The estimation of post-mortem interval (PMI) in reptiles and amphibians: Current knowledge and needs

Studies on post-mortem interval (PMI or time since death estimations) in reptiles and amphibians have been sparse. Some limited information exists but this has usually emanated from the work of veterinarians and biologists and is often restricted to individual case reports or small samples. As a result, there is little that can be used reliably in forensic cases and investigators often have to depend on data from mammalian and avian studies. Work on fish, mainly directed towards promoting food hygiene, may or may not be relevant. Reptiles and amphibians present a range of challenges in terms of accurately assessing changes due to autolysis and decomposition, owing to their high variability in morphology and lifestyle. In particular, there are effects due to ectothermy, the different anatomical features of these two groups of vertebrates, the marked variation in body size of diverse taxa of reptiles and amphibians, and seasonal fluctuations in subcutaneous and internal fat content. Eggs, embryos and fetuses present particular challenges and the presence of a larval stage in amphibians is a further complication. Many basic questions remain unanswered. Specific research is needed, and this should involve both amateur and professional herpetologists. Ways in which useful information may be collated include the keeping of properly recorded accounts of changes in dead reptiles and amphibians, especially those kept in captivity or which can be carefully monitored, such as road-kills. Experimental studies are also needed, carried out in collaboration with for example pathologists.