Data from: Early post-metamorphic, Carboniferous blastoid reveals the evolution and development of the digestive system in early echinoderms

Inferring the development of the earliest echinoderms is critical to uncovering the evolutionary assembly of the phylum-level body plan but has long proven problematic because early ontogenetic stages are rarely preserved as fossils. Here, we use synchrotron tomography to describe a new early post-metamorphic blastoid echinoderm from the Carboniferous (approx. 323 Ma) of China. The resulting three-dimensional reconstruction reveals a U-shaped tubular structure in the fossil interior, which is interpreted as the digestive tract. Comparisons with the developing gut of modern crinoids demonstrate that crinoids are an imperfect analogue for many extinct groups. Furthermore, consideration of our findings in a phylogenetic context allows us to reconstruct the evolution and development of the digestive system in echinoderms more broadly; there was a transition from a straight to a simple curved gut early in the phylum's evolution, but additional loops and coils of the digestive tract (as seen in crinoids) were not acquired until much later.,Data S2Interactive three-dimensional digital reconstruction of the early post-metamorphic, Carboniferous blastoid (NIGP 163236). The reconstruction is in VAXML format, compressed in a ZIP archive, and has been downsampled to reduce triangle count. To view: unpack the .zip file, install the SPIERS software suite (program and documentation available from www.spiers-software.org), and double-click the unpacked .vaxml file.Data_S2.zipVideo S1Video showing a three-dimensional digital reconstruction of the early post-metamorphic, Carboniferous blastoid (NIGP 163236).Video_S1.aviData S1Synchrotron tomography scan of the early post-metamorphic, Carboniferous blastoid (NIGP 163236). The slice images are in TIFF format, compressed in a ZIP archive.Data_S1.zip,