Torosaurus ‭(‬Perforated lizard‭)

Short Info

Torosaurus ‭(‬Perforated lizard‭)

Phonetic : Toh-ro-sore-us

Named By : Othniel Charles Marsh‭ ‬-‭ ‬1891

Diet : Herbivore

Size : Estimated 7.5 meters long

Type of Dinosaur : Ceratopsian

Type Species : T.‭ ‬latus‭ (‬type‭)‬

Found in : Canada,‭ ‬Alberta‭ ‬-‭ ‬Scollard Formation,‭ ‬Saskatchewan‭ ‬-‭ ‬Frenchman Formation.‭ ‬USA,‭ ‬Colorado‭ ‬-‭ ‬Laramie Formation,‭ ‬North Dakota‭ ‬-‭ ‬Hell Creek Formation,‭ ‬South Dakota‭ ‬-‭ ‬Hell Creek Formation,‭ ‬Texas‭ ‬-‭ ‬Javelina Formation,‭ ‬Utah‭ ‬-‭ ‬North Horn Formation,‭ ‬Wyoming‭ ‬-‭ ‬Lance Formation

When it Lived : Late Cretaceous, 70-65 million years ago

Torosaurus (“perforated Lizard” refers to the numerous holes within it’s frill) is a genus belonging to herbivorous dinosaurs. They lived in the latter part of the Maastrichtian phase in the Cretaceous period, which was between 65 and 66 million years ago. It could be that species ‘ range could extend up to 69 million years in the past. Fossils were discovered throughout in the Western Interior of North America across the entire Western Interior of North America, from Saskatchewan through the southern part of Texas.


CeratopsianDaniel Hendricks from Appleton, WI, USA, CC BY-SA 2.0, via Wikimedia Commons


Torosaurus was the owner of one of the biggest skulls of any land animal. The skull with frilled teeth grew as high as 2.77 meters (9.1 feet) across. From top to bottom Torosaurus is believed to have been between 8 to 9 meters (26 to 30 feet) long and weighed between eight to 12 tonnes. Torosaurus is distinguished from contemporaneous Triceratops by the frill’s length, which is elongated and has massive openings (fenestrae) as well as long squamosal bone of the frill that have an opening on their upper surfaces and at least five pairs of Hornlets (epoccipitals) at the frill’s back. Torosaurus also did not have the long nose horn that is found in Triceratops prorsus. It instead looked like the older or more basal Triceratops horridus with its shorter nose Horn. The three different species are identified, Torosaurus latus, T. gladius and T. utahensis. T. gladius has been deemed no longer to be a valid species, but it is still a valid one.

As of 2010, the authenticity of Torosaurus was challenged. An examination of fossil bone histology with an examination of frill shapes concluded that Torosaurus may have been the mature version of Triceratops and the bones of the typical Triceratops specimens being still in their embryonic stage and showing signs of initial appearance that was distinctive Torosaurus frills. When the skull was maturing, the frill could have been significantly longer and holes would have formed in the frill. In the years 2011 and 2013, however, research of the exterior features of well-known specimens have claimed that the morphological distinctions between the two genera disqualify their synonymy. The most significant issues are the absence of good transitional forms and the evidence of genuine Torosaurus subadults, and different skull proportions that are not related to maturation and the assumption that the development of holes at the adult stage is not a part of an normal ceratopsian maturation process.

In 1891, just two years after the first naming of Triceratops, a pair ceratopsian skulls with frills elongated with holes were discovered in the southeastern part of Wyoming in Niobrara County according to John Bell Hatcher. Hatcher’s boss, the Paleontologist Prof. Othniel Charles Marsh coined name Torosaurus for them.

Torosaurus is the name that has been used to describe it. Torosaurus is commonly used in the sense of “bull lizard” from the Latin noun taurus or Spanish toro. However, it is more likely , it comes of toro, which is the Greek word toreo (toreo, “to pierce, perforate”). The reference is to fenestrae, or (“window-like”) windows that form the frill’s long elongated form, which were traditionally used to distinguish this frill from that of Triceratops. The confusion about the etymological origins of the name stems due to it being that Marsh did not explicitly explain the origin of the name in his research papers.

There are two Torosaurus types have been identifiedas:

T. latus Marsh, 1891 (type species). Latus is “the wide one” in Latin and refers to frills.

T. utahensis (Gilmore, 1946) Lawson, 1976

Another species was then viewed as being identical in appearance to T. latus

T. gladius Marsh, 1891. Gladius means “sword” in Latin, in reference to the elongated form of the squamosal.

T. latus is based on the holotype YPM 1830, a fragmentary skull. The holotype for T. Gladius was specimen number YPM1831, which was a larger skull. Both fossils were discovered within the Lance Formation, dating from the Maastrichtian. Similar fossils discovered in Wyoming, Montana, South Dakota, North Dakota, Colorado, Utah and Saskatchewan have been identified as Torosaurus. They can be recognized with some certainty are: ANSP 15192, a smaller specimen from South Dakota uncovered by Edwin Harris Colbert in 1944; MPM VP6841 partially skeleton, with skull that is now in Milwaukee the SMM P97.6.1 which is a skull without the snout; as well as two partial skulls of the Hell Creek Formation reported in 2002 MOR 981, which was discovered in 1998, and MOR1122 which was discovered in 2001. Fragmentary remains that may be identified as belonging to the genus have been discovered within areas such as the Big Bend Region of Texas as well as in the San Juan Basin of New Mexico. Paleontologists have discovered the fact that Torosaurus specimens are rare in fossils The samples of Triceratops are more common.

Torosaurus Utahensis was first identified as Arrhinoceratops Utahensis in the work of Charles Whitney Gilmore in 1946 using specimen USNM 15583 frill fragments from Emery County, Utah. In 1976, it was renamed Torosaurus Utahensis by Douglas Lawson. A review conducted by Robert Sullivan et al. in 2005 identified the species as Torosaurus utahensis. It is also a little more advanced that T. latus. In 2008, Rebecca Hunt referred considerable additional material to the species. The research has not yet been published to determine if T. utahensis should be considered to be the first genus of its kind or, as previously suggested by T. latus. It is the maturing stage of a few varieties of Triceratops.

Source: Wikipedia