FOSSILIZED INSECT NODULE PROJECT OVERVIEW FARRALL S. SMITH

In 1985 I went with a number of friends on a camping trip to the Calico Hills, near Barstow, California, in an area very close to the old Borate mining site. Our campsite was located on a high mound of greenish colored mine tailings. In these tailings I found a number of unusual and interesting rocks which appeared to be sedimentary in nature and were of an unusual symmetrical shape. Abrading these rocks resulted in a petroleum-like odor.

Photo of the 1985 campsite on top of a mining tailings pile.

Going through some old Desert Magazines, I came across an article, “Fossil Insects from the Mojave” (January, 1959) which described these rocks as being nodules from the Barstow Formation. These Nodules, when dissolved in acid, can yield fossilized insects in a highly detailed, three dimensional state of preservation. The collection area for the nodules in this article was adjacent to the entrance of Mule Canyon (34 deg. 56' 04” N & 116 deg. 49' 46” W) while my nodules were collected in the vicinity of the old Borate mining site approximately 2.3 miles north-east of the Mule Canyon collection site. The tailings pile is at 34 deg. 56' 55.34” N & 116 deg. 48' 7.81” W.

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Additional investigation indicated that these nodules from the Barstow Formation were formed during the Serravalian Age of the Miocene Epoch and were approximately 14 million years old. Researchers have noted that these nodules do contain petroleum.

Having for years been interested in the further investigation of these nodules, I have purchased a stereo microscope and a USB digital microscope camera which is mounted in place of one of the two eyepieces.

AmScope microscope and USB digital camera.

Past researchers have described the nodules as being primarily composed of Calcium carbonate which can be dissolved in 10% Formic acid in order to free the fossil insects. Not having access to Formic acid, I initially employed white vinegar which was reasonably effective but somewhat slow. Later I switched over to Muriatic acid (Hydrochloric acid) which is used in swimming pools. The dissolving process of nodules is accompanied by the vigorous out-gassing of Carbon dioxide and a strong petroleum odor due to the petroliferous nature of the nodules.

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Typical nodules found in 1985. Each is less than 2 inches across.

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On 02 February 2010, while microscopically examining the acid insoluble particulate matter resulting from dissolving nodules in white vinegar, I found my first fossilized insect. To the unaided eye, it appeared barely visible as a reddish-yellow speck so it was quite small. Microscopically, the twin tail appendages appear very Spring Tail like although the head looks more fly like.

Microscope photos of fossil insect # 1.4

On 03 February 2010, I found the fossilized posterior portion of an insect abdomen.

Fossilized insect abdomen part.

On 06 February, a relatively large insect abdomen was found, approximately 1/8 th inch long.

Fossilized insect abdomen part.

This fossilized abdomen part was large enough to collect with tweezers and save in a specimen bottle.

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On 13 February 2010, I found a portion of an insect approximately 1/8 th inch long. Although in poor condition, the part appeared to be a head and thorax with portions of legs still attached to the thorax. The upper portion of the head appeared to be crushed downward although compound eyes could be seen when looking down on the crushed portion. Mouth-parts were largely intact and appeared to be consistent with those of a Grasshopper.

Upper head & compound eyes. Front of head & mouth-parts.

View side 1 View side 2

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On 02 April 2010, as a camping trip was scheduled to the One Ton mine site, I first made a side trip to Mule Canyon, just east of Calico Ghost Town, in order to visit the site where I had first collected the fossil insect containing nodules back in 1985. With the use of a laptop computer, USB GPS receiver and mapping program (Terrain Navigator) I was able to locate that same spot and collect a reasonable quantity of nodules.

Nodule collecting site in 1985.

Nodule collecting site in April 20108

Nodules as collected.

Cleaned nodules.

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On 06 – 08 April 2010, I dissolved a first few of the nodules collected (on 02 April 2010) in dilute Hydrochloric acid. In microscopically examining the remaining floating material, it appears that much of it is composed of biological residue including plant material. With this organic material being released from the dissolving rock as well as the strong, petroliferous smell accompanying the dissolving process, I have to think of these rock nodules as “instant swamp”. A number of insect parts were observed in the first dissolved new samples of nodules.

Possibly an aquatic larval insect head.

Head and thorax of a Leaf Hopper-like or Cicada-like insect.10

Head from an unidentified aquatic insect larva.

On 12 April 2010, I found an entire insect larva, the head being similar to individual detached heads that I had previously observed, as in the above photos.

Complete insect larva or nymph.11

Complete insect larva or nymph.

Anterior end, top & bottom, of complete insect larva or nymph.

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It should be noted that unfossilized organic materials have been observed. Insect larva parts, structurally consistent with the fossilized insect larva parts, have been seen in an unfossilized state. These have been of a reddish-brown color and have been pliable and subject to deformation by mechanical pressure. Also noted was a small spherical reddish-brown structure that, when crushed with a tweezers tip, appeared to contain a sticky plant resin.

On 13 April 2010, another sample of acid dissolved nodule residue was microscopically examined. The usual fragments of insect larva was seen as well as a cluster of small, spherical structures that could be some type of eggs.

Possible egg cluster?

Unidentified insect, insect larva or insect nymph.

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On 27 April 2010, I microscopically examined the acid insoluble material remaining from the acid dissolution of four Calcium carbonate nodules. A number of the usual fossilized aquatic insect parts were seen. A more unusual material, which appeared to be an organic plant pitch combined within a silica crystal matrix, was observed. This pitch-like material was dark, reddish-brown in color and was extremely viscous & sticky. Only with difficulty could a small amount of this material between the fingers be cleaned off. In addition to this pitch-like material, I observed some type of insect or insect larva of the same color as the pitch. This insect was not fossilized but soft and pliable. It would appear that organic material and organisms can be sequestered within these nodules without becoming fossilized. It is quite possible that the unfossilized insect was preserved in the pitch.

Organic pitch-like material intermixed within a silica crystal matrix.

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The soft, pliable, non-fossilized insect or insect larva which may have been preserved in pitch-like material appears to be very similar to the insect part found on 06 – 08 April 2010 and described as being a Leaf Hopper-like or Cicada-like insect.

Soft, pliable, non-fossilized insect or insect larva, bottom & top.

The following are a number of miscellaneous microscopic photographs of insect parts and other structures from the nodules.

Abdomen in silica crystal matrix. Abdomen posterior structures.

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Multiple insect larval parts.

Insect larva or nymph heads.

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Appears to be some type of head with eye structures.

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Coprolites, possibly from ghost shrimp, on silica crystal matrix.

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A crystal

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An insect larva or nymph

Head of insect larva or nymph.20

Head of larva or nymph.

Head & leg fragments of larva or nymph.

Unidentified spherical objects. 21

Abdomen part with markings. Crystal larva head.

On 03 May 2010, I found a fossilized insect that looked very much like a tick. Being very small, it is probably some type of mite.

Possibly a mite.

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On 03 May 2010, I also found a structure that appeared to be a tooth of a small reptile such as a snake. This may, in fact, be a tooth or else it is just some tooth-like natural formation.

A small tooth or tooth-like structure.

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On 20 May 2010, I observed a very tiny fossilized spider.

On 22 May 2010, I observed some type of head with what appeared to be eye structures and antennae.

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A relatively complete larva or nymph of some type of insect was also observed.

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The following are a few misc. photos.

Abdomen on silica matrix.

Possibly a mite. Posterior portion of a larva or nymph.

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Larva or nymph still partially embedded in silica matrix.

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For my final comments, I would like to point out that I am not an Entomologist or professional researcher of any type. I am an individual who enjoys camping and hiking in our Southern California deserts. On a desert camping trip in 1985 I had picked up some rather curious and interesting small rocks which had since resided in my garden. Fortunately, quite a few years later, I was going through some old Desert magazines and came across an article which explained a bit about these rocks and what could be found inside of them. So this paper is essentially a running log relating to a bit of a side hobby involving these rocks and the fossilized insect parts that I found inside of them. Perhaps someone may find this of some interest.

Farrall S. Smith 24 May 2010

References:

Fossil Insects From the Mojave by Ruth A. KirkbyThe Desert Magazine, January 1959.

Calicovatellus Petrodytes, a New Genus and Species of Primative Vatelline Diving Beetle(Coleoptera: Dytiscidae: Hydroporinae: Vatellini) From the Miocene Barstow Formation, Southern California, USA by Kelly B. Miller and Sara H. Lubkin.

AmScope Microscopes at http://www.amscope.com/. Source of microscope photos.

Mouthparts of Grasshopper at TutorVista.com. Source for diagram of Grasshopper mouthparts

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