Arrhinoceratops ‭(‬No nose-horn face‭)

Short Info

Arrhinoceratops ‭(‬No nose-horn face‭)

Phonetic : ay-rine-oh-ker-ah-tops.

Named By : William Arthur Parks‭ ‬-‭ ‬1925

Diet : Herbivore

Size : Estimated 6 meters long

Type of Dinosaur : Ceratopsian

Type Species : A.‭ ‬brachyops‭ (‬type‭)

Found in : Canada,‭ ‬Alberta‭ ‬-‭ ‬Horseshoe Canyon Formation

When it Lived : Late Cretaceous, 72-67 million years ago

Arrhinoceratops (meaning “no nose-horn face” is derived from the Ancient Greek “a-/a-” “no”, rhis/Ris “nose” “keras/keras” “horn”, “-ops/ops” “face”) is a genus that belongs to herbivore ceratopsian dinosaurs. This name came into existence when its first describer believed that it was distinct due to the fact that the nose-horn wasn’t an individual bone, but an examination revealed that the existence of an error. It lived in the latest Campanian/early Maastrichtian phase that was part of the Late Cretaceous, predating its famous cousin Triceratops by just a few million years however, it was contemporaneous with Anchiceratops. Its remains were discovered in Canada.

Arrhinoceratops brachyops skull, Near Drumheller, Alberta, Late Cretaceous - Royal Ontario Museum - DSC00076
Daderot, CC0, via Wikimedia Commons

The species was first described by William Arthur Parks in 1925, Arrhinoceratops is known from an incompletely crushed and slightly deformed skull that did not have lower jaws. The remains were found at the Neill’s Ranch site near the Red Deer River in Alberta through a 1923 trip from University of Toronto. University of Toronto.

Parks named the species type Arrhinoceratops bryops. The generic name comes from Greek A “without”, Ris,”without”, rhis “nose”, keras,”horn”, keras “horn”, and ops”face”, ops “face” as Parks had discovered that no separate nose-horn was found. The exact meaning is “short-faced” from Greek brakhus or brachys “short”.

The Holotype has been identified as ROM 796 (earlier ROM 5135), located in a layer of Horseshoe Canyon Formation dating from the most recent Campanian or maybe the first Maastrichtian. It is comprised of the original skull.

Other evidence from Utah that was discovered during the 1930s was later designated Arrhinoceratops? Utahensis in the name of Charles Whitney Gilmore in 1946. It was based on the the holotype USNM 1583. The question mark suggests that Gilmore himself was unsure regarding the identification. It was in 1976 that Douglas A. Lawson transferred the species to Torosaurus and identified it as Torosaurus utahensis.

In addition to the skull holotype, little fossil material from Arrhinoceratops the brachyops was discovered. The year 1981 saw Helen Tyson in a revision of the genus, had provisionally referenced specimen ROM 1439 however at the time of 2007 Andrew Farke moved this to Torosaurus.

Because this dinosaur is identified solely from the skull of its ancestor, researchers have only a few information about its general anatomy. The skull, when restored has a wide neck frill that is square with two oval-shaped openings. The frill is deep veined on the sides and on the top by veins of arterial blood. The frill’s sides are decorated with about nine osteoderms. The back part of the frill’s edge is made scalloped. The left squamosal of the frill-side of the holotype displays an opening that is pathological, possibly caused by an injury. The brow horns of the holotype were moderately long, however its nose horn was narrower and sharper than other ceratopids. The snout is small and high. The body of the animal is believed to belong to Ceratopsidae. Based on the skull , some popular science books estimate the body’s length to be around 6 meters (20 feet) tall when fully developed. In 2010 Gregory S. Paul estimated its length to be 4.5 metres (15 feet) and weight as 1.3 tonnes (2,900 pounds).

The genus was already in existence. Richard Swann Lull had in 1933 criticized Parks his original description and Tyson realized that Parks as an entomologist made numerous mistakes. The most prominent of these was that the trait that the genus was named for that is the absence of an individual ossification, or nasal horn os epinasale is actually normal for the ceratopids, which the nose-horn is an extension from the bone of the nose and not a separate component. Other incorrect conclusions made from Parks were the assumption that the os rostrale the bone-core of the beak’s upper part, direct contact was made with nasals, instead of being separated through the premaxillae. A presumptively anterior process that involved the jugal touching the premaxilla, and that the interparietal part of the frill was an individual skeletal component and was an interparietale os.

Source: Wikipedia