''Issi'' (meaning "cold" in Greenlandic) is a plateosaurid dinosaur described in 2021 from the

Late Triassic The Late Triassic is the third and final epoch (geology), epoch of the Triassic geologic time scale, Period in the geologic time scale, spanning the time between annum, Ma and Ma (million years ago). It is preceded by the Middle Triassic Epoch a ...

Fleming Fjord Formation The Fleming Fjord Formation, alternatively called the Fleming Fjord Group is an Upper Triassic geological formation in the northeastern coast of Jameson Land, Greenland. It consists of terrestrial sediments and is known for its fossil content. ...

Greenland Greenland is an autonomous territory in the Danish Realm, Kingdom of Denmark. It is by far the largest geographically of three constituent parts of the kingdom; the other two are metropolitan Denmark and the Faroe Islands. Citizens of Greenlan ...

. It contains one species, ''Issi saaneq''; the full

binomial name In taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, altho ...

means "cold bone". Fossils of ''Issi'' were previously assigned to the species ''

Plateosaurus trossingensis ''Plateosaurus'' (probably meaning "broad lizard", often mistranslated as "flat lizard") is a genus of plateosaurid dinosaur that lived during the Late Triassic period, around 214 to 204 million years ago, in what is now Central and Northern Eu ...

'', but new finds allowed for a reassessment of that material that showed that it possessed features thought to be exclusive to

Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...

ian sauropodomorphs such as ''

Unaysaurus ''Unaysaurus'' is a genus of unaysauridae, unaysaurid sauropodomorpha, sauropodomorph herbivore dinosaur. Discovered in southern Brazil, in the geopark of Paleorrota, in 1998, and announced in a press conference on Thursday, December 3, 2004, it ...

'' and ''

Macrocollum ''Macrocollum'' is a genus of unaysauridae, unaysaurid sauropodomorph dinosaur that lived during the Late Triassic period (geology), period (early Norian) in what is now Brazil. It is one of the oldest dinosaurs known. Discovery and naming ''Mac ...

''. This ultimately led to the designation of ''Issi'' as a distinct genus. ''Issi'' is the first non-avian dinosaur described from Greenland.

Discovery

On 27 July 1991, at the east coast of Greenland, on

Jameson Land Jameson Land is a peninsula in eastern Greenland. Geography Jameson Land is bounded to the southwest by Scoresby Sound (the world's largest fjord), to the northwest by the Stauning Alps, to the north by Scoresby Land, to the northeast by the F ...

, in the Iron Cake site on the northern slope of the MacKnight Bjerg near the Flemingfjord, by William W. Amaral, William R. Downs, Stephen M. Gatesy, Neil H. Shubin and Niels Bonde, members of a team from

Harvard University Harvard University is a Private university, private Ivy League research university in Cambridge, Massachusetts, United States. Founded in 1636 and named for its first benefactor, the History of the Puritans in North America, Puritan clergyma ...

headed by

Farish Jenkins Farish Alston Jenkins (May 19, 1940 – November 11, 2012) was a professor at Harvard University who studied and taught paleontology. His discoveries included a transitional creature with characteristics of both fish and land animals, '' Tiktaalik ...

, a skull was uncovered of a basal sauropodomorph. In 1994, the find was reported in the scientific literature and referred to ''Plateosaurus engelhardti''. In 2018, the correctness of this assignment was doubted. In 1995, a skull was discovered of a smaller juvenile animal. In 2012, an additional three skeletons were excavated. After a

CAT-scan A computed tomography scan (CT scan), formerly called computed axial tomography scan (CAT scan), is a medical imaging technique used to obtain detailed internal images of the body. The personnel that perform CT scans are called radiographers or ...

by Marco Marzola, Filippo Rotatori and Alexandra Fernandes of the first two finds, followed by a digital deformation, it was concluded in a

master's thesis A thesis (: theses), or dissertation (abbreviated diss.), is a document submitted in support of candidature for an academic degree or professional qualification presenting the author's research and findings.International Standard ISO 7144: D ...

by Victor Beccari that they represented a

taxon In biology, a taxon (back-formation from ''taxonomy''; : taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular name and ...

new to science.Campo, Victor Beccari Dieguez, 2021, ''The sauropodomorph dinosaurs from the Late Triassic (Norian) of Jameson Land, East Greenland'', Master's Thesis NOVA School of Science and Technology In 2021, the

type species In International_Code_of_Zoological_Nomenclature, 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 spe ...

''Issi saaneq'' was named and described by Victor Beccari Dieguez Campo,

Octávio Mateus Octávio Mateus (born 1975) is a Portugal, Portuguese dinosaur paleontologist and biologist Professor of Paleontology at the Faculdade de Ciências e Tecnologia da NOVA University Lisbon, Universidade Nova de Lisboa. He graduated in University of � ...

, Oliver Wings, Jesper Milàn and Lars Bjørn Clemmensen. The generic name means "cold" and the

specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...

"bone", both in Kalaallisut, a reference to the fact that it was the most northern basal sauropodomorph ever discovered. 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 ...

, NHMD 164741, was found in a layer of the Malmros Klint Formation of the Fleming Fjord Group, dating from the middle

Norian The Norian is a division of the Triassic geological period, Period. It has the rank of an age (geology), age (geochronology) or stage (stratigraphy), stage (chronostratigraphy). It lasted from ~227.3 to Mya (unit), million years ago. It was prec ...

. It consists of a relatively complete skull with lower jaws and teeth. It is the exemplar found in 1994. It mainly lacks parts of the right side and the rear side of the right lower side. The skull is partly articulated. It represents a later stage juvenile or subadult individual. 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 ...

is specimen NHMD 164758, found in 1995 in the same layer. It consists of a skull with lower jaws, more complete than the holotype. It only lacks the rear right corner of the skull roof. It represents a medium stage juvenile, about a third shorter than the holotype. Both types are part of the collection of the

Natural History Museum of Denmark The Natural History Museum of Denmark () is a natural history museum located in Copenhagen, Denmark. It is affiliated with the University of Copenhagen The museum became an organizational entity in 2004 with the merger of Copenhagen's Zoological ...

. The three skeletons discovered in 2012, specimens NHMD 164734, GM.V 2013‐683 and NHMD 164775, were in 2021 not formally referred or described; the latter skeleton had even not been fully prepared yet. This limited the description to the head.

Description

The skull of the holotype of ''Issi'' has a preserved length of 243.7 millimetres. The describing authors in 2021 indicated some distinguishing traits. Four of these are

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 ...

, unique derived characters. The base of the main body of the premaxilla is pierced by a small foramen. The

squamosal bone The squamosal is a skull bone found in most reptiles, amphibians, and birds. In fishes, it is also called the pterotic bone. In most tetrapods, the squamosal and quadratojugal bones form the cheek series of the skull. The bone forms an ancestral ...

has a rear branch that is long horizontally. The

quadrate bone The quadrate bone is a skull bone in most tetrapods, including amphibians, sauropsids ( reptiles, birds), and early synapsids. In most tetrapods, the quadrate bone connects to the quadratojugal and squamosal bones in the skull, and forms up ...

is rather tall relative to the height of the snout. The

articular bone The articular bone is part of the lower jaw of most vertebrates, including most jawed fish, amphibians, birds and various kinds of reptiles, as well as ancestral mammals. Anatomy In most vertebrates, the articular bone is connected to two othe ...

has a well-developed process at the rear upper side, with a rectangular profile in side view. Furthermore, a unique combination is present of six traits in themselves not unique. The depression around the bony nostril is weakly developed. The foramen below the nostril is small. The front edge of the nostril is positioned in front of the horizontal midpoint of the premaxilla. The horizontal length of the

antorbital fenestra An antorbital fenestra (plural: fenestrae) is an opening in the skull that is in front of the eye sockets. This skull character is largely associated with Archosauriformes, archosauriforms, first appearing during the Triassic Period. Among Extant ...

is less than the length of the eye socket. The depression around the antorbital fenestra ends in front of the descending branch of the

lacrimal bone The lacrimal bones are two small and fragile bones of the facial skeleton; they are roughly the size of the little fingernail and situated at the front part of the medial wall of the orbit. They each have two surfaces and four borders. Several bon ...

. The ectopterygoid the branch connecting to the

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

is strongly curved.

Classification

The holotype and paratype, NHMD 164741 and NHMD 164758, were initially considered to represent some species of ''Plateosaurus'', likely ''P. engelhardti'' or ''P. trossingensis''. However, in 2021 they were reinterpreted as belonging to a distinct genus, the

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 ...

of ''Plateosaurus''. The results of the describers'

phylogenetic analyses In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as Computational phylogenetics, phylogenetic inference. It infers the relationship among organ ...

are shown in the

cladogram A cladogram (from Greek language, Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an Phylogenetic tree, evolutionary tree because it does not s ...

below:

References

{{Taxonbar, from=Q109380018 Sauropodomorpha Dinosaur genera Norian dinosaurs Taxa named by Octávio Mateus Fossil taxa described in 2021 Dinosaurs of North America