La Brea Tar Pits and Museum

Bite marks on a baby bison pelvis?

According to Research Associate Chris Shaw, these marks were made by a carnivore. There are two clearly defined depressed fractures on the anterior medial (inner) surface of this ilium (part of the pelvis) and one on the lateral (outer) surface, suggesting that this animal was bitten by a carnivore hard enough for their teeth to puncture the bone. These sorts of paleo-pathologies are not very common at Rancho La Brea and this is the first evidence of possible bite marks identified from Project 23. In Box 1, excavators have found the remains of several baby bison.

Box 12 Oak Leaf

This leaf, most likely oak, was found in the hard asphalt of Box 12 last week. It is another example of the excellent preservation of plant material found at the La Brea Tar Pits, having retained its color from when it fell into the asphalt tens of thousands of years ago. Project 23 has even yielded mats of oak leaves, particularly in Box 1, in which we also find the remains of some of the detritivores who used to live in this habitat.

We can see the boards on the bottom of box 1!

Deposit 1 is the first box of Project 23 that has been opened, and it is also the largest at an estimated 123,000 pounds. From the surface to its base, the deposit is just more than nine levels or 230 cm (7.5 feet). After 3½ years of digging, we have just reached the bottom of it in grid A-1!

Cataloging Project 23

Although we have probably excavated over 16,000 bones from Project 23, there is a backlog of preparation, identification, cataloging, and databasing all of this material. This is specimen number P23-10,001. It is a proximal anterior rib of Clyde; a semi-articulated camel from Box 5B (Camelops hesternus). Clyde’s skull and lower jaws were also found and are currently still being prepared in the Fishbowl Lab by volunteer Nola.

Capromeryx terminal phalanx found in Box 14

Discovered this week in Box 14 by volunteer Beau, this tiny fossil is a terminal phalanx of a juvenile dwarf pronghorn, Capromeryx minor. It's an element that none of us current excavators had ever come across before! In fact, out of all the 602 records of Capromeryx minor in all of the collections here, only seven are terminal phalanges. Within Project 23, there are 40 records of Capromeryx minor so far. Five have been found in Box 14 and indicate at least one adult and one juvenile in that deposit so far. 

A shrew incisor

This tiny black tooth (a right lower incisor) measuring about 1mm, was just identified in the Fishbowl Lab under the microscope. It is pictured here with the complete right lower jaw of a modern specimen of long-tailed shrew (genus Sorex) for comparison. The red on the tips of the teeth is accumulated iron which may function to strengthen the enamel. The diet of a shrew consists mainly of arthropods and their closest relative is the mole. Either due to their diminutive size or their rarity in the L.A. basin, there are only 20 specimens known from the tar pits.

Zed’s left tusk plaster jacket is open in the Fishbowl Lab

Zed's tusk when it first came into the Fishbowl Lab
Lab assistant Trevor and curatorial assistant Gary examine Zed's tusk

Finally, after tens of thousands of years, our Columbian mammoth Zed’s left overgrown incisor sees the light of day. Well that is except for the few days when it was discovered and before it was covered with a protective plaster jacket. On public view in the Fishbowl Lab we have begun the process of carefully removing the protective plaster jacket to reveal the tusk. Thus far it looks to be well preserved with some asphalt on the surface between the sediment and the tusk.

Broken and healed tibiotarsus of a bird

Pathologic bird bone still in the ground
Pathologic bird bone cleaned and ready to be cataloged

Among the recent discoveries at Project 23 is this exquisite left tibiotarsus (shin bone) of a large bird of prey, probably a Golden Eagle. This is no ordinary shin bone, however. As you can see, the asphalt has preserved something from the life history of this bird — a healed compound fracture in the middle of the bone. This paleopathology also shows evidence of massive infection. The interesting thing to note is that this broken leg did not kill this animal since it lived long enough to show extensive healing.

It's time to glop

We are taking a break from excavating at Project 23 this morning to take care of some maintenance in Pit 91. Since this site is the lowest point in Hancock Park, water accumulates here. We are also constantly battling the seeping asphalt that clogs the drainage channels and covers the fossils. Suited up in protective gear, we are removing the asphalt by hand (known as glopping) and cleaning out the debris that has fallen in over the past few months.

Delicate articulated beetle leg discovered in Box 14!

Box 14 is turning out to be a very rich microfossil deposit. Careful excavation techniques revealed this articulated beetle leg still attached to its abdomen after tens of thousands of years!