An illustrated atlas of the vertebral morphology of extant non-caenophidian snakes, with special emphasis on the cloacal and caudal portions of the column Author Szyndlar, Zbigniew Institute of Systematics and Evolution of Animals, Polish Academy of Sciences, Slawkowska 17, 31 - 016 Krakow, Poland Author Georgalis, Georgios L. https://orcid.org/0000-0001-7759-6146 Institute of Systematics and Evolution of Animals, Polish Academy of Sciences, Slawkowska 17, 31 - 016 Krakow, Poland dimetrodon82@gmail.com text Vertebrate Zoology 2023 2023-09-27 73 717 886 http://dx.doi.org/10.3897/vz.73.e101372 journal article http://dx.doi.org/10.3897/vz.73.e101372 2625-8498-73-717 8F3D5EDA2F184E5CA53E2F7741FF1339 318B657A15AB5708B3C35FC1A82B4945 Boidae Gray, 1825 (sensu Pyron et al. 2014) General information. The concept of Boidae was once much enlarged, encompassing not only all Booidea but also most pythonoids, tropidophiids, bolyeriids, as well as the extinct madtsoiids (e.g., Bonaparte 1839 , 1845 , 1852 ; Boulenger 1893 ; Schmidt 1923 ; Stull 1935 ; Hoffstetter 1939a , 1960 , 1961 ; Loveridge 1942 ; Smith 1943 ; Angel 1950 ; Witte 1953 ; Dowling 1959 ; Kuhn 1961 ; Stimson 1969 ; Guibe 1970 ; Hoffstetter and Rage 1972 ; Rage 1974 , 1984 , 1987 ; McDowell 1975 ; Underwood 1976 ; Underwood and Stimson 1990 ; Szyndlar 1991a ; Kluge 1993a ; Szyndlar and Boehme 1996 ; Harvey et al. 2000 ; Ivanov et al. 2000 ). However, in recent taxonomic schemes, following the advance of phylogenetic analyses, the content of Boidae has dramatically decreased to encompass only the five extant genera Boa , Chilabothrus , Corallus , Epicrates , and Eunectes , all currently distributed in the Americas (see Pyron et al. 2014 ; Reynolds and Henderson 2018 ; Scanferla and Smith 2020b ). That taxonomic approach almost corresponds with the concept of the subfamily Boinae in previous decades (e.g., Stull 1935 ; Stimson 1969 ; Rage 1984 ; Szyndlar 1991a ; Ivanov et al. 2000 ; Szyndlar and Rage 2003 ). They have a rich fossil record, including also remains of all the extant genera ( Pregill 1981 ; Rage 2001 ; Head et al. 2006 , 2012 ; Albino and Carlini 2008 ; Hsiou and Albino 2009 ; Camolez and Zaher 2010 ; Sanchez-Villagra 2012 ; Albino and Brizuela 2014 ; Bochaton et al. 2015 ; Aranda et al. 2017 ; Mead and Steadman 2017 ; Onary et al. 2017 , 2018 ; Bochaton and Bailon 2018 ; Onary and Hsiou 2018 ; Carrillo-Briceno et al. 2021 ). Trunk vertebrae of Boidae closely resemble those of other booids (except for candoiids and ungaliophiids) as well as other constrictors and more particularly, Pythonidae . However, some (but not all) boas possess paracotylar foramina that are totally absent in pythons; this difference has been particularly applied as a potentially useful tool in palaeontological research (e.g., Rage 1984 ; Szyndlar 1991a ; Szyndlar and Rage 2003 ). Vertebrae of Boidae have regularly and extensively appeared in the literature, including some of the first studies of snake vertebral morphology (e.g., D'Alton 1836 ). As such, a large number of studies have so far presented figures of vertebrae of Boidae , including Grant (1841) , Rochebrune (1881) , Holman (1967) , Gasc (1974) , Lee and Scanlon (2002) , Szyndlar and Rage (2003) , Head et al. (2009 , 2022 ), Albino (2011) , Albino et al. (2018) , Onary and Hsiou (2018) , Palci et al. (2018) , Georgalis and Scheyer (2019) , Machado-Filho (2020) , and Georgalis et al. (2021a) , including even vertebrae of early ontogenetic stages, such as embryos ( Chuliver et al. 2022 ). Among these, vertebrae from the cloacal and/or caudal series were presented by Szyndlar and Rage (2003) , Machado-Filho (2020) , and Alfonso-Rojas et al. (2023) . Figures of the microanatomy and histology / transverse sections of boid vertebrae were presented by Buffrenil and Rage (1993) and Houssaye et al. (2010) . Quantitative studies on the intracolumnar variability of boid vertebrae were also conducted by Hoffstetter (1960) and Gasc (1974) .