10.5061/DRYAD.W6M905QN9
Varnham, Grace
0000-0002-1766-5127
University College London
Mannion, Philip
University College London
Kammerer, Christian
0000-0002-0596-623X
North Carolina Museum of Natural Sciences
Data from: Spatiotemporal variation in completeness of the early cynodont
fossil record and its implications for mammalian evolutionary history
Dryad
dataset
2020
Cynodontia
Fossil record bias
spatiotemporal sampling
Synapsida
2020-09-01T00:00:00Z
2020-09-01T00:00:00Z
en
https://doi.org/10.1111/pala.12524
4829032 bytes
5
CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
Mammals are the only surviving group of Cynodontia, a synapsid clade that
first appears in the fossil record in the late Permian, ~260 million years
ago. Here, using three metrics that capture skeletal completeness, we
quantify the quality of the early cynodont fossil record in time and space
to evaluate the impact of sampling and preservational biases on our
understanding of the group’s evolutionary history. There is no consistent
global sampling signal for early cynodonts. Completeness of the cynodont
fossil record increases across the Permian/Triassic boundary, peaking in
the Early–early Late Triassic. This peak is dominated by specimens from
southern Africa and South America, where a highly seasonal climate likely
favoured preservation. Completeness is generally lower thereafter,
correlated with a shift from a Gondwanan to a predominantly Laurasian
fossil record. Phylogenetic and stratigraphic congruence in early
cynodonts is high, although their fossil record exhibits less skeletal
completeness overall than other tetrapod clades, including the
contemporaneous anomodont synapsids. This discrepancy could be due to
differences in the diagnosability of their fossils, especially for
small-bodied species. Establishing the timing and assembly of derived
(‘mammalian’) anatomical features in Cynodontia is obscured by sampling.
Two of the major nodes at which acquisition of mammalian features is
concentrated (Cynodontia and Mammaliamorpha) suffer from lengthy intervals
of poor sampling prior to becoming abundant parts of tetrapod faunas. Low
completeness in these intervals limits our ability to determine when
certain ‘key’ mammalian characteristics evolved, or to identify the
selective pressures that might have driven their origins.
Please use the latest version of this dataset (December 14, 2020)
Supplementary Data 1 First and last appearance dates and locality
information for cynodont species included within this study. Supplementary
Data 2 Completeness scores used to calculate SCM. Supplementary Data 3
Completeness scores used to calculate BSCM. Supplementary Data 4
References used to estimate body size for each species. Supplementary Data
5 Mean averages, medians and standard deviations for spatiotemporal
completeness values. Supplementary Data 6 Statistical test results.
Supplementary Data 7 Phylogenetic and stratigraphic congruence results.
Supplementary Data 8 Phylogenetic and stratigraphic congruence results.