''Homalocephale'' (from

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

ὁμαλός, ''homalos'', "even", and κεφαλή, ''kephalē'', "head") is a genus of

pachycephalosaurid Pachycephalosauria (; from Greek παχυκεφαλόσαυρος for 'thick headed lizards') is a clade of ornithischian dinosaurs. Along with Ceratopsia, it makes up the clade Marginocephalia. With the exception of two species, most pachycephal ...

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...

that lived during the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', ...

period of what is now the

Nemegt Formation The Nemegt Formation (also known as Nemegtskaya Svita) is a geological formation in the Gobi Desert of Mongolia, dating to the Late Cretaceous. The formation consists of river channel sediments and contains fossils of fish, turtles, crocodilians, ...

Mongolia Mongolia; Mongolian script: , , ; lit. "Mongol Nation" or "State of Mongolia" () is a landlocked country in East Asia, bordered by Russia to the north and China to the south. It covers an area of , with a population of just 3.3 million, ...

, about 70 million years ago. The genus was described in 1974 by

Halszka Osmólska Halszka Osmólska (September 15, 1930 – March 31, 2008) was a Polish paleontologist who had specialized in Mongolian dinosaurs. Biography She was born in 1930 in Poznań. In 1949, she began to study biology at Faculty of Biology and Earth Scie ...

and

Teresa Maryańska Teresa Maryańska (1937 – 3 October 2019) was a Polish paleontologist who specialized in Mongolian dinosaurs, particularly pachycephalosaurians and ankylosaurians. Peter Dodson (1998 p. 9) states that in 1974 Maryanska together with Hals ...

, and consists of a single species, ''H. calathocercos''. Though ''Homalocephale'' has been regarded as a synonym (and juvenile form) of ''

Prenocephale ''Prenocephale'' (meaning "sloping head") is a genus of small pachycephalosaurid dinosaur from the Late Cretaceous Nemegt Formation of Mongolia. It was similar in many ways to its close relative, '' Homalocephale''. Description Adult ''Prenoce ...

'', juvenile specimens of the latter indicate that they were distinct. ''Homalocephale'' was long and possibly herbivorous.

Discovery

The

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specime ...

, ''H. calathocercos'', was described from an incomplete skull and postcranial material (

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of sever ...

MPC-D 100/1201) from the Nemegt locality of the

. The specimen has large openings on the top of the skull, a distinct frontoparietal suture, low and long infratemporal fenestrae, and a large, round eye socket. The forehead is notably rough, with multiple nodules on the lateral and posterior sides of the

squamosal The squamosal is a skull bone found in most reptiles, amphibians, and birds. In fishes, it is also called the pterotic bone. In most tetrapods, the squamosal and quadratojugal bones form the cheek series of the skull. The bone forms an ancestral co ...

bone. Paleontologists concluded that the specimen was an adult, despite the fact that the sutures are discernible and that it had a flat skull (a juvenile trait in many pachycephalosaurid species). In 2010, a study by Nick Longrich and colleagues suggested that flat-headed pachycephalosaurs were just juvenile forms of dome-headed adults, a view also supported by the earlier analysis of

Horner Horner is an English and German surname that derives from the Middle English word for the occupation ''horner'', meaning horn-worker or horn-maker, or even horn-blower. People *Alison Horner (born 1966), British businesswoman * Arthur Horner (dis ...

and Goodwin in 2009. Longrich and colleagues suggested that ''Homalocephale'' is actually the juvenile or sub-adult stage of ''

'' mainly based on the lack of a dome and being discovered in the same locality (Nemegt) as the latter.Longrich, N.R., Sankey, J. and Tanke, D. (2010). "''Texacephale langstoni'', a new genus of pachycephalosaurid (Dinosauria: Ornithischia) from the upper Campanian Aguja Formation, southern Texas, USA." ''Cretaceous Research'', . David C. Evans and team in 2018 reported juvenile specimens of ''Prenocephale'' from the Nemegt Formation, noting a relatively linear growth in this pachycephalosaur characterized by a rounded dome. This differs from the flat skull of ''Homalocephale'' and given that even juvenile ''Prenocephale'' possessed a rather rounded dome, both taxa should be regarded as separate.

Description

''Homalocephale'' was about long.Holtz, Thomas R. Jr. (2008) ''Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages'
Supplementary Information
Unlike other definitely adult pachycephalosaurs (though similar to probable juvenile specimens referred to ''

Dracorex ''Pachycephalosaurus'' (; meaning "thick-headed lizard", from Greek ''pachys-/'' "thick", ''kephale/'' "head" and ''sauros/'' "lizard") is a genus of pachycephalosaurid dinosaurs. The type species, ''P. wyomingensis'', is the only known species, ...

'' and ''

Goyocephale ''Goyocephale'' is an extinct genus of pachycephalosaurian ornithischian that lived in Mongolia during the Late Cretaceous about 76 million years ago. It was first described in 1982 by Altangerel Perle, Teresa Maryańska and Halszka Osmólska f ...

''), ''Homalocephale'' sported a flat, wedge-shaped skull roof. Nonetheless, the surface of the skull was fairly thickened.

Paleobiology

''Homalocephale'' is also noted for having an unusually broad pelvis, which lead some

paleontologist Paleontology (), also spelled palaeontology or palæontology, is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene epoch (roughly 11,700 years before present). It includes the study of fossi ...

s to suggest that the wide hips were for giving birth to live young. Others have suggested that the width served to protect vital organs from harm during flank-butting. ''Homalocephale'' also had rather long legs, indicating a fast-moving gait.

References

*''Fantastic Facts About Dinosaurs'' ()

External links

* https://web.archive.org/web/20061006225059/http://www.dino-nakasato.org/en/special97/Homa-e.html * https://web.archive.org/web/20070518001124/http://www.leute.server.de/frankmuster/H/Homalocephale.htm {{Taxonbar, from=Q134134 Pachycephalosaurs Late Cretaceous dinosaurs of Asia Maastrichtian life Nemegt fauna Fossil taxa described in 1974 Taxa named by Teresa Maryańska Taxa named by Halszka Osmólska Ornithischian genera

Discovery

Description

Paleobiology

See also

References

External links