A Dissertation submitted to the Faculty of Science, University of the Witwatersrand,
Johannesburg, in fulfilment of the requirements for the degree of Master of Science.
Johannesburg, 2012 / Various insect taxa are known to modify bone with their mandibles, including members
of the orders of Dermestidae, Tenebrionidae, Calliphoridae, Tineidae and Termitidae.
Despite bone modification being a known behavioural trait of many of these taxa, little
work has been done to record the distinctive ways in which they modify the bone
surface, and a lack of concise descriptions of modification suites inhibits decisive
identification and interpretation. The most widely inferred causal agents in
palaeontological literature are either termites or dermestid beetles, whilst cockroaches
as potential bone modifying agents have not yet been considered. The primary aims of
this investigation were to establish whether or not cockroaches and dermestids modify
bone, and if so in what ways, develop an interpretative framework to aid future
researchers in the identification and differentiation between the variously reported
agents of bone modifications, test whether or not the agents will modify bone of varying
densities (thin cortical, thick cortical, compact and cancellous bone) or in a particular
state of preservation/condition (fresh, dry, weathered or fossilised), and investigate
whether or not the occurrence of insect modifications on bone can be used as a proxy to
establish a broad climatic signature based on their known thermal physiological limits. A
single experimental trial of 18 bone specimens were exposed to the African cockroach
Periplaneta americana for a period of six months and a further four experimental trials
(totalling 80 bone specimens) were exposed to the Coleopteran Dermestes maculatus
for periods of four months each under the absence or presence of substrate and
variable feeding conditions. Experiments were conducted within an insectary at 28° C,
40 % humidity and 12 hour light/ 12 of darkness. Subsequently, all specimens were
viewed using an Olympus SZX 16 Multifocus microscope fitted with a digital camera at
magnifications between 7 and 115x. Three modification types were identified for P.
Americana, namely discolouration, destruction of bone and gnawing. A total of five
modification types were established for D. maculatus including the occurrence of
surface tunnels, destruction of bone, bore holes, surface pits (Classes 1–3) and gnawing.
Three distinctive surface pits morphologies were identified; Class 1 pits are highly
variable but most often semi-circular to elliptical shallow depressions with a U-shape
profile with striations radiating around the outer circumference of the depression. Class
2 surface pits are semi-circular shallow depressions with randomly orientated striations
occurring over the entire feature. Class 3 surface pits are irregular shaped depressions
with complex profiles not associated to gnawing striations. Broad climatic signatures for
both of these agents were developed based on their known physiological thermal limits.
The indistinct modification signature of P. americana in combination with limited
occurrence and frequency patterns may prove difficult to identify from an
archaeological or palaeontological context. Periplaneta americana and D. maculatus do
significant damage to aves bones, which could result in their under representation in the
archaeological and palaeontological records. The highly distinctive signature as well as
occurrence and frequency patterns of modifications produced by D. maculatus has
enabled the reinterpretation of existing palaeontological analyses, suggesting that
dermestids are in fact not responsible for reported instances in which they are
suggested as the causal agent during the Mesozoic and Cenozoic.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/13010 |
| Date | 07 August 2013 |
| Creators | Parkinson, Alexander Haig |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf |
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