Diceratus

Taxobox
name = "Diceratus"
fossil_range = Late Cretaceous

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image_width = 240px
regnum = Animalia
phylum = Chordata
classis = Sauropsida
superordo = Dinosauria
ordo = Ornithischia
infraordo = Ceratopsia
familia = Ceratopsidae
subfamilia = Ceratopsinae
genus = "Diceratus"
genus_authority = Mateus, 2008
subdivision_ranks = Species
subdivision =
* "D. hatcheri" (Lull, 1905) (type) originally "Diceratops", preoccupied by Foerster, 1868

"Diceratus" (meaning "two-horned") is a ceratopsid herbivorous dinosaur genus from the Late Cretaceous period of North America. It is known only from a single poorly preserved skull discovered in Wyoming and described in 1905 as "Diceratops". For many years, it had been considered a species within the genus "Triceratops", but recent analysis (Forster, 1996) suggests it is a distinct genus. Since the "Diceratops" name was preoccupied, it was renamed to "Diceratus" in 2008.

History

"Diceratus" was first described as "Diceratops" ("two horned face"), but it was found that the name was already in use for a hymenopteran (Foerster, 1868). It was given its current name by Octávio Mateus in 2008.cite journal |last=Mateus |first=O |year=2008 |title=Two ornithischian dinosaurs renamed: "Microceratops" Bohlin 1953 and "Diceratops" Lull 1905 |journal=Journal of Paleontology |volume=82 |issue=2 |pages=423 |doi=10.1666/07-069.1]

The paper that described "Diceratus" was originally part of O. C. Marsh's magnum opus, his Ceratopsidae monograph. Unfortunately, Marsh died (1899) before the work was completed, and John Bell Hatcher endeavored to complete the "Triceratops" section. However, he died of typhus in 1904 at the age of 42, leaving the paper still uncompleted. It fell to Richard Swann Lull to complete the monograph in 1905, publishing Hatcher's description of a skull separately and giving it the name "Diceratops hatcheri".

Since the "Diceratops" paper had been written by Hatcher, and Lull had only contributed the name and published the paper after Hatcher's death, Lull was not quite as convinced of the distinctiveness of "Diceratops", thinking it primarily pathological. By 1933, Lull had had second thoughts about "Diceratops" being a distinct genus and he put it in a subgenus of "Triceratops": "Triceratops" ("Diceratops"), including "T. obtusus"; largely attributing its differences to being that of an aged individual.

Description

The poorly preserved skull is the only fossil referred to "Diceratus". Like Hatcher's other "Triceratops" skulls, it was found in eastern Wyoming. Superficially, it resembles that of "Triceratops", but on closer examination, it is definitely odd: there is just a rounded stump where the nasal horn should be and the occipital (brow) horns stand almost vertically. Compared to other "Triceratops" skulls, it is slightly larger than average (2.0 m), but its face is rather short. There also are large holes in the frill, unlike other "Triceratops" skulls known. Some of these may be pathological, others seem to be genetic. Several authors have suggested that "Diceratus" may be directly ancestral to "Triceratops", or perhaps its nearest relative.

Classification

"Diceratus" belonged to the Ceratopsia (the name is Greek for "horned faces", "Keratopia"), a group of herbivorous dinosaurs with parrot-like beaks which thrived in North America and Asia during the Cretaceous Period, which ended roughly 65 million years ago. All ceratopsians became extinct at the end of this era.

pecies

Type:
*"Diceratus hatcheri" (Hatcher "vide" Lull, 1905 [originally "Diceratops"] ). Imperfectly preserved skull.

Diet

"Diceratus", like all ceratopsians, was a herbivore. During the Cretaceous, flowering plants were "geographically limited on the landscape", and so it is likely that this dinosaur fed on the predominant plants of the era: ferns, cycads and conifers. It would have used its sharp ceratopsian beak to bite off the leaves or needles.

References

*Peter Dodson; The Horned Dinosaurs (1996)

*Forster CA (1996): Species resolution in Triceratops: cladistic and morphometric approaches. J.Vert.Paleont. 16(2): 259-270

External links

* [http://www.dinosaurvalley.com/Visiting_Drumheller/Kids_Zone/Groups_of_Dinosaurs/index.php Scroll down for horned dinosaurs]
* [http://www.dinodata.org/index.php?option=com_content&task=view&id=6435&Itemid=67 "Diceratus" (as "Diceratops")] at DinoData
* [http://www.isgs.uiuc.edu/dinos/de_4/5a7951f.htm "Diceratops", from the Dinosaur Encyclopaedia] at Dino Russ' Lair