@misc{indiciae5a31a78c06a1,
  title = {Cycads: Fossil evidence of late Paleozoic origin},
  author = {S.H. Mamay},
  year = {1969},
  doi = {10.1126/science.164.3877.295},
  url = {https://pubs.usgs.gov/publication/70010258},
  note = {Source identifier: 70010258}
}