... Department of Geology, West Georgia College, Carrollton, Georgia 30117 Accepted: April 13, 19... more ... Department of Geology, West Georgia College, Carrollton, Georgia 30117 Accepted: April 13, 1977 ... In paleontology Fourier series has been applied to the shape of ostracode margins byYounker (1971) and Kaesler and Waters (1972), to zooecial shapes in fossil bryozoans by ...
... WATERS, Johnny, Geology, Appalachian State University, Boone, NC 28608, watersja@appstate. ed... more ... WATERS, Johnny, Geology, Appalachian State University, Boone, NC 28608, watersja@appstate. edu and SUMRALL, Colin, Earth and Planetary Science ... Waters and Marcus (2002a,b) have reinterpreted previous studies of blastoid development to propose a two stage larval ...
... Department of Geology, West Georgia College, Carrollton, Georgia 30117 Accepted: April 13, 19... more ... Department of Geology, West Georgia College, Carrollton, Georgia 30117 Accepted: April 13, 1977 ... In paleontology Fourier series has been applied to the shape of ostracode margins byYounker (1971) and Kaesler and Waters (1972), to zooecial shapes in fossil bryozoans by ...
... WATERS, Johnny, Geology, Appalachian State University, Boone, NC 28608, watersja@appstate. ed... more ... WATERS, Johnny, Geology, Appalachian State University, Boone, NC 28608, watersja@appstate. edu and SUMRALL, Colin, Earth and Planetary Science ... Waters and Marcus (2002a,b) have reinterpreted previous studies of blastoid development to propose a two stage larval ...
Inferring the development of the earliest echinoderms is critical to uncovering the evolutionary ... more 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 postmetamorphic 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.
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