Variety Of Species From A Single Site / Location

[Dakota]

Hello,

I'm very new to the forum. I am also a rank amateur, so please bear with me.

I thought I'd share something I found to be very interesting. There is a location I have visited near San Lucas, California, that has a variety of marine fossils all together in one small location. My guess is that the organisms didn't necessarily inhabit the same marine zone, but I suspect they all lived contemporaneously, and after death their remains were somehow deposited together. I hope this is of interest to some members . The location appears to be tertiary marine, and highly fossiliferous, but that's about all I can say about that. The matrix ranges from fine sandstone, course sandstone, rock made almost entirely of shell material, and some muddy sandstone.

I'll post a picture (from my notepad, sorry) of some of the representative fossils and say a few words about their relative abundance and condition under which I found them.

I'll start with the barnacles. There seem to be a variety of types represented. The largest, most obvious, and among the best preserved fossils at the location are the variety shown below. They are very abundant at the location.

[Dakota]

Also at this location are some very large mussels. They don't appear to be abundant, as I've only found two (including the one pictured here) and both were internal molds only, with no shell material preserved. It's interesting that this side of the mold has a chalky-white appearance. This side was embedded in the sandstone matrix. The other side had been exposed to the elements and is course and rock-like. Of my two examples, this is the larger of the two and also the best preserved.

[Dakota]

Nearly as abundant as the barnacles are the scallops, and equally well preserved. I have a few dozen of them, ranging in size from just over one centimeter, to over ten centimeters across. Many are exquisitely preserved, and have the appearance and feel of fine delicate china. There appears to be at least two, and maybe three varieties represented at this location, as the ornamentation appears to be different on some specimens. There are also some beautiful specimens with attached banacles that display really nicely, of which I have a few.

[Dakota]

This tiny little fellow is very delicate. It has a slight scallop like appearance, in that is has tiny "wings" near the beak of the shell. It is oval in shape, very thin-shelled, and has no apparent ribbing or ornamentation on the outside of the shell. I found this by sifting sand that had weathered off the outcrop, and it's the only one I found at the location. Please pardon the poor photography.

[Dakota]

These small gastropods are also fairly abundant at the location. I've tried and tried to identify them, but I've not been successful. I thought they might be some type of Cancellaria sp?

While they are abundant, I found none that were completely intact. Most had the top whorl (spire) of their shell damaged or missing. A good many of them appear to have met their death at the hands of another gastropod, as they have the tell-tale bore-hole.

[Dakota]

Sand dollars are in some abundance at the location, primarily this type. The range in size from just millimeters (tiny) the size of the damaged specimen shown in this photograph. I believe that is the largest one I'd found, and that's why I kept it despite the poor condition. There is another type also, which is not as inflated as these, and has a somewhat "scutella-like or dendraster-like" shape. I only have one of those, and it's just over 2 centimeters in diameter. It also has a small scallop cemented to it's underside, which probably helped it remain undamaged.

These sand dollars seem to have a fine-sand cemented to their outer shell, and so the petals and other ornamentation, such as spine bases, are difficult to impossible to make out.

[Dakota]

I only found the one of this strange shell. I can't for the life of me figure out what it is. Sometimes I start to think it might be some kind of oyster. Sometimes I think it might be some type of scallop. I wish the beak end was better preserved (if there was one). Whatever it is, I like it.

[Dakota]

These "Trophon-like" gastropods are also pretty abundant at the location. A few have the tell-tale bore-hole of having been predated upon. Some are extremely well preserved, showing highly ornate spires off the whorls of the shell. (I know this is not scientific language, but sadly, I'm not a scientist). Some are less well preserved. Honestly, it's hard to tell with some whetjer it's a different species, or just a better state of preservation.

[Dakota]

This gastropod is the only one of it's type I found. The aperture is very thick-walled. There appear to be some fine striations on the outer shell, but it's difficult to discern because of the poor preservation.

[Dakota]

I call these "fish bones", but I don't know what they are. They are the only two objects found at the location that even remotely looked like vertebrate remains. The darker one at the bottom gives me the impression of a bone. It is very light weight, and says bone to me. The object at the top I'm not so sure about. It seems to have weather differently, and seems to be of another material. It's also very light. If they are not fish bones, I don't know what else they could be.

[Dakota]

This is another object that I can't tell what it is. It's fairly round, but not exactly circular. It's fairly flat, but has some very slight undulations on the surface that have no apparent pattern. It is attached to some matrix (no seen in the photo) but the edge protrudes beyond the matrix in one section, showing this object to be wafer-thin. Like one millimeter thin. It's hard to imagine how it survived intact for all these years. This is the only object of this type that I found at the location.

[Dakota]

This is another type of gastropod found at the location, but not in abundance. I believe I've found only 2 or 3 of them. None were intact. Without showing the aperture side, I will say that the opening is small, round, and has no slot at the bottom of it. The bottom just truncates with the circular rim of the aperture.

[Dakota]

I'll include this partial internal most of a gastropod, only because it came from inside one very big snail shell. I wish I could have found some of the shells that made this, but I didn't see any.

[Dakota]

Bivalves don't appear to be very common at this location. I found only a couple, and this is the only one that appears to have any shell material left. the others are essentially steinkerns.

[Dakota]

I'm going to give everyone a break and close with this last picture. It is a mold of another bivalve shell. See the roundish protrusion at the lower left of the matrix? That's actually the mold of even another clam-like shell of a different king, being somewhat ovoid or almond-shaped.

Thanks for bearing with me. I know these aren't dinosaurs, but I find them fascinating just the same.

Of everything I've gotten from this site (I only visited it 3 times in 10 years, the most beautiful and abundant are the scallops, or which I have more than a dozen. Most are quite small and some look so pristine it's hard to believe they didn't die just yesterday. I also have a lot of the large banacles. Of the gastropods, I have a half dozen or so of the Cancellaria-like ones, and a similar number of the Trophon-like ones, with the others being one-offs or maybe two. I may have to take another trip there one day soon to see if I can add any new varieties to the list of creatures in that outcrop. Happy fossil hunting.

[sseth]

You have some beautiful fossils there. Thanks for sharing them with us. What a great way to start off in the forum.

[Troodon]

Very nice assortment of fossils. Did you find any vertebrate material?

[Dakota]

No, other than the one possible fish bone, I didn't find anything else. Next time I go I'm going to try to do more sifting and see what might turn up. I hoped for some shark teeth, but didn't find any. I wouldn't be surprised if there weren't some there, but I wasn't looking specifically for them, and may have been looking in the wrong place. I was sort of focused on the larger material. Next time I'm going to specifically look for smaller stuff. I'll be sure to report back if something really interesting turns up.

[Auspex]

Good images and information!

The varied rock types speak either of a changing depositional environment, or of reworking after the fact. Given the fine condition of these fragile specimens, I suspect the former scenario.

[Dakota]

Sadly, I drove two hours (one way) from San Jose to revisit this site for the first time in over 10 years, and it's no longer there. It used to be open land, and now it's been plowed over and grapes have been planted over the spot (and acres in each directly). Another reason to preserve what we find, before it gets plowed over and a parking lot (or a vineyard in this case) is established on top of it.