Fuxianhuia

Indeed, on the grounds that these structures seem to lie between two cuticular layers, Waloszek and colleagues have suggested that they are not appendages at all, but rather gut diverticula;[3] a reassignment that has however not been universally accepted.[5] In general, the Fuxianhuia brain shows the same tripartite morphology of Malacostraca, Chilopoda and Insecta, indicating that such an organization could be precedent to the divergence between these clades.[5] In 2014 a fossil was described[6] that preserved in exquisite, unequaled detail the tubular heart and blood vessels, which represent the oldest cardiovascular system yet identified."The rich vascularization in the head... suggests that the brain of this species required a good supply of oxygen for its performance," said University of Arizona neuroscientist Nicholas Strausfeld, one of the researchers.Its articulated head region, lack of tergite-segment correspondence and undifferentiated limbs have all been taken to indicate a very basal position in the arthropods,[2][9][10] even though an early cladistic analysis suggested, rather, that it was a stem-group chelicerate.