Grippia
Grippia is a genus of early ichthyopterygian, an extinct group of reptiles that resembled dolphins. Its only species is Grippia longirostris. These ichthyopteygians were small, at 1–1.5 m (3.3–4.9 ft) in length. Fossil remains from Svalbard from the specimen SVT 203 were originally assigned to "G. longirostris" but are now thought to have belonged to a non-ichthyopterygian diapsid related to "Helveticosaurus". Discovery. Fossils have been found along the coasts of Greenland, China, Japan, Norway, and Canada (Sulfur Mountain Formation); of Early Triassic age. No complete skeletons has ever been found. However, well-preserved remains have been found, with  the most notable ones including: 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 on Germany in WWII. "Grippia longirostris" was an entirely marine species and is considered to be the most basal example of Ichthyopterygia. "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 and metacarpals that constitute the forelimbs and the morphology of the skull . Members of this species swam via lateral movements of their tail similar to that of a modern-day eel. 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 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: 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 “hoofs” 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: Classification. Ichthyopterygia are fully aquatic reptiles that evolved from terrestrial tetrapods, 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 – Anisian 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 when compared to older ichthyosaurs and because "Grippia" is the most thoroughly studied out of all basal ichthyosaurs. Below is a cladogram 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, which suggests that these animals practiced an omnivorous 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. All of these results were based on samples that did not include an existing snout, therefore they were highly speculative and paleontologists 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.