Several species have been assumed to exist, but due to a lack of physical evidence they can only be regarded as potential species . Hypothetical species are usually believed to be extinct. They have caused confusion, as they may have been a separate species , a subspecies , an introduced species or a misidentification.[1]
A 1722 illustration by Jean-Baptiste Labat of three parrots on Guadeloupe . There are no remains of these parrots and so accurate taxonomic classification is impossible.
Gopalakrishnan, Shyam; Sinding, Mikkel-Holger S.; Ramos-Madrigal, Jazmín; Niemann, Jonas; Samaniego Castruita, Jose A.; Vieira, Filipe G.; Carøe, Christian; Montero, Marc de Manuel; Kuderna, Lukas; Serres, Aitor; González-Basallote, Víctor Manuel; Liu, Yan-Hu; Wang, Guo-Dong; Marques-Bonet, Tomas; Mirarab, Siavash; Fernandes, Carlos; Gaubert, Philippe; Koepfli, Klaus-Peter; Budd, Jane; Rueness, Eli Knispel; Sillero, Claudio; Heide-Jørgensen, Mads Peter; Petersen, Bent; Sicheritz-Ponten, Thomas; Bachmann, Lutz; Wiig, Øystein; Hansen, Anders J.; Gilbert, M. Thomas P. (2018). "Interspecific Gene Flow Shaped the Evolution of the Genus Canis" . Current Biology . 28 (21): 3441–3449.e5. Bibcode :2018CBio...28E3441G . doi :10.1016/j.cub.2018.08.041 . PMC 6224481 . PMID 30344120 .
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Beebe, William (1934). Half Mile Down (PDF) . New York: Harcourt, Brace and Company.