“…A number of studies have thoroughly assessed the swimming abilities in plesiosaurs and discussed the differences in the two main plesiosaur 'body plans' -the 'long-' and 'short-necked' forms (e.g., Frey & Riess, 1982;Tarsitano & Riess, 1982;Godfrey, 1984;Halstead, 1989;Nicholls & Russell, 1991;Lingham-Soliar, 2000;O'Keefe, 2001;Carpenter et al, 2010;Liu et al, 2015;Muscutt et al, 2017;Noè, Taylor & Gómez-Pérez, 2017;Troelsen et al, 2019). The same applies to mosasauroids whose swimming abilities and especially their origin have been assessed through detailed studies of various aspects of their anatomy (see, e.g., Lindgren, Jagt & Caldwell, 2007;Lindgren et al, 2010;Lindgren, Polcyn & Young, 2011;Konishi et al, 2012;LeBlanc, Caldwell & Lindgren, 2013;Lindgren, Kaddumi & Polcyn, 2013;Houssaye & Bardet, 2013;Cuthbertson et al, 2015;D'Emic, Smith & Ansley, 2015). The mode of swimming in the two clades is known to have differed greatly.…”