TY - JOUR
T1 - Preservational Pathways of Corresponding Brains of a Cambrian Euarthropod
AU - Ma, Xiaoya
AU - Edgecombe, Gregory D.
AU - Hou, Xianguang
AU - Goral, Tomasz
AU - Strausfeld, Nicholas J.
N1 - Funding Information:
This work was supported by the Natural Environment Research Council (NERC) Independent Research Fellowship (NE/L011751/1) to X.M., a Leverhulme Trust Research Project Grant (F/00 696/T) to G.D.E, a joint grant of the National Natural Science Foundation and Yunnan Province of China (U1302232) to X.M. and X.H., a grant from the Air Force Research Laboratory (FA86511010001) to N.J.S., and funding from the Center for Insect Science, University of Arizona to N.J.S. We thank R.R. Gaines and an anonymous reviewer for their constructive reviews, T. Salge (The Natural History Museum) for assistance with elemental mapping, and C. Qi (Yunnan University) for discussions.
Publisher Copyright:
© 2015 The Authors.
PY - 2015/11/16
Y1 - 2015/11/16
N2 - The record of arthropod body fossils is traceable back to the "Cambrian explosion," marked by the appearance of most major animal phyla. Exceptional preservation provides crucial evidence for panarthropod early radiation. However, due to limited representation in the fossil record of internal anatomy, particularly the CNS, studies usually rely on exoskeletal and appendicular morphology. Recent studies [1-3] show that despite extreme morphological disparities, euarthropod CNS evolution appears to have been remarkably conservative. This conclusion is supported by descriptions from Cambrian panarthropods of neural structures that contribute to understanding early evolution of nervous systems and resolving controversies about segmental homologies [4-12]. However, the rarity of fossilized CNSs, even when exoskeletons and appendages show high levels of integrity, brought into question data reproducibility because all but one of the aforementioned studies were based on single specimens [13]. Foremost among objections is the lack of taphonomic explanation for exceptional preservation of a tissue that some see as too prone to decay to be fossilized. Here we describe newly discovered specimens of the Chengjiang euarthropod Fuxianhuia protensa with fossilized brains revealing matching profiles, allowing rigorous testing of the reproducibility of cerebral structures. Their geochemical analyses provide crucial insights of taphonomic pathways for brain preservation, ranging from uniform carbon compressions to complete pyritization, revealing that neural tissue was initially preserved as carbonaceous film and subsequently pyritized. This mode of preservation is consistent with the taphonomic pathways of gross anatomy, indicating that no special mode is required for fossilization of labile neural tissue.
AB - The record of arthropod body fossils is traceable back to the "Cambrian explosion," marked by the appearance of most major animal phyla. Exceptional preservation provides crucial evidence for panarthropod early radiation. However, due to limited representation in the fossil record of internal anatomy, particularly the CNS, studies usually rely on exoskeletal and appendicular morphology. Recent studies [1-3] show that despite extreme morphological disparities, euarthropod CNS evolution appears to have been remarkably conservative. This conclusion is supported by descriptions from Cambrian panarthropods of neural structures that contribute to understanding early evolution of nervous systems and resolving controversies about segmental homologies [4-12]. However, the rarity of fossilized CNSs, even when exoskeletons and appendages show high levels of integrity, brought into question data reproducibility because all but one of the aforementioned studies were based on single specimens [13]. Foremost among objections is the lack of taphonomic explanation for exceptional preservation of a tissue that some see as too prone to decay to be fossilized. Here we describe newly discovered specimens of the Chengjiang euarthropod Fuxianhuia protensa with fossilized brains revealing matching profiles, allowing rigorous testing of the reproducibility of cerebral structures. Their geochemical analyses provide crucial insights of taphonomic pathways for brain preservation, ranging from uniform carbon compressions to complete pyritization, revealing that neural tissue was initially preserved as carbonaceous film and subsequently pyritized. This mode of preservation is consistent with the taphonomic pathways of gross anatomy, indicating that no special mode is required for fossilization of labile neural tissue.
KW - Cambrian
KW - Chengjiang biota
KW - arthropod
KW - brains
KW - exceptional preservation
KW - geochemistry
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U2 - 10.1016/j.cub.2015.09.063
DO - 10.1016/j.cub.2015.09.063
M3 - Article
C2 - 26526373
AN - SCOPUS:84960801202
VL - 25
SP - 2969
EP - 2975
JO - Current Biology
JF - Current Biology
SN - 0960-9822
IS - 22
ER -