Homalocephale
Encyclopedia
Homalocephale is a genus of 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...

 belonging to the pachycephalosaurid family, which lived during the late Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...

 period of what is now Mongolia
Mongolia
Mongolia is a landlocked country in East and Central Asia. It is bordered by Russia to the north and China to the south, east and west. Although Mongolia does not share a border with Kazakhstan, its western-most point is only from Kazakhstan's eastern tip. Ulan Bator, the capital and largest...

, 80 million years ago. The genus was described in 1974 by Osmólska & Maryañska, and consists of a single species, H. calathocercos, though this may be a synonym (and juvenile form) of Prenocephale
Prenocephale
Prenocephale was a small pachycephalosaurid dinosaur genus from the Late Cretaceous and was similar in many ways to its close relative, Homalocephale, which may simply represent Prenocephale juveniles. Adult Prenocephale probably weighed around and measured around long...

. Homalocephale was 1.8 metres (5.9 ft) long and herbivorous.

Description

Unlike other definitely adult pachycephalosaurs (though similar to probable juvenile specimens referred to Dracorex
Dracorex
Dracorex is a dinosaur genus of the family Pachycephalosauridae, from the Late Cretaceous of North America.The type species is Dracorex hogwartsia, meaning "dragon king of Hogwarts". It is known from one nearly complete skull , as well as four cervical vertebrae including the atlas, third, ninth...

and Goyocephale
Goyocephale
Goyocephale is a genus of pachycephalosaurid dinosaur which lived during the Late Cretaceous period. It lived in what is now Mongolia.Goyocephale probably weighed 10–40 kg. The type species, Goyocephale lattimorei, was formally described by Perle, Maryañska, and Osmólka from an incomplete...

), Homalocephale sported a flat, wedge-shaped skull roof
Skull roof
The skull roof , or the roofing bones of the skull are a set of bones covering the brain, eyes and nostrils in bony fishes and all land living vertebrates. The bones are derived from dermal bone, hence the alternative name dermatocranium...

. Nonetheless, the surface of the skull was fairly thickened.

The species is also noted for having an unusually broad pelvis, which lead some paleontologists 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.

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...

, H. calathocercos, was described from an incomplete skull and postcranial material. 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
Squamosal
The squamosal is a bone of the head of higher vertebrates. It is the principal component of the cheek region in the skull, lying below the temporal series and otic notch and bounded anteriorly by postorbital. Posteriorly, the squamosal articulates with the posterior elements of the palatal complex,...

 bone. Palaeontologists 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 and Goodwin in 2009. Longrich and colleagues suggested that Homalocephale is actually the juvenile or sub-adult stage of Prenocephale
Prenocephale
Prenocephale was a small pachycephalosaurid dinosaur genus from the Late Cretaceous and was similar in many ways to its close relative, Homalocephale, which may simply represent Prenocephale juveniles. Adult Prenocephale probably weighed around and measured around long...

.

External links

  • http://www.dino-nakasato.org/en/special97/Homa-e.html
  • http://www.leute.server.de/frankmuster/H/Homalocephale.htm
The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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