• Silhouettes for American paddlefish based on https://commons.wikimedia.org/wiki/File:FMIB_51145_Paddle-Fish.jpeg which is in public domain
• Silhouette for Chinese paddlefish is based on https://commons.wikimedia.org/wiki/File:Psephurus_gladius.jpg from 1868, which is in public domain, with shape of tail fin modified after modern photographs of Chinese paddlefish
• Silhouettes for Crossopholis and Parapsephurus are based on https://commons.wikimedia.org/wiki/File:Parapsephurus.png and https://commons.wikimedia.org/wiki/File:Crossopholis.png by AraucariaHeterophylla, under a CC-BY 4.0 license
• Silhouette for Protopsephurus is based on https://www.phylopic.org/images/01d1b294-736a-4f66-9ad2-2082427d9574/protopsephurus-liui by T. Michael Keesey, in the public domain
• Silhouette for Paleopsephurus is based on a figure by Wikipedia/Commons user Gasmasque (personal communication), released under a compatible license.

Size estimates of paddlefish based on:

• "Is there evidence that the Chinese paddlefish ( Psephurus gladius ) still survives in the upper Yangtze River? Concerns inferred from hydroacoustic and capture surveys, 2006-2008" (2003 Chinese paddlefish length)
• "Paleopsephurus wilsoni a new polyodontid fish from the Upper Cretaceous of Montana, with a discussion of allied fish, living and fossil" (Paleopsephurus total length estimate)
• "A Large Polyodon from Iowa" (largest American paddlefish)
• "New paddlefishes (Acipenseriformes, Polyodontidae) from the Late Cretaceous Tanis Site of the Hell Creek Formation in North Dakota, USA" (Parapsephurus length)
• Grande, Lance; Jin, Fan; Yabumoto, Yoshitaka; Bemis, William E. (2002-07-08). "Protopsephurus liui, a well-preserved primitive paddlefish (Acipenseriformes: Polyodontidae) from the Lower Cretaceous of China" (Protopsephurus largest individual length)
• WWF entry on American paddlefish https://web.archive.org/web/20140723073024/http://wwf.panda.org/what_we_do/endangered_species/paddlefish/ (average American paddlefish length)