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Hypselospinus fittoni

Reptilia

Taxonomy

Iguanodon fittoni was named by Lydekker (1889). Its type specimen is BMNH R1635, a partial skeleton (incomplete left ilium, partial sacrum, midcaudal centrum, the eroded proximal end of an ischium (very dubious association). In addition, three isolated teeth (o), and it is a 3D body fossil. Its type locality is Shornden Quarry (sand), which is in a Valanginian terrestrial sandstone in the Wadhurst Clay Formation of the United Kingdom. It is the type species of Hypselospinus.

It was recombined as Wadhurstia fittoni by Carpenter and Ishida (2010); it was considered a nomen dubium by Paul (2008); it was recombined as Hypselospinus fittoni by Norman (2010), Pereda Suberbiola et al. (2010), McDonald et al. (2010), McDonald et al. (2010), Pereda-Suberbiola et al. (2011), McDonald et al. (2012), Norman (2013), Zheng et al. (2013), Pereda Suberbiola and Ruiz-Omeñaca (2013), Norman (2014), Norman (2014), Fuentes Vidarte et al. (2016), Ibiricu et al. (2019), Santos-Cubedo et al. (2021), Verdú et al. (2021), Ji and Zhang (2022) and Bonsor et al. (2023).

Synonyms

Darwinsaurus evolutionis was named by Paul (2012). Its type specimen is NHMUK R1831, 1833, 1835, 1836, a partial skeleton, and it is a 3D body fossil.

It was synonymized subjectively with Hypselospinus fittoni by Norman (2013).
Iguanodon hollingtoniensis was named by Lydekker (1889). It is a 3D body fossil. Its type locality is Hollington Quarry (BMNH), which is in a Valanginian lacustrine - small horizon in the Wadhurst Clay Formation of the United Kingdom.

It was synonymized subjectively with Iguanodon fittoni by Norman and Weishampel (1990), Blows (1998) and Norman (2004); it was corrected as Iguanodon hollingtonensis by Galton (2009); it was recombined as Huxleysaurus hollingtoniensis by Paul (2012); it was misspelled as Iguanodon hollingtonensis by Norman (1997); it was considered a nomen dubium by Paul (2008); it was synonymized subjectively with Hypselospinus fittoni by Norman (2010), McDonald et al. (2010), Pereda-Suberbiola et al. (2011), Norman (2013), Pereda Suberbiola and Ruiz-Omeñaca (2013), Norman (2014) and Bonsor et al. (2023).

Synonymy list

Year	Name and author
1889	Iguanodon fittoni Lydekker p. 354
1889	Iguanodon hollingtoniensis Lydekker p. 355
1890	Iguanodon fittoni Lydekker pp. 38-40
1890	Iguanodon hollingtoniensis Lydekker pp. 40-43 fig. 2
1890	Iguanodon fittoni Woodward and Sherborn p. 243
1890	Iguanodon hollingtoniensis Woodward and Sherborn p. 243
1890	Iguanodon fittoni Zittel p. 762
1890	Iguanodon hollingtoniensis Zittel p. 762
1896	Iguanodon fittoni Mansel-Pleydell p. 119
1896	Iguanodon hollingtoniensis Mansel-Pleydell p. 119
1900	Iguanodon fittoni Van Den Broeck p. 92
1900	Iguanodon hollingtoniensis Van Den Broeck p. 92
1901	Iguanodon fittoni Nopcsa p. 211
1901	Iguanodon hollingtonensis Nopcsa p. 211
1902	Iguanodon fittoni Mansel-Pleydell p. lxxxiii
1902	Iguanodon hollingtoniensis Mansel-Pleydell p. lxxxiii
1902	Iguanodon fittoni Nopcsa p. 151
1902	Iguanodon hollingtoniensis Nopcsa p. 151
1964	Iguanodon fittoni Kuhn p. 11
1964	Iguanodon hollingtoniensis Kuhn p. 11
1981	Iguanodon fittoni Bartholomai and Molnar p. 343
1981	Iguanodon hollingtoniensis Bartholomai and Molnar p. 343
1987	Iguanodon fittoni Norman p. 165
1990	Iguanodon fittoni Norman and Weishampel p. 530
1992	Iguanodon fittoni Martin and Buffetaut p. 68
1997	Iguanodon hollingtonensis Norman p. 784
1998	Iguanodon fittoni Blows p. 31
1998	Iguanodon fittoni Ruiz-Omeñaca et al. p. 275
2004	Iguanodon fittoni Norman p. 416
2009	Iguanodon fittoni Galton p. 245
2009	Iguanodon hollingtonensis Galton p. 246
2009	Iguanodon fittoni Pascual-Arribas et al. p. 121
2010	Wadhurstia fittoni Carpenter and Ishida p. 157
2010	Hypselospinus fittoni McDonald et al. p. 2
2010	Hypselospinus fittoni McDonald et al. p. 32
2010	Hypselospinus fittoni Norman pp. 55-57 figs. 5-10
2010	Hypselospinus fittoni Pereda Suberbiola et al. p. 64
2011	Hypselospinus fittoni Pereda-Suberbiola et al. p. 556
2012	Hypselospinus fittoni McDonald et al. p. 61
2012	Darwinsaurus evolutionis Paul
2012	Huxleysaurus hollingtoniensis Paul
2013	Hypselospinus fittoni Norman p. 394
2013	Hypselospinus fittoni Pereda Suberbiola and Ruiz-Omeñaca p. 14
2013	Hypselospinus fittoni Zheng et al.
2014	Hypselospinus fittoni Norman
2016	Hypselospinus fittoni Fuentes Vidarte et al. p. 436
2019	Hypselospinus fittoni Ibiricu et al. p. 281
2021	Hypselospinus fittoni Santos-Cubedo et al. p. 11
2021	Hypselospinus fittoni Verdú et al. p. 9
2022	Hypselospinus fittoni Ji and Zhang p. 6
2023	Hypselospinus fittoni Bonsor et al. p. 1

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Rank	Name	Author
kingdom	Animalia	()
—	Bilateria
—	Eubilateria	Ax 1987
—	Deuterostomia
phylum	Chordata	Haeckel 1874
subphylum	Vertebrata
superclass	Gnathostomata
—	Osteichthyes	()
subclass	Sarcopterygii	()
subclass	Dipnotetrapodomorpha	(Nelson 2006)
subclass	Tetrapodomorpha	()
—	Tetrapoda
—	Reptiliomorpha
—	Anthracosauria
subclass	Amphibiosauria	Kuhn 1967
—	Cotylosauria	()
—	Amniota
—	Sauropsida
class	Reptilia
subclass	Eureptilia	()
—	Romeriida
—	Diapsida	()

Rank	Name	Author
—	Archosauromorpha	(Huene 1946)
—	Crocopoda
—	Archosauriformes	Gauthier 1986
—	Eucrocopoda
—	Archosauria	()
informal	Avemetatarsalia
—	Ornithodira
—	Dinosauromorpha
—	Dinosauriformes
—	Dinosauria	()
—	Ornithischia	()
—	Genasauria
—	Cerapoda
—	Ornithopoda	()
—	Clypeodonta
—	Iguanodontia	()
—	Dryomorpha
—	Ankylopollexia
—	Neoiguanodontia
genus	Hypselospinus
species	fittoni	()

If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.

†Hypselospinus fittoni Lydekker 1889

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Invalid names: Darwinsaurus evolutionis Paul 2012 [synonym], Huxleysaurus hollingtoniensis Lydekker 1889 [synonym]

Diagnosis

Reference	Diagnosis
D. B. Norman 2010	Iguanodontian with the following unique character combination (indicates autapomorphies - all other characters are apomorphic within basal iguanodontians, even if they occur sporadically within ornithopods more generally), summarised by element: Ilium (Fig. 5): preacetabular process (prp) vertically orientated, laterally compressed and comparatively deep proximally; ventral edge of the preacetabular process is thicker than the dorsal edge; a low-relief, curved, ridge is present on the medial surface of the preacetabular process; the main portion of the iliac blade is flat; the dorsal edge of the iliac blade is transversely compressed (Fig. 5D, nde); the dorsal edge of the central portion of the iliac blade, in profile view (Fig. 5A), is straight (rather than being bowed dorsally); the postacetabular blade tapers to a blunt, thickened bar (Fig. 5A,B); strong medial inturning of the postacetabular blade to form a thick shelf that roofs a well-defined brevis fossa (brf); the brevis fossa is bordered laterally by a horizontal ridge (lr); the scarring for the posterior sacral ribs (Fig. 5C, srs) follows the ventral margin of the postacetabular blade as it rises obliquely toward the posterior end of the blade to merge with the more dorsally positioned facets along the lower border of the postacetabular blade. Vertebrae (Fig. 6): the ventral surfaces of the posterior centra of the sacrum bear midline keels; mid-anterior caudal vertebral centrum (Fig. 6), which bears a well-marked haemal facet posteriorly, has cylindrical proportions*.
K. Carpenter and Y. Ishida 2010	Ilium very deep, anteroposteriorly short, lateral surface concave, very wide brevis shelf medially, no medial ridge on preacetabular process, nor lateral iliac crest; suprailiac notch posteriorly placed on the postacetabular process, distal end of process abruptly truncated.