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...
Published in: | Palaeontologia Electronica |
---|---|
Main Authors: | , , , , , , , , |
Format: | Report |
Language: | English |
Published: |
COQUINA PRESS
2024
|
Subjects: | |
Online Access: | http://ir.nigpas.ac.cn/handle/332004/43534 https://doi.org/10.26879/1356 |
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. |
---|