Carboniferous human bones -- an evaluation

This document evaluates some of the claims of "human bones in Carboniferous-age rocks" in eastern Pennsylvania, as presented by Ted Holden ( medved@access5.digex.net ) and initially discovered and interpreted by Ed Conrad ( edconrad@postoffice.ptd.net ). Ted and Ed have graciously provided specimens of their material for analysis, and the results are presented here. My thanks to them for making this possible.

Ed and Ted's claims

 You can read the details of the claims being made for these fossils at: "human bones in Carboniferous-age rocks". Basically, they can be summarized as three key claims:
  1. The specimens consist of fossil bone
  2. The fossil bone is not from an expected Carboniferous animal, it is HUMAN bone
  3. The specimens occur in situ in Carboniferous bedrock

By examining specimens, only the first two claims can be tested. Even if the specimens are fossil bone (#1), and are human (#2), Ted and Ed would still have to fully document the geologic context for these specimens (#3) before their claims would be fully substantiated. The importance of this can not be overemphasized -- fossil human bone without unambiguous, detailed, irrefutable documentation of the collection point of the same specimen (not just any specimen) is an absolute requirement. Without this, the isolated specimens are worthless for demonstrating the case even if they are fossil human bone.

Ted makes additional claims, but they implicitly depend upon the validity of the ones stated above.

Background geology

 The rocks in the Shenandoah area are part of the Appalachian mountain belt and have been extensively folded and faulted. Most of the deformation is dominated by anticlines and synclines (like the crests and troughs of waves, respectively) with axes roughly parallel the Atlantic coast, and large thrust (reverse) faults with similar surface orientation. Smaller normal faults also occur at other orientations. Shenandoah occurs within a roughly east-west-oriented syncline, known as the "Western Middle Anthracite Field" containing Late Carboniferous (Pennsylvanian) age rocks, mainly of the Pottsville Group (Pp) and overlying Llewellyn Formation (Pl). The syncline is surrounded by older Early Carboniferous (Mississippian) age rocks of the Mauch Chunk Formation (may have been raised to "Group" status). Many of these units contain river-deposited shales, siltstones, sandstones, conglomerates, coal, and paleosols (fossil soils). Plant fossils are common as impressions and casts, particularly in association with the coal seams. Apparently there are even upright tree trunks in the Llewellyn Formation (p.38 of Wood et al., 1986).

Due to the uplift related to the mountain-building, the coal of this area was heated to high temperatures and experieced high pressures that converted it to anthracite, the highest grade of coal. Mining occured mainly in the Llewellyn Formation, both in underground and surface (strip) mining operations that have substantially altered the surface of the area. A good summary of the geology of the region can be found in Wood et al., 1986, and see also Paul Heinrich's summary below, which has references to more detailed information.

excerpt from the Geologic Map of Pennsylvania, 1980, compiled by Berg et al.

Key (quoted from Berg et al., 1980):

Detailed discussion of local geology by Paul Heinrich, heinrich@intersurf.com

What to expect in the Carboniferous

 During the Carboniferous, land areas with enough water supply were covered with vegetation dominated by sphenopsids ("giant horsetails"), giant lycopod trees, both spore and seed tree ferns, and a few types of early conifer. The sphenopsids and giant lycopods were particularly common, and were responsible for much of the coal formed during this period. Often the upright stumps and roots of these plants are preserved in directly in association with the coal and other fossil remains. Because of their pithy core, these plants commonly occur as sandstone-infilled casts which were produced when the core of the plant rotted out, and a cavity was left. For details of the anatomy of the plants of the Carboniferous, see Taylor (1981) and Stewart and Rothwell (1993) in the references section.

Animal life included insects (dragonflies, cockroaches, millepedes, and others) and other arthropods (e.g., arthropleurids and eurypterids), and a variety of vertebrates. The vertebrate life on land included amphibians and reptiles. In rivers and lakes, many types of amphibians and fish occured. The fish included freshwater sharks and large, carnivorous lobe-finned fish.

In terms of size, some of these vertebrates got quite large. For example, the Carboniferous embolomere amphibian Eogyrinus attained a length of 2 metres (Carroll, 1993, p.175), and ancathodian fish like Acanthodopsis and the gyracanthids (see p.93 to 95 of Long, 1995), and the xenacanthid sharks (see p.75-76 of Long, 1955) reached lengths of 1 to 4 metres. But the ultimate in vertebrate size in the Carboniferous may have been attained by the rhizodontiform lobe-finned (crosspterygian) fish. These had heavy skeletons with armoured skulls and large pointed teeth known as Rhizodus. These animals are estimated to have reached lengths of 6-7 metres (Long, 1993, p.190 talks about a jaw from the Carboniferous of Scotland that is 1 metre long!), and individual teeth approach 22cm in length. Smaller examples of Rhizodus teeth are figured below.

Obviously, the mere size of fossil bone material from the Carboniferous is not enough to establish that something anomalous is present.

Big teeth

Ted has claimed that some of the "tooth" structures found are too large to plausibly be from any Carboniferous animal. However, both fish and land vertebrates of the Carboniferous are known to have relatively large teeth. The teeth of certain lobe-finned fish were particularly large and are particularly common in Carboniferous sediments (even I have some specimens from the Carboniferous of Nova Scotia). For more details, see: tooth examples.

Tusks and spines

Ted has claimed that in the Carboniferous, "fish do not have tusks". While the vertebrate animals of the Carboniferous did not possess tusks, there were fish with large dermal spines which are superficially similar, got quite large, and which could be confused with tusks.

Summary

In summary, there are many types of vertebrate remains known from the Carboniferous. The detailed morphology of the fossil bone must be used to distinguish between organisms which are expected from this interval, and ones that are not. Size is not enough.

Fossil bone

 Fossil bone is usually recognized on the basis of its microscopic structure, including the presence of tubular channels -- the haversian canals -- with laminated mineral structure around them. These channels are larger, and the surrounding laminated structure thinner, towards the centre of most types of bone, defining the "marrow"; and the bone is denser and the channels narrower towards the exterior. The tubular channels are typically aligned along the length of the bone, and often branch and interconnect with other channels. Even if the channels have been infilled with minerals (i.e. the specimen is permineralized), the channels will usually still be recognizable in microscopic cross section. In exceptionally well-preserved fossil bone, additional structures, including laminae and canaliculae will be observable, and represent structures developed around the individual bone cells that were once embedded in the mineral framework of the bone. By far, bone microstructure is the most conclusive means by which fossil bone can be identified.

Compositionally, bone is originally the mineral hydroxyapatite, which is approximately CaPO4, calcium phosphate (give or take some trace elements and water). Although the fossil preservation process often replaces the calcium phosphate, composition can be a secondary indication of fossil bone, particularly because it is common for the primary calcium phosphate to be preserved, even if the fossils are from rocks older than Carboniferous. In hand sample, calcium phosphate from bone is usually black or dark brown and slightly vitreous in lustre on fresh surfaces, but as it wheathers it often aquires a dark blue colour and eventually it turns white. Because of the distinctive colouration (particulaly the blue), it is often easy to recognize even tiny fragments of bone.

Shape is probably the least diagnostic of characteristics of fossil bone. However, it can be used if the bone is complete, so the points of articulation between bones are visible. Often there is a distinct difference in texture between the articulating and non-articulating surface, and the articulating surfaces are usually developed into distinctive shapes (e.g., ball and socket). It is also sometimes possible to recognize muscle/tendon scars and the apertures of blood vessels on the surface of the bone. Identification of fossil bone from shape alone without complete specimens is unreliable, because many other fossil and non-fossil structures can correspond to the typical sub-cylindrical shape of a fossil bone.

An example

For comparison purposes, a hand sample with a polished surface and thin sections of a well-preserved Cretaceous-age dinosaur bone have been prepared. Although this specimen is not from the Carboniferous, bone from that period is too valuable to sacrifice for destructive preparation, and a dinosaur bone shows basically the same microstructural features of fossil bone found from the Carboniferous. For that matter, land vertebrate bone is so similar at microscopic scale that it would take an expert to recognize a difference anyway. For gross structure, it is effectively identical to what would be expected if fossil bone is present. If you do not believe me, look up a text on bone histology of humans. Perhaps surprisingly, you will see very similar microscopic structures to what is present in this dinosaur bone.

dinosaur bone, Cretaceous, Alberta, Canada.

Specimen TH96-001

 TH96-001 -- click for details with minimal interpretation, so you can evaluate the images yourself without being biased by my interpretation.

This specimen was collected by Ted Holden in the area around Shenandoah, Pennsylvania, apparently from Carboniferous bedrock, sometime in early 1996. It was provided to the author for study in early April, 1996. The specimen has been designated the temporary number TH96-001, and has been prepared with a polished surface and two thin sections.

TH96-001 -- click for details with my interpretation

Specimen EC96-001

 EC96-001 -- click for details with minimal interpretation, so you can evaluate the images yourself without being biased by my interpretation.

This specimen was collected by Ed Conrad from a spill bank in the area of Mahanoy City, a town about 3 miles from Shenandoah, Pennsylvania. It was collected in 1981. I have not received confirmation, but I believe it is the specimen illustrated at the right of http://www.access.digex.net/~medved/conrad/bone1.jpg on Ted's WWW page. The specimen was provided to the author for study in late April, 1996. It been designated the temporary number EC96-001, and has been cut into 3 pieces (A, B, and C), with polished surfaces on each cut.

EC96-001 -- click for details with my interpretation

Conclusions

 Conclusions are hidden here, so you have a chance to view the specimens before seeing them.

References

 Berg, T.M. (chief compiler) et al., 1980. Geologic Map of Pennsylvania, 1980. State of Pennsylvania Department of Environmental Resources. 1:250 000.

Carroll, R.L., 1988. Vertebrate Paleontology and Evolution. W.H. Freeman and Company: New York, p.1-698. ISBN 0-716-71822-7.

Dawson, John William, 1868. Acadian Geology. The Geological Structure, Organic Remains, and Mineral Resources of Nova Scotia, New Brunswick, and Prince Edward Island. Second edition. MacMillan and Co.:London, p.1-694.

Eastman, C.R., (translator and editor) 1932. Text-Book of Palaeontology, by Karl A. von Zittel. Volume II. MacMillan and Co.:London, p.1-464.

Long, J.A., 1995. The Rise of Fishes. 500 Million Years of Evolution. Johns Hopkins University Press: Baltimore, p.1-223. ISBN 0-8018-4992-6.

Stewart, W.N. and Rothwell, G.W., 1993. Paleobotany and the Evolution of Plants, Second Edition. Cambridge University Press: Cambridge, p.1-521. ISBN 0-521-38294-7.

Taylor, T.N., 1981. Paleobotany. An Introduction to Fossil Plant Biology. McGraw-Hill Book Company: New York, p.1-589. ISBN 0-07-062954-4.

Wood, G.H., Jr.; Kehn, T.M.; and Eggleston, J.R., 1986. Depositional and structural history of the Pennsylvania Anthracite region. Geological Society of America, Special Paper 210, p.31-47.

Zittel, Karl A., 1887-1890. Handbuch der Palaeontologie. Abteilung I. Palaeozoologie. Band III. Vertebrata (Pisces, Amphibia, Reptilia, Aves). Druck Und Verlag Von R. Oldenburg: München und Leipzig, p.1-900.

First released, May 22, 1996.

Andrew MacRae macrae@geo.ucalgary.ca Opinions expressed here are those of the author unless otherwise indicated. Please ask for permission prior to using this material in a form other than a WWW link.