Orange County’s Fossil Legacy

Editor's Note: Meredith Rivin, associate curate of paleontology at the John D. Cooper Center for Archaeology and Paleontology, recently gave a talk on the center and its collections. The following is a transcript from her talk, which can be heard using this link.

I wanted to talk to you not only about the collections — what they mean and how significant they are — but also what the Cooper Center is and what we’re doing there.

When we think of Orange County, we often think of shopping malls and freeways and crowds of people. I want to give you more of an idea of what's laying underneath all those shopping malls and freeways, and give you a real sense of place for where it is that we live.

The Cooper Center is located in Santa Ana; not on campus. It’s in the industrial portion of town, in a rather discreet building that’s actually intentional and partially for security reasons. That way we're just not attracting a lot of attention in the neighborhood.

But when you get past the nondescript exterior and get into the interior, that’s where you really see where the wonders are.

By studying and caring for these fossils in this facility, we’re then able to bring them out to the community and really share them with the citizens of Orange County, which we haven't been able to do in the past.

The Cooper Center actually occupies three building. The main warehouse is called the “Indiana Jones Warehouse.” If you’ve been there, you know exactly why. It looks just like the scene from the “Raiders of the Lost Ark.” This is where the majority of the collection is housed. It’s 20,000 cubic feet, and it’s full to the rafters.

The building was actually allowed to be used for the collections in 1978, a year after legislation was passed in Orange County requiring that material be saved from the construction sites in the county. It was full by the end of the decade, by the end of the ’80s, actually, because of the housing boom.

Another building is actually a World War II-era barn, and primarily holds the toll roads collections, so when they built the toll roads that went through the Santa Ana mountains and the San Joaquin hills, the collections ended up here.

The third is our lab and office building. It was a two‑story facility, which we gutted and converted to just one story, and we now have offices, preparation space and collection space.

The Cooper Center exists as a partnership between the County of Orange and Cal State Fullerton. The county is the legal owner of the collection, but Cal State Fullerton manages it, and in that way we can bring in the expertise and scientific minds to help to really make the collection what it's meant to be.

We have a memorandum of understanding with the county, and I’d like to go over that just to kind of show you what it is we’re trying to accomplish. There are a number of goals lined in that. The first is establishment of a collection management team and technical advisory committee.

Second, the most obvious goal, is the collection, curation and management of the collection. We are right now in the process of not only opening up field jackets that haven’t been looked at since they were excavated, but also repackaging material that’s in old cardboard boxes. We’re repackaging it into archival materials that’ll help against moisture and pests. And then we can move the more important collections into our new collection space.

Another goal is the public display and exhibition of collection items. This is particularly important, because this is when we’re able to get out to the community and really show them what it is we’re doing and why it’s important. I’ve been able to accomplish that in a number of ways already.

At the Ralph Clark Regional Park they have a beautiful exhibit, which they’re now working on expanding, and we've loaned them some specimens to use in their new exhibit hall. We also had a temporary exhibit up at the Fullerton Museum.

And we’re working on something at the Orange County Courthouse. In addition, there are specimens that are on loan from us that are displayed at the Los Angeles County Natural History Museum.

Our final goal is the accession of new items into the collection. When the county facility got full, the mitigation companies that are actually out there collecting materials from construction sites began storing this material and have done so for as long as 15 or 20 years. You can imagine the volume of materials that is out there.

The rocks of Orange County span the last 180 million years of earth history. This brings us back to the time of the dinosaurs, although dinosaurs in this area are very rare. Most of the rocks in Orange County are marine, which means they were lain down at the bottom of the ocean.

This period of time is very interesting because it signals the arrival of the major groups of mammals that we know today. And many of these units are actually from time periods that are not well represented anywhere else in the world.

The fossils themselves are collected as part of paleoentological mitigation. These are part of the environmental mitigation requirements required by the county.

The bulk of these collections are from construction projects. We have over 3,600 boxes, bags, flats and matrix blocks, and 360 field jackets of material. Now field jackets are the casings that field paleontologists use to protect items found in the field. In many cases we have no idea what’s inside these jackets until we can take them to the lab and excavate them in a controlled environment.

That’s the process we’re starting now. Approximately 6,000 specimens have been inventoried, but this is just a drop in the bucket because we estimate we have over one‑and‑a‑half million specimens from 600 sites in the county. The number of sites actually is probably going to grow as well.

Our new lab facility enables our volunteers to work in clean, controlled conditions to prepare and curate the fossils. We have hookups for pneumatic tools for the harder rock and a dust collection system, so you’re not breathing the dust and making a mess of the entire lab.

Once they’re cleaned and identified, our most important specimens don’t go back into the warehouse but are kept in our new collection storage area. The space is limited, but it represents a major step forward for the collection.

It’s climate controlled, temperature and humidity controlled, a locked room with locking cabinets in an alarmed building, so security's very good. This is where we're going to keep our most important specimens for the time being, until we have room to keep all of our specimens in these kinds of conditions.

Stepping Back in Time

This is my impression of the history of time in Orange County. We start back as far as the Jurassic, although we don’t have a whole lot of fossils from that time. Most of the bulk actually starts as you get into the more recent times, particularly the Miocene.

If you’re going through the Jurassic and the Cretaceous, just for those of you who aren’t particularly familiar with the time periods, this is the time of the dinosaurs. We were under ocean at this time, so dinosaurs are very rare.

We go through that time, there is, of course, the asteroid that wiped out the dinosaurs and heralded the age of the mammals. The first of this time period is called the Paleocene. We’re watching sea levels rise and fall throughout this time period, and then sometime in the early Miocene, the San Andreas Fault was activated. Then we get into marine rocks entirely, up until the Pleistocene, the very most recent time period.

Age of Dinosaurs

We’ll start with the earliest period of time in Orange County, the Mesozoic or the age of the dinosaurs. Giant marine reptiles and the dolphin‑like ichthyosaurs would have swam in our seas but we don't have a lot of record of them.

The county rocks primarily produce invertebrates — animals like ammonites and clams, and sharks, actually. These rocks haven’t been particularly excavated like some of the other units, because they exist in the Santa Ana Mountains. Some evidence of these animals might still be there waiting to be found.

More typical of what we find from this time are ammonites. They’re like a nautilus, a coiled cephalopod.

I can’t give a talk about paleontology without talking about dinosaurs. Only a handful have been found here, and they all represent one type of dinosaur, a hadrosaur, or duck‑billed dinosaur. They’re often called the cows of the Cretaceous because they’re big, common herbivores that were kind of everywhere.

There are places where you can go and see Orange County dinosaurs. There’s a nice display of some material found during the toll roads collection in the office of the Transportation Corridor Authorities in Irvine. Also, the Natural History Museum at L.A. County just opened a fabulous new “Age of Dinosaurs” exhibit. There, if you walk past the T. Rexes, past the Sauropods, the Triceratops, upstairs, around the marine reptiles and the Pterosaurs, in a dark little corner, there’s an exhibit of California dinosaurs. If you look very carefully on that exhibit, there’s one specimen, about two inches long, of a tooth of a Hadrosaur and that is from Orange County.

After this asteroid wiped out the dinosaurs and the ammonites, times were ripe for some pretty major changes to life on Earth. We all know the story. With dinosaurs gone, mammals were free to move out of the shadows and diversify into forms we know today.

The Paleocene and Eocene Eras

The first of these periods is known as the Paleocene. The Paleocene would have been much different than today's Orange County. It was a very warm period of time, and major groups of mammals that we recognize today had not yet appeared.

In Orange County, not many animal fossils have been found. We do, however, have a lot of plant fossils, including broad‑leafed trees, carbonized tree trunks and coal, and these testify to the dense jungles that covered the area.

The next period of time is known as the Eocene. The warm climate that started in the Paleocene continues through the Eocene. It is during this time that most of the major groups of mammals evolved, including horses, rhinos, primitive deer and primates. Modern dog and cat‑like carnivores didn't show up until later.

Most animals remained on the small side, likely because of the warm temperatures. The exception to this are the Brontotheres and their relatives. The Talega Rhino Quarry is a large deposit of what was happening during the Eocene in Orange County. We have 44 jackets from this one bone bed from San Clemente, and our volunteers are just now working to find out what's in these jackets.

What, exactly, is a Brontothere? They’re actually closely related to rhinos, though they’re not exactly rhinos. One species is called Parvicornis, and it is likely the same species as what we’re finding in the Talega beds.

Brontotheres came in a variety of shapes and sizes, some with bizarre horns and headgear. Their horns are actually made of bone, unlike rhinoceros horns, and were most likely used for display, not head‑butting.

Transition to Marine Environments

The Oligocene and the early Miocene record the transition from terrestrial environments in Orange County to marine environments. Some important animals have been found during this time period.

Those deer and camel relatives, the Oreodonts, were little browsing animals that lived in the undergrowth of heavy forest. We’re not seeing big grasslands with grazers arising in this area yet. Found in the Talega beds was Orange County’s first and only primate, though I’m anticipating finding more in the Talega beds, and California’s first bear, the Phoborogale, who represents the first immigration of bears from Eurasia. This animal was actually only about the size of a raccoon.

Later, in the Miocene, we get into the marine rocks, which make up the bulk of the record in the area. There have been four groups of mammals that have evolved to live all or most of their lives in the sea. These are the Sirenians, the manatees and the dugongs, the pinnipeds, particularly the seals and sea lions, the Desmostylians, which I’ll talk more about in a bit, and the cetaceans, which are whales and dolphins.

Probably the one that you don't recognize out of this group are the Desmostylians. These are an enigmatic group of fossils, in fact we know very little about them. They have been found in marine rocks, but still have four legs, capable of supporting them on land.

There is debate to how these animals stood on land, what group they are related to, what they eat, even whether they were herbivorous or carnivorous. They have very strange teeth that are made up of a closely packed cluster of polyps. There are aspects in the way that the teeth grew that indicate they may be closely related to elephants, and also to manatees and dugongs.

Orange County has a very large record of these animals, which are only known from the North Pacific. A cast of the skull a desmostylian is on display at the Toll Roads Office in San Clemente. It’s the largest skull of a desmostylian ever found: about four feet long.

There’s also a beautiful specimen on display at the new Age of Mammals Hall at the LA County Natural History Museum. This is a type of mammal called a paleoparadoxia, which means “ancient riddle”; a good name for the group.

The animal is actually on loan from the Cooper Center, although they cleaned it and had it prepared for their exhibit.

Pinnipeds Now and In History

Three common types of pinnipeds known off the coast of Orange County today are Harbor and Elephant seas and sea lions. Another family known in modern times, but not in Orange County is the walrus. In the past, they were quite common in this area.

Waldo is our most famous Orange County walrus. Unlike modern walruses, he doesn’t have the two large tusks that are diagnostic for the group today. Waldo is actually called an Imagotaria, which means imaginary sea lion. That’s because he would have acted and hunted something like a sea lion. He has got large canines and teeth that would have been good for hunting for fish. Also in Orange County is an animal called Gomphotaria, which is a walrus that had both upper and lower tusks.

Now, my personal favorite group are the whales. When I talk about whales I’m talking about the entire group that includes dolphins. Modern whales are made up of two different groups. The baleen whales, which includes the giant whales, including the blue fin and humpback.

Another group is composed of dolphins and their kin, including killer whales, sperm whales, river dolphins and beaked whales. Both groups arose from a common ancestor that had large teeth. In fact, the earliest baleen whales had teeth like these early ancestors. In a way, toothless baleen whales represented an actual missing link between these different groups. It’s not missing anymore. We now know several specimens of this group.

We have found at least four types of toothed baleen whales in Orange County, from a time period when it was thought that all these types of whales had gone extinct. The Orange County collections changed that and round out that diversity.

The Pleistocene

Now, the final period I want to talk about is the Pleistocene, which started two and a half‑million years ago. The Pleistocene is often called the Ice Age. When I talk to kids, I know they imagine the world covered in snow and ice.

That’s actually not true for Southern California, except for the highest altitudes. The glaciers didn’t quite get down this far.

But we still have all the familiar characters of the Ice Age: the giant ground sloth, horses, mastodons and American lions.

The most famous place you think of when you think of Ice Age animals is the La Brea Tar pits. Now, you have to remember that prehistoric animals didn’t really understand county lines and would often walk across them. A lot of the animals that we find at the La Brea tar pits are also found in Orange County, although not quite in the volume and level of preservation that they have there.

Again, if you would like to see them, you should go to Ralph Clark Regional Park, which is a beautiful museum on Orange County Pleistocene fossils. They’re actually building a new room, which will house some of the marine fossils, like I have shown you earlier.

I want to thank you all for coming and listening to me and what I had to say here. I would also encourage you to get more involved as a volunteer at the Cooper Center. You can visit our web page.

We also have a Facebook page, where I keep the up‑to‑date activities at the Cooper Center. Pictures from the lab, talks that are coming up, I keep them updated on the Facebook page.

Thank you very much.

 

Dec. 16, 2011