10.5061/DRYAD.V7Q827K
Paterson, John R.
University of New England
Edgecombe, Gregory D.
Natural History Museum
Lee, Michael S. Y.
Flinders University
Data from: Trilobite evolutionary rates constrain the duration of the
Cambrian explosion
Dryad
dataset
2019
Cambrian explosion
Bayesian tip-dating
Trilobita
2019-02-19T12:57:52Z
2019-02-19T12:57:52Z
en
https://doi.org/10.1073/pnas.1819366116
945210 bytes
1
CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
Trilobites are often considered exemplary for understanding the Cambrian
explosion of animal life, due to their unsurpassed diversity and
abundance. These biomineralized arthropods appear abruptly in the fossil
record with an established diversity, phylogenetic disparity, and
provincialism at the beginning of Cambrian Series 2 (~521 Ma), suggesting
a protracted but cryptic earlier history that possibly extends into the
Precambrian. However, recent analyses indicate elevated rates of
phenotypic and genomic evolution for arthropods during the early Cambrian,
thereby shortening the phylogenetic fuse. Furthermore, comparatively
little research has been devoted to understanding the duration of the
Cambrian explosion, after which normal Phanerozoic evolutionary rates were
established. We test these hypotheses by applying Bayesian tip-dating
methods to a comprehensive new dataset of Cambrian trilobites. We show
that trilobites have a Cambrian origin, as supported by the trace fossil
record and molecular clocks. Surprisingly, they exhibit constant
evolutionary rates across the entire Cambrian, for all aspects of the
preserved phenotype: discrete, meristic and continuous morphological
traits. Our data therefore provide robust, quantitative evidence that by
the time the ‘typical’ Cambrian fossil record begins (~521 Ma), the
Cambrian explosion had already largely concluded. This suggests that a
modern-style marine biosphere had rapidly emerged during the latest
Ediacaran and earliest Cambrian (~20 million years), followed by
broad-scale evolutionary stasis throughout the remainder of the Cambrian.
Dataset_1_Taxa,Dates,CodingRefsExcel file containing the taxon list,
associated stratigraphic/age data, and references for character
codings.Dataset_2_Discrete_charactersNexus file containing the discrete
data matrix; characters and states are described in annotations (see
detailed list in SI on journal
website).Dataset_3_Meristic_Continuous_charactersExcel file containing the
meristic and continuous data matrices; characters and states are described
more fully in SI on journal website. The measurements underlying
continuous character 111 are also
presented.Dataset_4_BEAST_and_BEAST2Zipped file containing the executable
xml files for the BEAST and BEAST2 analyses of the combined discrete,
meristic and continuous data, as well as the consensus trees in Nexus
(FigTree) and pdf format. The Nexus trees contain extensive node and
branch annotations, only some of which are shown in the
pdf.Dataset_5_TNTZipped file containing the executable plain-text file for
the TNT analysis of the combined discrete, meristic and continuous data,
as well as the output log and tree files in Nexus and pdf format.