The Systematics Of Millioedes From Late Cretaceous Burmese Amber

Millipedes(Diplopoda),as the earliest known terrestrial arthropod group,are of great signif icance to investigate the evolution of early arthropods.However,there is a gap in the Mesozoic,with only a dozen fossils being known.Burmese amber,precisely dated to the Late Cretaceous,is known for an apparently rich but still undescribed millipede fauna.These records might provide an ideal bridge to fill in the Mesozoic gap in the evolution of Millipedes.Here,three new genera and four new species of millipedes,i.e.,Maatarius burmensis gen.et sp.nov.,Anbaresmus burmensis gen.et sp.nov.,Wilsonesmus burmensis gen.et sp.nov.and Gosodesmus burmensis sp.nov.,from Late Cretaceous Burmese amber were set up and described.They are the earliest fossil representatives of Plydesmida and P latydesmida.The phylogeny of our fossil millipedes was discussed.In addition,modern micro-computed tomography(Micro-CT)technology was utilized to reconstruct the 3D model of fossil specimens.By the analysis of the relationship between the body size of millipedes and atmospheric oxygen partial pressure in geologic time,the correlation between the maximum body size of millipedes and the atmospheric oxygen partial pressure in geologic time was confirmed.It suggested that the oxygen partial pressure in the atmosphere is a key factor to control the body size of millipedes.Finally,through the analysis of the morphology and individual development of the early marine fossils,the possible evolutionary model and origin groups of Diplopoda were briefly discussed.