Grippia

Fossils have been found along the coasts of Greenland, China, Japan, Norway, and Canada (Sulfur Mountain Formation); of Early Triassic age. No complete skeletons have 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 fossil; however, it was lost during World War II and presumably destroyed.[4]
• Previously, the Vega Phroso Siltstone Member of the Sulphur Mountain Formation in British Columbia. This specimen consists of a well preserved forelimb, several ribs, and a single centrum.[5] However, it has now been reclassified as Gulosaurus helmi, a close relative of Grippia.[5]

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.

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.

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.[8]

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.[3]

Below is a cladogram which represents Ichthyopterygia showing how Grippia diverged early in the lineage.[9]

G. longirostris were well adapted to an aquatic lifestyle during early – mid Triassic.[7] 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.[8] 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.[2] 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.

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.[9]

• List of ichthyosaurs
• Timeline of ichthyosaur research

• Grippia - A Triassic Ichthyosaur (Backup at Wayback Machine)
• Grippia Longirostris Wilman 1929