The quality of the early hominin fossil record : implications for evolutionary analyses

Maxwell, Simon Joseph (2018) The quality of the early hominin fossil record : implications for evolutionary analyses. Doctoral thesis, Birkbeck, University of London.

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Abstract

Hominins (the clade including modern humans and their fossil ancestors) were a taxonomically and morphologically diverse group during the Plio-Pleistocene, and their evolution documents the only known transition to obligate bipedalism in primates. However,many aspects of their shared evolutionary history remain frustratingly unclear due to uncertainty about whether change in the fossil record reflects genuine evolutionary change or variation in our sampling of the rock record. Here, a comprehensive assessment of the quality of the early African hominin fossil record is presented. A specimen database of all early African hominin fossils (>5000) has been compiled including taxonomic, geological, anatomical, and bibliographic information. Using a range of sampling metrics (fossil-bearing formations, collection effort, sampled area, and ghost lineage diversity), it is shown that the pulsedlike pattern of uncorrected (taxic) hominin diversity is almost entirely controlled by rock availability. By contrasting taxic with phylogenetically corrected diversity, hominin diversification appears unconstrained through the lateMiocene and Pliocene, with diversity constantly increasing until a single peak is reached in the early Pleistocene. Phylogenetically corrected diversity shows no discernible link with sampling metrics and there is no direct evidence that shifts in climatic conditions drove diversification. A study of specimen completeness through geological time shows that while sampling metrics (specifically sustained collection effort at rich deposits) have a major influence on patterns of specimen completeness, specimen completeness has only a moderate influence on diversity patterns. It also shows that specimen completeness is poorest during the period most pertinent to human origins, the estimated Pan-Homo divergence date, in large part due to under-sampling (<4% of Africa by sampled area). In combination, this work illustrates that the hominin fossil record is by no means an unbiased depiction of evolutionary events, and therefore its quality and incompleteness should be fully understood before any interpretation of macroevolutionary patterns.

Item Type: Thesis (Doctoral)
Copyright Holders: The copyright of this thesis rests with the author, who asserts his/her right to be known as such according to the Copyright Designs and Patents Act 1988. No dealing with the thesis contrary to the copyright or moral rights of the author is permitted.
School/Department: School of Science > Earth & Planetary Sciences
Depositing User: ORBIT Editor
Date Deposited: 20 Dec 2018 13:27
Last Modified: 20 Dec 2018 13:27
URI: http://bbktheses.da.ulcc.ac.uk/id/eprint/360

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