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How good is dinosaur fossil record? (free pdf)

Ben Creisler

A new paper in open access:

Michael J. Benton (2015)
Palaeodiversity and formation counts: redundancy or bias?
Palaeontology (advance online publication)
DOI: 10.1111/pala.12191

Free pdf:

A key question in palaeontology is whether the fossil record taken at
face value is adequate to represent true patterns of diversity through
time. Some methods of assessing data quality have depended on the
commonly observed covariation of palaeodiversity and fossiliferous
formation counts through time, based on the assumption that the count
of formations containing fossils, to a greater or lesser extent,
drives diversity; but what if diversity drives formations? Close study
of two fossil records, early tetrapods (Devonian–Jurassic) and
dinosaurs, shows how the relationship between new taxa and new
fossiliferous formations varies through research time. Initially, each
new find represents a new fossiliferous formation and discovery
follows the ‘bonanza’ model (fossils drive formations). In unexplored
parts of the world, new taxa are identified frequently in new
regions/formations. Only after time, in well-explored continents such
as Europe and North America, does collecting style switch to a mix of
exploration for new formations and re-sampling of known fossiliferous
formations. Data are most striking for dinosaurs, where the
Triassic–Jurassic record largely comprises finds from Europe and North
America, where new formation discoveries reached their half-life in
1914. This contrasts with the Cretaceous, which is dominated by
rapidly rising discoveries from regions outside Europe and North
America and the formation half-life for these ‘new’ lands is 1986,
showing that 50% of new Cretaceous dinosaur-bearing formations were
identified only in the past 30 years. The relationship between
dinosaur-bearing formations and palaeodiversity then combines three
signals in variable amounts, reflecting the original diversity
(relative abundances of particular taxa in different formations),
redundancy (new fossiliferous formations accruing because of new
fossil finds) and sampling (intensity of exploration for new
fossiliferous formations, and of search within already-sampled
formations). For fossil vertebrates at least, formation counts of
various kinds are poor predictors of sampling, missing, for example,
the bonanza samples of Lagerstätten such as the Yixian Formation in
China: thousands of specimens, dozens of species, but counted as one
formation. These observations suggest that formation count cannot be
regarded as an unbiased metric of sampling.

Press release:

Just how good (or bad) is the fossil record of dinosaurs?