A neck frill is the relatively extensive margin seen on the back of the heads of

reptile Reptiles, as most commonly defined are the animals in the class Reptilia ( ), a paraphyletic grouping comprising all sauropsids except birds. Living reptiles comprise turtles, crocodilians, squamates (lizards and snakes) and rhynchocephalians ( ...

s with either a bony support such as those present on the

skull The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, the ...

s of

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 ...

s of the suborder

Marginocephalia Marginocephalia (/mär′jə-nō-sə-făl′ē-ən/ Latin: margin-head) is a clade of ornithischian dinosaurs that is characterized by a bony shelf or margin at the back of the skull. These fringes were likely used for display. There are two clad ...

or a

cartilaginous Cartilage is a resilient and smooth type of connective tissue. In tetrapods, it covers and protects the ends of long bones at the joints as articular cartilage, and is a structural component of many body parts including the rib cage, the neck and ...

one as in the

frill-necked lizard The frilled lizard (''Chlamydosaurus kingii''), also known as the frill-necked lizard or frilled dragon, is a species of lizard in the family Agamidae. It is native to northern Australia and southern New Guinea. This species is the only member o ...

. In technical terms, the bone-supported frill is composed of an enlarged

parietal bone The parietal bones () are two bones in the Human skull, skull which, when joined at a fibrous joint, form the sides and roof of the Human skull, cranium. In humans, each bone is roughly quadrilateral in form, and has two surfaces, four borders, an ...

flanked by elongated

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 ...

s and sometimes ringed by

epoccipital Ceratopsia or Ceratopia ( or ; Ancient Greek, Greek: "horned faces") is a group of herbivore, herbivorous, beaked dinosaurs that thrived in what are now North America, Europe, and Asia, during the Cretaceous Period (geology), Period, although anc ...

s, bony knobs that gave the margin a jagged appearance. In the early 1900s, the parietal bone was known among

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 as the dermosupraoccipital. The feature is now referred to as the parietosquamosal frill. In some

genera Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclat ...

, such as ''

Triceratops ''Triceratops'' ( ; ) is a genus of herbivore, herbivorous Chasmosaurinae, chasmosaurine Ceratopsidae, ceratopsid dinosaur that first appeared during the late Maastrichtian stage of the Late Cretaceous Period (geology), period, about 68 m ...

'', ''

Pentaceratops ''Pentaceratops'' ("five-horned face") is a genus of herbivorous ceratopsid dinosaur from the late Cretaceous Period of what is now North America. Fossils of this animal were first discovered in 1921, but the genus was named in 1923 when its ty ...

'', ''

Centrosaurus ''Centrosaurus'' ( ; ) is a genus of herbivorous ceratopsian dinosaur from the Late Cretaceous of Canada. Their remains have been found in the Dinosaur Park Formation, dating from 76.5 to 75.5 million years ago. Discovery and naming The firs ...

'' and ''

Torosaurus ''Torosaurus'' ("perforated lizard", in reference to the large openings in its frill) is a genus of herbivorous ceratopsid dinosaur that lived during the late Maastrichtian stage of the Cretaceous period, between 68 and 66 million years ago, th ...

'', this extension is very large. Despite the neck frill predominantly being made of hard bone, some neck frills are made of skin, as is the case with the frill-necked lizard of today that resides in

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

. The use of the neck frill in dinosaurs is uncertain; it may have been used for

thermoregulation Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different. A thermoconforming organism, by contrast, simply adopts the surrounding temperature ...

or simply as a defense mechanism. Indeed, during battles for territory, competing ''Triceratops'' crashed heads together with their elongated horns and the neck frill may have been employed as a kind of shield, protecting the rest of the animal from harm. However, usage of the neck frill in modern reptiles is better documented. Two chief and disparate examples are the

horned lizard Horned lizards (''Phrynosoma''), also known as horny toads or horntoads, are a genus of North American lizards and the type genus of the family Phrynosomatidae. The common names refer directly to their horns or to their flattened, rounded bodies, ...

s (genus ''Phrynosoma'') with a bony frill, and the frill-necked lizard (genus ''Chlamydosaurus'') with a cartilaginous frill. The frill-necked lizard's frill is mainly made up of flaps of skin, which are usually coloured pink, supported by cartilaginous spines. Similar to the portrayal of the dinosaur ''

Dilophosaurus ''Dilophosaurus'' ( ) is a genus of theropod dinosaurs that lived in what is now North America during the Early Jurassic, about 193 million years ago. Three skeletons were discovered in northern Arizona in 1940, and the two best preserve ...

'' in

Steven Spielberg Steven Allan Spielberg (; born December 18, 1946) is an American director, writer, and producer. A major figure of the New Hollywood era and pioneer of the modern blockbuster, he is the most commercially successful director of all time. Spie ...

's '' Jurassic Park'', and in

Colin Trevorrow Colin Trevorrow (;) is an American filmmaker. He made his feature directorial debut with the science fiction comedy ''Safety Not Guaranteed'' (2012) to critical and commercial success. Trevorrow achieved mainstream recognition for his work on the ...

's'' Jurassic World Dominion'', frill-necked lizard puff out these neck frills on either side of its head when threatened. The lizards often raise their frills when battling for territory or when coming into contact with another lizard, especially during mating season. There is, however, no evidence that suggests that ''Dilophosaurus'' had the same abilities, as many of its features in the ''Jurassic Park'' film were mostly fictional. Numerous other animals of both modern and prehistoric times use both skin or bone protrusions to make themselves seem more threatening, attract mates or to thermoregulate. Examples of these are the usage of

dewlap A dewlap is a longitudinal flap of skin or similar flesh that hangs beneath the lower jaw or neck of many vertebrates. More loosely, it can be various similar structures in the neck area, such as those caused by a double chin or the submandibul ...

s and

crest Crest or CREST may refer to: Buildings *The Crest (Huntington, New York), a historic house in Suffolk County, New York *"The Crest", an alternate name for 63 Wall Street, in Manhattan, New York *Crest Castle (Château Du Crest), Jussy, Switzerla ...

s in lizards, dinosaurs and birds. The unusual

red-fan parrot The red-fan parrot (''Deroptyus accipitrinus''), also known as the hawk-headed parrot, is a New World parrot hailing from the Amazon Rainforest. It is the only member of the genus ''Deroptyus''. It dwells in Brazil, Suriname, Bolivia, Ecuador, ...

has a feathery neck frill which is used for display purposes.

References

*Weldon Owen Pty Ltd. (1993). ''Encyclopedia of animals - Mammals, Birds, Reptiles, Amphibians.'' Reader's Digest Association, Inc. . Reptile anatomy Dinosaur anatomy {{Vertebrate anatomy-stub

See also

References