recognizing fossil bones

Many fossils are misidentified as bones (horn, teeth, etc.) by amateur collectors, because they have a horn or bone-like shape. Many common fossils have shapes that can look very bone-like. In addition, some naturally occurring rocks look like bones (rocks that are mistaken for fossils are called pseudofossils). The distinctive feature of bones is that they typically have a fibrous or spongy texture on the inside or where the ends of long bones are exposed.

Close up of bones structure from elephant bones. Bone has fibrous or spongy texture inside

Also, the outer layer of bone may be somewhat polished, and long bone shapes will tend to have elongate markings parallel to the length of the bone. Bone fossils also have very specific, rather than general shapes. For example, a lower leg bone (tibia) on vertebrate animals will have bulges at each end where the bone attached to cartilage and muscles at the shin and knee. The bulges have a specific shape. You can look at specific bones of animals (lizards, fish, etc.) on the internet for comparison to specimens you think might be bone.

Some bones are obvious, like the Pleistocene mammoth skull shown below. But most fossil bones are smaller or are fragments and are not as easily recognized. In fact, many types of fossils, such as corals and cephalopods are commonly misidentified as bone. Most fossil bones have texture (see below right) that are porous or fibrous and have canals just like modern bones when examined closely, which is unlike other types of fossils.

Pleistocene mammoth skull, fossil bones
fossil bones, filled poresfilled canals, fossil bones

The location in which a fossil was found may also be a clue to the likelihood that it is actually a fossil bone. Recognizable vertebrate fossils would not be expected in rocks older than the Devonian in Kentucky. If you live in an area with Ordovician or Silurian bedrock, and the fossil you found was in bedrock, it is not likely that it is a vertebrate fossil. The only vertebrate fossils found in the areas of central and northern Kentucky have been found in sediments of streams and sinkholes (Pleistocene age), rather than bedrock. If you live in the Knobs region of Kentucky, where Devonian-age black shales form the bedrock, plates of bony fish called arthrodires have been found, but can easily be confused with plant fossils such as logs, which also occur in the shales. In Mississippian limestones, fossil shark teeth have been found. In Mississippian-age sandstones and shales fossil shark teeth and amphibian bones have been found, but are very rare and may be confused with plant fossils. In Pennsylvanian-age shales, fossil sharks teeth and fish bones have been found, but are rare. Most occur as dark (bluish to black) fossils in dark gray to black shales. Fossilized reptile and amphibian tracks have also been documented. Reptile and amphibian bones could also be found, but could easily be confused with plant fossils and siderite nodules, which are abundant. Mammal bones have been found in the quaternary-age sediments of Kentucky, mainly in old floodplain deposits, sinkholes, and in some caves, but are not found in bedrock.

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Last Modified on 2020-09-29
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