''Suskityrannus'' (meaning "

coyote The coyote (''Canis latrans''), also known as the American jackal, prairie wolf, or brush wolf, is a species of canis, canine native to North America. It is smaller than its close relative, the Wolf, gray wolf, and slightly smaller than the c ...

tyrant", ''suski'' meaning "coyote" in Zuni) is a genus of small tyrannosauroid theropod from the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the more recent 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 ''cre ...

in southern

Laramidia Laramidia was an island continent that existed during the Late Cretaceous period (99.6–66 Year#SI prefix multipliers, Ma), when the Western Interior Seaway split the continent of North America in two. In the Mesozoic era, Laramidia was an island ...

. It contains a single species, ''Suskityrannus hazelae'', and the type specimen was found in the

Turonian The Turonian is, in the International Commission on Stratigraphy, ICS' geologic timescale, the second age (geology), age in the Late Cretaceous epoch (geology), Epoch, or a stage (stratigraphy), stage in the Upper Cretaceous series (stratigraphy), ...

-age Moreno Hill Formation of the

Zuni Basin The Zuni (Zuñi) River is a tributary of the Little Colorado River in the southwestern United States. It has its origin in Cibola County, New Mexico, in the Zuñi Mountains at the Continental Divide. The river flows off the western slopes of ...

in western

New Mexico New Mexico is a state in the Southwestern United States, Southwestern region of the United States. It is one of the Mountain States of the southern Rocky Mountains, sharing the Four Corners region with Utah, Colorado, and Arizona. It also ...

Discovery and naming

First mentioned as a small

dromaeosaurid Dromaeosauridae () is a family (biology), family of feathered coelurosaurian Theropoda, theropod dinosaurs. They were generally small to medium-sized feathered carnivores that flourished in the Cretaceous period (geology), Period. The name Drom ...

by Wolfe and Kirkland in their description of ''

Zuniceratops ''Zuniceratops'' ('Zuni-horned face') is a genus of ceratopsian dinosaurs that lived during the Turonian stage of the Late Cretaceous in what is now New Mexico, United States. Only a single species is known, ''Zuniceratops christopheri''. Histor ...

'', ''Suskityrannus'' was informally referred to as the "Zuni coelurosaur", "Zuni tyrannosaur", and by the 2011 documentary ''

Planet Dinosaur ''Planet Dinosaur'', is a six-part documentary television series created by Nigel Paterson and Phil Dobree, produced by the BBC, and narrated by John Hurt. It first aired in the United Kingdom in 2011, with VFX studio Jellyfish Pictures as it ...

'' "Zunityrannus" prior to its scientific description. The original fossils were found in 1998 by Robert Denton, a professional geologist from Virginia, and a native Mesa teen

Sterling Nesbitt Sterling Nesbitt (born March 25, 1982, in Mesa, Arizona) is an American paleontologist best known for his work on the origin and early evolutionary patterns of archosaurs. He is currently an associate professor at Virginia Tech in the Departme ...

, who was a museum volunteer that came to a dig with paleontologist Doug Wolfe. In 2019 ''Suskityrannus'' was formally described as a genus of primitive tyrannosauroid.Supplementary Information
/ref> Both the

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

specimen MSM P4754 (partially articulated skull and a few postcranial bones) and the

paratype In zoology and botany, a paratype is a specimen of an organism that helps define what the scientific name of a species and other taxon actually represents, but it is not the holotype (and in botany is also neither an isotype (biology), isotype ...

specimen MSM P6178 (partially articulated and associated remains including a few skull bones and an incomplete postcranial skeleton) are preserved in the collections of the Arizona Museum of Natural History, and they both show the phylogenetically earliest known arctometatarsalian foot in tyrannosauroids.

Description

''Suskityrannus'' is a small tyrannosaur, with the skull of known specimens measuring long, which grew similarly to earlier

tyrannosauroid Tyrannosauroidea (meaning 'tyrant lizard forms') is a superfamily (or clade) of coelurosaurian theropod dinosaurs that includes the family Tyrannosauridae as well as more basal relatives. Tyrannosauroids lived on the Laurasian supercontinen ...

s like '' Guanlong''. The holotype and the paratype belong to young individuals that didn't reach skeletal maturity, but the histological analyses revealed that the bone tissues and vascularization are different from those found in young individuals of large-bodied

tyrannosaurid Tyrannosauridae (or tyrannosaurids, meaning "tyrant lizards") is a family of coelurosaurian theropod dinosaurs that comprises two subfamilies containing up to fifteen genera, including the eponymous ''Tyrannosaurus''. The exact number of genera ...

s during 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. Campa ...

Maastrichtian The Maastrichtian ( ) is, in the International Commission on Stratigraphy (ICS) geologic timescale, the latest age (geology), age (uppermost stage (stratigraphy), stage) of the Late Cretaceous epoch (geology), Epoch or Upper Cretaceous series (s ...

age, so the adults would have been significantly smaller than mature tyrannosaurids.

Classification

''Suskityrannus'' filled the major phylogenetic, morphological and temporal gaps that researchers needed to piece together

evolution. Below is the phylogenetic analysis on the placement of ''Suskityrannus''.

Paleoenvironment

Specimens of ''Suskityrannus'' are known from the Moreno Hill Formation which documents a time of tectonic upheaval, volcanic activities, humid paleoclimate, and North American coastal margin shifts. Other dinosaurs fossils recovered from this formation are ''

'', ''

Nothronychus ''Nothronychus'' (meaning "slothful claw") is a genus of therizinosaurid theropod dinosaurs that lived in North America during the Late Cretaceous period. The type species, ''Nothronychus mckinleyi'', was described by James Kirkland and Dougla ...

'', '' Jeyawati'', and undescribed

ankylosaur Ankylosauria is a group of herbivorous dinosaurs of the clade Ornithischia. It includes the great majority of dinosaurs with armor in the form of bony osteoderms, similar to turtles. Ankylosaurs were bulky quadrupeds, with short, powerful l ...

remains. Three groups of turtle fossils have been reported: a baenid ''Edowa'', a helochelydrid ''

Naomichelys ''Naomichelys'' is an extinct genus of helochelydrid stem turtle known from the Cretaceous (Aptian-Campanian) of North America. It is the only member of the family known to be native to North America. Distribution ''Naomichelys'' is known nume ...

'' and an indeterminate trionychid. Other vertebrate fossils include

crocodyliform Crocodyliformes is a clade of Crurotarsi, crurotarsan archosaurs, the group often traditionally referred to as "crocodilians". They are the first members of Crocodylomorpha to possess many of the features that define later relatives. They are the ...

teeth, amiid teeth and gar scales.

References

{{Taxonbar, from=Q20728010 Tyrannosauroidea Dinosaur genera Turonian dinosaurs Taxa named by Sterling Nesbitt Taxa named by Stephen L. Brusatte Taxa named by James I. Kirkland Fossil taxa described in 2019 Dinosaurs of the United States