Pronunciation: ste-NOP-uh-liks
Meaning: Narrow pelvis
Author/s: von Meyer (1857)
Synonyms: None known
First Discovery: Lower Saxony, NW Germany
Discovery Chart Position: #16
Stenopelix valdensis
Stenopelix valdensis is based on a partial skeleton preserved as mere impressions on two sandstone slabs that only partly overlap because its bones were terribly mangled and lost during preparation. That being said, it still represents the most completely known dinosaur specimen from the "Wealden" (Lower Cretaceous) of northwestern Germany and the oldest pachycephalosaur from the Early Cretaceous of Europe. Although the latter is based on the assumption that it really is a pachycephalosaur, as its first meaningful analysis concluded.
As with most 1800s-named dinosaurs, the classification of Stenopelix is a tumultuous affair. It was considered a hypsilophodontid by Nopcsa (1928), Rozhdestvensky and Tatarinov (1964) and Romer (1966), and a member of Psittacosauridae by Huene (1956), Romer (1956) and Colbert (1961). Then, in 1974, Maryanska and Osmólska assigned it to Pachycephalosauria—a group of bipedal herbivores known affectionately as "headbangers". Eight years later, a contradiction arrived via Sues and Galton, who thought it was an obvious member of Ceratopsia ("horn faces"), followed by a position as Ornithischia incertae sedis via Lucas and Sullivan, who neatly side-stepped several reclassifications themselves. Although fragile and poorly preserved, Stenopelix is still being bounced around the ornithischian branch of the dinosaurian family tree as palaeontologists wrestle with its enigmatic...ness.
Both headbangers and horn faces sport thickened bony ridges around their skulls. However, they can be easily distinguished if you have their skulls to study, which is a problem in the case of Stenopelix, as its remains don't include one. They sport similarities in their pelvic girdles, too, which led Butler and Sullivan to classify Stenopelix within Marginocephalia—a group that houses both pachycephalosaurs and ceratopsians—in 2009. But when Butler et al. fed its stats, based on recent re-descriptions and reconsiderations, into their analysis of an archaic ornithopod known as Changchunsaurus in 2011, they tipped the scales, at least temporarily, in favour of ceratopsian affinities. Morschhauser et al. (2019), Yu et al. (2020), and Fonseca et al. (2024) concurred, referring Stenopelix to Ceratopsia as either a neoceratopsian or a chaoyangsaurid.
Although named and described as a reptile by Hermann von Meyer in 1857, Stenopelix was identified as a dinosaur for the first time by Ernst Koken in 1887.
As with most 1800s-named dinosaurs, the classification of Stenopelix is a tumultuous affair. It was considered a hypsilophodontid by Nopcsa (1928), Rozhdestvensky and Tatarinov (1964) and Romer (1966), and a member of Psittacosauridae by Huene (1956), Romer (1956) and Colbert (1961). Then, in 1974, Maryanska and Osmólska assigned it to Pachycephalosauria—a group of bipedal herbivores known affectionately as "headbangers". Eight years later, a contradiction arrived via Sues and Galton, who thought it was an obvious member of Ceratopsia ("horn faces"), followed by a position as Ornithischia incertae sedis via Lucas and Sullivan, who neatly side-stepped several reclassifications themselves. Although fragile and poorly preserved, Stenopelix is still being bounced around the ornithischian branch of the dinosaurian family tree as palaeontologists wrestle with its enigmatic...ness.
Both headbangers and horn faces sport thickened bony ridges around their skulls. However, they can be easily distinguished if you have their skulls to study, which is a problem in the case of Stenopelix, as its remains don't include one. They sport similarities in their pelvic girdles, too, which led Butler and Sullivan to classify Stenopelix within Marginocephalia—a group that houses both pachycephalosaurs and ceratopsians—in 2009. But when Butler et al. fed its stats, based on recent re-descriptions and reconsiderations, into their analysis of an archaic ornithopod known as Changchunsaurus in 2011, they tipped the scales, at least temporarily, in favour of ceratopsian affinities. Morschhauser et al. (2019), Yu et al. (2020), and Fonseca et al. (2024) concurred, referring Stenopelix to Ceratopsia as either a neoceratopsian or a chaoyangsaurid.
Although named and described as a reptile by Hermann von Meyer in 1857, Stenopelix was identified as a dinosaur for the first time by Ernst Koken in 1887.
(Narrow pelvis from the Weald)Etymology
Stenopelix is derived from the Greek "stenos" (narrow) and "pelyx" (pelvis), named for the construction of the pelvis, to which "the narrow, long form of the bones bestows a peculiar appearance".
The species epithet, valdensis, is derived from the Latin "valdus" ("Weald" referring to the Weald clay) and "-ensis" (from, place of origin).
Discovery
The remans of Stenopelix were discovered in the Obernkirchen Member of the Bückeberg Formation at the Obernkirchen Sandstein Quarry on Harrl Hill, near Bückeburg, Niedersachsen (Lower Saxony), northwestern Germany, in 1855.
The holotype (GZG 741/2 — formerly GPI Gö 741-2) is the impression of an almost complete skeleton, lacking the skull and the neck, of a small individual (less than one metre in length) on two sandstone plates. It was originally part of the collection of Max Ballerstedt preserved in the Bückeburg Gymnsasium Adolfinum but was moved to the Georg-August-Universität Göttingen in 1976 and resides in the Geowissenschaftliches Zentrum der Universität Göttingen collection.
