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 rhynchocephalia ...

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, th ...

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 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 a ...

one as in the frill-necked lizard. In technical terms, the bone-supported frill is composed of an enlarged

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

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 epoccipitals, 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 herbivorous chasmosaurine ceratopsid dinosaur that first appeared during the late Maastrichtian stage of the Late Cretaceous period, about 68 million years ago in what is now North America. It is one ...

'', '' Pentaceratops'', ''

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'', 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 country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. With an area of , Australia is the largest country by ...

. 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 temperatur ...

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. Sp ...

's ''

Jurassic Park ''Jurassic Park'', later also referred to as ''Jurassic World'', is an American science fiction media franchise created by Michael Crichton and centered on a disastrous attempt to create a theme park of cloned dinosaurs. It began in 1990 when ...

'', 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 th ...

's''

Jurassic World Dominion ''Jurassic World Dominion'' is a 2022 American science fiction action film directed by Colin Trevorrow, who co-wrote the screenplay with Emily Carmichael from a story by Derek Connolly and Trevorrow. The sequel to '' Jurassic World: Fallen ...

'', 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 dewlaps and crests 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