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Grippia is a genus of early , an extinct group of reptiles that resembled dolphins. Its Monotypic taxon is Grippia longirostris. It was a relatively small ichthyopterygian, measuring around long. 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- diapsid related to Helveticosaurus.
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.
Montani constructed several diagrams based on his analysis, which depict the skull of G. longirostris as:
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 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.
The exact diet of these animals is highly debated. Analysis of Teeth 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.
Classification
Ichthyopterygia are fully aquatic reptiles that evolved from terrestrial , 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.
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.
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.
See also
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