I've certainly had a long-held fascination and interest in minute paleo-material. One of my favorite fossil localities occurs in the middle Miocene Barstow Formation, Mojave Desert, California, a specific place situated within a rather vast geographic area of outcrop that produces exceptionally well preserved three dimensional silicified fresh water insects, spiders, and crustaceans--a lacustrine (deposited in a lake paleoenvironment) arthropod fauna, primarily--that can be freed intact from calcareous concretions dissolved in a diluted organic acid bath (although some investigators prefer commercial muriatic acid); the specimens rarely exceed 8 millimeters in length (.31 inch) and are best examined with a microscoope under low to moderate powers of magnification. This is one of only a mere handful of localities on earth where fossil insects can be successfully freed whole and intact in three dimensional form from the matrixes within which they've been preserved.
Here's an example of what I'm talking about. It's an adult midge recovered from the insoluble residues of a Barstow Formation calcareous concretion dissolved with diluted acid by Mr. Farrall S. Smith--a very talented "Barstow Bug" collector who graciously provided me with several photomicrographs of his finds for use at my web site, linked below. Specimen in actual size is approximately 4 millimeters long (.16 of an inch). It's called scientifically Dasyhelea australis antiqua and is most closely related to the modern Dasyhelea australis australis, now living on the islands of Islas Juan Fernandez, about 400 miles west of Santiago, Chile. Age is middle Miocene, around 17 million years old.
And here's a series of silicified--that is, replaced by the mineral chalcedony (silicon dioxide)--midge pupae I recovered from the middle Miocene Barstow Formation (some 17 million years old at the paleoentomological locality), Mojave Desert, California; in actual life, the adult Dasyhelea australis antiqua midges (an example of which is seen above) would have emerged and flown away from such pupal cases after undergoing metamorphosis. For perspective, the pupa at far right in the upper row is 4 millimeter long (.16 inch).
After dissolving the insects out of calcium carbonate (limestone) concretions with a diluted solution of formic acid, I photographed them with a Nikon CoolPix 995 digital camera in indirect lighting, with a flash unit.
Here's an example of what I'm talking about. It's an adult midge recovered from the insoluble residues of a Barstow Formation calcareous concretion dissolved with diluted acid by Mr. Farrall S. Smith--a very talented "Barstow Bug" collector who graciously provided me with several photomicrographs of his finds for use at my web site, linked below. Specimen in actual size is approximately 4 millimeters long (.16 of an inch). It's called scientifically Dasyhelea australis antiqua and is most closely related to the modern Dasyhelea australis australis, now living on the islands of Islas Juan Fernandez, about 400 miles west of Santiago, Chile. Age is middle Miocene, around 17 million years old.
And here's a series of silicified--that is, replaced by the mineral chalcedony (silicon dioxide)--midge pupae I recovered from the middle Miocene Barstow Formation (some 17 million years old at the paleoentomological locality), Mojave Desert, California; in actual life, the adult Dasyhelea australis antiqua midges (an example of which is seen above) would have emerged and flown away from such pupal cases after undergoing metamorphosis. For perspective, the pupa at far right in the upper row is 4 millimeter long (.16 inch).
After dissolving the insects out of calcium carbonate (limestone) concretions with a diluted solution of formic acid, I photographed them with a Nikon CoolPix 995 digital camera in indirect lighting, with a flash unit.
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