Evolution of metazoan morphological disparity

Bradley Deline*, Jennifer M Greenwood, James W. Clark, Mark N. Puttick, Kevin J. Peterson, Philip C.J. Donoghue

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

23 Citations (Scopus)
354 Downloads (Pure)


The animal kingdom exhibits a great diversity of organismal form (i.e., disparity). Whether the extremes of disparity were achieved early in animal evolutionary history or clades continually explore the limits of possible morphospace is subject to continuing debate. Here we show, through analysis of the disparity of the animal kingdom, that, even though many clades exhibit maximal initial disparity, arthropods, chordates, annelids, echinoderms, and mollusks have continued to explore and expand the limits of morphospace throughout the Phanerozoic, expanding dramatically the envelope of disparity occupied in the Cambrian. The “clumpiness” of morphospace occupation by living clades is a consequence of the extinction of phylogenetic intermediates, indicating that the original distribution of morphologies was more homogeneous. The morphological distances between phyla mirror differences in complexity, body size, and species-level diversity across the animal kingdom. Causal hypotheses of morphologic expansion include time since origination, increases in genome size, protein repertoire, gene family expansion, and gene regulation. We find a strong correlation between increasing morphological disparity, genome size, and microRNA repertoire, but no correlation to protein domain diversity. Our results are compatible with the view that the evolution of gene regulation has been influential in shaping metazoan disparity whereas the invasion of terrestrial ecospace appears to represent an additional gestalt, underpinning the post-Cambrian expansion of metazoan disparity.

Original languageEnglish
Pages (from-to)E8909-E8918
Number of pages10
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number38
Early online date4 Sep 2018
Publication statusPublished - 18 Sep 2018


  • Cambrian explosion
  • Disparity
  • Evolution
  • Metazoa
  • Morphology

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