text: Despite its feathers , most palaeontologists do not consider Sinosauropteryx to be a bird . Phylogenetically , it is only distantly related to the clade Aves , usually defined as Archaeopteryx plus modern birds .
simplified: Most paleontologists do not consider Sinosauropteryx to be a bird , because phylogenetically , it lies far from the clade Aves , usually defined as Archaeopteryx plus modern birds .