''Dynamoterror'' (meaning "powerful terror") is a

monospecific In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispec ...

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

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

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 ...

from

New Mexico ) , population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano) , seat = Santa Fe , LargestCity = Albuquerque , LargestMetro = Tiguex , OfficialLang = None , Languages = English, Spanish ( New Mexican), Navajo, Ke ...

that lived during 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'', ...

(lower

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 ...

stage, 78 Ma) in what is now the upper Allison Member of the

Menefee Formation The Menefee Formation is a lower Campanian geologic formation found in Colorado and New Mexico, United States. Description The Menefee Formation consists of fluvial sandstone, shale, and coal. Based on ammonite biostratigraphy, the age of the Me ...

. The type and only species, ''Dynamoterror dynastes'', is known from a

subadult A juvenile is an individual organism that has not yet reached its adult form, sexual maturity or size. Juveniles can look very different from the adult form, particularly in colour, and may not fill the same niche as the adult form. In many o ...

or adult individual about 9 metres (30 feet) long with an incomplete associated skeleton. It was named in

2018 File:2018 Events Collage.png, From top left, clockwise: The 2018 Winter Olympics opening ceremony in PyeongChang, South Korea; Protests erupt following the Assassination of Jamal Khashoggi; March for Our Lives protests take place across the Unit ...

by Andrew T. McDonald, Douglas G. Wolfe and Alton C. Dooley, Jr. ''Dynamoterror'' was closely related to ''

Teratophoneus ''Teratophoneus'' ("monstrous murderer"; Greek: ''teras'', "monster" and ''phoneus'', "murderer") is a genus of tyrannosaurid dinosaur which lived during the late Cretaceous period (late Campanian age, about 77 to 76 million years ago) in what i ...

'' and ''

Lythronax ''Lythronax'' () is a genus of tyrannosaurid dinosaur that lived in North America around 81.9-81.5 million years ago during the Late Cretaceous period. The only known specimen was discovered in Utah in the Wahweap Formation of the Grand Stairca ...

''.

Discovery

In August 2012, a partial skeleton of a

was discovered, and later collected, from the Lower

Allison Member of the

in the

San Juan Basin The San Juan Basin is a geologic structural basin located near the Four Corners region of the Southwestern United States. The basin covers 7,500 square miles and resides in northwestern New Mexico, southwestern Colorado, and parts of Utah ...

of northwestern

. The remains were found by geology students Brian Watkins and Eric Gutiérrez on an expedition led by Andrew McDonald of the

Western Science Center The Western Science Center (WSC), formerly the Western Center for Archaeology & Paleontology, is a museum located near Diamond Valley Lake in Hemet, California. The WSC is home to a large collection of Native American artifacts and Ice Age fossil ...

, and Douglas Wolfe, the CEO of the Zuni Dinosaur Institute for Geosciences. Subsequent expeditions at the Menefee Formation in 2013 and 2018 did not reveal any additional elements. The specimen was subsequently named and described in 2018 by Andrew T. McDonald, Douglas G. Wolfe and Alton C. Dooley, Jr. 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 sever ...

specimen, UMNH VP 28348, consists of the left and right frontals, fragmentary vertebral centra, fragments of dorsal ribs, right

metacarpal In human anatomy, the metacarpal bones or metacarpus form the intermediate part of the skeletal hand located between the phalanges of the fingers and the carpal bones of the wrist, which forms the connection to the forearm. The metacarpal bones ar ...

II, supraacetabular crest of the right ilium,

phalanx The phalanx ( grc, φάλαγξ; plural phalanxes or phalanges, , ) was a rectangular mass military formation, usually composed entirely of heavy infantry armed with spears, pikes, sarissas, or similar pole weapons. The term is particularly ...

2 of left pedal digit IV, phalanx 4 of left pedal digit IV, and other unidentifiable bone fragments. The holotype specimen is currently housed at the

Natural History Museum of Utah The Natural History Museum of Utah (NHMU) is a museum located in Salt Lake City, Utah, United States. The museum shows exhibits of natural history subjects, with an emphasis on Utah and the Intermountain West. The mission of the museum is to il ...

Salt Lake City Salt Lake City (often shortened to Salt Lake and abbreviated as SLC) is the capital and most populous city of Utah, United States. It is the seat of Salt Lake County, the most populous county in Utah. With a population of 200,133 in 2020, th ...

Utah Utah ( , ) is a state in the Mountain West subregion of the Western United States. Utah is a landlocked U.S. state bordered to its east by Colorado, to its northeast by Wyoming, to its north by Idaho, to its south by Arizona, and to it ...

. The generic name, ''Dynamoterror'', is derived from 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 ...

word "''dynamis''" (power) and the

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

word "''terror''". The specific name, ''dynastes'', is derived from the Latin word "''dynastēs''" (ruler). The binomial name honours “''Dynamosaurus imperiosus''”, a junior synonym of ''

Tyrannosaurus ''Tyrannosaurus'' is a genus of large theropod dinosaur. The species ''Tyrannosaurus rex'' (''rex'' meaning "king" in Latin), often called ''T. rex'' or colloquially ''T-Rex'', is one of the best represented theropods. ''Tyrannosaurus'' live ...

'', as it had been a "childhood favourite" of one of the authors. In 2020, Chan-gyu Yun considered ''Dynamoterror'' a nomen dubium due to the highly fragmentary nature of the holotype specimen and lack of

autapomorphies In phylogenetics, an autapomorphy is a distinctive feature, known as a derived trait, that is unique to a given taxon. That is, it is found only in one taxon, but not found in any others or outgroup taxa, not even those most closely related to t ...

as two of the original autapomorphies are present in other tyrannosaurids. Additionally, the fragmentary nature of the frontal makes it uncertain whether the autapomorphies are even comparable to other tyrannosaurids. In 1993, Adrian P. Hunt and

Spencer G. Lucas Spencer George Lucas is an American paleontologist and stratigrapher, and curator of paleontology at the New Mexico Museum of Natural History and Science. His main areas of study are late Paleozoic, Mesozoic and early Cenozoic vertebrate fossils ...

reported

tooth A tooth ( : teeth) is a hard, calcified structure found in the jaws (or mouths) of many vertebrates and used to break down food. Some animals, particularly carnivores and omnivores, also use teeth to help with capturing or wounding prey, t ...

fragments and a

metatarsal The metatarsal bones, or metatarsus, are a group of five long bones in the foot, located between the tarsal bones of the hind- and mid-foot and the phalanges of the toes. Lacking individual names, the metatarsal bones are numbered from the me ...

of a tyrannosaurid from the Menefee Formation, and in 2006, ''Lewis et al.'' reported another tooth fragment. McDonald ''et al.'' (2018) suggested that, due to the lack of overlapping material, the previously reported tyrannosaurid material could not be referred to ''Dynamoterror''. In 2018, Sebastian G. Dalman and Spencer G. Lucas described five tyrannosaurid specimens from the Menefee Formation: NMMNH P-8313, a right anterior

scapula The scapula (plural scapulae or scapulas), also known as the shoulder blade, is the bone that connects the humerus (upper arm bone) with the clavicle (collar bone). Like their connected bones, the scapulae are paired, with each scapula on eith ...

; NMMNH P-22133, a metatarsal II; NMMNH P-61274, a shaft of an anterior thoracic rib; NMMNH P-71332, a lateral tooth; and NMMNH P-78032, a left

postorbital The ''postorbital'' is one of the bones in vertebrate skulls which forms a portion of the dermal skull roof and, sometimes, a ring about the orbit. Generally, it is located behind the postfrontal and posteriorly to the orbital fenestra. In some ...

Description

Size and distinguishing traits

Based on a specimen of a subadult ''Tyrannosaurus'', LACM 23845, the holotype specimen of ''Dynamoterror'' had a similar body length of 9 metres (30 feet). ''McDonald et al.'' (2018) originally diagnosed ''Dynamoterror'' based on the prefrontonasal and prefrontolacrimal processes being in close proximity to each other, separated only by a shallow notch, and the presence of a subrectangular, concave, laterally-projecting caudal part of the postorbital suture, separated from the rostral part by a deep groove. However, they noted that the second diagnostic trait should be provisional, given the ontogenetic variation observed in the postorbital suture in other tyrannosaurids.

Cranium

The measurements and depth/width

ratio In mathematics, a ratio shows how many times one number contains another. For example, if there are eight oranges and six lemons in a bowl of fruit, then the ratio of oranges to lemons is eight to six (that is, 8:6, which is equivalent to the ...

of the frontals suggests that the holotype specimen of ''Dynamoterror'' represents a subadult or adult individual. The base of the nasal process consists of the medial-most feature on the rostral surface of the frontal. The nasal process projects towards the

rostrum Rostrum may refer to: * Any kind of a platform for a speaker: **dais **pulpit * Rostrum (anatomy), a beak, or anatomical structure resembling a beak, as in the mouthparts of many sucking insects * Rostrum (ship), a form of bow on naval ships * Ros ...

and possesses a deep notch towards the sides of the base. The deep notch marks the posterior-most point of the contact with the nasal. As in ''

'' and ''

'', towards the sides of the deep notch is the conical prefrontonasal process. Towards the sides of the prefrontal process is a shallower notch that marks where the prefrontal exposure is on the skull roof, and towards the side of the shallow notch is the prefrontolacrimal process. The prefrontolacrimal process differs from that of '' Nanuqsaurus'' and ''Teratophoneus'' by its smaller size, but is similar to that of ''Lythronax'', ''

Daspletosaurus ''Daspletosaurus'' ( ; meaning "frightful lizard") is a genus of tyrannosaurid dinosaur that lived in Laramidia between about 79.5 and 74 million years ago, during the Late Cretaceous Period. The genus ''Daspletosaurus'' contains three species ...

'', ''

'' and ''

Tarbosaurus ''Tarbosaurus'' ( ; meaning "alarming lizard") is a genus of tyrannosaurid dinosaur that flourished in Asia about 70 million years ago, at the end of the Late Cretaceous Period, considered to contain a single known species, ''Tarbosaurus ba ...

''. The close proximity of the prefrontonasal and prefrontolacrimal processes, separated by a shallow notch, is a unique trait of ''Dynamoterror''. Towards the sides of the prefrontolacrimal process is a smooth surface that extends towards the back and then begins to curve towards the sides, which marks the medial-most point of the lacrimal suture. Towards the sides of the smooth surface is ventrolateral portion of the lacrimal suture that forms a rostrally facing cup-like structure that is as rostrally concave and ventrolaterally convex as in ''Lythronax'', ''Daspletosaurus'', ''Tyrannosaurus'', ''Tarbosaurus'' and ''Nanuqsaurus''. Dynamoterror_frontals_in_ventral_view

The right frontal's dorsal surface possesses a slight swelling posterior to the nasal, prefrontonasal, and prefrontolacrimal processes. Towards the rear of the swelling, the dorsal surface becomes concave and begins to slope towards the rear and sides to form the frontal portion of the supratemporal fossa. The dorsal surface rises towards the rear and the middle to form the frontal portion of the sagittal crest, which would have been very tall. Such a prominent sagittal crest is also seen in ''Teratophoneus'', ''Lythronax'', ''

Bistahieversor ''Bistahieversor'' (meaning "Bistahi destroyer"), also known as the "Bisti Beast", is a genus of eutyrannosaurian tyrannosauroid dinosaur; the genus contains only a single known species, ''B. sealeyi'', described in 2010, from the Late Cretaceo ...

'' and an unnamed tyrannosaurine from the Aguja Formation of

Texas Texas (, ; Spanish: ''Texas'', ''Tejas'') is a state in the South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2020, it is the second-largest U.S. state by ...

. The tall sagittal crest of ''Dynamoterror'' and other tyrannosaurines differs from that of albertosaurines such as ''

Albertosaurus ''Albertosaurus'' (; meaning "Alberta lizard") is a genus of tyrannosaurid theropod dinosaurs that lived in western North America during the Late Cretaceous Period, about 71 million years ago. The type species, ''A. sarcophagus'', wa ...

'' and ''

Gorgosaurus ''Gorgosaurus'' ( ; ) is a genus of tyrannosaurid theropod dinosaur that lived in western North America during the Late Cretaceous Period (Campanian), between about 76.6 and 75.1 million years ago. Fossil remains have been found in the Ca ...

'' as both have much lower sagittal crests on the frontals. The large supratemporal fossae and tall sagittal crest on the frontals provide an expanded attachment area for large jaw-closing

muscles Skeletal muscles (commonly referred to as muscles) are organs of the vertebrate muscular system and typically are attached by tendons to bones of a skeleton. The muscle cells of skeletal muscles are much longer than in the other types of musc ...

. The rostral region of the ventral surface is covered by an elongated and wide fossa that is defined towards the rostrum by the prefrontal suture, towards the middle by the interfrontal suture, towards the sides by the crista cranii, and towards the rear by the ethmoid scar. The fossae form the rear extent of the olfactory region of the

nasal cavity The nasal cavity is a large, air-filled space above and behind the human nose, nose in the middle of the face. The nasal septum divides the cavity into two cavities, also known as fossae. Each cavity is the continuation of one of the two nostrils. ...

, which would have been lined with a

mucous membrane A mucous membrane or mucosa is a membrane that lines various cavities in the body of an organism and covers the surface of internal organs. It consists of one or more layers of epithelial cells overlying a layer of loose connective tissue. It i ...

in life. The ethmoid scar separates the rostral fossa from the

olfactory bulb The olfactory bulb (Latin: ''bulbus olfactorius'') is a neural structure of the vertebrate forebrain involved in olfaction, the sense of smell. It sends olfactory information to be further processed in the amygdala, the orbitofrontal cortex ( ...

fossa. The orbitosphenoid suture is lined with a set of ridges, bumps, and depressions. The medial surface of the frontal possesses a vertical interfrontal suture that consists of a series of overlapping, V-shaped ridges. A narrow, deep, vertical groove separates the lacrimal and postorbital sutures as in ''Lythronax'', ''Teratophoneus'' and ''Albertosaurus''. The postorbital suture is composed of a rostral part and caudal part. The rostral part possesses an abdominal margin that is convex and projects farther towards the sides than the upper side margin. Towards the underside of the rostral part is the orbit wall. Both the rostral and caudal parts are separated by a deep, inclined groove that opens towards the underside onto the orbital wall. This inclined groove is present on both frontals. The caudal part of the postorbital suture is subrectangular and slightly concave, which is unique to ''Dynamoterror'' but might be subject to ontogenetic variation.

Postcrania

One of the most complete vertebral fragments is known to be part of the centrum of a middle

caudal vertebra The spinal column, a defining synapomorphy shared by nearly all vertebrates,Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristic ...

. As in ''Tyrannosaurus'', the middle caudal centrum exhibits a pronounced

chevron Chevron (often relating to V-shaped patterns) may refer to: Science and technology * Chevron (aerospace), sawtooth patterns on some jet engines * Chevron (anatomy), a bone * '' Eulithis testata'', a moth * Chevron (geology), a fold in rock ...

articulation facet. The articulation facet is offset from the underside margin of the caudal face of the centrum. Based on comparisons of the ilia of ''Teratophoneus'' and ''Tyrannosaurus'', a broadly arched bone fragment was identified as the supraacetabular crest of the right ilium. The underside surface of the right ilium fragment is smooth and gently concave. The supraacetabular crest is very thin at the side margins, but becomes considerably thicker towards the rear and middle, as its upper margin slopes steeply dorsally to merge with the side surface of the blade of the ilium. Based on the right manus of ''Tyrannosaurus'' and the left manus of ''Daspletosaurus'', the right

II was identified. The right metacarpal II is nearly straight and the articular surface nearest to the centre tapers and curves towards its upper side margin. The underside surface of the metacarpal II shaft is flat and becomes wider towards the distal articular surface. The metacarpal II does not have an apparent articulation surface on the side surfaces, while the medial surface is broad and gently concave. The broadness and concave shape of the medial surface of the metacarpal II forms a surface for articulation with the side surfaces of metacarpal I. Pedal digit IV-2 has a proximal articular surface that is subrectangular and divided into two facets by a ridge. Away from the centre of the proximal articular surface, the shaft of pedal digit IV-2 is constricted towards the middle and sides, and towards the upper side and sides. A deep circular pit with a pronounced bump is present on the underside of the medial surface of the shaft. In comparison to pedal digit IV-2, pedal digit IV-4 is smaller in all dimensions. The proximal articular surface of pedal digit IV-4 is similarly divided as pedal digit IV-2. However, the facets of IV-4 are equal in size and are separated by a distinct ridge. The distal articular surface possesses a much deeper trochlea than on IV-2 that separates the medial and lateral

condyle A condyle (;Entry "condyle"
in

Classification

''McDonald et al.'' (2018) originally placed ''Dynamoterror'' within

Tyrannosaurinae The tyrannosaurines (Tyrannosaurinae) is an extinct subfamily of Tyrannosauridae a family of coelurosaurian theropod dinosaurs that consists of at least three tribes and several genera. All fossils of these genera have been found in the Late Cret ...

, in a

polytomy An internal node of a phylogenetic tree is described as a polytomy or multifurcation if (i) it is in a rooted tree and is linked to three or more child subtrees or (ii) it is in an unrooted tree and is attached to four or more branches. A tr ...

with ''Lythronax'', ''Nanuqsaurus'', ''Teratophoneus'', ''Daspletosaurus'', ''Zhuchengtyrannus'', and a clade containing ''Tarbosaurus'' and ''Tyrannosaurus''. The authors suggested that the polytomy was likely caused by the fragmentary nature of the holotype specimen of ''Dynamoterror''. The authors also suggested that the area of origin for the large-bodied tyrannosaurine clade is difficult to determine due to the small amount of

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 supercontinent b ...

specimens known from the Campanian of

Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an are ...

and the lack of diagnostic early tyrannosaurid material from northern

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 A ...

. However, ''Voris et al.'' (2020) later assigned ''Dynamoterror'' within a clade containing ''Teratophoneus'' and ''Lythronax'' only. The authors suggested that this clade likely had different feeding strategies to tyrannosaurids belonging to the clade Daspletosaurini due to the differing skull morphologies. A study by Yun (2020) determined ''Dynamoterror'' to be a nomen dubium due to the holotype's undiagnostic, fragmentary nature. A phylogenetic analysis conducted by Voris et al. (2020) is reproduced below. The results of an earlier analysis by McDonald et al. (2018) are reproduced below.

Paleoecology

Deinosuchus_hatcheri_-_Natural_History_Museum_of_Utah_-_DSC07251

''Dynamoterror'' is known from the upper Allison Member of the Menefee Formation which has been dated to the lower

stage, 78.5 Ma. The Menefee Formation represents a widespread alluvial floodplain and consists of mudstone, siltstone,

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates ...

, and

coal Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other elements, chiefly hydrogen, sulfur, oxygen, and nitrogen. Coal is formed when ...

. The sandstones that compose the Menefee Formation that are fixed within carbonaceous shales of coastal swamp or

lagoon A lagoon is a shallow body of water separated from a larger body of water by a narrow landform, such as reefs, barrier islands, barrier peninsulas, or isthmuses. Lagoons are commonly divided into ''coastal lagoons'' (or ''barrier lagoons'') ...

origin and are thought to have been created by flood tidal deltas that north and east across New Mexico and towards the retreating

Western Interior Seaway The Western Interior Seaway (also called the Cretaceous Seaway, the Niobraran Sea, the North American Inland Sea, and the Western Interior Sea) was a large inland sea that split the continent of North America into two landmasses. The ancient sea ...

. ''Dynamoterror'' was contemporaneous with an indeterminate ankylosaur, the indeterminate

nodosaurid Nodosauridae is a family of ankylosaurian dinosaurs, from the Late Jurassic to the Late Cretaceous period in what is now North America, South America, Europe, and Asia. Description Nodosaurids, like their close relatives the ankylosaurids, we ...

Invictarx ''Invictarx'' (meaning "unconquerable fortress") is a monospecific genus of nodosaurid dinosaur from New Mexico that lived during the Late Cretaceous (lower Campanian, 78.5 Ma) in what is now the upper Allison Member of the Menefee Formation. Th ...

'', an indeterminate hadrosaurid, the

centrosaurine Centrosaurinae (from the Greek, meaning "pointed lizards") is a subfamily of ceratopsid dinosaurs, a group of large quadrupedal ornithischians. Centrosaurine fossil remains are known primarily from the northern region of Laramidia (modern day Al ...

ceratopsid '' Menefeeceratops'', the brachylophosaurin hadrosaurid ''

Ornatops ''Ornatops'' (meaning "ornate face") is a genus of brachylophosaurin saurolophine hadrosaur from the Late Cretaceous Menefee Formation of New Mexico, United States. The genus contains a single species, ''Ornatops incantatus''. Discovery and n ...

'', an indeterminate tyrannosaurid, and a

dromaeosaurid Dromaeosauridae () is a family of feathered theropod dinosaurs. They were generally small to medium-sized feathered carnivores that flourished in the Cretaceous Period. The name Dromaeosauridae means 'running lizards', from Greek ('), meaning ...

similar to ''

Saurornitholestes ''Saurornitholestes'' ("lizard-bird thief") is a genus of carnivorous dromaeosaurid theropod dinosaur from the late Cretaceous of Canada (Alberta) and the United States (Montana, New Mexico, Alabama, North Carolina, and South Carolina). Two spec ...

''. Non-dinosaur taxa contemporaneous with ''Dynamoterror'' include an indeterminate

crocodylia Crocodilia (or Crocodylia, both ) is an order of mostly large, predatory, semiaquatic reptiles, known as crocodilians. They first appeared 95 million years ago in the Late Cretaceous period (Cenomanian stage) and are the closest living ...

n, the alligatoroids '' Brachychampsa'' and ''

Deinosuchus ''Deinosuchus'' () is an extinct genus of alligatoroid crocodilian, related to modern alligators and caimans, that lived 82 to 73 million years ago (Ma), during the late Cretaceous period. The name translates as "terrible crocodile" and i ...

'', an indeterminate baenid

turtle Turtles are an order of reptiles known as Testudines, characterized by a special shell developed mainly from their ribs. Modern turtles are divided into two major groups, the Pleurodira (side necked turtles) and Cryptodira (hidden necked t ...

, an indeterminate turtle, and an indeterminate trionychid turtle.

References

{{Taxonbar, from=Q57194687 Tyrannosaurids Late Cretaceous dinosaurs of North America Monotypic dinosaur genera Cretaceous animals of North America Fossil taxa described in 2018 Nomina dubia

Discovery

Description

Size and distinguishing traits

Cranium

Postcrania

Classification

Paleoecology

See also

References