Dear Aurelie, dear Richard,
my last mail was written as a first impression from abroad without being able to check my literature. I checked the examples of chemical corrosion I could find in the references when I was back in my lab , but I could not find anything that resembles your traces. There are some good examples of digestive acid corrosion (e.g. in Andrews 1990 amongst others) but these traces of liquid corrosion always affect complete areas of bone surfaces and do not produce distinct marks like the ones on your bones. So Richard is most probably right in dismissing my suggestion.
Following up Richards suggestion of insect feeding traces I came across Gautier (1993, 515, fig. 2.3), who shows traces of what he assumes to be made by ants. In the picture of a turtle carapace these are much denser than on your bone and more like ditches but might be worth considering, especially because ants use acids, which may be an explanation for the rounded edges of the marks that caused my initial doubt towards the traces of the more mechanical action of other insects mandibles. Kaiser (2000) for instances discusses insect feeding traces which he attributes to adult insects mandibles. They look different from your marks. Probably unlikely because of the shape of the marks, but what about snails... (see von Proschwitz 2002).
Like Richard and Jean-Bernard I am curious about the final answer of the riddle.
Best
Christian
References:
# Andrews, Peter (1990): Owls, Caves and Fossils, London
# Gautier, Achilles (1993): Trace Fossils in Archaeozoology. – Journal of Archaeological Science 20, 511-523
# Kaiser, Thomas (2000): Proposed Fossil Insect Modification to Fossil Mammalian Bone from Plio-Pleistocene Hominid-Bearing Deposits of Laetoli (Northern Tanzania). – Annals of the Entomological Society of America 93, 693-700
# von Proschwitz, Ted (2002): Tierknochen als Kalkquellen für landlebende Mollusken. in: Falkner, Margit / Groh, Klaus / Specht, Martin C. D. (eds.): Collectanea Malacologica, 519-524, Hackenheim
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Am 21.04.2015 um 14:55 schrieb Aurelie Guidez:
> Hello Christian,
>
> Thanks for the references. My first idea was also about insects but from what references I saw, the marks on my faunal remains where too small, too regular, too numerous, and too superficial, so I was (and still am) not convinced.
>
> Do you have any references on chemical corrosion in archaeological context ? I didn't go that way because of the regularity of the cupules but if you could provide an example, I will explore that lead.
>
> Cheers,
> Aurélie Guidez
> Doctorante
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Am 22.04.2015 um 05:24 schrieb Richard Wright:
> Aurélie
>
> I have never seen anything like the marks you illustrate. They are a challenge.
>
> Christian suggests the possibility of chemical corrosion. My problem is that I can't see what corrosive agent could produce marks, in cortical bone, that were so consistent in shape and size, and separated from each other.
>
> So my bet is borings by some invertebrate organism. To that extent I agree with Adam's post suggesting dermestsid beetles.
>
> However your marks are virtually all roughly circular, and so do not mimic the elongated pupal chambers of dermestids.
>
> Interestingly, Hasiotis (Sedimentary Geology 167 (2004) 177–268) discusses borings on dinosaur bones that seem to closely resemble those you have. He describes them thus:
>
>
> START QUOTE
> (C) Small hemispherical borings on the surface of a femur of D4.18. Type 18—circular to elliptical borings in dinosaur bone, Fig. 13C–H
>
> Description: Predominantly circular to slightly elliptical in plan-view, the borings are preserved as molds and casts within the bone and are shallow hemispheres typically 0.01–4.0 mm deep. Some elliptical pits appear to be incomplete borings. The borings range from 0.5–1, 2.5–3, and 4–5.0 mm in diameter. Clusters of borings are random with no particular distribution between borings. Some skeletal elements contain both small and large borings, but one size always dominates the bone surface. Borings from different quarries have similar diameters, shapes, and distributions across bone surfaces. None of the dinosaur bones examined contain deep or fully penetrating holes or trails.
>
> Occurrence: Dinosaur bone borings were observed in quarries in the Brushy Basin Member in Colorado, Utah, and Wyoming.
>
> Tracemaker: The morphologies suggest that these borings were most likely produced by the larvae of carrion beetles (Coleoptera: Dermestidae) and are very similar to the traces of modern dermestids(Fig. 13G–H)."
> END QUOTE
>
>
> In case you can't get to Hasiotis's original article, there is an image of Fig. 13C at https://app.box.com/s/f1r7ece5menr1rucboe8kk50x7b7ez0v
>
> A final question. Among the pits, are there any deeper borings that turn into tunnels that are perpendicular to the surface of the cortical bone? In the image with three separate bones, I wondered whether this was the case for some of the marks on the bone on the right.
>
> Please let us know if you solve this intriguing problem.
>
> Richard Wright
>
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