Table 1. Hypotheses for helical or spiral burrows across 21 extant and extinct genera and ichnogenera representing 59–184 spp . (see text for explanation of why there is a range in the number of species). Designations include ‘poss.’ (possible), ‘unlikely’, or ‘n/a’ (not applicable, not possible, or highly unlikely). Scores = the proportion (%) possible for each taxon. X = ichnotaxa & modern taxa; y = could also result in post-construction benefits. Data based on deductive reasoning and the following sources: Anuroctonus(Williams, 1966); Axianassa (Dworschak and Rodriguez, 1997; Felder, 2001; Netto et al., 2007); Axiopsis (Dworschak and Ott, 1993); Callianassa (Dworschak and Pervesler, 1988; Atkinson and Nash, 1990; James et al., 1990; Nickell and Atkinson, 1995);Cratogeomys (Villa, 1989; Roberts et al., 1997; Wilkins and Roberts, 2007); Cylindrichnus (de Gibert et al., 2006);Cynomys (Wood & Wood, 1933; Schultz, 1942; Ceballos-G and Wilson, 1985); Daimonelix (Fischer and Hasiotis, 2018; Raisanen and Hasiotis, 2018); Diictodon (Smith, 1987; Smith, 1993; King, 1996; Smith et al., 2021); Geomys (Brown and Hickman, 1973; Cameron et al., 1988; Wilkins and Roberts, 2007); Gyrolithes(Gernant, 1972; Bromley and Frey, 1974; Powell, 1977; Ekdale et al., 1984; Beynon and Pemberton, 1992; Mayoral and Muñiz, 1995; Bromley, 1996; Dworschak and Rordrigues, 1997; Mayoral and Muñiz, 1998; Buatois et al., 2005; Netto et al., 2007; Wetzel et al., 2010; de Gibert et al., 2012; Hasiotis et al., 2013; Jackson et al., 2016; Laing et al., 2018; Muniz and Belastegui, 2019; Moosavizadeh and Knaust, 2021; Oligmueller and Hasiotis, 2022); Helicodromites (Poschmann, 2015);Lapispira (Lanes et al., 2007; de Gibert et al., 2012);Notomastus (Powell, 1977); Ocypode (Parenzan, 1931, in: Eshky, 1985; Fellows, 1966, in: Vannini, 1980; Schober and Christy, 1993; Clayton, 2005); Ophiomorpha (Loope and Dingus, 1999; de Gibert et al., 2012); Opisthophthalmus (Lamoral, 1978);Paleocaster (Martin and Bennett, 1977; Meyer, 1999);Paruroctonus (Bradley, 1988); Urodacus (Koch, 1977; 1978; Shorthouse and Marples, 1980; White, 2001; Adams et al., 2016);Varanus (Doody et al., 2014; Doody et al., 2015; Doody et al., 2018a,b; Doody et al., 2020).