underneath we decided to remove the rest of the skeleton in one block...

which was accomplished by gently prying the layer of asphaltic sand it was rested in with well-placed screwdrivers and chisels.

Though this skeleton is exciting in and of itself, its context may actually be more important. As regular blog readers may remember, up until now Deposit 1 has been more dirt than fossils. There's a dense cluster of bones in the southeast corner that has yielded at least 1000 specimens (and at least that many more to come), but about 3/4ths of the box has been largely sterile. Not anymore. As we dig deeper into the so-called "sterile" areas, we've found a new layer of fossils:

This is a different style of deposition than in the "main" bone cluster we've previously worked on:

1. These fossils are spaced further apart, and spread out more evenly -- not all jumbled together like pick-up-sticks.
2. These bones are broken, weathered, and worn. The bones in the other cluster are largely complete
3. Many of the longer bones and bone fragments point in the same direction (scroll back up to the top of the page to get a closer look) -- perhaps implying stream movement? We don't know! But it's interesting...

Kevin was found in the northwest corner of this grid (near where the meter sticks cross) in a slightly separate layer of asphaltic sand -- perhaps implying that he flew in and got stuck after the rest of these unlucky beasts? Again -- we don't know! But also interesting! We will keep you posted as things and finds progress.

update: the demise of deposit 10a, the flattening of deposit 1

After about 8 months of digging, Deposit 1 is finally starting to look markedly different than it did when we first unveiled it -- well, to us, at least. Yes, it's still a dusty hunk of rock, but now it's a dusty hunk of rock that's around half a meter shorter than when we first got it.

As I've hopefully mentioned before, we work in 1m x 1m grids, and dig down 25 cm at a time. You've seen this before:

...the large, convoluted bone mass that was keeping us from "closing" grids B-1 and B-2 and moving on to other portions of the box. In both grids, we're working on level 3, which is the section of dirt 50-75 cm below the original ground level of the deposit. Does that make sense? Those large saber-toothed cat scapulae and innominates were sticking out above floor (the bottom of each 25 cm deep level) and needed to be removed before moving on.


Now the grids look like this:

Yes, there are still bones, but if you look carefully, you'll note a wonderful lack of scapulae...

...because Tara got the last one out! Everything left in place is too far below floor to excavate at this time. The grids surrounding the bone mass are still at level 2, so we have to get those down to level 3 before we can open up grids b-1 and b-2 at level 4. Did that all make sense? Excavational peccadilloes are difficult to describe via the interwebs. To sum up: if we keep excavating just the main bone deposit, we'll wind up with a giant hole in the ground (in the box) which will be too deep to keep digging at. So: sterile grids for us, for a while.

In non deposit 1 news: as Ryan and I have both mentioned, 10A is no more! We time lapsed it's final moments:

I have to say, I like the soundtrack to this one better than last week's, but I don't think anything will match excavation to the tune of "I Am the Walrus." Ah well.

Next week: we just laid grid lines out for 5 new deposits -- 7A-E! We're very excited to start work in new, softer dirt. Pictures soon to follow. OH! And click through to flickr to check out the giant freaky black (and brown) widows Laura and Michelle found under 10A.

more fun with time lapse

We've been having a lot of fun with the built-in intervalometer on our new camera:

expect more videos like this in weeks to come! To our email subscribers -- the blank space you see above (and in my last post) is actually a youtube video embedded in the blogpost, which unfortunately doesn't seem to translate to email. Go to excavatrix.blogspot.com to view.

Note from the Lone Male Excavator:

Y'all need to chime in and tell Andrea what a good job she is doing on this here blog a'ight!

We've got a lot done since my last post. Finished another box, matter-O'-fact (10A)! We've busted out them there scapulae from box 1 and got loads more dirt out to, eh.

Keep yer eyes open for a new "what is it" post coming soon!

-Ryan

8ish hours in 80ish seconds

weekly update: all in a day's work.

Yes indeedy, as Ryan pointed out last week, we have finished excavating our very first deposit from Project 23:

10B is no more! And its big sister 10A is soon to follow:

We're down to Project 21-and-a-half. The small patch of fossils from this deposit seems to have petered out. We can't be sure, but we're thinking the remaining few feet of dirt are largely -- if not entirely sterile. The boundaries between grids are left in place until they're completely exposed, and then mapped and photographed. This way, we can reconstruct the deposit's geology long after the deposit has been excavated.

And 5B looks much the same is it did last time I posted, only sans a level of plywood around the sides.

We're waiting to speak to one of the geologists who originally supervised the salvage before we begin digging.

Meanwhile, in Deposit 1....

We're still plugging away at the main bone jumble in Box 1. We've measured out at least another 100 fossils from this area. Right now, however, we're at a bit of a standstill, stuck between a rock and a hard place so to speak. Or rather, a scapula (shoulder blade) and an innominate (one half of a pelvis):

Pleistocene pick-up sticks once again! From left to right: we can't get the first innominate out without removing the scapula immediately above it, but we can't get that scapula out because of the saber cat vertebra immediately above it. THAT's stuck under the middle scapula, which is in turn pinned in place by next-to-last scapula, which is, of course, covered by both a cat humerus (lion or saber cat, not sure though) and yet another scapula.

This is all very detailed, very slow work. However, on the other side of Box 1, we get the other end of the paleo-work perspective:

This is Grid D-3/Level 2 at 9am. Mouse over to see it at 5. Or, just scroll down:

D-3 is largely sterile, except for the occasional articulated millipede or bit of plant matter. This means we can power through it as quickly as our muscles allow. Spencer and I worked on D-3 all day, and chiseled out about 5 full buckets of matrix! Hard, hard work, as evidenced below:

6 blisters on my right hand! Badges of honor, all.

weekly update: back to basics

It has been one heck of a week here at Rancho La Brea; we were on almost every local news channel, the LA Times, the NY Times, the Brisbane Times, and even a couple papers from Norway ("We can not so many of these, such as deer to tigers sword" indeed!). In light of this newfound limelight (and in light of the exponential increase of blog subscribers!) I want to take a minute to get back to basics.

So for those just joining us: I'm Andie, and I work here, along with lead excavator Kristen Brown, fellow full-time excavator and lone male Ryan Long, and part-time excavators Michelle Tabencki and Laura Tewksbury. Project 23's intial beginnings are described in this blog post and many others found on this site. To date, we've excavated at least 700 fossils (and calculated a minimum number of individual animals of at least 2 dozen). Current tally includes at least:
-3 saber-tooth cats
-1 lynx
-1 North American lion
-6 dire wolves
-2 coyotes
-1 Harlan's Ground Sloth
-1 baby bison
-1 baby horse
-2 dwarf pronghorns
-LOTS of turtle
-at least 5 birds (including a teratorn!)
-LOTS of millipedes
-LOTS of oak leaves
and much much more

And our excavation site currently looks like this:

If anyone reading this works in the Variety building, we really want to take pictures from your rooftop...

Deposit 1 (on the right) is the first one APRMI found during the salvage, the biggest box overall, and the first one we started digging in. Also, it looks like a pirate ship, which pleases us immensely.

Deposit 10A (more lifeboat sized...) is also being actively worked on.

looks like Laura found a fossilized meter stick!

It hasn't yielded nearly as many fossils as Deposit 1, but did give us an interesting piece of turtle which might be new to Rancho La Brea, so that's pretty nifty.

Box 10B -- 10A's smaller, slouchier half -- is also being worked on, but can't be seen from the fence. Part of it collapsed while APRMI was boxing it up, however, so we're not taking as much locational data as we usually do.

And finally, Box 5B. We just opened this one a couple weeks ago, mostly to get an idea of what our next area of focus will be when we finish the 10s. We won't actively begin excavation until they're done. However, we've already found some neat stuff in it...

seriously: it is NOT A FOSSIL

...like this NOT FOSSIL wasp nest. It was on the side of the box under the tarp (again, NOT A FOSSIL). A neat instance of modern life co-existing (well, until the nest was abandoned..) with the extinct.

We continue to excavate 7 days a week (except for bank holidays and whatnot) and will happily talk to you if you stop by, provided we are not lunching, operating heavy machinery, or performing particularly delicate fossil extractions, and you do not try to throw things or yell rude questions (i.e. "Did you find my lost contact yet? Hyuk hyuk hyuk.") at us. We love our jobs, and love sharing our discoveries with you, and THANK YOU for your continued interest and support of natural sciences in general, and Project 23 in particular!

Additionally, there have been a number of questions posted as blog comments over the past week, which we'll answer ASAP. But as for now, we have some serious digging to do.

update: PROGRESS

Remember this?

Flip it upside down, replace employee Michelle with volunteer Christina, add in a heat gun, and you get THIS:

That, paleo-friends, is the skull of a North American Lion -- Panthera atrox. We finally finished removing all the bones around it, and thus successfully excavated the skull!

But first, here are some interesting inferences about North American Lions, provided by our fair leader, collections manager Christopher A Shaw:

- North American Lions showed up in their eponymous continent (North America) around 400k years ago

- They were probably not social animals -- in other words, there were no prides of these particular lions. We think this for two reasons:

1. We don't find nearly as many of them as we do dire wolves and sabertooth cats, and not with nearly the same range of ontogenetic age. For example, we've found approximately 6 North American Lions in Pit 91, compared to around 50 Saber-toothed Cats.
2. In a pride of African lions, the ratio of males to females is 1:6 or 1:7. Here at Rancho La Brea the ratio is about 1:1. Thus: no African Lion-esque prides. North American Lions likely had a more solitary lifestyle, more akin to that of a mountain lion.

- These lions likely did not have manes. Cave drawings in North America exclusively feature mane-less lions -- either that, or only females, which doesn't seem very likely.


Back to our skull: after months of carefully using dental picks to clear out the surrounding matrix, we eventually had to resort to brute force to get the lion skull out.

That's me on the left, Michelle on the right. I'm rocking the skull back and forth on its side to loosen it from the surrounding matrix; Michelle is holding on to a bone underneath the skull to keep it from coming out along with the lion. Aisling wisely thought to film the entire process:

Background soundtrack provided by: Marketplace with Kai Ryssdal on NPR; Laura Tewksbury singing; various lab volunteers cheering; and me saying "there's a frickin humerus attached to it!" A great orator, I am not...

Though quality on this video isn't the best, it is good enough to show just how tough it is to get something out of an asphaltic deposit. Even after putting all of my weight behind the skull, at first it barely moves. However, after some artful wiggling (and a decent amount of luck) it's out!

And there was much rejoicing! Yes, I could have continued removing matrix with the heatgun and a dental pick until the skull basically fell out. However, the more you use a sharp pointy object near a priceless artifact, the more likely it is that you scratch aforementioned priceless artifact (or one of the other 20 priceless artifacts under the skull that you can't even see and will therefore probably put a hole into). Thus, every once in a great while, it's better to use your bare hands and just push.

The skull itself is an absolutely beautiful specimen; it's the most complete P. atrox skull we've gotten out of the current excavations (i.e. Pit 91 and Project 23).

Look at all those bones I could have damaged had I continued using a dental pick! The crescent shaped bone in the lion's mouth is a horse hoof; there's a complete saber cat rib in the back; and yes, on the right -- there's a fricken humerus attached to it. Sabertoothed cat humerus, to be exact.

And now that the skull's out, we can get on with our excavation.

These are just a few of the bones that are now accessible thanks to the skull's removal. Click the picture above to be taken to our flickr site, where you can mouse-over individual bones and find out what they are.

As for our skull...

Laura promptly carried it off to the lab, and rumor has it that Herb will begin cleaning it in a few weeks. We think we'll name it Fluffy.

update

happy non-denominational seasons greetings and new year

It is 85 degrees Fahrenheit in Los Angeles right now. In January. In what is supposed to be the dead of winter. We are mildly confused, but not complaining; digging in asphalt is so much easier in the warm sun! The matrix in two particular grids -- A-1 and A-2 -- has been soft enough to dig through using our fingers. Findings of note:

This jaw is from a small wildcat, most likely a Lynx, per collections manager Christopher Shaw. We don't have that many bones from smaller cats in our collection at the Page Museum for two reasons: 1) these smaller cats were likely solitary, so when they got stuck in an asphalt seep, they got stuck alone -- not with 15 of their closest friends, as with Dire Wolves and Saber-toothed Cats. 2) smaller cats have small bones, and early fossil collectors (during the early 1900s) would have likely passed them over for larger, more obviously interesting fossils like, again, those of the Saber-toothed Cat. This is what's called a collection bias: the arbitrary favoring of one kind of fossil or specimen over another. One of the main goals of the excavation in Pit 91 and with Project 23 is to correct this bias. Thus, we collect and keep everything -- even the stuff that might not seem obviously important at the time. For instance:

In grid A-2/Level 3 I found two bird tibiotarsi (i.e. drumsticks) immediately on top of one another. They're definitely from the same species (but I don't know which one), one tibiotarsus was a left and the other was a right, and they are about the same size. This may be a case of association (two fossils from the same individual animal), or it may be just a really weird coincidence. But it kind of doesn't matter: it's an unusual enough case to warrant thorough documentation. Pictures, notes, and measurements have been taken, and preserved for posterity. I am but a lowly excavatrix -- not a proper paleontologist -- and I haven't the years of schooling necessary to interpret this assemblage. But good data collection will hopefully benefit actual paleontologists of the future, as they dive through field notes and make the interpretations that we excavators couldn't. Ryan, our sole man, noted the following:

The orange bits are a complete oak leaf found from a largely sterile portion of Deposit 1. We've found a large number of plant parts, and a good number of oak leaves in this deposit. We don't know what plant is worth collecting and what isn't, so we try to collect as much as possible. Again, this is something for future scientists to interpret. And it's our job to make sure everything's collected in as complete a manner as possible. Finally, an eagle-eyed volunteer (hi Spencer) spotted the following:

a pile of orange dirt. While this wouldn't be surprising in any other fossil deposit, anything with any hint of color at the La Brea Tar Pits is worth noting. So a sample was collected, notes were taken, and hopefully this will give us some insight into the depositional environment around this particular deposit.