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Article: Trilobite ‘pelotons’: possible hydrodynamic drag effects between leading and following trilobites in trilobite queues

Palaeontology - Volume 60 Part 4 - Cover
Publication: Palaeontology
Volume: 60
Part: 4
Publication Date: July 2017
Page(s): 557 569
Author(s): Hugh Trenchard, Carlton E. Brett, and Matjaž Perc
Addition Information

How to Cite

TRENCHARD, H., BRETT, C.E., PERC, M. 2017. Trilobite ‘pelotons’: possible hydrodynamic drag effects between leading and following trilobites in trilobite queues. Palaeontology, 60, 4, 557-569. DOI: 10.1111/pala.12301

Author Information

  • Hugh Trenchard - Victoria BC Canada (Email:
  • Carlton E. Brett - Geology Department University of Cincinnati Cincinnati OH USA
  • Matjaž Perc - Faculty of Natural Sciences & Mathematics University of Maribor Maribor Slovenia
  • Matjaž Perc - Center for Applied Mathematics & Theoretical Physics University of Maribor Maribor Slovenia

Publication History

  • Issue published online: 12 June 2017
  • Manuscript Accepted: 11 April 2017
  • Manuscript Received: 17 January 2017

Online Version Hosted By

Wiley Online Library
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Energy saving mechanisms in nature allow following organisms to expend less energy than leaders. Queues, or ordered rows of individuals, may form when organisms exploit the available energy saving mechanism while travelling at near‐maximal sustainable metabolic capacities; compact clusters form when group members travel well below maximal sustainable metabolic capacities. The group size range, given here as the ratio of the difference between the size of the largest and smallest group members, and the size of the largest member (as a percentage), has been hypothesized to correspond proportionately to the energy saving quantity because weaker, smaller, individuals sustain the speeds of stronger, larger, individuals by exploiting the energy saving mechanism (as a percentage). During migration, small individuals outside this range may perish, or form sub‐groups, or simply not participate in migratory behaviour. We approximate drag forces for leading and following individuals in queues of the late Devonian (c. 370 Ma) trilobite Trimerocephalus chopini. Applying data from literature on Rectisura herculea, a living crustacean, we approximate the hypothetical walking speed and maximal sustainable speeds for T. chopini. Our findings reasonably support the hypothesis that among the population of fossilized queues of T. chopini reported in the literature, trilobite size range was 75%, while the size range within queues was 63%; this corresponds reasonably with drag reductions in following positions that permit c. 61.5% energy saving for trilobites following others in optimal low‐drag positions. We model collective trilobite behaviour associated with hydrodynamic drafting.

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