Despite the rarity of complete fossils, these very rare intact specimens do allow us to gain an insight into the internal organ arrangement of the Thelodonts. Some specimens described in 1993 were the first to be found with a significant degree of three-dimensionality, ending speculations that the Thelodonts were flattened fish. Further, these fossils allowed the gut morphology to be interpreted, which generated much excitement: their guts were unlike those of any other agnathans, and a stomach was clearly visible: this was unexpected, as it was previously thought that stomachs evolved "after" jaws. Distinctive fork-shaped tails – usually characteristic of the jawed fish (gnathostomes) – were also found, linking the two groups to an unexpected degree.