The platypus is a monotreme mammal that has both reptile and mammalian traits, such as laying eggs and a duck bill like reptiles and birds, and a coat of fur like mammals. It is native to Australia. This reference assembly of has been produced as part of the G10K-VGP Project and a BGI project on mammal evolution. The male sample was collected for Guojie Zhang and sequenced at Pacific Biosciences, BGI for Illumina data, and the Rockefeller University Vertebrate Genome lab for Bioanano and 10X data. HiC data was generated from a different individual at Phase Genomics. Genome assembly was conducted by the G10K-VGP group, namely Arang Rhie and Sergey Koren of Adam Phillippy's lab at NIH. Manual curation of chromosomes and other genomic features was conducted by the gEVAL group led by Kerstin Howe at the Sanger Institute, Harris Lewin and Joanna Damas at UC Davis, the Phillippy Lab, and Guojie Zhang and Yang Zhou of BGI. The primary haplotype contains the longest contigs of the Pacbio FALCON unzip assembly, scaffolded with 10X linked reads, Bionano optical maps, and Phase Genomics HiC reads, with multiple tools to further separate out haplotypes. Funding was provided by Pacbio as part of a promotion, BGI to Guojie Zhang, HHMI and Rockefeller start-up funds to Erich Jarvis, and individual grants and awards to the persons listed above. Released from embargo April 29, 2021.