''Grippia'' is a

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 ...

of early

ichthyopterygia Ichthyopterygia ("fish flippers") was a designation introduced by Sir Richard Owen in 1840 to designate the Jurassic ichthyosaurs that were known at the time, but the term is now used more often for both true Ichthyosauria and their more primitiv ...

n, an extinct group of reptiles that resembled

dolphins A dolphin is an aquatic mammal within the infraorder Cetacea. Dolphin species belong to the families Delphinidae (the oceanic dolphins), Platanistidae (the Indian river dolphins), Iniidae (the New World river dolphins), Pontoporiidae (t ...

. Its only species is ''Grippia longirostris''. It was a relatively small ichthyopterygian, measuring long and weighing .

Fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

remains from Svalbard from the specimen SVT 203 were originally assigned to ''G. longirostris'' but are now thought to have belonged to a non-

diapsid Diapsids ("two arches") are a clade of sauropsids, distinguished from more primitive eureptiles by the presence of two holes, known as temporal fenestrae, in each side of their skulls. The group first appeared about three hundred million years a ...

related to '' Helveticosaurus''.

Discovery

Fossils have been found along the coasts of

Greenland Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is an island country in North America that is part of the Kingdom of Denmark. It is located between the Arctic and Atlantic oceans, east of the Canadian Arctic Archipelago. Greenland i ...

, China, Japan,

Norway Norway, officially the Kingdom of Norway, is a Nordic country in Northern Europe, the mainland territory of which comprises the western and northernmost portion of the Scandinavian Peninsula. The remote Arctic island of Jan Mayen and the ...

, and

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...

(

Sulfur Mountain Formation The Sulphur Mountain Formation is a geologic formation of Early to Middle Triassic age. It is present on the western edge of the Western Canada Sedimentary Basin in the foothills and Rocky Mountains of western Alberta and northeastern British Col ...

); of

Early Triassic The Early Triassic is the first of three epochs of the Triassic Period of the geologic timescale. It spans the time between Ma and Ma (million years ago). Rocks from this epoch are collectively known as the Lower Triassic Series, which is a un ...

age. No complete skeletons has ever been found. However, well-preserved remains have been found, with the most notable ones including: *The Marine Ironstone found in Agardh Bay Norway. This specimen consists of a partial

skull The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, th ...

fossil; however, it was lost during

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposing ...

and presumably destroyed. *Previously, the Vega Phroso Siltstone Member of the Sulphur Mountain Formation in

British Columbia British Columbia (commonly abbreviated as BC) is the westernmost province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include rocky coastlines, sandy beaches, ...

. This specimen consists of a well preserved forelimb, several

ribs The rib cage, as an enclosure that comprises the ribs, vertebral column and sternum in the thorax of most vertebrates, protects vital organs such as the heart, lungs and great vessels. The sternum, together known as the thoracic cage, is a semi- ...

, and a single

centrum (Latin for ''center'') may refer to: Places In Greenland * Nuuk Centrum, a district of Nuuk, Greenland * Centrum Lake, Greenland In the Netherlands * Amsterdam-Centrum, the inner-most borough of Amsterdam, Netherlands * Rotterdam Centrum, a borou ...

. However, it has now been reclassified as '' Gulosaurus helmi,'' a close relative of ''Grippia.'' The first ''G. longirostris'' skull was found in 1929. Many palaeontologists believe it was the most complete specimen ever found, however, it was destroyed in a

bombing raid Strategic bombing is a military strategy used in total war with the goal of defeating the enemy by destroying its morale, its economic ability to produce and transport materiel to the theatres of military operations, or both. It is a systemati ...

Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwe ...

in WWII. ''Grippia longirostris'' was an entirely marine

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

and is considered to be the most basal example of

Ichthyopterygia Ichthyopterygia ("fish flippers") was a designation introduced by Sir Richard Owen in 1840 to designate the Jurassic ichthyosaurs that were known at the time, but the term is now used more often for both true Ichthyosauria and their more primitiv ...

. ''G. longirostris'' measured in at 1-1.5m (3.3-4.9 feet) in length making it the smallest species within the superorder Ichthyopterygia. Other definitive features of ''G. longirostris'' include the arrangement of

carpals The carpal bones are the eight small bones that make up the wrist (or carpus) that connects the hand to the forearm. The term "carpus" is derived from the Latin carpus and the Greek καρπός (karpós), meaning "wrist". In human anatomy, th ...

and

metacarpals 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 ...

that constitute the

forelimbs A forelimb or front limb is one of the paired articulated appendages (limbs) attached on the cranial (anterior) end of a terrestrial tetrapod vertebrate's torso. With reference to quadrupeds, the term foreleg or front leg is often used instead. ...

and the

morphology Morphology, from the Greek and meaning "study of shape", may refer to: Disciplines * Morphology (archaeology), study of the shapes or forms of artifacts * Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies ...

of the

. Members of this species swam via lateral movements of their tail similar to that of a modern-day

eel Eels are ray-finned fish belonging to the order Anguilliformes (), which consists of eight suborders, 19 families, 111 genera, and about 800 species. Eels undergo considerable development from the early larval stage to the eventual adult stage ...

Description

The skeletal structure of ''G. longirostris'' has been documented, especially the forelimbs by Ryosuke Motani in 1998 and the skull by Ryosuke Motani in 2000. These studies involved modern documentation and research of previously discovered specimens.

Skull

Several different ''Grippia'' skulls have been analyzed since 1929. Seven well known

cranial Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position pro ...

specimens belonging to ''G. longirostris'' were reanalyzed, in order to construct detailed descriptions of each specimen and to form a coherent compilation to represent the genus as a whole. An important thing to note is how no skull has been found to have a snout; therefore any descriptions of the snout are speculative. Montani constructed several diagrams based on his analysis, which depict the skull of ''G. longirostris'' as: *Having a narrow shape. *Possessing

orbits In celestial mechanics, an orbit is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such as a p ...

that are larger than the upper

temporal fenestra An infratemporal fenestra, also called the lateral temporal fenestra or simply temporal fenestra, is an opening in the skull behind the orbit in some animals. It is ventrally bordered by a zygomatic arch. An opening in front of the eye sockets ...

. *The

quadratojugal The quadratojugal is a skull bone present in many vertebrates, including some living reptiles and amphibians. Anatomy and function In animals with a quadratojugal bone, it is typically found connected to the jugal (cheek) bone from the front and ...

does not enter the upper temporal fenestra. *The anterior margin of the external

naris A nostril (or naris , plural ''nares'' ) is either of the two orifices of the nose. They enable the entry and exit of air and other gasses through the nasal cavities. In birds and mammals, they contain branched bones or cartilages called turbi ...

is formed by the

premaxilla The premaxilla (or praemaxilla) is one of a pair of small cranial bones at the very tip of the upper jaw of many animals, usually, but not always, bearing teeth. In humans, they are fused with the maxilla. The "premaxilla" of therian mammal has ...

. *The postfrontal have a posterior process that overlaps the bone of the large

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 ...

, similar to the skulls of other basal ichthyosaurs.

Forelimbs

The forelimbs of ''G. longirostris'' are characteristic of the species. Descriptions created by Wiman in 1933 originally depicted ''G. longirostris'' as having very primitive forelimbs that were not yet completely specialized for aquatic life. These descriptions involved the presence of “

hoof The hoof (plural: hooves) is the tip of a toe of an ungulate mammal, which is covered and strengthened with a thick and horny keratin covering. Artiodactyls are even-toed ungulates, species whose feet have an even number of digits, yet the rum ...

s” at the tips of each digit, this observation has since been discredited. The most recent descriptions of the forelimbs were performed in 1998 by Motani. This analysis focused on one specimen that was nearly complete, although it was determined to be missing several distal segments of the phalanges. This study revealed: *''Grippia'' possesses pentadactyl limbs. *The humerus and phalanges are well developed. *It possessed an articular

radius In classical geometry, a radius ( : radii) of a circle or sphere is any of the line segments from its center to its perimeter, and in more modern usage, it is also their length. The name comes from the latin ''radius'', meaning ray but also the ...

. *The

ulna The ulna (''pl''. ulnae or ulnas) is a long bone found in the forearm that stretches from the elbow to the smallest finger, and when in anatomical position, is found on the medial side of the forearm. That is, the ulna is on the same side of t ...

and radius extend in a wide fan shape. *The first four proximal and distal carpals aid in separating the metacarpals. *The second to fourth metacarpals and phalanges are similar to that of other amniotes, however they are flattened. *The first and fifth metacarpals and phalanges are lunate in appearance and concave inwards towards the interior carpals. *The phalanges of the distal end of the fourth and fifth digits appear to take more of an oval shape.

Classification

Ichthyopterygia are fully aquatic reptiles that evolved from

terrestrial Terrestrial refers to things related to land or the planet Earth. Terrestrial may also refer to: * Terrestrial animal, an animal that lives on land opposed to living in water, or sometimes an animal that lives on or near the ground, as opposed to ...

tetrapod Tetrapods (; ) are four-limbed vertebrate animals constituting the superclass Tetrapoda (). It includes extant and extinct amphibians, sauropsids ( reptiles, including dinosaurs and therefore birds) and synapsids ( pelycosaurs, extinct t ...

s, with no transitional lineage being discovered so far. ''Grippia'' is one of earliest examples of the superorder Ichthyopterygia and is fully adapted to aquatic life. ''Grippia'' are believed to have lived from 250 to 235 Ma during the

Olenekian In the geologic timescale, the Olenekian is an age in the Early Triassic epoch; in chronostratigraphy, it is a stage in the Lower Triassic series. It spans the time between Ma and Ma (million years ago). The Olenekian is sometimes divided i ...

–

Anisian In the geologic timescale, the Anisian is the lower stage or earliest age of the Middle Triassic series or epoch and lasted from million years ago until million years ago. The Anisian Age succeeds the Olenekian Age (part of the Lower Triassic ...

of the early to mid-Triassic. ''Grippia'' are considered to be basal ichthyosaurs along with several other early genera, with ''Grippia'' being the most basal of all of them. This is due to its primitive

anatomy Anatomy () is the branch of biology concerned with the study of the structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old science, having it ...

when compared to older ichthyosaurs and because ''Grippia'' is the most thoroughly studied out of all basal ichthyosaurs. Below is a

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

which represents Ichthyopterygia showing how ''Grippia'' diverged early in the lineage.

Paleobiology

''G. longirostris'' were well adapted to an aquatic lifestyle during early – mid Triassic. They inhabited equatorial to equatorial shallow coastal seas. This paleohabitat was based upon how areas where fossils are found were at equatorial latitudes during the early Triassic when these animals lived. The exact diet of these animals is highly debated. Analysis of dental remains belonging to ''G. Longirostris'' has shown blunt posterior teeth and replacement

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

, which suggests that these animals practiced an

omnivorous An omnivore () is an animal that has the ability to eat and survive on both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize the nut ...

feeding style. This evidence is contradictory when cross examined against previous work done in the thirties and eighties, which theorized that ''G. Longirostris'' practiced a diet specialized in mollusca and small

fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of ...

. All of these results were based on samples that did not include an existing snout, therefore they were highly speculative and

paleontologists Paleontology (), also spelled palaeontology or palæontology, is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene epoch (roughly 11,700 years before present). It includes the study of foss ...

will not know what these animals ate until a full skull is found.

Paleoecology

It is hypothesised that ''Grippia'' became extinct because it was outcompeted by more advanced ichthyosaurs. This limited the amount of food that ''Grippia'' could secure, eventually leading it to its extinction around 235 Ma.

References

External links

Grippia - A Triassic Ichthyosaur (Backup at Wayback Machine)Grippia Longirostris Wilman 1929
{{Taxonbar, from1=Q18578320, from2=Q1014860 Triassic ichthyopterygians Early Triassic reptiles of Asia Triassic reptiles of North America Anisian life Ichthyosauromorph genera