Was Hancock Park Beachfront Property 120,000 Years Ago?

August 16, 2016


Pacific Gaper Clam: A large, common bivalve that inhabits sandy areas of bays along an open coast, often buried a foot or more. Today it ranges from Humboldt Bay northern California to Punta Rompiente, Baja California Sur.

Metro Fossils

Asphalt soaked fossils are not new to the Hancock Park area of Los Angeles and most residents are already familiar with the iconic mammoths, saber-tooth cats, and dire wolves on exhibit at the La Brea Tar Pits and Museum that are between 11,000 and 40,000 years old. However, in 2014 during test excavations for a future Metro Purple Line Station at the corner of Wilshire Blvd. and Ogden Dr., a deposit of late Pleistocene marine fossils (120,000 to 300,000 years old) was excavated.

Big News for L.A.

The find made the front page of the Los Angeles Times and indicated that more fossils would likely be discovered as construction continues. What made this fossil collection unique from other marine Pleistocene deposits in the Los Angeles Basin is that the fossils are saturated with gooey asphalt much like the specimens collected from the La Brea Tar Pits. However, at 120,000 to 300,000 years old, these fossils are much older than those from the tar pits and were deposited much deeper. How did this occur? Asphalt migrated towards the surface along a buried fault, possibly the San Vicente Fault, from the Salt Lake Oil Field beneath Hancock Park. As it rose the asphalt encountered marine fossils in strata of the “San Pedro Formation” and saturated them completely. The asphalt eventually reached the surface where the tar pits ultimately formed.

A California Butter Clam found during Metro Purple Line construction. A large, common bivalve that lives in muddy/sandy areas of bays. Its modern range is from Kodiak, Alaska to Bahía Magdalena, Baja California Sur.

A Marine Fossil Bonanza

The 2014 discovery included a suite of invertebrates (animals without a backbone) that are indicative of a shallow-marine environment very much like that of modern Santa Monica Bay. In fact, large numbers of near-shore species such as the Pacific Gaper Clam (Tresus nuttallii) and the California Butterclam (Saxidomus nuttalli) indicate that the shoreline may have been in the Hancock Park area over 100,000 years ago! Over 60 species of mollusks, sea urchins and sand dollars, barnacles and crabs, worm tubes, moss animals, and encrusting hydrozoans were identified from this exploratory site that is 60 to 80 feet below street level.

One Extinct Species

With one exception all of these invertebrate species are still living. The single extinct species is a large Slipper Shell (Crepidula princeps). In 1970 paleontologists James Valentine and Jere Lipps reported a small assemblage of asphalt soaked marine invertebrates from a construction site just east of the current excavation. Unfortunately, the collection was lost, but field notes made available by Jere Lipps indicate that these two faunal assemblies are very similar. As subway construction proceeds westward it is anticipated that there will be a lot more of these marvelously preserved fossils unearthed for ongoing and future research.

So … over a 100,000 years ago the surf was indeed up in Hancock Park! Cowabunga dudes!

A tray of Pacific Gaper Clam specimens, ranging from juveniles to adults.

**Writing and photographs by Lindsey Groves, @Malacology Collections Manager.

Reference:

Valentine, J.W. and Lipps, J.H. 1970.  Marine fossils at Rancho La Brea. Science 169(3942):277-278, fig. 1.

 


(Posted by: Lindsey Groves)


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Kid Citizen Scientist Finds First Snail for Project S.L.I.M.E.

March 18, 2015

A few weekends ago, citizen scientists from all over L.A. came to the Museum to see what they could find hiding in the damp and cool shadows of our Nature Gardens. Twenty people joined Museum experts (Lindsey Groves and Florence Nishida) to search for slugs, snails, and fungi—those often overlooked decomposers that break down dead and decaying material. They were also the first people to test out our latest and greatest citizen science project, S.L.I.M.E. (Snails and Slugs Living in Metropolitan Environments). Within ten minutes, one of our youngest citizen scientists made the first S.L.I.M.E. discovery - a glass snail (Oxychilus draparnaudi) in the Pollinator Garden.

Check out what else we found:

A bunch of turkey tail fungus on a dead log:

A pile of dog's vomit slime mold on the edge of a path:

Florence shows off some inky capped mushrooms found by Christopher Lanus (which he later submitted to iNaturalist):

And our Project S.L.I.M.E. results included 45 vials of snails and slugs:

There were 18 glass snails, like this one here:

Eleven gray field slugs (Deroceras reticulatum), like this one here:

And 27 banded garden slugs (Lemannia valentiana), like this one here:

Wow, so many specimens! We learned a lot from this test of Project S.L.I.M.E. Firstly, all of the snails and slugs we found are non-native to Los Angeles! Secondly, the group found most specimens in the Pollinator Garden, but none of the gray field slugs were found there at all!  Perhaps gray banded slugs don't like the plants in that part of the garden?

As you can tell see this test has raised a lot of questions for us; How does the diversity of snails and slugs we found in the Nature Gardens compare to the diversity in the surrounding neighborhoods and the rest of the L.A. basin? Are most of L.A.’s urban snails and slugs non-native?  How are our native snails and slugs fairing throughout the L.A. basin? Right now we don't know the answers, but when we publicly launch Project S.L.I.M.E. we'll be able to begin answering these questions because of citizen scientists like this group:

**Thanks to Jann Vendetti, Project S.L.I.M.E.'s creator! She couldn't join us for the event as she was giving birth to her daughter. Congratulations Jann!

Written by Miguel Ordeñana

 


(Posted by: Lila Higgins)


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New Snail Record for North Campus and Los Angeles County

March 23, 2012

We've discovered a snail never before found in L.A.! A few weeks ago, I was wandering through the North Campus and  happened upon a tiny gastropod snailing along the Living Wall! Most snails don't catch my attention as they are usually of the common garden variety, aka Brown Garden snails, Helix aspersa. This particular specimen caught my eye, because unlike the Brown Garden snail, this snail was much smaller and flatter (the shell is only 6.9 mm wide). I grabbed the snail, placed it in a vial and took it to our snail expert, Lindsey Groves.

 



Brown Garden snail, Helix aspersa

 



Southern Flatcoil snails photographed in Cathedral City

(Image courtesy of Patrick LaFollette, Museum Research Associate) 

Lindsey is the Museum's Malacology Collections Manager and when I showed him the snail, he got pretty excited. Although some people may find this strange, I did not. In fact, I was excited too. What I did find strange was that Lindsey already had another specimen of the exact same species sitting under his microscope at that very moment!

 

 



 

 

 

 

Malacology Collections Manager, Lindsey Groves

It turns out that the snail I found is a Southern Flatcoil snail, Polygyra cereolus. According to Lindsey, this species of snail ranges from southern Florida to South Carolina and across much of the Gulf coastal states to Texas, as well as several areas of northeast Mexico. Over the past few of decades, it has become common in other locations such as Wisconsin, Hawaii, and even a number of countries in the Middle East including Qatar, Saudi Arabia, and the United Arab Emirates! These range extensions are attributable to accidental introductions through importation of sod and/or ornamental landscape plants.

The specimen that Lindsey was examining under his microscope was recently collected in the Laguna Hills area of Orange County. He is currently working on documentation of this new county record and will also document the snail found on the North Campus, which is now preserved in the Museum's Malacology collection. The snail has also been discovered a bit further afield in Cathedral City, Riverside County.

 

 



 

 

Top view of Southern Flatcoil snail.

 

Another in a long list of introduced terrestrial mollusc species in our area, 20 to be exact, it is reported that the Southern Flatcoil snail feeds on clover and alfalfa. As such, they have in some instances been reported as agricultural pests, but will likely feed on many other types of vegetation found in parks and gardens. In Florida, they have been observed assembling in large numbers on sides of buildings and walls without apparent regard to sun exposure, which is very unlike many snails. In one building at the University of North Florida, an aggregation of thousands of individuals were found coating the building surface! According to one of Lindsey's colleagues in Florida, "they are like a weed."

 



Side view of snail. Apparently the characteristic apertural 'tooth'

for this genus must have broken off when it was collected.

 


(Posted by: Lila Higgins)


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