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Quantitative palaeontology

For a few hundred years palaeontology was largely an exercise in properly iden­tifying and classifying fossil remains. Up until the 1980s, scientists relied on hand drawings, written descriptions, and the occasional photograph to assist them with their palaeontological investigations. Classifying fossils and inter­preting the nature of the strata in which they were discovered were qualitative tasks; the tools of the trade included shovels, brushes, sieves, microscopes, and notebooks. Quantitative information was tabulated manually on paper.

With the advent of the computer, quantitative palaeontology emerged on several fronts. With the ability to capture, store, and manipulate digital data related to fossils, we gained the ability to analyse and understand our data, and derive previously obscured relationships. Let’s look at how this evolution of the disci­pline transpired with two examples.

Digital data tables

Before the digital age, micropalaeontologists and biostratigraphers were con­cerned first with identification, aided by published drawings of specimens, and then with the presence or relative abundance of a species in a sample for purpos­es of understanding stratigraphic age or environment of deposition. Diagnostic ‘marker species’ were especially interesting as they were considered critical for placing rocks within a stratigraphic age or formation. Published studies frequently included data tables reporting the absolute or relative abundance of species by sample location and/or depth in a well. Many studies were of a limited scope with regard to geography or stratigraphy and did not summarize results over larger areas.

Efforts in the 1980s led to the capture of count data digitally where it was stored in tables on personal computers. Additionally, published data tables of interest to researchers were digitized and stored. With the ability to store and analyse millions of samples representing the full fossil assemblage from all corners of the globe and all stratigraphic ages, a new quantitative biostratigraphy emerged. Scientists adapted probabilistic methods (such as cluster analysis and principle components analysis) from other disciplines and applied them to large quanti­ties of microfossil data to discern subtle trends. Fully numeric comparisons of large sample sets, each sample with dozens of different microfossils, could be made and similarity indices calculated to establish co-occurrence of species, measure diversity, or identify subtle biostratigraphic breaks and unconformities. Modern methods have extended to automated identification of microfossils using image analysis tools (see also Biostratigraphy at a distance).

Macrofossil imagery

At the other end of the size spectrum, vertebrate palaeontologists have evolved from digging up and making plaster casts of dinosaur bones to digital imaging of fossils in situ and after recovery. Scientists use LiDAR laser scanning to map bone sets and create high-resolution 3D models of specimens. Non-invasive x-ray computer tomography, adapted from the medical and forensic world, has been applied to digitally explore the interior of fossil remains, revealing structures important to understanding their genealogy, function, and evolution. The computerized representation of fossils in 3D allows them to be effectively animated for further study, understanding, and even entertainment. Widely ac­cessible 3D models of type specimens provide efficient means for obscure fossil fragments to be identified and conclusively tied to their full remains.

Fossil identification is just the beginning. Large publicly accessible databases of fossil specimens of all ages and locations, containing digital morphological information, can be cross-checked with databases on environmental conditions to reveal new patterns of ecological significance. New insights into animal be­haviour and evolution seem certain.

Pemberton’s laws of stratigraphy, part 1

Resolution on maps and sections