Stenopelix
Encyclopedia
Stenopelix is a genus
of small ornithischia
n dinosaur
from the Early Cretaceous
of Germany
. It was perhaps a basal ceratopsia
n from the Barremian
Stage
of the Cretaceous period, sometime between 130 and 125 million years ago. The genus is based on a partial skeleton lacking the skull, and its classification is based on characteristics of the hips.
quarry near Bückeburg
on the Harrl heights, a fossil was found of a small dinosaur. Most of its bones were in a poor condition and removed on preparation, leaving two sets of hollow impressions on the plate and counterplate. The two plates do not overlap completely. The hollows, serving as a natural mold, have since been used to produce several casts in gypsum
and latex
to facilitate the study of the specimen. It was originally part of the collection of Max Ballerstedt preserved in the Bückeburg Gymnsasium Adolfinum but was in 1976 moved to the Georg-August-Universität Göttingen were it now resides in the collection of the Geowissenschaftliches Zentrum der Universität Göttingen.
In 1857, based on this fossil, Christian Erich Hermann von Meyer
named the type species
Stenopelix valdensis. The generic name is derived from Greek stenos, "narrow", and pelyx, "pelvis". The specific name refers to the Wealden Formation
. The holotype
, GZG 741/2 (earlier GPI 741-1, 2), found in the Obernkirchen Sandstein Formation, consists of the impressions of an almost complete skeleton, lacking the skull and the neck.
uniformly tapers ending in a rounded point. The shaft of the ischium is thickest in the middle and there shows a distinctive kink.
group. In 1974 Teresa Maryańska
suggested it to be a pachycephalosaur, one of the oldest known, due to the apparent exclusion of the pubis
from the acetabulum
, and the presence of strong caudal ribs. Peter Galton
in 1982 showed that the "pubis" was actually part of the acetabulum, and the so-called "caudal ribs" were sacral
ribs. The curvature of the ischium and absence of an obturator foramen
were not characteristics seen in other pachycephalosaurs. Galton concluded Stenopelix to be ceratopian.
However, exact cladistic analyses by Paul Sereno
have resulted in a position in the Pachycephalosauria
. But paleontologists
Richard Butler
and Robert Sullivan
nonetheless view the species as being Marginocephalia
incertae sedis
, rejecting the presumed synapomorphies with the Pachycephalosauria as incorrect identifications or lacking cogency because of a possible presence in ceratopsian groups. In 2011, cladistic analysis performed by Butler et al. showed that Stenopelix is a basal member of the Ceratopsia
, and its sister taxon is Yinlong
.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of small ornithischia
Ornithischia
Ornithischia or Predentata is an extinct order of beaked, herbivorous dinosaurs. The name ornithischia is derived from the Greek ornitheos meaning 'of a bird' and ischion meaning 'hip joint'...
n dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
from the Early Cretaceous
Early Cretaceous
The Early Cretaceous or the Lower Cretaceous , is the earlier or lower of the two major divisions of the Cretaceous...
of Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
. It was perhaps a basal ceratopsia
Ceratopsia
Ceratopsia or Ceratopia is a group of herbivorous, beaked dinosaurs which thrived in what are now North America, Europe, and Asia, during the Cretaceous Period, although ancestral forms lived earlier, in the Jurassic. The earliest known ceratopsian, Yinlong downsi, lived between 161.2 and 155.7...
n from the Barremian
Barremian
The Barremian is an age in the geologic timescale between 130.0 ± 1.5 Ma and 125.0 ± 1.0 Ma). It is a subdivision of the Early Cretaceous epoch...
Stage
Faunal stage
In chronostratigraphy, a stage is a succession of rock strata laid down in a single age on the geologic timescale, which usually represents millions of years of deposition. A given stage of rock and the corresponding age of time will by convention have the same name, and the same boundaries.Rock...
of the Cretaceous period, sometime between 130 and 125 million years ago. The genus is based on a partial skeleton lacking the skull, and its classification is based on characteristics of the hips.
Discovery and Species
In 1855, in a sandstoneSandstone
Sandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains.Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any colour, but the most common colours are tan, brown, yellow,...
quarry near Bückeburg
Bückeburg
Bückeburg is a town in Lower Saxony, Germany, on the border with North Rhine Westphalia. It was once the capital of the tiny principality of Schaumburg-Lippe and is today located in the district of Schaumburg close to the northern slopes of the Weserbergland ridge...
on the Harrl heights, a fossil was found of a small dinosaur. Most of its bones were in a poor condition and removed on preparation, leaving two sets of hollow impressions on the plate and counterplate. The two plates do not overlap completely. The hollows, serving as a natural mold, have since been used to produce several casts in gypsum
Gypsum
Gypsum is a very soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO4·2H2O. It is found in alabaster, a decorative stone used in Ancient Egypt. It is the second softest mineral on the Mohs Hardness Scale...
and latex
Latex
Latex is the stable dispersion of polymer microparticles in an aqueous medium. Latexes may be natural or synthetic.Latex as found in nature is a milky fluid found in 10% of all flowering plants . It is a complex emulsion consisting of proteins, alkaloids, starches, sugars, oils, tannins, resins,...
to facilitate the study of the specimen. It was originally part of the collection of Max Ballerstedt preserved in the Bückeburg Gymnsasium Adolfinum but was in 1976 moved to the Georg-August-Universität Göttingen were it now resides in the collection of the Geowissenschaftliches Zentrum der Universität Göttingen.
In 1857, based on this fossil, Christian Erich Hermann von Meyer
Christian Erich Hermann von Meyer
Christian Erich Hermann von Meyer was a German palaeontologist.He was born at Frankfurt am Main.In 1832 von Meyer issued a work entitled Palaeologica, and in course of time he published a series of memoirs on various fossil organic remains: molluscs, crustaceans, fishes and higher vertebrata,...
named the type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
Stenopelix valdensis. The generic name is derived from Greek stenos, "narrow", and pelyx, "pelvis". The specific name refers to the Wealden Formation
Wealden Formation
The Wealden Group is a group in the lithostratigraphy of southern England. The Wealden group consists of paralic to continental facies sedimentary rocks of Valanginian to Barremian age and thus forms part of the English Lower Cretaceous. It is composed of alternating sands and clays...
. The holotype
Holotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...
, GZG 741/2 (earlier GPI 741-1, 2), found in the Obernkirchen Sandstein Formation, consists of the impressions of an almost complete skeleton, lacking the skull and the neck.
Paleobiology
Stenopelix was a small herbivorous animal. The preserved rump and tail have a combined length of just 97 centimetres; the femur is fourteen centimetres long. The species can be distinguished by several details of the pelvis. The aft part of the iliumIlium
-Places:* Ilion or, Latinized, Ilium, another name for the legendary city of Troy, hence the title of Homer's Iliad*Ilium , an ancient city in Epirus...
uniformly tapers ending in a rounded point. The shaft of the ischium is thickest in the middle and there shows a distinctive kink.
Classification
The classification of Stenopelix is controversial and has ever been problematic because of the lacking skull. In the past, until the sixties of the twentieth century, it was often assigned to some ornithopodOrnithopod
Ornithopods or members of the clade Ornithopoda are a group of ornithischian dinosaurs that started out as small, bipedal running grazers, and grew in size and numbers until they became one of the most successful groups of herbivores in the Cretaceous world, and dominated the North American...
group. In 1974 Teresa Maryańska
Teresa Maryanska
Teresa Maryańska is a Polish paleontologist who has specialized in Mongolian dinosaurs, particularly pachycephalosaurians and ankylosaurians. A member of the 1964, 1965, 1970, and 1971 Polish–Mongolian expeditions to the Gobi Desert, she has described many finds from these rocks, often with...
suggested it to be a pachycephalosaur, one of the oldest known, due to the apparent exclusion of the pubis
Pubis (bone)
In vertebrates, the pubic bone is the ventral and anterior of the three principal bones composing either half of the pelvis.It is covered by a layer of fat, which is covered by the mons pubis....
from the acetabulum
Acetabulum
The acetabulum is a concave surface of the pelvis. The head of the femur meets with the pelvis at the acetabulum, forming the hip joint.-Structure:...
, and the presence of strong caudal ribs. Peter Galton
Peter Galton
Peter M. Galton is a British vertebrate paleontologist working in America, who has to date written or co-written about a hundred papers in scientific journals or chapters in paleontology textbooks, especially on ornithischian and prosauropod dinosaurs.With Robert Bakker in a joint article...
in 1982 showed that the "pubis" was actually part of the acetabulum, and the so-called "caudal ribs" were sacral
Sacrum
In vertebrate anatomy the sacrum is a large, triangular bone at the base of the spine and at the upper and back part of the pelvic cavity, where it is inserted like a wedge between the two hip bones. Its upper part connects with the last lumbar vertebra, and bottom part with the coccyx...
ribs. The curvature of the ischium and absence of an obturator foramen
Obturator foramen
The obturator foramen is the hole created by the ischium and pubis bones of the pelvis through which nerves and muscles pass.- General structure :...
were not characteristics seen in other pachycephalosaurs. Galton concluded Stenopelix to be ceratopian.
However, exact cladistic analyses by Paul Sereno
Paul Sereno
Paul Callistus Sereno is an American paleontologist from the University of Chicago who discovered several new dinosaur species on several continents. He has conducted excavations at sites as varied as Inner Mongolia, Argentina, Morocco, and Niger...
have resulted in a position in the Pachycephalosauria
Pachycephalosauria
Pachycephalosauria is a clade of ornithischian dinosaurs. Well-known genera include Pachycephalosaurus, Stegoceras, Stygimoloch, and Dracorex. Most lived during the Late Cretaceous Period, in what is now North America and Asia. They were all bipedal, herbivorous/omnivorous animals with thick skulls...
. But paleontologists
Paleontology
Paleontology "old, ancient", ὄν, ὀντ- "being, creature", and λόγος "speech, thought") is the study of prehistoric life. It includes the study of fossils to determine organisms' evolution and interactions with each other and their environments...
Richard Butler
Richard Butler
- Military :*Richard Butler, 1st Earl of Arran , 1st Earl of Arran, marshal of the army in Ireland, lord deputy of Ireland*Richard Butler , American Revolutionary War General, later killed fighting Native Americans in Ohio...
and Robert Sullivan
Robert Sullivan
Robert Sullivan may refer to:*Robert Sullivan *Robert Baldwin Sullivan, Canadian lawyer, judge, and the second Mayor of Toronto*Robert J. Sullivan, Jr. , American politician...
nonetheless view the species as being Marginocephalia
Marginocephalia
Marginocephalia is a clade of ornithischian dinosaurs that includes the thick-skulled pachycephalosaurids, and horned ceratopsians. They were all herbivores, walking on two or four legs, and are characterized by a bony ridge or frill the back of the skull...
incertae sedis
Incertae sedis
, is a term used to define a taxonomic group where its broader relationships are unknown or undefined. Uncertainty at specific taxonomic levels is attributed by , , and similar terms.-Examples:*The fossil plant Paradinandra suecica could not be assigned to any...
, rejecting the presumed synapomorphies with the Pachycephalosauria as incorrect identifications or lacking cogency because of a possible presence in ceratopsian groups. In 2011, cladistic analysis performed by Butler et al. showed that Stenopelix is a basal member of the Ceratopsia
Ceratopsia
Ceratopsia or Ceratopia is a group of herbivorous, beaked dinosaurs which thrived in what are now North America, Europe, and Asia, during the Cretaceous Period, although ancestral forms lived earlier, in the Jurassic. The earliest known ceratopsian, Yinlong downsi, lived between 161.2 and 155.7...
, and its sister taxon is Yinlong
Yinlong
Yinlong is a genus of basal ceratopsian dinosaur from the Late Jurassic Period of central Asia. It was a small, primarily bipedal herbivore, approximately 1.2 meters long...
.