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Troodon formosus

Reptilia - Avetheropoda - Troodontidae

Troodon formosus was named by Leidy (1856). Its type specimen is ANSP 9259, a tooth, and it is a 3D body fossil. Its type locality is Judith River badlands (USGS), which is in a Campanian/Campanian terrestrial horizon in the Judith River Formation of Montana. It was considered monophyletic by Currie (2000).

It was synonymized subjectively with Saurornithoides inequalis by Carpenter (1982); it was considered a nomen vanum by Sues (1977).

Synonymy list
YearName and author
1856Troodon formosus Leidy p. 72
1857Troodon formosus Leidy p. 90
1860Troodon formosus Leidy p. 147
1870Troodon formosus Cope p. 120
1874Troodon formosus Cope p. 26
1875Troodon formosus Cope p. 248
1877Troodon formosus Cope p. 572
1902Troodon formosus Hay p. 490
1902Troodon formosus Lambe p. 47
1905Troodon formosus Lambe p. 25
1908Troodon formosus Brown p. 192
1914Troodon formosus Brown p. 378
1915Troodon formosus Hennig p. 14
1924Troodon formosus Gilmore p. 8
1927Troodon formosus Huene p. 261
1930Troodon formosus Russell p. 142
1931Troodon formosus Gilmore p. 5
1932Polyodontosaurus grandis Gilmore p. 117
1932Stenonychosaurus inequalis Sternberg
1943Troodon formosus Brown and Schlaikjer p. 127
1946Troodon formosus Russell p. 171
1948Troodon formosus Russell p. 629
1951Polyodontosaurus grandis Sternberg p. 257
1951Troodon formosus Sternberg p. 257
1951Stenonychosaurus inequalis Sternberg p. 258
1964Troodon formosus Russell p. 10
1966Stenonychosaurus inequalis Russell p. 25
1969Stenonychosaurus inequalis Ostrom p. 148
1969Stenonychosaurus inequalis Russell p. 595
1970Troodon formosus Steel p. 17
1970Polyodontosaurus grandis Steel p. 44
1970Stenonychosaurus inequalis Steel p. 44
1970Troodon formosus Swinton p. 229
1977Stenonychosaurus inequalis Sues p. 591
1978Stenonychosaurus inequalis Sues p. 395
1980Troodon formosus Wolberg p. 50
1981Stenonychosaurus inequalis McIntosh p. 10
1981Stenonychosaurus inequalis Osmolska p. 89
1982Saurornithoides inequalis Carpenter p. 127
1985Stenonychosaurus inequalis Currie p. 1644
1985Stenonychosaurus inequalis Wilson and Currie p. 1813
1986Troodon formosus Gauthier p. 11
1987Troodon formosus Currie
1988Troodon formosus Paul p. 397
1988Stenonychosaurus inequalis Rich et al. p. 1405
1990Troodon formosus Currie et al. p. 113
1992Troodon formosus Currie p. 238
1994Troodon formosus Chure p. 14
1994Troodon formosus Currie and Peng p. 2226
1994Troodon formosus Currie and Zhao p. 2233
1994Troodon formosus Rauhut and Kriwet p. 181
1994Troodon formosus Russell and Dong p. 2166
1997Troodon formosus Eberth p. 201
1997Troodon formosus Erickson p. 5
1997Troodon formosus Hernández-Rivera p. 434
1997Troodon formosus Norell and Makovicky p. 20
1997Troodon formosus Ryan and Vickaryous p. 170
1997Troodon formosus Varricchio p. 749
1998Troodon formosus Makovicky and Norell p. 3
2000Troodon formosus Currie p. 276
2000Troodon formosus Norell et al. p. 9
2001Troodon formosus Currie and Dong p. 1753
2001Troodon formosus Eberth et al. p. 58
2001Troodon formosus Horner et al. p. 8
2001Troodon formosus Larsson p. 23
2001Troodon formosus Peng et al. p. 37
2002Troodon formosus Sankey et al. p. 755
2002Troodon formosus Varricchio et al. p. 564
2003Troodon formosus Makovicky et al. p. 25 fig. 21
2003Troodon formosus Rauhut p. 42
2004Troodon formosus Makovicky and Norell p. 185
2004Troodon formosus Senter et al. p. 5
2005Troodon formosus Buffetaut et al. p. 480
2006Troodon formosus Johnson et al. p. 579
2007Troodon formosus Averianov and Sues p. 94
2007Troodon formosus Turner et al. p. 3
2008Troodon formosus Cooper et al.
2008Troodon formosus Fiorillo p. 323
2008Troodon inequalis Longrich p. 994
2009Troodon formosus Bever and Norell p. 3
2009Troodon formosus Fiorillo et al. p. 181
2009Troodon formosus Godefroit et al.
2009Troodon formosus Norell et al. p. 5
2010Troodon formosus Jackson et al. p. 255
2010Troodon formosus Lü et al. p. 381
2010Troodon formosus Paulina Carabajal and Canale p. 249
2011Troodon formosus Brown and Druckenmiller p. 1343
2011Troodon formosus Genise and Sarzetti p. 820
2011Troodon formosus Porfiri et al. p. 112
2011Troodon formosus Zanno et al. p. 2
2011Troodon inequalis Zanno et al. p. 2
2012Troodon formosus Gao et al. p. 5
2012Troodon formosus Prieto-Marquez et al. p. 122
2013Troodon formosus Araújo et al. p. 7
2013Troodon formosus Larson and Currie p. 9
2014Troodon formosus Williamson and Brusatte p. 17
2015Troodon formosus Peecook and Sidor p. 9
2015Troodon formosus Varricchio et al. p. 3
2016Troodon formosus Mallon et al. p. 33

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phylumChordataHaeckel 1847
OlfactoresJefferies 1991
subclassDipnotetrapodomorpha(Nelson 2006)
SauriaGauthier 1984
Archosauromorpha(Huene 1946)
ArchosauriformesGauthier 1986
AverostraPaul 2002

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.

B. Brown and E. M. Schlaikjer 1943Premaxillary tooth with smoothly curved conves central area of the outer side. Marginal denticulations strong and clearly defined.
P. J. Currie 1985 (Stenonychosaurus inequalis)Medium-sized carnivorous dinosaur, closely related to Saurornithoides of Mongolia. It differs from both Saurornithoides mongoliensis Osborn 1924, and Saurornithoides junior Barsbold 1974 in that the anterior margin of maxillary fenestra is more rounded; sculpturing on surface of nasal process of maxilla does not extend as far posteriorly; the post-temporal region is longer relative to the height of the skull; the basioccipital tubers are much more pronounced; the lateral depression of the braincase is subdibided by a single vertical ridge rather than a pair of diverging ridges; the presphenoid is more anterior in relation to the laterosphenoid; there is no sulcus or trough on the ventral surface of the braincase posrterior to the parasphenoid capsule; and the supraoccipital seems to be narrower.