''Sierraceratops'' (meaning " Sierra horned face") is a genus of chasmosaurine

ceratopsia Ceratopsia or Ceratopia ( or ; Greek: "horned faces") is a group of herbivorous, beaked dinosaurs that thrived in what are now North America, Europe, and Asia, during the Cretaceous Period, although ancestral forms lived earlier, in the Jurassi ...

n from the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', ...

Hall Lake Formation of

New Mexico ) , population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano) , seat = Santa Fe, New Mexico, Santa Fe , LargestCity = Albuquerque, New Mexico, Albuquerque , LargestMetro = Albuquerque metropolitan area, Tiguex , Offi ...

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., federal district, five ma ...

. The genus contains a single species, ''Sierraceratops turneri'', known from a partial skeleton discovered in 1997.

Discovery

In 1997, geologist Gregory H. Mack discovered fossils of a large horned dinosaur on the Armendaris ranch of

Ted Turner Robert Edward "Ted" Turner III (born November 19, 1938) is an American entrepreneur, television producer, media proprietor, and philanthropist. He founded the Cable News Network (CNN), the first 24-hour cable news channel. In addition, he ...

, founder of CNN, near

Truth or Consequences ''Truth or Consequences'' is an American game show originally hosted on NBC radio by Ralph Edwards (1940–1957) and later on television by Edwards (1950–1954), Jack Bailey (1954–1956), Bob Barker (1956–1975), Steve Dunne (1957–1958), ...

in Sierra County,

. They had been exposed on the surface by erosion. A team of the Natural History Museum of New Mexico subsequently uncovered more bones with the cooperation of the ranch manager, Tom Wadell. In 1998, the discovery was reported in the scientific literature and referred to '' Torosaurus latus''.Lucas, S.G.; Mark, G.H. & Estep, J.W. 1998. "The ceratopsian ''Torosaurus'' from the Upper Cretaceous McRae Formation, Sierra County, New Mexico" In: ''New Mexico Geological Society Guidebook, 49th Field Conference, Las Cruces County Il.'' p. 223-227 More fossils were collected in 2014, 2015, and 2016. They were first prepared by volunteers and later by Sebastian Dalman. In 2021, the

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen( ...

''Sierraceratops turneri'' was named and described by Sebastian G. Dalman, Spencer G. Lucas, Steven E. Jasinski, and Nicholas R. Longrich; the final article version was published in 2022. The generic name combines a reference to Sierra County with the

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

''keras'', "horn", and ''ops'', "face", a common suffix in ceratopsian names. The specific name honours Turner. The

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of seve ...

, NMMNH P-76870, was found in a layer of the Hall Lake Formation, dating from the

Campanian The Campanian is the fifth of six ages of the Late Cretaceous Epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campani ...

Maastrichtian The Maastrichtian () is, in the ICS geologic timescale, the latest age (uppermost stage) of the Late Cretaceous Epoch or Upper Cretaceous Series, the Cretaceous Period or System, and of the Mesozoic Era or Erathem. It spanned the interv ...

, about seventy-two million years old. It consists of a partial skeleton with skull. It preserves a left premaxilla, a jugal bone with epijugal, a right postorbital horn core, a quadrate, a quadratojugal, the interparietal bar, a squamosal, a pterygoid, a rear left dentary, two neck vertebrae, two back vertebrae, sacral vertebrae, two ribs, a shoulder blade connected to a coracoid, an ulna, a hand claw and an ilium. About 16% of the skeleton has been preserved. It was disarticulated but the various elements were found in close association in a natural position. The fossils are part of the collection of the New Mexico Museum of Natural History & Science.

Description

Sierraceratops silhouette by Nick Longrich

''Sierraceratops'' was a medium-sized horned

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 ...

. The skull was a little less than long and the animal measured around in length. Compared to other chasmosaurs, it has short but massive brow horns that are relatively short and robust and a long cheek horn on the

jugal The jugal is a skull bone found in most reptiles, amphibians and birds. In mammals, the jugal is often called the malar or zygomatic. It is connected to the quadratojugal and maxilla, as well as other bones, which may vary by species. Anat ...

. The frill was relatively long and had large holes, the parietal

fenestra A fenestra (fenestration; plural fenestrae or fenestrations) is any small opening or pore, commonly used as a term in the biological sciences. It is the Latin word for "window", and is used in various fields to describe a pore in an anatomical ...

e, separated by an oval-shaped midline bar.

Classification

''Sierraceratops'' was originally referred to the genus '' Torosaurus'', based in part on the assumption that the fossils dated to the Late

. Closer study later revealed that the animal was distinct from ''Torosaurus''; ''Torosaurus'' has a flat midline bar of the parietal, while that of ''Sierraceratops'' is oval. Furthermore, radiometric dates suggest that the animal is significantly older than ''Torosaurus'', dating to the latest

or early Maastrichtian, rather than the late Maastrichtian. Phylogenetic analysis by Dalman ''et al.'' recovered ''Sierraceratops'' as a

sister species In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and ...

to '' Bravoceratops'' and '' Coahuilaceratops'', part of a group

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found els ...

to the southwestern United States and Mexico. This further proves that there was a high level of endemism in southern

Laramidia Laramidia was an island continent that existed during the Late Cretaceous period (99.6–66 Ma), when the Western Interior Seaway split the continent of North America in two. In the Mesozoic era, Laramidia was an island land mass separated from ...

during the latest

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...

References

{{Marginocephalia, T. Chasmosaurines Fossil taxa described in 2021 Ornithischian genera Late Cretaceous dinosaurs of North America