TY - JOUR
T1 - Calibrating the temporal and spatial dynamics of the Ediacaran - Cambrian radiation of animals
AU - Bowyer, Fred T.
AU - Zhuravlev, Andrey Yu
AU - Wood, Rachel
AU - Shields, Graham A.
AU - Zhou, Ying
AU - Curtis, Andrew
AU - Poulton, Simon W.
AU - Condon, Daniel J.
AU - Yang, Chuan
AU - Zhu, Maoyan
N1 - Funding Information:
FB, RW, GS, SWP, YZ and MZ acknowledge funding from the joint NERC-NSFC Biosphere Evolution Transitions and Resilience (BETR) programme ( NE/P013643/1 , NSFC/41661134048 ), MZ from the Strategic Priority Research Program (B) of the Chinese Academy of Sciences ( XDB18000000 , XDB 26000000 ), FB, SWP and GS from NERC project NE/R010129/1 , and RW, SWP and FB from NERC Project NE/T008458/1 . SWP acknowledges support from a Royal Society Wolfson Research Merit Award . AZ from Scientific Project 04-1-21 of the State Order of the Government of the Russian Federation to the Lomonosov Moscow State University (No. 121031600198-2 ). We thank C. Chilcott for technical support. We are grateful to H. Mocke and C. Hoffmann of the Geological Survey of Namibia and the Ministry of Mines and Energy, Namibia. We thank B. Romer and L. Gessert for access to Farm Swartpunt. We thank Irene Gomez Perez for enlightening discussion regarding Ara Group stratigraphy. We thank Lucas Warren and one anonymous reviewer for constructive comments and suggestions that improved the paper.
Funding Information:
FB, RW, GS, SWP, YZ and MZ acknowledge funding from the joint NERC-NSFC Biosphere Evolution Transitions and Resilience (BETR) programme (NE/P013643/1, NSFC/41661134048), MZ from the Strategic Priority Research Program (B) of the Chinese Academy of Sciences (XDB18000000, XDB 26000000), FB, SWP and GS from NERC project NE/R010129/1, and RW, SWP and FB from NERC Project NE/T008458/1. SWP acknowledges support from a Royal Society Wolfson Research Merit Award. AZ from Scientific Project 04-1-21 of the State Order of the Government of the Russian Federation to the Lomonosov Moscow State University (No. 121031600198-2). We thank C. Chilcott for technical support. We are grateful to H. Mocke and C. Hoffmann of the Geological Survey of Namibia and the Ministry of Mines and Energy, Namibia. We thank B. Romer and L. Gessert for access to Farm Swartpunt. We thank Irene Gomez Perez for enlightening discussion regarding Ara Group stratigraphy. We thank Lucas Warren and one anonymous reviewer for constructive comments and suggestions that improved the paper.
Publisher Copyright:
© 2021 The Author(s)
PY - 2022/2/1
Y1 - 2022/2/1
N2 - The Ediacaran-Cambrian transition, which incorporates the radiation of animals, lacks a robust global temporal and spatial framework, resulting in major uncertainty in the evolutionary dynamics of this critical radiation and its relationship to changes in palaeoenvironmental geochemistry. We first present a new δ13Ccarb composite reference curve for the Ediacaran Nama Group of southern Namibia, and we then outline four new possible global age models (A to D) for the interval 551–517 million years ago (Ma). These models comprise composite carbonate‑carbon isotope (δ13Ccarb) curves, which are anchored to radiometric ages and consistent with strontium isotope chemostratigraphy, and are used to calibrate metazoan distribution in space and time. These models differ most prominently in the temporal position of the basal Cambrian negative δ13Ccarb excursion (BACE). Regions that host the most complete records show that the BACE nadir always predates the Ediacaran-Cambrian boundary as defined by the first appearance datum (FAD) of the ichnospecies Treptichnus pedum. Whilst treptichnid traces are present in the late Ediacaran fossil record, the FAD of the ichnospecies T. pedum appears to post-date the LAD of in situ Cloudina and Namacalathus in all environments with high-resolution δ13Ccarb data. Two age models (A and B) place the BACE within the Ediacaran, and yield an age of ~538.8 Ma for the Ediacaran-Cambrian boundary; however models C and D appear to be the most parsimonious and may support a recalibration of the boundary age by up to 3 Myr younger. All age models reveal a previously underappreciated degree of variability in the terminal Ediacaran, incorporating notable positive and negative excursions that precede the BACE. Nothwithstanding remaining uncertainties in chemostratigraphic correlation, all models support a pre-BACE first appearance of Cambrian-type shelly fossils in Siberia and possibly South China, and show that the Ediacaran-Cambrian transition was a protracted interval represented by a series of successive radiations.
AB - The Ediacaran-Cambrian transition, which incorporates the radiation of animals, lacks a robust global temporal and spatial framework, resulting in major uncertainty in the evolutionary dynamics of this critical radiation and its relationship to changes in palaeoenvironmental geochemistry. We first present a new δ13Ccarb composite reference curve for the Ediacaran Nama Group of southern Namibia, and we then outline four new possible global age models (A to D) for the interval 551–517 million years ago (Ma). These models comprise composite carbonate‑carbon isotope (δ13Ccarb) curves, which are anchored to radiometric ages and consistent with strontium isotope chemostratigraphy, and are used to calibrate metazoan distribution in space and time. These models differ most prominently in the temporal position of the basal Cambrian negative δ13Ccarb excursion (BACE). Regions that host the most complete records show that the BACE nadir always predates the Ediacaran-Cambrian boundary as defined by the first appearance datum (FAD) of the ichnospecies Treptichnus pedum. Whilst treptichnid traces are present in the late Ediacaran fossil record, the FAD of the ichnospecies T. pedum appears to post-date the LAD of in situ Cloudina and Namacalathus in all environments with high-resolution δ13Ccarb data. Two age models (A and B) place the BACE within the Ediacaran, and yield an age of ~538.8 Ma for the Ediacaran-Cambrian boundary; however models C and D appear to be the most parsimonious and may support a recalibration of the boundary age by up to 3 Myr younger. All age models reveal a previously underappreciated degree of variability in the terminal Ediacaran, incorporating notable positive and negative excursions that precede the BACE. Nothwithstanding remaining uncertainties in chemostratigraphic correlation, all models support a pre-BACE first appearance of Cambrian-type shelly fossils in Siberia and possibly South China, and show that the Ediacaran-Cambrian transition was a protracted interval represented by a series of successive radiations.
U2 - 10.1016/j.earscirev.2021.103913
DO - 10.1016/j.earscirev.2021.103913
M3 - Article
SN - 0012-8252
VL - 225
JO - Earth-Science Reviews
JF - Earth-Science Reviews
M1 - 103913
ER -