An early Cambrian pelago-benthic acorn worm and the origin of the hemichordate larva

Enteropneusts (acorn worms) are hemichordates, the sister group to echinoderms. Together they form the clade Ambulacraria, which is closely related to chordates. All three groups appear in the lower Cambrian, but their interrelationships remain problematic, which impedes the understanding of early d...

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Bibliographic Details
Published in:Palaeontologia Electronica
Main Authors: Yang, Xianfeng, Kimmig, Julien, Cameron, Christopher B., Nanglu, Karma, Kimmig, Sara R., de Carle, Danielle, Zhang, Caixia, Yu, Mengxiao, Peng, Shanchi
Format: Report
Language:English
Published: COQUINA PRESS 2024
Subjects:
new genus
new species
lower Cambrian
Chengjiang
Enteropneusta
Ambulacraria
MACKENZIE MOUNTAINS
ROCKSLIDE FORMATION
DISPERSAL DISTANCE
SPECIES LONGEVITY
EVOLUTION
HARRIMANIIDAE
INVERTEBRATES
MORPHOLOGY
WATERBORNE
Paleontology
Mackenzie mountains
Online Access:http://ir.nigpas.ac.cn/handle/332004/43535
http://ir.nigpas.ac.cn/handle/332004/43536
https://doi.org/10.26879/1356
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Summary:Enteropneusts (acorn worms) are hemichordates, the sister group to echinoderms. Together they form the clade Ambulacraria, which is closely related to chordates. All three groups appear in the lower Cambrian, but their interrelationships remain problematic, which impedes the understanding of early deuterostome evolution. Enteropneusts are also extremely rare in the fossil record, only a few species are known from Lagerstatten-type deposits. Here, we describe the earliest known enteromens, including tornaria larvae and juveniles, from the lower Cambrian (Epoch 2, Stage 3) Haiyan Lagerstatte, Chengjiang biota, of China. The enteropneust larvae and post-metamorphic juveniles are the first reported in the fossil record and provide direct evidence for a pelago-benthic lifestyle in a Cambrian deuterostome animal, bolstering the hypothesis that an indirect development is primitive to the enteropneusts and maybe the hemichordates or whole of Ambulacraria.

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